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| -rw-r--r-- | docs/html/guide/components/index.jd | 4 | ||||
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| -rw-r--r-- | docs/html/guide/components/services.jd | 54 |
5 files changed, 2818 insertions, 1128 deletions
diff --git a/docs/html/guide/components/fundamentals.jd b/docs/html/guide/components/fundamentals.jd index ce50022..fd1a7a8 100644 --- a/docs/html/guide/components/fundamentals.jd +++ b/docs/html/guide/components/fundamentals.jd @@ -4,24 +4,9 @@ page.title=Application Fundamentals <div id="qv-wrapper"> <div id="qv"> -<h2>Quickview</h2> -<ul> - <li>Android applications are composed of one or more application components (activities, -services, content providers, and broadcast receivers)</li> - <li>Each component performs a different role in the overall application behavior, and each -one can be activated individually (even by other applications)</li> - <li>The manifest file must declare all components in the application and should also declare -all application requirements, such as the minimum version of Android required and any hardware -configurations required</li> - <li>Non-code application resources (images, strings, layout files, etc.) should include -alternatives for different device configurations (such as different strings for different -languages and different layouts for different screen sizes)</li> -</ul> - - <h2>In this document</h2> <ol> -<li><a href="#Components">Application Components</a> +<li><a href="#Components">App Components</a> <ol> <li><a href="#ActivatingComponents">Activating components</a></li> </ol> @@ -29,98 +14,91 @@ languages and different layouts for different screen sizes)</li> <li><a href="#Manifest">The Manifest File</a> <ol> <li><a href="#DeclaringComponents">Declaring components</a></li> - <li><a href="#DeclaringRequirements">Declaring application requirements</a></li> + <li><a href="#DeclaringRequirements">Declaring app requirements</a></li> </ol> </li> -<li><a href="#Resources">Application Resources</a></li> +<li><a href="#Resources">App Resources</a></li> </ol> </div> </div> -<p>Android applications are written in the Java programming language. The Android SDK tools compile -the code—along with any data and resource files—into an <i>Android package</i>, an -archive file with an {@code .apk} suffix. All the code in a single {@code .apk} file is considered -to be one application and is the file that Android-powered devices use to install the -application.</p> +<p>Android apps are written in the Java programming language. The Android SDK tools compile +your code—along with any data and resource files—into an APK: an <i>Android package</i>, +which is an archive file with an {@code .apk} suffix. One APK file contains all the contents +of an Android app and is the file that Android-powered devices use to install the app.</p> -<p>Once installed on a device, each Android application lives in its own security sandbox: </p> +<p>Once installed on a device, each Android app lives in its own security sandbox: </p> <ul> - <li>The Android operating system is a multi-user Linux system in which each application is a + <li>The Android operating system is a multi-user Linux system in which each app is a different user.</li> -<li>By default, the system assigns each application a unique Linux user ID (the ID is used only by -the system and is unknown to the application). The system sets permissions for all the files in an -application so that only the user ID assigned to that application can access them. </li> +<li>By default, the system assigns each app a unique Linux user ID (the ID is used only by +the system and is unknown to the app). The system sets permissions for all the files in an +app so that only the user ID assigned to that app can access them. </li> -<li>Each process has its own virtual machine (VM), so an application's code runs in isolation from -other applications.</li> +<li>Each process has its own virtual machine (VM), so an app's code runs in isolation from +other apps.</li> -<li>By default, every application runs in its own Linux process. Android starts the process when any -of the application's components need to be executed, then shuts down the process when it's no longer -needed or when the system must recover memory for other applications.</li> +<li>By default, every app runs in its own Linux process. Android starts the process when any +of the app's components need to be executed, then shuts down the process when it's no longer +needed or when the system must recover memory for other apps.</li> </ul> <p>In this way, the Android system implements the <em>principle of least privilege</em>. That is, -each application, by default, has access only to the components that it requires to do its work and -no more. This creates a very secure environment in which an application cannot access parts of +each app, by default, has access only to the components that it requires to do its work and +no more. This creates a very secure environment in which an app cannot access parts of the system for which it is not given permission.</p> -<p>However, there are ways for an application to share data with other applications and for an -application to access system services:</p> +<p>However, there are ways for an app to share data with other apps and for an +app to access system services:</p> <ul> - <li>It's possible to arrange for two applications to share the same Linux user ID, in which case -they are able to access each other's files. To conserve system resources, applications with the + <li>It's possible to arrange for two apps to share the same Linux user ID, in which case +they are able to access each other's files. To conserve system resources, apps with the same user ID can also arrange to run in the same Linux process and share the same VM (the -applications must also be signed with the same certificate).</li> - <li>An application can request permission to access device data such as the user's +apps must also be signed with the same certificate).</li> + <li>An app can request permission to access device data such as the user's contacts, SMS messages, the mountable storage (SD card), camera, Bluetooth, and more. All -application permissions must be granted by the user at install time.</li> +app permissions must be granted by the user at install time.</li> </ul> -<p>That covers the basics regarding how an Android application exists within the system. The rest of +<p>That covers the basics regarding how an Android app exists within the system. The rest of this document introduces you to:</p> <ul> - <li>The core framework components that define your application.</li> + <li>The core framework components that define your app.</li> <li>The manifest file in which you declare components and required device features for your -application.</li> - <li>Resources that are separate from the application code and allow your application to +app.</li> + <li>Resources that are separate from the app code and allow your app to gracefully optimize its behavior for a variety of device configurations.</li> </ul> -<!-- -<p class="note"><strong>Tip:</strong> If you're new to Android development, we suggest that you -follow the Beginner's Path link at the bottom of this page. For each document in the Application -Fundamentals, the Beginner's Path points you to the document we suggest you read next, in order -to get up to speed on the core Android concepts.</p> ---> -<h2 id="Components">Application Components</h2> +<h2 id="Components">App Components</h2> -<p>Application components are the essential building blocks of an Android application. Each -component is a different point through which the system can enter your application. Not all +<p>App components are the essential building blocks of an Android app. Each +component is a different point through which the system can enter your app. Not all components are actual entry points for the user and some depend on each other, but each one exists as its own entity and plays a specific role—each one is a unique building block that -helps define your application's overall behavior.</p> +helps define your app's overall behavior.</p> -<p>There are four different types of application components. Each type serves a distinct purpose +<p>There are four different types of app components. Each type serves a distinct purpose and has a distinct lifecycle that defines how the component is created and destroyed.</p> -<p>Here are the four types of application components:</p> +<p>Here are the four types of app components:</p> <dl> <dt><b>Activities</b></dt> <dd>An <i>activity</i> represents a single screen with a user interface. For example, -an email application might have one activity that shows a list of new +an email app might have one activity that shows a list of new emails, another activity to compose an email, and another activity for reading emails. Although -the activities work together to form a cohesive user experience in the email application, each one -is independent of the others. As such, a different application can start any one of these -activities (if the email application allows it). For example, a camera application can start the -activity in the email application that composes new mail, in order for the user to share a picture. +the activities work together to form a cohesive user experience in the email app, each one +is independent of the others. As such, a different app can start any one of these +activities (if the email app allows it). For example, a camera app can start the +activity in the email app that composes new mail, in order for the user to share a picture. <p>An activity is implemented as a subclass of {@link android.app.Activity} and you can learn more about it in the <a href="{@docRoot}guide/components/activities.html">Activities</a> @@ -133,7 +111,7 @@ developer guide.</p> <dd>A <i>service</i> is a component that runs in the background to perform long-running operations or to perform work for remote processes. A service does not provide a user interface. For example, a service might play music in the background while -the user is in a different application, or it might fetch data over the network without +the user is in a different app, or it might fetch data over the network without blocking user interaction with an activity. Another component, such as an activity, can start the service and let it run or bind to it in order to interact with it. @@ -145,21 +123,21 @@ guide.</p> <dt><b>Content providers</b></dt> -<dd>A <i>content provider</i> manages a shared set of application data. You can store the data in +<dd>A <i>content provider</i> manages a shared set of app data. You can store the data in the file system, an SQLite database, on the web, or any other persistent storage location your -application can access. Through the content provider, other applications can query or even modify +app can access. Through the content provider, other apps can query or even modify the data (if the content provider allows it). For example, the Android system provides a content -provider that manages the user's contact information. As such, any application with the proper +provider that manages the user's contact information. As such, any app with the proper permissions can query part of the content provider (such as {@link android.provider.ContactsContract.Data}) to read and write information about a particular person. <p>Content providers are also useful for reading and writing data that is private to your -application and not shared. For example, the <a -href="{@docRoot}resources/samples/NotePad/index.html">Note Pad</a> sample application uses a +app and not shared. For example, the <a +href="{@docRoot}resources/samples/NotePad/index.html">Note Pad</a> sample app uses a content provider to save notes.</p> <p>A content provider is implemented as a subclass of {@link android.content.ContentProvider} -and must implement a standard set of APIs that enable other applications to perform +and must implement a standard set of APIs that enable other apps to perform transactions. For more information, see the <a href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a> developer guide.</p> @@ -171,7 +149,7 @@ guide.</p> <dd>A <i>broadcast receiver</i> is a component that responds to system-wide broadcast announcements. Many broadcasts originate from the system—for example, a broadcast announcing that the screen has turned off, the battery is low, or a picture was captured. -Applications can also initiate broadcasts—for example, to let other applications know that +Apps can also initiate broadcasts—for example, to let other apps know that some data has been downloaded to the device and is available for them to use. Although broadcast receivers don't display a user interface, they may <a href="{@docRoot}guide/topics/ui/notifiers/notifications.html">create a status bar notification</a> @@ -188,26 +166,26 @@ see the {@link android.content.BroadcastReceiver} class.</p> -<p>A unique aspect of the Android system design is that any application can start another -application’s component. For example, if you want the user to capture a -photo with the device camera, there's probably another application that does that and your -application can use it, instead of developing an activity to capture a photo yourself. You don't -need to incorporate or even link to the code from the camera application. -Instead, you can simply start the activity in the camera application that captures a -photo. When complete, the photo is even returned to your application so you can use it. To the user, -it seems as if the camera is actually a part of your application.</p> +<p>A unique aspect of the Android system design is that any app can start another +app’s component. For example, if you want the user to capture a +photo with the device camera, there's probably another app that does that and your +app can use it, instead of developing an activity to capture a photo yourself. You don't +need to incorporate or even link to the code from the camera app. +Instead, you can simply start the activity in the camera app that captures a +photo. When complete, the photo is even returned to your app so you can use it. To the user, +it seems as if the camera is actually a part of your app.</p> -<p>When the system starts a component, it starts the process for that application (if it's not +<p>When the system starts a component, it starts the process for that app (if it's not already running) and instantiates the classes needed for the component. For example, if your -application starts the activity in the camera application that captures a photo, that activity -runs in the process that belongs to the camera application, not in your application's process. -Therefore, unlike applications on most other systems, Android applications don't have a single entry +app starts the activity in the camera app that captures a photo, that activity +runs in the process that belongs to the camera app, not in your app's process. +Therefore, unlike apps on most other systems, Android apps don't have a single entry point (there's no {@code main()} function, for example).</p> -<p>Because the system runs each application in a separate process with file permissions that -restrict access to other applications, your application cannot directly activate a component from -another application. The Android system, however, can. So, to activate a component in -another application, you must deliver a message to the system that specifies your <em>intent</em> to +<p>Because the system runs each app in a separate process with file permissions that +restrict access to other apps, your app cannot directly activate a component from +another app. The Android system, however, can. So, to activate a component in +another app, you must deliver a message to the system that specifies your <em>intent</em> to start a particular component. The system then activates the component for you.</p> @@ -217,7 +195,7 @@ start a particular component. The system then activates the component for you.</ broadcast receivers—are activated by an asynchronous message called an <em>intent</em>. Intents bind individual components to each other at runtime (you can think of them as the messengers that request an action from other components), whether the component belongs -to your application or another.</p> +to your app or another.</p> <p>An intent is created with an {@link android.content.Intent} object, which defines a message to activate either a specific component or a specific <em>type</em> of component—an intent @@ -273,21 +251,21 @@ href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers <h2 id="Manifest">The Manifest File</h2> -<p>Before the Android system can start an application component, the system must know that the -component exists by reading the application's {@code AndroidManifest.xml} file (the "manifest" -file). Your application must declare all its components in this file, which must be at the root of -the application project directory.</p> +<p>Before the Android system can start an app component, the system must know that the +component exists by reading the app's {@code AndroidManifest.xml} file (the "manifest" +file). Your app must declare all its components in this file, which must be at the root of +the app project directory.</p> -<p>The manifest does a number of things in addition to declaring the application's components, +<p>The manifest does a number of things in addition to declaring the app's components, such as:</p> <ul> - <li>Identify any user permissions the application requires, such as Internet access or + <li>Identify any user permissions the app requires, such as Internet access or read-access to the user's contacts.</li> <li>Declare the minimum <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Level</a> -required by the application, based on which APIs the application uses.</li> - <li>Declare hardware and software features used or required by the application, such as a camera, +required by the app, based on which APIs the app uses.</li> + <li>Declare hardware and software features used or required by the app, such as a camera, bluetooth services, or a multitouch screen.</li> - <li>API libraries the application needs to be linked against (other than the Android framework + <li>API libraries the app needs to be linked against (other than the Android framework APIs), such as the <a href="http://code.google.com/android/add-ons/google-apis/maps-overview.html">Google Maps library</a>.</li> @@ -297,7 +275,7 @@ library</a>.</li> <h3 id="DeclaringComponents">Declaring components</h3> -<p>The primary task of the manifest is to inform the system about the application's components. For +<p>The primary task of the manifest is to inform the system about the app's components. For example, a manifest file can declare an activity as follows: </p> <pre> @@ -314,7 +292,7 @@ example, a manifest file can declare an activity as follows: </p> <p>In the <code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> element, the {@code android:icon} attribute points to resources for an icon that identifies the -application.</p> +app.</p> <p>In the <code><a href="{@docRoot}guide/topics/manifest/activity-element.html"><activity></a></code> element, @@ -322,7 +300,7 @@ the {@code android:name} attribute specifies the fully qualified class name of t android.app.Activity} subclass and the {@code android:label} attributes specifies a string to use as the user-visible label for the activity.</p> -<p>You must declare all application components this way:</p> +<p>You must declare all app components this way:</p> <ul> <li><code><a href="{@docRoot}guide/topics/manifest/activity-element.html"><activity></a></code> elements @@ -345,7 +323,7 @@ receivers can be either declared in the manifest or created dynamically in code {@link android.content.BroadcastReceiver} objects) and registered with the system by calling {@link android.content.Context#registerReceiver registerReceiver()}.</p> -<p>For more about how to structure the manifest file for your application, see <a +<p>For more about how to structure the manifest file for your app, see <a href="{@docRoot}guide/topics/manifest/manifest-intro.html">The AndroidManifest.xml File</a> documentation. </p> @@ -356,28 +334,43 @@ documentation. </p> <p>As discussed above, in <a href="#ActivatingComponents">Activating Components</a>, you can use an {@link android.content.Intent} to start activities, services, and broadcast receivers. You can do so by explicitly naming the target component (using the component class name) in the intent. However, -the real power of intents lies in the concept of intent actions. With intent actions, you simply -describe the type of action you want to perform (and optionally, the data upon which you’d like to -perform the action) and allow the system to find a component on the device that can perform the +the real power of intents lies in the concept of <em>implicit intents</em>. An implicit intent +simply describes the type of action to perform (and, optionally, the data upon which you’d like to +perform the action) and allows the system to find a component on the device that can perform the action and start it. If there are multiple components that can perform the action described by the intent, then the user selects which one to use.</p> <p>The way the system identifies the components that can respond to an intent is by comparing the -intent received to the <i>intent filters</i> provided in the manifest file of other applications on +intent received to the <i>intent filters</i> provided in the manifest file of other apps on the device.</p> -<p>When you declare a component in your application's manifest, you can optionally include -intent filters that declare the capabilities of the component so it can respond to intents -from other applications. You can declare an intent filter for your component by +<p>When you declare an activity in your app's manifest, you can optionally include +intent filters that declare the capabilities of the activity so it can respond to intents +from other apps. You can declare an intent filter for your component by adding an <a href="{@docRoot}guide/topics/manifest/intent-filter-element.html">{@code <intent-filter>}</a> element as a child of the component's declaration element.</p> -<p>For example, an email application with an activity for composing a new email might declare an -intent filter in its manifest entry to respond to "send" intents (in order to send email). An -activity in your application can then create an intent with the “send” action ({@link -android.content.Intent#ACTION_SEND}), which the system matches to the email application’s “send” -activity and launches it when you invoke the intent with {@link android.app.Activity#startActivity -startActivity()}.</p> +<p>For example, if you've built an email app with an activity for composing a new email, you can +declare an intent filter to respond to "send" intents (in order to send a new email) like this:</p> +<pre> +<manifest ... > + ... + <application ... > + <activity android:name="com.example.project.ComposeEmailActivity"> + <intent-filter> + <action android:name="android.intent.action.SEND" /> + <data android:type="*/*" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> + </activity> + </application> +</manifest> +</pre> + +<p>Then, if another app creates an intent with the {@link +android.content.Intent#ACTION_SEND} action and pass it to {@link android.app.Activity#startActivity +startActivity()}, the system may start your activity so the user can draft and send an +email.</p> <p>For more about creating intent filters, see the <a href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filters</a> document. @@ -385,102 +378,57 @@ href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filter -<h3 id="DeclaringRequirements">Declaring application requirements</h3> +<h3 id="DeclaringRequirements">Declaring app requirements</h3> <p>There are a variety of devices powered by Android and not all of them provide the -same features and capabilities. In order to prevent your application from being installed on devices -that lack features needed by your application, it's important that you clearly define a profile for -the types of devices your application supports by declaring device and software requirements in your +same features and capabilities. In order to prevent your app from being installed on devices +that lack features needed by your app, it's important that you clearly define a profile for +the types of devices your app supports by declaring device and software requirements in your manifest file. Most of these declarations are informational only and the system does not read them, but external services such as Google Play do read them in order to provide filtering -for users when they search for applications from their device.</p> - -<p>For example, if your application requires a camera and uses APIs introduced in Android 2.1 (<a -href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Level</a> 7), you should declare these as -requirements in your manifest file. That way, devices that do <em>not</em> have a camera and have an -Android version <em>lower</em> than 2.1 cannot install your application from Google Play.</p> +for users when they search for apps from their device.</p> -<p>However, you can also declare that your application uses the camera, but does not -<em>require</em> it. In that case, your application must perform a check at runtime to determine -if the device has a camera and disable any features that use the camera if one is not available.</p> +<p>For example, if your app requires a camera and uses APIs introduced in Android 2.1 (<a +href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Level</a> 7), +you should declare these as requirements in your manifest file like this:</p> -<p>Here are some of the important device characteristics that you should consider as you design and -develop your application:</p> - -<dl> - <dt>Screen size and density</dt> - <dd>In order to categorize devices by their screen type, Android defines two characteristics for -each device: screen size (the physical dimensions of the screen) and screen density (the physical -density of the pixels on the screen, or dpi—dots per inch). To simplify all the different -types of screen configurations, the Android system generalizes them into select groups that make -them easier to target. -<p>The screen sizes are: small, normal, large, and extra large.<br/> -The screen densities are: low density, medium density, high density, and extra high density.</p> - -<p>By default, your application is compatible with all screen sizes and densities, -because the Android system makes the appropriate adjustments to your UI layout and image -resources. However, you should create specialized layouts for certain screen sizes and provide -specialized images for certain densities, using alternative layout resources, and by declaring in -your manifest exactly which screen sizes your application supports with the <a -href="{@docRoot}guide/topics/manifest/supports-screens-element.html">{@code -<supports-screens>}</a> element.</p> -<p>For more information, see the <a -href="{@docRoot}guide/practices/screens_support.html">Supporting Multiple Screens</a> -document.</p></dd> - - <dt>Input configurations</dt> - <dd>Many devices provide a different type of user input mechanism, such as a hardware keyboard, a -trackball, or a five-way navigation pad. If your application requires a particular kind of input -hardware, then you should declare it in your manifest with the <a -href="{@docRoot}guide/topics/manifest/uses-configuration-element.html">{@code -<uses-configuration>}</a> element. However, it is rare that an application should require -a certain input configuration.</dd> - - <dt>Device features</dt> - <dd>There are many hardware and software features that may or may not exist on a given -Android-powered device, such as a camera, a light sensor, bluetooth, a certain -version of OpenGL, or the fidelity of the touchscreen. You should never assume that a certain -feature is available on all Android-powered devices (other than the availability of the standard -Android library), so you should declare any features used by your application with the <a -href="{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code <uses-feature>}</a> -element.</dd> - - <dt>Platform Version</dt> - <dd>Different Android-powered devices often run different versions of the Android platform, -such as Android 1.6 or Android 2.3. Each successive version often includes additional APIs not -available in the previous version. In order to indicate which set of APIs are available, each -platform version specifies an <a -href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Level</a> (for example, Android 1.0 is API Level -1 and Android 2.3 is API Level 9). If you use any APIs that were added to the platform after -version 1.0, you should declare the minimum API Level in which those APIs were introduced using the -<a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html">{@code <uses-sdk>}</a> -element.</dd> -</dl> - -<p>It's important that you declare all such requirements for your application, because, when you -distribute your application on Google Play, the store uses these declarations to filter which -applications are available on each device. As such, your application should be available only to -devices that meet all your application requirements.</p> - -<p>For more information about how Google Play filters applications based on these (and other) -requirements, see the <a href="{@docRoot}google/play/filters.html">Filters on Google Play</a> +<pre> +<manifest ... > + <uses-feature android:name="android.hardware.camera.any" + android:required="true" /> + <uses-sdk android:minSdkVersion="7" android:targetSdkVersion="19" /> + ... +</manifest> +</pre> + +<p>Now, devices that do <em>not</em> have a camera and have an +Android version <em>lower</em> than 2.1 cannot install your app from Google Play.</p> + +<p>However, you can also declare that your app uses the camera, but does not +<em>require</em> it. In that case, your app must set the <a href= +"{@docRoot}guide/topics/manifest/uses-feature-element.html#required">{@code required}</a> +attribute to {@code "false"} and check at runtime whether +the device has a camera and disable any camera features as appropriate.</p> + +<p>More information about how you can manage your app's compatibility with different devices +is provided in the <a href="{@docRoot}guide/practices/compatibility.html">Device Compatibility</a> document.</p> -<h2 id="Resources">Application Resources</h2> +<h2 id="Resources">App Resources</h2> -<p>An Android application is composed of more than just code—it requires resources that are +<p>An Android app is composed of more than just code—it requires resources that are separate from the source code, such as images, audio files, and anything relating to the visual -presentation of the application. For example, you should define animations, menus, styles, colors, -and the layout of activity user interfaces with XML files. Using application resources makes it easy -to update various characteristics of your application without modifying code and—by providing -sets of alternative resources—enables you to optimize your application for a variety of +presentation of the app. For example, you should define animations, menus, styles, colors, +and the layout of activity user interfaces with XML files. Using app resources makes it easy +to update various characteristics of your app without modifying code and—by providing +sets of alternative resources—enables you to optimize your app for a variety of device configurations (such as different languages and screen sizes).</p> <p>For every resource that you include in your Android project, the SDK build tools define a unique -integer ID, which you can use to reference the resource from your application code or from -other resources defined in XML. For example, if your application contains an image file named {@code +integer ID, which you can use to reference the resource from your app code or from +other resources defined in XML. For example, if your app contains an image file named {@code logo.png} (saved in the {@code res/drawable/} directory), the SDK tools generate a resource ID named {@code R.drawable.logo}, which you can use to reference the image and insert it in your user interface.</p> @@ -504,15 +452,45 @@ depending on the orientation, you can define two different layouts and apply the qualifier to each layout's directory name. Then, the system automatically applies the appropriate layout depending on the current device orientation.</p> -<p>For more about the different kinds of resources you can include in your application and how -to create alternative resources for various device configurations, see the <a -href="{@docRoot}guide/topics/resources/index.html">Application Resources</a> developer guide.</p> - - -<!-- -<h2>Beginner's Path</h2> +<p>For more about the different kinds of resources you can include in your application and how to +create alternative resources for different device configurations, read <a href= +"{@docRoot}guide/topics/resources/providing-resources.html">Providing Resources</a>.</p> + + + +<div class="next-docs"> +<div class="col-6"> + <h2 class="norule">Continue reading about:</h2> + <dl> + <dt><a href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filters</a> + </dt> + <dd>Information about how to use the {@link android.content.Intent} APIs to + activate app components, such as activities and services, and how to make your app components + available for use by other apps.</dd> + <dt><a href="{@docRoot}guide/components/activities.html">Activities</a></dt> + <dd>Information about how to create an instance of the {@link android.app.Activity} class, + which provides a distinct screen in your application with a user interface.</dd> + <dt><a +href="{@docRoot}guide/topics/resources/providing-resources.html">Providing Resources</a></dt> + <dd>Information about how Android apps are structured to separate app resources from the + app code, including how you can provide alternative resources for specific device + configurations. + </dd> + </dl> +</div> +<div class="col-6"> + <h2 class="norule">You might also be interested in:</h2> + <dl> + <dt><a href="{@docRoot}guide/practices/compatibility.html" + >Device Compatibility</a></dt> + <dd>Information about Android works on different types of devices and an introduction + to how you can optimize your app for each device or restrict your app's availability + to different devices.</dd> + <dt><a href="{@docRoot}guide/topics/security/permissions.html" + >System Permissions</a></dt> + <dd>Information about how Android restricts app access to certain APIs with a permission + system that requires the user's consent for your app to use those APIs.</dd> + </dl> +</div> +</div> -<p>For a close look at implementing activities—the components your users use to -interact with your application—continue with the <b><a -href="{@docRoot}guide/components/activities.html">Activities</a></b> document.</p> ---> diff --git a/docs/html/guide/components/index.jd b/docs/html/guide/components/index.jd index 87bae53..811d015 100644 --- a/docs/html/guide/components/index.jd +++ b/docs/html/guide/components/index.jd @@ -1,7 +1,9 @@ page.title=App Components page.landing=true -page.landing.intro=Android's application framework lets you create extremely rich and innovative apps using a set of reusable components. This section explains how Android apps work and how you use components to build them. +page.landing.intro=Android's application framework lets you create rich and innovative apps using a set of reusable components. This section explains how you can build the components that define the building blocks of your app and how to connect them together using intents. +page.metaDescription=Android's application framework lets you create rich and innovative apps using a set of reusable components. This section explains how you can build the components that define the building blocks of your app and how to connect them together using intents. page.landing.image=images/develop/app_components.png +page.image=images/develop/app_components.png @jd:body diff --git a/docs/html/guide/components/intents-common.jd b/docs/html/guide/components/intents-common.jd new file mode 100644 index 0000000..b4813a5 --- /dev/null +++ b/docs/html/guide/components/intents-common.jd @@ -0,0 +1,1858 @@ +page.title=Common Intents +page.tags="IntentFilter" +@jd:body + +<div id="qv-wrapper"> +<div id="qv"> + + <h2>In this document + <a href="#" onclick="hideNestedItems('#tocIntents',this);return false;" class="header-toggle"> + <span class="more">show more</span> + <span class="less" style="display:none">show less</span></a></h2> + +<ol id="tocIntents" class="hide-nested"> + <li><a href="#Clock">Alarm Clock</a> + <ol> + <li><a href="#CreateAlarm">Create an alarm</a></li> + <li><a href="#CreateTimer">Create a timer</a></li> + <li><a href="#ShowAlarms">Show all alarms</a></li> + </ol> + </li> + <li><a href="#Calendar">Calendar</a> + <ol> + <li><a href="#AddEvent">Add a calendar event</a></li> + </ol> + </li> + <li><a href="#Camera">Camera</a> + <ol> + <li><a href="#ImageCapture">Capture a picture or video and return it</a></li> + </ol> + </li> + <li><a href="#Contacts">Contacts/People App</a> + <ol> + <li><a href="#PickContact">Select a contact</a></li> + <li><a href="#PickContactDat">Select specific contact data</a></li> + <li><a href="#ViewContact">View a contact</a></li> + <li><a href="#EditContact">Edit an existing contact</a></li> + <li><a href="#InsertContact">Insert a contact</a></li> + </ol> + </li> + <li><a href="#Email">Email</a> + <ol> + <li><a href="#ComposeEmail">Compose an email with optional attachments</a></li> + </ol> + </li> + <li><a href="#Storage">File Storage</a> + <ol> + <li><a href="#GetFile">Retrieve a specific type of file</a></li> + <li><a href="#OpenFile">Open a specific type of file</a></li> + </ol> + </li> + <li><a href="#Maps">Maps</a> + <ol> + <li><a href="#ViewMap">Show a location on a map</a></li> + </ol> + </li> + <li><a href="#Music">Music or Video</a> + <ol> + <li><a href="#PlayMedia">Play a media file</a></li> + <li><a href="#PlaySearch">Play music based on a search query</a></li> + </ol> + </li> + <li><a href="#Phone">Phone</a> + <ol> + <li><a href="#DialPhone">Initiate a phone call</a></li> + </ol> + </li> + <li><a href="#Settings">Settings</a> + <ol> + <li><a href="#OpenSettings">Open a specific section of Settings</a></li> + </ol> + </li> + <li><a href="#Messaging">Text Messaging</a> + <ol> + <li><a href="#SendMessage">Compose an SMS/MMS message with attachment</a></li> + </ol> + </li> + <li><a href="#Browser">Web Browser</a> + <ol> + <li><a href="#ViewUrl">Load a web URL</a></li> + <li><a href="#SearchWeb">Perform a web search</a></li> + </ol> + </li> +</ol> + + <h2>See also</h2> + <ol> + <li><a href="{@docRoot}guide/components/intents-filters.html">Intents and Intent +Filters</a></li> + </ol> +</div> +</div> + + +<p>An intent allows you to start an activity in another app by describing a simple +action you'd like to perform (such as "view a map" or "take a picture") +in an {@link android.content.Intent} object. This type of intent is +called an <em>implicit</em> intent because it does not specify the app component +to start, but instead specifies an <em>action</em> and provides some +<em>data</em> with which to perform the action.</p> + +<p>When you call +{@link android.content.Context#startActivity startActivity()} or +{@link android.app.Activity#startActivityForResult startActivityForResult()} and pass it an +implicit intent, the system <a href="{@docRoot}guide/components/intents-filters.html#Resolution" +>resolves the intent</a> to an app that can handle the intent +and starts its corresponding {@link android.app.Activity}. If there's more than one app +that can handle the intent, the system presents the user with a dialog to pick which app +to use.</p> + +<p>This page describes several implicit intents that you can use to perform common actions, +organized by the type of app that handles the intent. Each section also shows how you can +create an <a href="{@docRoot}guide/components/intents-filters.html#Receiving">intent filter</a> to +advertise your app's ability to perform the same action.</p> + +<p class="caution"><strong>Caution:</strong> If there are no apps on the device that can receive +the implicit intent, your app will crash when it calls {@link android.content.Context#startActivity +startActivity()}. To first verify that an app exists to receive the intent, call {@link +android.content.Intent#resolveActivity resolveActivity()} on your {@link android.content.Intent} +object. If the result is non-null, there is at least one app that can handle the intent and +it's safe to call {@link android.content.Context#startActivity startActivity()}. If the result is +null, you should not use the intent and, if possible, you should disable the feature that invokes +the intent.</p> + + +<p>If you're not familiar with how to create intents or intent filters, you should first read +<a href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filters</a>.</p> + + + + + + + + + +<h2 id="Clock">Alarm Clock</h2> + + +<h3 id="CreateAlarm">Create an alarm</h3> + +<p>To create a new alarm, use the {@link android.provider.AlarmClock#ACTION_SET_ALARM} +action and specify alarm details such as the time and message using extras defined below.</p> + +<p class="note"><strong>Note:</strong> Only the hour, minutes, and message extras are available +since Android 2.3 (API level 9). The other extras were added in later versions of the platform.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.provider.AlarmClock#ACTION_SET_ALARM}</dd> + +<dt><b>Data URI</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>None +</dd> + +<dt><b>Extras</b></dt> +<dd> + <dl> + <dt>{@link android.provider.AlarmClock#EXTRA_HOUR}</dt> + <dd>The hour for the alarm.</dd> + <dt>{@link android.provider.AlarmClock#EXTRA_MINUTES}</dt> + <dd>The minutes for the alarm.</dd> + <dt>{@link android.provider.AlarmClock#EXTRA_MESSAGE}</dt> + <dd>A custom message to identify the alarm.</dd> + <dt>{@link android.provider.AlarmClock#EXTRA_DAYS}</dt> + <dd>An {@link java.util.ArrayList} including each week day on which this alarm should + be repeated. Each day must be declared with an integer from the {@link java.util.Calendar} + class such as {@link java.util.Calendar#MONDAY}. + <p>For a one-time alarm, do not specify this extra.</dd> + <dt>{@link android.provider.AlarmClock#EXTRA_RINGTONE}</dt> + <dd>A {@code content:} URI specifying a ringtone to use with the alarm, or {@link + android.provider.AlarmClock#VALUE_RINGTONE_SILENT} for no ringtone. + <p>To use the default ringtone, do not specify this extra.</dd> + <dt>{@link android.provider.AlarmClock#EXTRA_VIBRATE}</dt> + <dd>A boolean specifying whether to vibrate for this alarm.</dd> + <dt>{@link android.provider.AlarmClock#EXTRA_SKIP_UI}</dt> + <dd>A boolean specifying whether the responding app should skip its UI when setting the alarm. + If true, the app should bypass any confirmation UI and simply set the specified alarm.</dd> + </dl> +</dd> + + +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void createAlarm(String message, int hour, int minutes) { + Intent intent = new Intent(AlarmClock.ACTION_SET_ALARM) + .putExtra(AlarmClock.EXTRA_MESSAGE, message) + .putExtra(AlarmClock.EXTRA_HOUR, hour) + .putExtra(AlarmClock.EXTRA_MINUTES, minutes); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + +<div class="note"><strong>Note:</strong> +<p>In order to invoke the {@link +android.provider.AlarmClock#ACTION_SET_ALARM} intent, your app must have the +{@link android.Manifest.permission#SET_ALARM} permission:</p> +<pre> +<uses-permission android:name="com.android.alarm.permission.SET_ALARM" /> +</pre> +</div> + + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.SET_ALARM" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + + + +<h3 id="CreateTimer">Create a timer</h3> + +<p>To create a countdown timer, use the {@link android.provider.AlarmClock#ACTION_SET_TIMER} +action and specify timer details such as the duration using extras defined below.</p> + +<p class="note"><strong>Note:</strong> This intent was added +in Android 4.4 (API level 19).</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.provider.AlarmClock#ACTION_SET_TIMER}</dd> + +<dt><b>Data URI</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>None +</dd> + +<dt><b>Extras</b></dt> +<dd> + <dl> + <dt>{@link android.provider.AlarmClock#EXTRA_LENGTH}</dt> + <dd>The length of the timer in seconds.</dd> + <dt>{@link android.provider.AlarmClock#EXTRA_MESSAGE}</dt> + <dd>A custom message to identify the timer.</dd> + <dt>{@link android.provider.AlarmClock#EXTRA_SKIP_UI}</dt> + <dd>A boolean specifying whether the responding app should skip its UI when setting the timer. + If true, the app should bypass any confirmation UI and simply start the specified timer.</dd> + </dl> +</dd> + + +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void startTimer(String message, int seconds) { + Intent intent = new Intent(AlarmClock.ACTION_SET_TIMER) + .putExtra(AlarmClock.EXTRA_MESSAGE, message) + .putExtra(AlarmClock.EXTRA_LENGTH, seconds) + .putExtra(AlarmClock.EXTRA_SKIP_UI, true); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + +<div class="note"><strong>Note:</strong> +<p>In order to invoke the {@link +android.provider.AlarmClock#ACTION_SET_TIMER} intent, your app must have the +{@link android.Manifest.permission#SET_ALARM} permission:</p> +<pre> +<uses-permission android:name="com.android.alarm.permission.SET_ALARM" /> +</pre> +</div> + + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.SET_TIMER" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + + + + + +<h3 id="ShowAlarms">Show all alarms</h3> + +<p>To show the list of alarms, use the {@link android.provider.AlarmClock#ACTION_SHOW_ALARMS} +action.</p> + +<p>Although not many apps will invoke this intent (it's primarily used by system apps), +any app that behaves as an alarm clock should implement +this intent filter and respond by showing the list of current alarms.</p> + +<p class="note"><strong>Note:</strong> This intent was added +in Android 4.4 (API level 19).</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.provider.AlarmClock#ACTION_SHOW_ALARMS}</dd> + +<dt><b>Data URI</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>None +</dd> +</dl> + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.SHOW_ALARMS" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + + + + + + +<h2 id="Calendar">Calendar</h2> + + +<h3 id="AddEvent">Add a calendar event</h3> + +<p>To add a new event to the user's calendar, use the {@link android.content.Intent#ACTION_INSERT} +action and specify the data URI with {@link android.provider.CalendarContract.Events#CONTENT_URI +Events.CONTENT_URI}. You can then specify various event details using extras defined below.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_INSERT}</dd> + +<dt><b>Data URI</b></dt> +<dd>{@link android.provider.CalendarContract.Events#CONTENT_URI +Events.CONTENT_URI}</dd> + +<dt><b>MIME Type</b></dt> +<dd>{@code "vnd.android.cursor.dir/event"} +</dd> + +<dt><b>Extras</b></dt> +<dd> + <dl> + <dt>{@link android.provider.CalendarContract#EXTRA_EVENT_ALL_DAY}</dt> + <dd>A boolean specifying whether this is an all-day event.</dd> + <dt>{@link android.provider.CalendarContract#EXTRA_EVENT_BEGIN_TIME}</dt> + <dd>The start time of the event (milliseconds since epoch).</dd> + <dt>{@link android.provider.CalendarContract#EXTRA_EVENT_END_TIME}</dt> + <dd>The end time of the event (milliseconds since epoch).</dd> + <dt>{@link android.provider.CalendarContract.EventsColumns#TITLE}</dt> + <dd>The event title.</dd> + <dt>{@link android.provider.CalendarContract.EventsColumns#DESCRIPTION}</dt> + <dd>The event description.</dd> + <dt>{@link android.provider.CalendarContract.EventsColumns#EVENT_LOCATION}</dt> + <dd>The event location.</dd> + <dt>{@link android.content.Intent#EXTRA_EMAIL}</dt> + <dd>A comma-separated list of email addresses that specify the invitees.</dd> + </dl> + <p>Many more event details can be specified using the constants defined in the + {@link android.provider.CalendarContract.EventsColumns} class.</p> +</dd> + + +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void addEvent(String title, String location, Calendar begin, Calendar end) { + Intent intent = new Intent(Intent.ACTION_INSERT) + .setData(Events.CONTENT_URI) + .putExtra(Events.TITLE, title) + .putExtra(Events.EVENT_LOCATION, location) + .putExtra(CalendarContract.EXTRA_EVENT_BEGIN_TIME, begin) + .putExtra(CalendarContract.EXTRA_EVENT_END_TIME, end); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.INSERT" /> + <data android:mimeType="vnd.android.cursor.dir/event" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + + + + + + + + + + + + + +<h2 id="Camera">Camera</h2> + + + +<h3 id="ImageCapture">Capture a picture or video and return it</h3> + +<p>To open a camera app and receive the resulting photo or video, use the {@link +android.provider.MediaStore#ACTION_IMAGE_CAPTURE} or {@link +android.provider.MediaStore#ACTION_VIDEO_CAPTURE} action. Also specify the URI location where you'd +like the camera to save the photo or video, in the {@link android.provider.MediaStore#EXTRA_OUTPUT} +extra.</p> + + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.provider.MediaStore#ACTION_IMAGE_CAPTURE} or<br> + {@link android.provider.MediaStore#ACTION_VIDEO_CAPTURE}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>None</dd> + +<dt><b>Extras</b></dt> +<dd> + <dl> + <dt>{@link android.provider.MediaStore#EXTRA_OUTPUT}</dt> + <dd>The URI location where the camera app should save the photo or + video file (as a {@link android.net.Uri} object).</dd> + </dl> +</dd> +</dl> + +<p>When the camera app successfully returns +focus to your activity (your app receives the {@link android.app.Activity#onActivityResult +onActivityResult()} callback), you can access the photo or video at the URI you specified +with the {@link android.provider.MediaStore#EXTRA_OUTPUT} value.</p> + +<p class="note"><strong>Note:</strong> When you use {@link +android.provider.MediaStore#ACTION_IMAGE_CAPTURE} to capture a photo, the camera may also return a +downscaled copy (a thumbnail) of the photo in the result {@link +android.content.Intent}, saved as a {@link android.graphics.Bitmap} in an extra field named +<code>"data"</code>.</p> + + +<p><b>Example intent:</b></p> +<pre> +static final int REQUEST_IMAGE_CAPTURE = 1; +static final Uri mLocationForPhotos; + +public void capturePhoto(String targetFilename) { + Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); + intent.putExtra(MediaStore.EXTRA_OUTPUT, + Uri.withAppendedPath(mLocationForPhotos, targetFilename); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivityForResult(intent, REQUEST_IMAGE_CAPTURE); + } +} + +@Override +protected void onActivityResult(int requestCode, int resultCode, Intent data) { + if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) { + Bitmap thumbnail = data.getParcelable("data"); + // Do other work with full size photo saved in mLocationForPhotos + ... + } +} +</pre> + +<p>For more information about how to use this intent to capture a photo, including +how to create an appropriate {@link android.net.Uri} for the output location, read +<a href="{@docRoot}training/camera/photobasics.html">Taking Photos Simply</a> or +<a href="{@docRoot}training/camera/videobasics.html">Taking Videos Simply</a>.</p> + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.media.action.IMAGE_CAPTURE" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + +<p>When handling this intent, your activity should check for the {@link +android.provider.MediaStore#EXTRA_OUTPUT} extra in the incoming {@link android.content.Intent}, +then save the captured image or video at the location specified by that extra and call {@link +android.app.Activity#setResult(int,Intent) setResult()} with an +{@link android.content.Intent} that includes a compressed thumbnail +in an extra named <code>"data"</code>.</p> + + + + + +<h2 id="Contacts">Contacts/People App</h2> + + +<h3 id="PickContact">Select a contact</h3> + +<p>To have the user select a contact and provide your app access to all the contact information, +use the {@link android.content.Intent#ACTION_PICK} action and specify the MIME type to +{@link android.provider.ContactsContract.Contacts#CONTENT_TYPE +Contacts.CONTENT_TYPE}.</p> + +<p>The result {@link android.content.Intent} delivered to your {@link +android.app.Activity#onActivityResult onActivityResult()} callback contains the +<code>content:</code> URI pointing to the selected contact. The response grants +your app temporary permissions to read that contact using the <a +href="{@docRoot}guide/topics/providers/contacts-provider.html">Contacts Provider</a> API even if +your app does not include the {@link android.Manifest.permission#READ_CONTACTS} permission.</p> + +<p class="note"><strong>Tip:</strong> If you need access to only a specific piece of contact +information, such as a phone number or email address, instead see the next section about how to +<a href="#PickContactData">select specific contact data</a>.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_PICK}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>{@link android.provider.ContactsContract.Contacts#CONTENT_TYPE +Contacts.CONTENT_TYPE} +</dd> +</dl> + +<p><b>Example intent:</b></p> +<pre> +static final int REQUEST_SELECT_CONTACT = 1; + +public void selectContact() { + Intent intent = new Intent(Intent.ACTION_PICK); + intent.setType(ContactsContract.Contacts.CONTENT_TYPE); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivityForResult(intent, REQUEST_SELECT_CONTACT); + } +} + +@Override +protected void onActivityResult(int requestCode, int resultCode, Intent data) { + if (requestCode == REQUEST_SELECT_CONTACT && resultCode == RESULT_OK) { + Uri contactUri = data.getData(); + // Do something with the selected contact at contactUri + ... + } +} +</pre> + +<p>For information about how to retrieve contact details once you have the contact URI, +read <a href="{@docRoot}training/contacts-provider/retrieve-details.html">Retrieving Details +for a Contact</a>. Remember, when you retrieve the contact URI with the above intent, you +<strong>do not</strong> need the {@link android.Manifest.permission#READ_CONTACTS} permission +to read details for that contact.</p> + + + + +<h3 id="PickContactDat">Select specific contact data</h3> + +<p>To have the user select a specific piece of information from a contact, such as +a phone number, email address, or other data type, use the +{@link android.content.Intent#ACTION_PICK} action and specify the MIME type to one +of the content types listed below, such as +{@link android.provider.ContactsContract.CommonDataKinds.Phone#CONTENT_TYPE +CommonDataKinds.Phone.CONTENT_TYPE} to get the contact's phone number.</p> + +<p>If you need to retrieve only one type of data from a contact, this technique with a +{@code CONTENT_TYPE} from the +{@link android.provider.ContactsContract.CommonDataKinds} classes is more efficient than +using the {@link android.provider.ContactsContract.Contacts#CONTENT_TYPE +Contacts.CONTENT_TYPE} (as shown in the previous section) because the result provides you direct +access to the desired data without requiring you to perform a more complex query to <a +href="{@docRoot}guide/topics/providers/contacts-provider.html">Contacts Provider</a>.</p> + +<p>The result {@link android.content.Intent} delivered to your {@link +android.app.Activity#onActivityResult onActivityResult()} callback contains the +<code>content:</code> URI pointing to the selected contact data. The response grants +your app temporary permissions to read that contact data even if your app does +not include the {@link android.Manifest.permission#READ_CONTACTS} permission.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_PICK}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd> + <dl> + <dt>{@link android.provider.ContactsContract.CommonDataKinds.Phone#CONTENT_TYPE +CommonDataKinds.Phone.CONTENT_TYPE}</dt> + <dd>Pick from contacts with a phone number.</dd> + <dt>{@link android.provider.ContactsContract.CommonDataKinds.Email#CONTENT_TYPE +CommonDataKinds.Email.CONTENT_TYPE}</dt> + <dd>Pick from contacts with an email address.</dd> + <dt>{@link android.provider.ContactsContract.CommonDataKinds.StructuredPostal#CONTENT_TYPE +CommonDataKinds.StructuredPostal.CONTENT_TYPE}</dt> + <dd>Pick from contacts with a postal address.</dd> + </dl> + <p>Or one of many other {@code CONTENT_TYPE} values + under {@link android.provider.ContactsContract}.</p> +</dd> +</dl> + +<p><b>Example intent:</b></p> +<pre> +static final int REQUEST_SELECT_PHONE_NUMBER = 1; + +public void selectContact() { + // Start an activity for the user to pick a phone number from contacts + Intent intent = new Intent(Intent.ACTION_PICK); + intent.setType(CommonDataKinds.Phone.CONTENT_TYPE); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivityForResult(intent, REQUEST_SELECT_PHONE_NUMBER); + } +} + +@Override +protected void onActivityResult(int requestCode, int resultCode, Intent data) { + if (requestCode == REQUEST_SELECT_PHONE_NUMBER && resultCode == RESULT_OK) { + // Get the URI and query the content provider for the phone number + Uri contactUri = data.getData(); + String[] projection = new String[]{CommonDataKinds.Phone.NUMBER}; + Cursor cursor = getContentResolver().query(contactUri, projection, + null, null, null); + // If the cursor returned is valid, get the phone number + if (cursor != null && cursor.moveToFirst()) { + int numberIndex = cursor.getColumnIndex(CommonDataKinds.Phone.NUMBER); + String number = cursor.getString(numberIndex); + // Do something with the phone number + ... + } + } +} +</pre> + + + + + +<h3 id="ViewContact">View a contact</h3> + +<p>To display the details for a known contact, use the {@link android.content.Intent#ACTION_VIEW} +action and specify the contact with a {@code content:} URI as the intent data.</p> + +<p>There are primarily two ways to initially retrieve the contact's URI:</p> +<ul> + <li>Use the contact URI returned by the {@link android.content.Intent#ACTION_PICK}, + shown in the previous section (this does not require any app permissions).</li> + <li>Access the list of all contacts directly, as described in <a + href="{@docRoot}training/contacts-provider/retrieve-names.html">Retrieving a List of + Contacts</a> (this requires the {@link android.Manifest.permission#READ_CONTACTS} + permission).</li> +</ul> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_VIEW}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>{@code content:<URI>}</dd> + +<dt><b>MIME Type</b></dt> +<dd>None. The type is inferred from contact URI. +</dd> +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void viewContact(Uri contactUri) { + Intent intent = new Intent(Intent.ACTION_VIEW, contactUri); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + + +<h3 id="EditContact">Edit an existing contact</h3> + +<p>To edit a known contact, use the {@link android.content.Intent#ACTION_EDIT} +action, specify the contact with a {@code content:} URI +as the intent data, and include any known contact information in extras specified by +constants in {@link android.provider.ContactsContract.Intents.Insert}.</p> + +<p>There are primarily two ways to initially retrieve the contact URI:</p> +<ul> + <li>Use the contact URI returned by the {@link android.content.Intent#ACTION_PICK}, + shown in the previous section (this does not require any app permissions).</li> + <li>Access the list of all contacts directly, as described in <a + href="{@docRoot}training/contacts-provider/retrieve-names.html">Retrieving a List of + Contacts</a> (this requires the {@link android.Manifest.permission#READ_CONTACTS} + permission).</li> +</ul> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_EDIT}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>{@code content:<URI>}</dd> + +<dt><b>MIME Type</b></dt> +<dd>The type is inferred from contact URI. +</dd> + +<dt><b>Extras</b></dt> +<dd>One or more of the extras defined in {@link android.provider.ContactsContract.Intents.Insert} +so you can populate fields of the contact details. +</dd> +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void editContact(Uri contactUri, String email) { + Intent intent = new Intent(Intent.ACTION_EDIT); + intent.setData(contactUri); + intent.putExtra(Intents.Insert.EMAIL, email); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + +<p>For more information about how to edit a contact, read <a +href="{@docRoot}training/contacts-provider/modify-data.html">Modifying +Contacts Using Intents</a>.</p> + + + + +<h3 id="InsertContact">Insert a contact</h3> + +<p>To insert a new contact, use the {@link android.content.Intent#ACTION_INSERT} action, +specify {@link android.provider.ContactsContract.Contacts#CONTENT_TYPE Contacts.CONTENT_TYPE} as +the MIME type, and include any known contact information in extras specified by +constants in {@link android.provider.ContactsContract.Intents.Insert}. + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_INSERT}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>{@link android.provider.ContactsContract.Contacts#CONTENT_TYPE Contacts.CONTENT_TYPE}</dd> + +<dt><b>Extras</b></dt> +<dd>One or more of the extras defined in {@link android.provider.ContactsContract.Intents.Insert}. +</dd> +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void insertContact(String name, String email) { + Intent intent = new Intent(Intent.ACTION_INSERT); + intent.setType(Contacts.CONTENT_TYPE); + intent.putExtra(Intents.Insert.NAME, name); + intent.putExtra(Intents.Insert.EMAIL, email); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + +<p>For more information about how to insert a contact, read <a +href="{@docRoot}training/contacts-provider/modify-data.html">Modifying +Contacts Using Intents</a>.</p> + + + + + + + +<h2 id="Email">Email</h2> + + +<h3 id="ComposeEmail">Compose an email with optional attachments</h3> + + +<p>To compose an email, use one of the below actions based on whether you'll include attachments, +and include email details such as the recipient and subject using the extra keys listed below.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_SENDTO} (for no attachment) or<br> + {@link android.content.Intent#ACTION_SEND} (for one attachment) or<br> + {@link android.content.Intent#ACTION_SEND_MULTIPLE} (for multiple attachments)</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd> + <dl> + <dt>{@link org.apache.http.protocol.HTTP#PLAIN_TEXT_TYPE} ("text/plain") + <dt><code>"*/*"</code> + </dl> +</dd> + +<dt><b>Extras</b></dt> +<dd> + <dl> + <dt>{@link android.content.Intent#EXTRA_EMAIL Intent.EXTRA_EMAIL}</dt> + <dd>A string array of all "To" recipient email addresses.</dd> + <dt>{@link android.content.Intent#EXTRA_CC Intent.EXTRA_CC}</dt> + <dd>A string array of all "CC" recipient email addresses.</dd> + <dt>{@link android.content.Intent#EXTRA_BCC Intent.EXTRA_BCC}</dt> + <dd>A string array of all "BCC" recipient email addresses.</dd> + <dt>{@link android.content.Intent#EXTRA_SUBJECT Intent.EXTRA_SUBJECT}</dt> + <dd>A string with the email subject.</dd> + <dt>{@link android.content.Intent#EXTRA_TEXT Intent.EXTRA_TEXT}</dt> + <dd>A string with the body of the email.</dd> + <dt>{@link android.content.Intent#EXTRA_STREAM Intent.EXTRA_STREAM}</dt> + <dd>A {@link android.net.Uri} pointing to the attachment. If using the + {@link android.content.Intent#ACTION_SEND_MULTIPLE} action, this should instead + be an {@link java.util.ArrayList} containing multiple {@link android.net.Uri} objects.</dd> + </dl> +</dd> + +</dl> + + +<p><b>Example intent:</b></p> +<pre> +public void composeEmail(String[] addresses, String subject, Uri attachment) { + Intent intent = new Intent(Intent.ACTION_SEND); + intent.setType("*/*"); + intent.putExtra(Intent.EXTRA_EMAIL, addresses); + intent.putExtra(Intent.EXTRA_SUBJECT, subject); + intent.putExtra(Intent.EXTRA_STREAM, attachment); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + +<p>If you want to ensure that your intent is handled only by an email app (and not other +text messaging or social apps), then use the {@link android.content.Intent#ACTION_SENDTO} action +and include the {@code "mailto:"} data scheme. For example:</p> + +<pre> +public void composeEmail(String[] addresses, String subject) { + Intent intent = new Intent(Intent.ACTION_SENDTO); + intent.setData(Uri.parse("mailto:")); // only email apps should handle this + intent.putExtra(Intent.EXTRA_EMAIL, addresses); + intent.putExtra(Intent.EXTRA_SUBJECT, subject); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.SEND" /> + <data android:type="*/*" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> + <intent-filter> + <action android:name="android.intent.action.SENDTO" /> + <data android:scheme="mailto" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + + + + + + + + + + + + + + + + +<h2 id="Storage">File Storage</h2> + + + +<h3 id="GetFile">Retrieve a specific type of file</h3> + +<p>To request that the user select a file such as a document or photo and return a reference to +your app, use the {@link android.content.Intent#ACTION_GET_CONTENT} action and specify your desired +MIME type. The file reference returned to your app is transient to your activity's current +lifecycle, so if you want to access it later you must import a copy that you can read later. +This intent also allows the user to create a new file in the process (for +example, instead of selecting an existing photo, the user can capture a new photo with the camera). +</p> + +<p>The result intent delivered to your {@link android.app.Activity#onActivityResult +onActivityResult()} method includes data with a URI pointing to the file. +The URI could be anything, such as an {@code http:} URI, {@code file:} URI, or {@code content:} +URI. However, if you'd like to restrict selectable files to only those that are accessible +from a content provider (a {@code content:} URI) and that are available as a file stream with {@link +android.content.ContentResolver#openFileDescriptor openFileDescriptor()}, you should add +the {@link android.content.Intent#CATEGORY_OPENABLE} category to your intent.</p> + +<p>On Android 4.3 (API level 18) and higher, +you can also allow the user to select multiple files by adding +{@link android.content.Intent#EXTRA_ALLOW_MULTIPLE} to the intent, set to {@code true}. +You can then access each of the selected files in a {@link android.content.ClipData} +object returned by {@link android.content.Intent#getClipData()}.</p> + + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_GET_CONTENT}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>The MIME type corresponding to the file type the user should select. +</dd> + +<dt><b>Extras</b></dt> +<dd> + <dl> + <dt>{@link android.content.Intent#EXTRA_ALLOW_MULTIPLE} + <dd>A boolean declaring whether the user can select more than one file at a time. + </dd> + <dt>{@link android.content.Intent#EXTRA_LOCAL_ONLY} + <dd>A boolean that declares whether the returned file must be available directly from + the device, rather than requiring a download from a remote service. + </dd> + </dl> +</dd> + +<dt><b>Category</b> (optional)</dt> +<dd> + <dl> + <dt>{@link android.content.Intent#CATEGORY_OPENABLE}</dt> + <dd>To return only "openable" files that can be represented as a file stream + with {@link android.content.ContentResolver#openFileDescriptor openFileDescriptor()}.</dd> + </dl> +</dd> + +</dl> + +<p><b>Example intent to get a photo:</b></p> +<pre> +static final int REQUEST_IMAGE_GET = 1; + +public void selectImage() { + Intent intent = new Intent(Intent.ACTION_GET_CONTENT); + intent.setType("image/*"); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivityForResult(intent, REQUEST_IMAGE_GET); + } +} + +@Override +protected void onActivityResult(int requestCode, int resultCode, Intent data) { + if (requestCode == REQUEST_IMAGE_GET && resultCode == RESULT_OK) { + Bitmap thumbnail = data.getParcelable("data"); + Uri fullPhotoUri = data.getData(); + // Do work with photo saved at fullPhotoUri + ... + } +} +</pre> + +<p><b>Example intent filter to return a photo:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.GET_CONTENT" /> + <data android:type="image/*" /> + <category android:name="android.intent.category.DEFAULT" /> + <!-- The OPENABLE category declares that the returned file is accessible + from a content provider that supports {@link android.provider.OpenableColumns} + and {@link android.content.ContentResolver#openFileDescriptor ContentResolver.openFileDescriptor()} --> + <category android:name="android.intent.category.OPENABLE" /> + </intent-filter> +</activity> +</pre> + + + + + + +<h3 id="OpenFile">Open a specific type of file</h3> + +<p>Instead of retrieving a copy of a file that you must import to your app +(by using the {@link android.content.Intent#ACTION_GET_CONTENT} action), when running on Android +4.4 or higher, you can instead request to <em>open</em> a file that's managed by another app by +using the {@link android.content.Intent#ACTION_OPEN_DOCUMENT} action and specifying a MIME type. +To also allow the user to instead create a new document that your app can write to, use the {@link +android.content.Intent#ACTION_CREATE_DOCUMENT} action instead. For example, instead of +selecting from existing PDF documents, the {@link android.content.Intent#ACTION_CREATE_DOCUMENT} +intent allows users to select where they'd like to create a new document (within another app +that manages the document's storage)—your app then receives the URI location of where it +can write the new document.</p> + +<p>Whereas the intent delivered to your {@link android.app.Activity#onActivityResult +onActivityResult()} method from the {@link android.content.Intent#ACTION_GET_CONTENT} action may +return a URI of any type, the result intent from {@link android.content.Intent#ACTION_OPEN_DOCUMENT} +and {@link android.content.Intent#ACTION_CREATE_DOCUMENT} always specify the chosen file as a {@code +content:} URI that's backed by a {@link android.provider.DocumentsProvider}. You can open the +file with {@link android.content.ContentResolver#openFileDescriptor openFileDescriptor()} and +query its details using columns from {@link android.provider.DocumentsContract.Document}.</p> + +<p>The returned URI grants your app long-term read access to the file (also possibly +with write access). So the {@link android.content.Intent#ACTION_OPEN_DOCUMENT} action is +particularly useful (instead of using {@link android.content.Intent#ACTION_GET_CONTENT}) +when you want to read an existing file without making a copy into your app, +or when you want to open and edit a file in place.</p> + +<p>You can also allow the user to select multiple files by adding +{@link android.content.Intent#EXTRA_ALLOW_MULTIPLE} to the intent, set to {@code true}. +If the user selects just one item, then you can retrieve the item from {@link +android.content.Intent#getData()}. If the user selects more than one item, then {@link +android.content.Intent#getData()} returns null and you must instead +retrieve each item from a {@link android.content.ClipData} +object that is returned by {@link android.content.Intent#getClipData()}.</p> + +<p class="note"><strong>Note:</strong> Your intent <strong>must</strong> specify a MIME type and +<strong>must</strong> declare the {@link android.content.Intent#CATEGORY_OPENABLE} category. If +appropriate, you can specify more than one MIME type by adding an array of MIME types with the +{@link android.content.Intent#EXTRA_MIME_TYPES} extra—if you do so, you must set the +primary MIME type in {@link android.content.Intent#setType setType()} to {@code "*/*"}.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_OPEN_DOCUMENT} or<br/> +{@link android.content.Intent#ACTION_CREATE_DOCUMENT}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>The MIME type corresponding to the file type the user should select. +</dd> + +<dt><b>Extras</b></dt> +<dd> + <dl> + <dt>{@link android.content.Intent#EXTRA_MIME_TYPES} + <dd>An array of MIME types corresponding to the types of files your app is + requesting. When you use this extra, you must set the primary MIME type in + {@link android.content.Intent#setType setType()} to {@code "*/*"}.</dd> + <dt>{@link android.content.Intent#EXTRA_ALLOW_MULTIPLE} + <dd>A boolean that declares whether the user can select more than one file at a time. + </dd> + <dt>{@link android.content.Intent#EXTRA_TITLE} + <dd>For use with {@link android.content.Intent#ACTION_CREATE_DOCUMENT} to specify + an initial file name. + </dd> + <dt>{@link android.content.Intent#EXTRA_LOCAL_ONLY} + <dd>A boolean that declares whether the returned file must be available directly from + the device, rather than requiring a download from a remote service. + </dd> + </dl> +</dd> + +<dt><b>Category</b></dt> +<dd> + <dl> + <dt>{@link android.content.Intent#CATEGORY_OPENABLE}</dt> + <dd>To return only "openable" files that can be represented as a file stream + with {@link android.content.ContentResolver#openFileDescriptor openFileDescriptor()}.</dd> + </dl> +</dd> + +</dl> + +<p><b>Example intent to get a photo:</b></p> +<pre> +static final int REQUEST_IMAGE_OPEN = 1; + +public void selectImage() { + Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT); + intent.setType("image/*"); + intent.addCategory(Intent.CATEGORY_OPENABLE); + // Only the system receives the ACTION_OPEN_DOCUMENT, so no need to test. + startActivityForResult(intent, REQUEST_IMAGE_OPEN); +} + +@Override +protected void onActivityResult(int requestCode, int resultCode, Intent data) { + if (requestCode == REQUEST_IMAGE_OPEN && resultCode == RESULT_OK) { + Uri fullPhotoUri = data.getData(); + // Do work with full size photo saved at fullPhotoUri + ... + } +} +</pre> + +<p>Third party apps cannot actually respond to an intent with the +{@link android.content.Intent#ACTION_OPEN_DOCUMENT} action. Instead, the system receives this +intent and displays all the files available from various apps in a unified user interface.</p> + +<p>To provide your app's files in this UI and allow other apps to open them, you must implement +a {@link android.provider.DocumentsProvider} and include an intent filter for +{@link android.provider.DocumentsContract#PROVIDER_INTERFACE} +({@code "android.content.action.DOCUMENTS_PROVIDER"}). For example: + +<pre> +<provider ... + android:grantUriPermissions="true" + android:exported="true" + android:permission="android.permission.MANAGE_DOCUMENTS"> + <intent-filter> + <action android:name="android.content.action.DOCUMENTS_PROVIDER" /> + </intent-filter> +</provider> +</pre> + +<p>For more information about how to make the files managed by your app openable from other apps, +read the <a href="{@docRoot}guide/topics/providers/document-provider.html">Storage Access +Framework</a> guide.</p> + + + + + + + + + + + +<h2 id="Maps">Maps</h2> + +<h3 id="ViewMap">Show a location on a map</h3> + +<p>To open a map, use the {@link android.content.Intent#ACTION_VIEW} action and specify +the location information in the intent data with one of the schemes defined below.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_VIEW}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd> +<dl> + <dt><code>geo:<em>latitude</em>,<em>longitude</em></code></dt> + <dd>Show the map at the given longitude and latitude. + <p>Example: <code>"geo:47.6,-122.3"</code> + </dd> + <dt><code>geo:<em>latitude</em>,<em>longitude</em>?z=<em>zoom</em></code></dt> + <dd>Show the map at the given longitude and latitude at a certain zoom level. A zoom level of + 1 shows the whole Earth, centered at the given <em>lat</em>,<em>lng</em>. The highest + (closest) zoom level is 23. + <p>Example: <code>"geo:47.6,-122.3?z=11"</code> + </dd> + <dt><code>geo:0,0?q=lat,lng(label)</code></dt> + <dd>Show the map at the given longitude and latitude with a string label. + <p>Example: <code>"geo:0,0?q=34.99,-106.61(Treasure)"</code> + </dd> + <dt><code>geo:0,0?q=my+street+address</code></dt> + <dd>Show the location for "my street address" (may be a specific address or location query). + <p>Example: <code>"geo:0,0?q=1600+Amphitheatre+Parkway%2C+CA"</code></p> + <p class="note"><strong>Note:</strong> All strings passed in the {@code geo} URI must + be encoded. For example, the string {@code 1st & Pike, Seattle} should become + {@code 1st%20%26%20Pike%2C%20Seattle}. Spaces in the string can be encoded with + {@code %20} or replaced with the plus sign ({@code +}).</p> + </dd> +</dl> +</dd> + +<dt><b>MIME Type</b></dt> +<dd>None</dd> + +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void showMap(Uri geoLocation) { + Intent intent = new Intent(Intent.ACTION_VIEW); + intent.setData(geoLocation); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.VIEW" /> + <data android:scheme="geo" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + + + + + + + + +<h2 id="Music">Music or Video</h2> + + +<h3 id="PlayMedia">Play a media file</h3> + +<p>To play a music file, use the {@link android.content.Intent#ACTION_VIEW} action and +specify the URI location of the file in the intent data.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_VIEW}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd> + <dl> + <dt>{@code file:<em><URI></em>} + <dt>{@code content:<em><URI></em>} + <dt>{@code http:<em><URL></em>} + </dl> +</dd> + +<dt><b>MIME Type</b></dt> +<dd> + <dl> + <dt><code>"audio/*"</code> + <dt><code>"application/ogg"</code> + <dt><code>"application/x-ogg"</code> + <dt><code>"application/itunes"</code> + <dt>Or any other that your app may require. + </dl> +</dd> + +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void playMedia(Uri file) { + Intent intent = new Intent(Intent.ACTION_VIEW); + intent.setData(file); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.VIEW" /> + <data android:type="audio/*" /> + <data android:type="application/ogg" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + + +<h3 id="PlaySearch">Play music based on a search query</h3> + +<p>To play music based on a search query, use the +{@link android.provider.MediaStore#INTENT_ACTION_MEDIA_PLAY_FROM_SEARCH} intent. An app may fire +this intent in response to the user's voice command to play music. The receiving app for this +intent performs a search within its inventory to match existing content to the given query and +starts playing that content.</p> + +<p>This intent should include the {@link android.provider.MediaStore#EXTRA_MEDIA_FOCUS} string +extra, which specifies the inteded search mode. For example, the search mode can specify whether +the search is for an artist name or song name.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.provider.MediaStore#INTENT_ACTION_MEDIA_PLAY_FROM_SEARCH}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>None</dd> + +<dt><b>Extras</b></dt> +<dd> +<dl> +<dt>{@link android.provider.MediaStore#EXTRA_MEDIA_FOCUS MediaStore.EXTRA_MEDIA_FOCUS} (required)</dt> +<dd> +<p>Indicates the search mode (whether the user is looking for a particular artist, album, song, +playlist, or radio channel). Most search modes take additional extras. For example, if the user +is interested in listening to a particular song, the intent might have three additional extras: +the song title, the artist, and the album. This intent supports the following search modes for +each value of {@link android.provider.MediaStore#EXTRA_MEDIA_FOCUS}:</p> +<dl> +<dt><p><em>Any</em> - <code>"vnd.android.cursor.item/*"</p></code></dt> +<dd> +<p>Play any music. The receiving app should play some music based on a smart choice, such +as the last playlist the user listened to.</p> +<p>Additional extras:</p> +<ul> + <li>{@link android.app.SearchManager#QUERY} (required) - An empty string. This extra is always + provided for backward compatibility: existing apps that do not know about search modes can + process this intent as an unstructured search.</li> +</ul> +</dd> +<dt><p><em>Unstructured</em> - <code>"vnd.android.cursor.item/*"</code></p></dt> +<dd> +<p>Play a particular song, album or genre from an unstructured search query. Apps may generate +an intent with this search mode when they can't identify the type of content the user wants to +listen to. Apps should use more specific search modes when possible.</p> +<p>Additional extras:</p> +<ul> + <li>{@link android.app.SearchManager#QUERY} (required) - A string that contains any combination + of: the artist, the album, the song name, or the genre.</li> +</ul> +</dd> +<dt><p><em>Genre</em> - +{@link android.provider.MediaStore.Audio.Genres#ENTRY_CONTENT_TYPE Audio.Genres.ENTRY_CONTENT_TYPE}</p></dt> +<dd> +<p>Play music of a particular genre.</p> +<p>Additional extras:</p> +<ul> + <li><code>"android.intent.extra.genre"</code> (required) - The genre.</li> + <li>{@link android.app.SearchManager#QUERY} (required) - The genre. This extra is always provided + for backward compatibility: existing apps that do not know about search modes can process + this intent as an unstructured search.</li> +</ul> +</dd> +<dt><p><em>Artist</em> - +{@link android.provider.MediaStore.Audio.Artists#ENTRY_CONTENT_TYPE Audio.Artists.ENTRY_CONTENT_TYPE}</p></dt> +<dd> +<p>Play music from a particular artist.</p> +<p>Additional extras:</p> +<ul> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ARTIST} (required) - The artist.</li> + <li><code>"android.intent.extra.genre"</code> - The genre.</li> + <li>{@link android.app.SearchManager#QUERY} (required) - A string that contains any combination of + the artist or the genre. This extra is always provided for backward compatibility: + existing apps that do not know about search modes can process this intent as an unstructured + search.</li> +</ul> +</dd> +<dt><p><em>Album</em> - +{@link android.provider.MediaStore.Audio.Albums#ENTRY_CONTENT_TYPE Audio.Albums.ENTRY_CONTENT_TYPE}</p></dt> +<dd> +<p>Play music from a particular album.</p> +<p>Additional extras:</p> +<ul> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ALBUM} (required) - The album.</li> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ARTIST} - The artist.</li> + <li><code>"android.intent.extra.genre"</code> - The genre.</li> + <li>{@link android.app.SearchManager#QUERY} (required) - A string that contains any combination of + the album or the artist. This extra is always provided for backward + compatibility: existing apps that do not know about search modes can process this intent as an + unstructured search.</li> +</ul> +</dd> +<dt><p><em>Song</em> - <code>"vnd.android.cursor.item/audio"</code></p></dt> +<dd> +<p>Play a particular song.</p> +<p>Additional extras:</p> +<ul> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ALBUM} - The album.</li> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ARTIST} - The artist.</li> + <li><code>"android.intent.extra.genre"</code> - The genre.</li> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_TITLE} (required) - The song name.</li> + <li>{@link android.app.SearchManager#QUERY} (required) - A string that contains any combination of: + the album, the artist, the genre, or the title. This extra is always provided for + backward compatibility: existing apps that do not know about search modes can process this + intent as an unstructured search.</li> +</ul> +</dd> +<dt><p><em>Radio channel</em> - <code>"vnd.android.cursor.item/radio"</code></p></dt> +<dd> +<p>Play a particular radio channel or a radio channel that matches some criteria specified +by additional extras.</p> +<p>Additional extras:</p> +<ul> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ALBUM} - The album.</li> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ARTIST} - The artist.</li> + <li><code>"android.intent.extra.genre"</code> - The genre.</li> + <li><code>"android.intent.extra.radio_channel"</code> - The radio channel.</li> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_TITLE} - The song name that the radio + channel is based on.</li> + <li>{@link android.app.SearchManager#QUERY} (required) - A string that contains any combination + of: the album, the artist, the genre, the radio channel, or the title. This extra is + always provided for backward compatibility: existing apps that do not know about search + modes can process this intent as an unstructured search.</li> +</ul> +</dd> +<dt><p><em>Playlist</em> - {@link android.provider.MediaStore.Audio.Playlists#ENTRY_CONTENT_TYPE Audio.Playlists.ENTRY_CONTENT_TYPE}</p></dt> +<dd> +<p>Play a particular playlist or a playlist that matches some criteria specified +by additional extras.</p> +<p>Additional extras:</p> +<ul> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ALBUM} - The album.</li> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_ARTIST} - The artist.</li> + <li><code>"android.intent.extra.genre"</code> - The genre.</li> + <li><code>"android.intent.extra.playlist"</code> - The playlist.</li> + <li>{@link android.provider.MediaStore#EXTRA_MEDIA_TITLE} - The song name that the playlist is + based on.</li> + <li>{@link android.app.SearchManager#QUERY} (required) - A string that contains any combination + of: the album, the artist, the genre, the playlist, or the title. This extra is always + provided for backward compatibility: existing apps that do not know about search modes can + process this intent as an unstructured search.</li> +</ul> +</dd> +</dl> +</dd> +</dl> +</dd> +</dl> + + + +<p><b>Example intent:</b></p> +<p>If the user wants to listen to a radio station that plays songs from a particular artist, +a search app may generate the following intent:</p> +<pre> +public void playSearchRadioByArtist(String artist) { + Intent intent = new Intent(MediaStore.INTENT_ACTION_MEDIA_PLAY_FROM_SEARCH); + intent.putExtra(MediaStore.EXTRA_MEDIA_FOCUS, + "vnd.android.cursor.item/radio"); + intent.putExtra(MediaStore.EXTRA_MEDIA_ARTIST, artist); + intent.putExtra(SearchManager.QUERY, artist); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.media.action.MEDIA_PLAY_FROM_SEARCH" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> +<p>When handling this intent, your activity should check the value of the +{@link android.provider.MediaStore#EXTRA_MEDIA_FOCUS} extra in the incoming +{@link android.content.Intent} to determine the search mode. Once your activity has identified +the search mode, it should read the values of the additional extras for that particular search mode. +With this information your app can then perform the search within its inventory to play the +content that matches the search query. For example:</p> +<pre> +protected void onCreate(Bundle savedInstanceState) { + ... + Intent intent = this.getIntent(); + if (intent.getAction().compareTo(MediaStore.INTENT_ACTION_MEDIA_PLAY_FROM_SEARCH) == 0) { + + String mediaFocus = intent.getStringExtra(MediaStore.EXTRA_MEDIA_FOCUS); + String query = intent.getStringExtra(SearchManager.QUERY); + + // Some of these extras may not be available depending on the search mode + String album = intent.getStringExtra(MediaStore.EXTRA_MEDIA_ALBUM); + String artist = intent.getStringExtra(MediaStore.EXTRA_MEDIA_ARTIST); + String genre = intent.getStringExtra("android.intent.extra.genre"); + String playlist = intent.getStringExtra("android.intent.extra.playlist"); + String rchannel = intent.getStringExtra("android.intent.extra.radio_channel"); + String title = intent.getStringExtra(MediaStore.EXTRA_MEDIA_TITLE); + + // Determine the search mode and use the corresponding extras + if (mediaFocus == null) { + // 'Unstructured' search mode (backward compatible) + playUnstructuredSearch(query); + + } else if (mediaFocus.compareTo("vnd.android.cursor.item/*") == 0) { + if (query.isEmpty()) { + // 'Any' search mode + playResumeLastPlaylist(); + } else { + // 'Unstructured' search mode + playUnstructuredSearch(query); + } + + } else if (mediaFocus.compareTo(MediaStore.Audio.Genres.ENTRY_CONTENT_TYPE) == 0) { + // 'Genre' search mode + playGenre(genre); + + } else if (mediaFocus.compareTo(MediaStore.Audio.Artists.ENTRY_CONTENT_TYPE) == 0) { + // 'Artist' search mode + playArtist(artist, genre); + + } else if (mediaFocus.compareTo(MediaStore.Audio.Albums.ENTRY_CONTENT_TYPE) == 0) { + // 'Album' search mode + playAlbum(album, artist); + + } else if (mediaFocus.compareTo("vnd.android.cursor.item/audio") == 0) { + // 'Song' search mode + playSong(album, artist, genre, title); + + } else if (mediaFocus.compareTo("vnd.android.cursor.item/radio") == 0) { + // 'Radio channel' search mode + playRadioChannel(album, artist, genre, rchannel, title); + + } else if (mediaFocus.compareTo(MediaStore.Audio.Playlists.ENTRY_CONTENT_TYPE) == 0) { + // 'Playlist' search mode + playPlaylist(album, artist, genre, playlist, title); + } + } +} +</pre> + + + + +<h2 id="Phone">Phone</h2> + + +<h3 id="DialPhone">Initiate a phone call</h3> + +<p>To open the phone app and dial a phone number, use the {@link +android.content.Intent#ACTION_DIAL} action and specify a phone number using +the URI scheme defined below. When the phone app opens, it displays the phone number +but the user must press the <em>Call</em> button to begin the phone call.</p> + + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_DIAL}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>{@code tel:<phone-number>}</dd> + +<dt><b>MIME Type</b></dt> +<dd>None</dd> + +</dl> + + +<p>Valid telephone numbers are those defined +in <a href="http://tools.ietf.org/html/rfc3966">the IETF RFC 3966</a>. +Valid examples include the following:</p> +<ul> +<li><code>tel:2125551212</code> </li> +<li><code>tel:(212) 555 1212</code></li> +</ul> +<p>The Phone's dialer is good at normalizing schemes, such as +telephone numbers. So the scheme described isn't strictly required in the +{@link android.net.Uri#parse(String) Uri.parse()} method. +However, if you have not tried a scheme or are unsure whether it +can be handled, use the {@link android.net.Uri#fromParts Uri.fromParts()} +method instead.</p> + + +<p><b>Example intent:</b></p> +<pre> +public void dialPhoneNumber(String phoneNumber) { + Intent intent = new Intent(Intent.ACTION_DIAL); + intent.setData(Uri.parse("tel:" + phoneNumber)); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + + + + + + + + + +<h2 id="Settings">Settings</h2> + +<h3 id="OpenSettings">Open a specific section of Settings</h3> + +<p>To open a screen in the system settings when your app requires the user to change something, +use one of the following intent actions to open the settings screen respective to the action name. +</p> + +<dl> +<dt><b>Action</b></dt> +<dd> +{@link android.provider.Settings#ACTION_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_WIRELESS_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_AIRPLANE_MODE_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_WIFI_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_APN_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_BLUETOOTH_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_DATE_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_LOCALE_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_INPUT_METHOD_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_DISPLAY_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_SECURITY_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_LOCATION_SOURCE_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_INTERNAL_STORAGE_SETTINGS}<br/> +{@link android.provider.Settings#ACTION_MEMORY_CARD_SETTINGS}<br/> +<p>See the {@link android.provider.Settings} documentation for additional settings screens +that are available.</p> +</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd>None</dd> + +<dt><b>MIME Type</b></dt> +<dd>None</dd> + +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void openWifiSettings() { + Intent intent = new Intent(Intent.ACTION_WIFI_SETTINGS); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + + + + + + +<h2 id="Messaging">Text Messaging</h2> + +<h3 id="SendMessage">Compose an SMS/MMS message with attachment</h3> + +<p>To initiate an SMS or MMS text message, use one of the intent actions below and specify message +details such as the phone number, subject, and message body using the extra keys listed below.</p> + +<dl> +<dt><b>Action</b></dt> +<dd>{@link android.content.Intent#ACTION_SENDTO} or<br> + {@link android.content.Intent#ACTION_SEND} or<br> + {@link android.content.Intent#ACTION_SEND_MULTIPLE}</dd> + +<dt><b>Data URI Scheme</b></dt> +<dd> + <dl> + <dt>{@code sms:<em><phone_number></em>} + <dt>{@code smsto:<em><phone_number></em>} + <dt>{@code mms:<em><phone_number></em>} + <dt>{@code mmsto:<em><phone_number></em>} + </dl> + <p>Each of these schemes are handled the same. +</dd> + +<dt><b>MIME Type</b></dt> +<dd> + <dl> + <dt>{@link org.apache.http.protocol.HTTP#PLAIN_TEXT_TYPE} (<code>"text/plain"</code>) + <dt><code>"image/*"</code> + <dt><code>"video/*"</code> + </dl> +</dd> + +<dt><b>Extras</b></dt> +<dd> + <dl> + <dt><code>"subject"</code></dt> + <dd>A string for the message subject (usually for MMS only).</dd> + <dt><code>"sms_body"</code></dt> + <dd>A string for the text message.</dd> + <dt>{@link android.content.Intent#EXTRA_STREAM}</dt> + <dd>A {@link android.net.Uri} pointing to the +image or video to attach. If using the {@link android.content.Intent#ACTION_SEND_MULTIPLE} action, +this extra should be an {@link java.util.ArrayList} of {@link +android.net.Uri}s pointing to the images/videos to attach.</dd> + <dl> +</dd> + +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void composeMmsMessage(String message, Uri attachment) { + Intent intent = new Intent(Intent.ACTION_SEND); + intent.setType(HTTP.PLAIN_TEXT_TYPE); + intent.putExtra("sms_body", message); + intent.putExtra(Intent.EXTRA_STREAM, attachment); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + +<p>If you want to ensure that your intent is handled only by a text messaging app (and not other +email or social apps), then use the {@link android.content.Intent#ACTION_SENDTO} action +and include the {@code "smsto:"} data scheme. For example:</p> + +<pre> +public void composeMmsMessage(String message, Uri attachment) { + Intent intent = new Intent(Intent.ACTION_SEND); + intent.setData(Uri.parse("smsto:")); // This ensures only SMS apps respond + intent.putExtra("sms_body", message); + intent.putExtra(Intent.EXTRA_STREAM, attachment); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.SEND" /> + <data android:type="text/plain" /> + <data android:type="image/*" /> + <category android:name="android.intent.category.DEFAULT" /> + </intent-filter> +</activity> +</pre> + +<p class="note"><strong>Note:</strong> If you're developing an SMS/MMS messaging app, you must +implement intent filters for several additional actions in order to be available as the +<em>default SMS app</em> on Android 4.4 and higher. For more information, see the documentation +at {@link android.provider.Telephony}.</p> + + + + + + + + + + +<h2 id="Browser">Web Browser</h2> + +<h3 id="ViewUrl">Load a web URL</h3> + +<p>To open a web page, use the {@link android.content.Intent#ACTION_VIEW} action +and specify the web URL in the intent data.</p> + +<dl> + <dt><b>Action</b></dt> + <dd>{@link android.content.Intent#ACTION_VIEW}<dd> + + <dt><b>Data URI Scheme</b></dt> + <dd>{@code http:<em><URL></em>}<br/> + {@code https:<em><URL></em>}</dd> + + <dt><b>MIME Type</b></dt> + <dd> + <dl> + <dt>{@link org.apache.http.protocol.HTTP#PLAIN_TEXT_TYPE} (<code>"text/plain"</code>) + <dt><code>"text/html"</code> + <dt><code>"application/xhtml+xml"</code> + <dt><code>"application/vnd.wap.xhtml+xml"</code> + </dl> + </dd> +</dl> + + +<p><b>Example intent:</b></p> +<pre> +public void openWebPage(String url) { + Uri webpage = Uri.parse(url); + Intent intent = new Intent(Intent.ACTION_VIEW, webpage); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + +<p><b>Example intent filter:</b></p> +<pre> +<activity ...> + <intent-filter> + <action android:name="android.intent.action.VIEW" /> + <!-- Include the host attribute if you want your app to respond + only to URLs with your app's domain. --> + <data android:scheme="http" android:host="www.example.com" /> + <category android:name="android.intent.category.DEFAULT" /> + <!-- The BROWSABLE category is required to get links from web pages. --> + <category android:name="android.intent.category.BROWSABLE" /> + </intent-filter> +</activity> +</pre> + + +<p class="note"><strong>Tip:</strong> If your Android app provides functionality similar to +your web site, include an intent filter for URLs that point to your web site. Then, +if users have your app installed, links from emails or other web pages pointing to your web site +open your Android app instead of your web page.</p> + + + + +<h3 id="SearchWeb">Perform a web search</h3> + +<p>To initiate a web search, use the {@link android.content.Intent#ACTION_WEB_SEARCH} action +and specify the search string in the +{@link android.app.SearchManager#QUERY SearchManager.QUERY} extra.</p> + + +<dl> + <dt><b>Action</b></dt> + <dd>{@link android.content.Intent#ACTION_WEB_SEARCH}</dd> + + <dt><b>Data URI Scheme</b></dt> + <dd>None</dd> + + <dt><b>MIME Type</b></dt> + <dd>None</dd> + + <dt><b>Extras</b></dt> + <dd> + <dl> + <dt>{@link android.app.SearchManager#QUERY SearchManager.QUERY}</dt> + <dd>The search string.</dd> + </dl> + </dd> +</dl> + +<p><b>Example intent:</b></p> +<pre> +public void searchWeb(String query) { + Intent intent = new Intent(Intent.ACTION_SEARCH); + intent.putExtra(SearchManager.QUERY, query); + if (intent.resolveActivity(getPackageManager()) != null) { + startActivity(intent); + } +} +</pre> + + + diff --git a/docs/html/guide/components/intents-filters.jd b/docs/html/guide/components/intents-filters.jd index dfe5fac..2f8c407 100644 --- a/docs/html/guide/components/intents-filters.jd +++ b/docs/html/guide/components/intents-filters.jd @@ -1,4 +1,5 @@ page.title=Intents and Intent Filters +page.tags="IntentFilter" @jd:body <div id="qv-wrapper"> @@ -6,1049 +7,906 @@ page.title=Intents and Intent Filters <h2>In this document</h2> <ol> -<li><a href="#iobjs">Intent Objects</a></li> -<li><a href="#ires">Intent Resolution</a></li> -<li style="margin-left: 2em"><a href="#ifs">Intent filters</a></li> -<li style="margin-left: 2em"><a href="#ccases">Common cases</a></li> -<li style="margin-left: 2em"><a href="#imatch">Using intent matching</a></li> -<li><a href="#npex">Note Pad Example</a></li> + <li><a href="#Types">Intent Types</a></li> + <li><a href="#Building">Building an Intent</a> + <ol> + <li><a href="#ExampleExplicit">Example explicit intent</a></li> + <li><a href="#ExampleSend">Example implicit intent</a></li> + <li><a href="#ForceChooser">Forcing an app chooser</a></li> + </ol> + </li> + <li><a href="#Receiving">Receiving an Implicit Intent</a> + <ol> + <li><a href="#ExampleFilters">Example filters</a></li> + </ol> + </li> + <li><a href="#PendingIntent">Using a Pending Intent</a></li> + <li><a href="#Resolution">Intent Resolution</a> + <ol> + <li><a href="#ActionTest">Action test</a></li> + <li><a href="#CategoryTest">Category test</a></li> + <li><a href="#DataTest">Data test</a></li> + <li><a href="#imatch">Intent matching</a></li> + </ol> + </li> </ol> -<h2>Key classes</h2> +<h2>See also</h2> <ol> -<li>{@link android.content.Intent}</li> -<li>{@link android.content.IntentFilter}</li> -<li>{@link android.content.BroadcastReceiver}</li> -<li>{@link android.content.pm.PackageManager}</li> +<li><a href="{@docRoot}training/basics/intents/index.html">Interacting with Other Apps</a></li> +<li><a href="{@docRoot}training/sharing/index.html">Sharing Content</a></li> </ol> </div> </div> -<p> -Three of the core components of an application — activities, services, and -broadcast receivers — are activated through messages, called <i>intents</i>. -Intent messaging is a facility for late run-time binding between components in the same -or different applications. The intent itself, an {@link android.content.Intent} -object, is a passive data structure holding an abstract description of an operation -to be performed — or, often in the case of broadcasts, a description of something -that has happened and is being announced. There are separate mechanisms for -delivering intents to each type of component: -</p> + + +<p>An {@link android.content.Intent} is a messaging object you can use to request an action +from another <a href="{@docRoot}guide/components/fundamentals.html#Components">app component</a>. +Although intents facilitate communication between components in several ways, there are three +fundamental use-cases:</p> <ul> -<li>An Intent object is passed to <code>{@link android.content.Context#startActivity -Context.startActivity()}</code> or <code>{@link android.app.Activity#startActivityForResult -Activity.startActivityForResult()}</code> to launch an activity or get an existing -activity to do something new. (It can also be passed to -<code>{@link android.app.Activity#setResult(int, Intent) Activity.setResult()}</code> -to return information to the activity that called {@code startActivityForResult()}.)</li> - -<li><p>An Intent object is passed to <code>{@link android.content.Context#startService -Context.startService()}</code> to initiate a service or deliver new instructions to an -ongoing service. Similarly, an intent can be passed to <code>{@link -android.content.Context#bindService Context.bindService()}</code> to establish a -connection between the calling component and a target service. It can optionally -initiate the service if it's not already running.</p></li> - -<li><p>Intent objects passed to any of the broadcast methods (such as <code>{@link -android.content.Context#sendBroadcast(Intent) Context.sendBroadcast()}</code>, -<code>{@link android.content.Context#sendOrderedBroadcast(Intent, String) -Context.sendOrderedBroadcast()}</code>, or <code>{@link -android.content.Context#sendStickyBroadcast Context.sendStickyBroadcast()}</code>) -are delivered to all interested broadcast receivers. Many kinds of broadcasts -originate in system code.</p></li> +<li><b>To start an activity:</b> +<p>An {@link android.app.Activity} represents a single screen in an app. You can start a new +instance of an {@link android.app.Activity} by passing an {@link android.content.Intent} +to {@link android.content.Context#startActivity startActivity()}. The {@link android.content.Intent} +describes the activity to start and carries any necessary data.</p> + +<p>If you want to receive a result from the activity when it finishes, +call {@link android.app.Activity#startActivityForResult +startActivityForResult()}. Your activity receives the result +as a separate {@link android.content.Intent} object in your activity's {@link +android.app.Activity#onActivityResult onActivityResult()} callback. +For more information, see the <a +href="{@docRoot}guide/components/activities.html">Activities</a> guide.</p></li> + +<li><b>To start a service:</b> +<p>A {@link android.app.Service} is a component that performs operations in the background +without a user interface. You can start a service to perform a one-time operation +(such as download a file) by passing an {@link android.content.Intent} +to {@link android.content.Context#startService startService()}. The {@link android.content.Intent} +describes the service to start and carries any necessary data.</p> + +<p>If the service is designed with a client-server interface, you can bind to the service +from another component by passing an {@link android.content.Intent} to {@link +android.content.Context#bindService bindService()}</code>. For more information, see the <a +href="{@docRoot}guide/components/services.html">Services</a> guide.</p></li> + +<li><b>To deliver a broadcast:</b> +<p>A broadcast is a message that any app can receive. The system delivers various +broadcasts for system events, such as when the system boots up or the device starts charging. +You can deliver a broadcast to other apps by passing an {@link android.content.Intent} +to {@link android.content.Context#sendBroadcast(Intent) sendBroadcast()}, +{@link android.content.Context#sendOrderedBroadcast(Intent, String) +sendOrderedBroadcast()}, or {@link +android.content.Context#sendStickyBroadcast sendStickyBroadcast()}.</p> +</li> </ul> -<p> -In each case, the Android system finds the appropriate activity, service, or set -of broadcast receivers to respond to the intent, instantiating them if necessary. -There is no overlap within these messaging systems: Broadcast intents are delivered -only to broadcast receivers, never to activities or services. An intent passed to -{@code startActivity()} is delivered only to an activity, never to a service or -broadcast receiver, and so on. -</p> -<p> -This document begins with a description of Intent objects. It then describes the -rules Android uses to map intents to components — how it resolves which -component should receive an intent message. For intents that don't explicitly -name a target component, this process involves testing the Intent object against -<i>intent filters</i> associated with potential targets. -</p> -<h2><a name="iobjs"></a>Intent Objects</h2> +<h2 id="Types">Intent Types</h2> -<p> -An {@link android.content.Intent} object is a bundle of information. It -contains information of interest to the component that receives the intent -(such as the action to be taken and the data to act on) plus information -of interest to the Android system (such as the category of component that -should handle the intent and instructions on how to launch a target activity). -Principally, it can contain the following: +<p>There are two types of intents:</p> + +<ul> +<li><b>Explicit intents</b> specify the component to start by name (the +fully-qualified class name). You'll typically use an explicit intent to start a component in +your own app, because you know the class name of the activity or service you want to start. For +example, start a new activity in response to a user action or start a service to download +a file in the background.</li> + +<li><b>Implicit intents</b> do not name a specific component, but instead declare a general action +to perform, which allows a component from another app to handle it. For example, if you want to +show the user a location on a map, you can use an implicit intent to request that another capable +app show a specified location on a map.</li> +</ul> + +<p>When you create an explicit intent to start an activity or service, the system immediately +starts the app component specified in the {@link android.content.Intent} object.</p> + +<div class="figure" style="width:446px"> +<img src="{@docRoot}images/components/intent-filters@2x.png" width="446" alt=""/> +<p class="img-caption"><strong>Figure 1.</strong> Illustration of how an implicit intent is +delivered through the system to start another activity: <b>[1]</b> <em>Activity A</em> creates an +{@link android.content.Intent} with an action description and passes it to {@link +android.content.Context#startActivity startActivity()}. <b>[2]</b> The Android System searches all +apps for an intent filter that matches the intent. When a match is found, <b>[3]</b> the system +starts the matching activity (<em>Activity B</em>) by invoking its {@link +android.app.Activity#onCreate onCreate()} method and passing it the {@link android.content.Intent}. </p> +</div> + +<p>When you create an implicit intent, the Android system finds the appropriate component to start +by comparing the contents of the intent to the <em>intent filters</em> declared in the <a href= +"{@docRoot}guide/topics/manifest/manifest-intro.html">manifest file</a> of other apps on the +device. If the intent matches an intent filter, the system starts that component and delivers it +the {@link android.content.Intent} object. If multiple intent filters are compatible, the system +displays a dialog so the user can pick which app to use.</p> + +<p>An intent filter is an expression in an app's manifest file that +specifies the type of intents that the component +would like to receive. For instance, by declaring an intent filter for an activity, +you make it possible for other apps to directly start your activity with a certain kind of intent. +Likewise, if you do <em>not</em> declare any intent filters for an activity, then it can be started +only with an explicit intent.</p> + +<p class="caution"><strong>Caution:</strong> To ensure your app is secure, always use an explicit +intent when starting a {@link android.app.Service} and do not +declare intent filters for your services. Using an implicit intent to start a service is a +security hazard because you cannot be certain what service will respond to the intent, +and the user cannot see which service starts.</p> + + + + + +<h2 id="Building">Building an Intent</h2> + +<p>An {@link android.content.Intent} object carries information that the Android system uses +to determine which component to start (such as the exact component name or component +category that should receive the intent), plus information that the recipient component uses in +order to properly perform the action (such as the action to take and the data to act upon).</p> + + +<p>The primary information contained in an {@link android.content.Intent} is the following:</p> <dl> -<dt><b>Component name</b><a name="cname"></a></dt> -<dd>The name of the component that should handle the intent. This field is -a {@link android.content.ComponentName} object — a combination of the -fully qualified class name of the target component (for example "{@code -com.example.project.app.FreneticActivity}") and the package name set -in the manifest file of the application where the component resides (for -example, "{@code com.example.project}"). The package part of the component -name and the package name set in the manifest do not necessarily have to match. - -<p> -The component name is optional. If it is set, the Intent object is -delivered to an instance of the designated class. If it is not set, -Android uses other information in the Intent object to locate a suitable -target — see <a href="#ires">Intent Resolution</a>, later in this -document. -</p> +<dt><b>Component name</b></dt> +<dd>The name of the component to start. + +<p>This is optional, but it's the critical piece of information that makes an intent +<b>explicit</b>, meaning that the intent should be delivered only to the app component +defined by the component name. Without a component name, the intent is <b>implicit</b> and the +system decides which component should receive the intent based on the other intent information +(such as the action, data, and category—described below). So if you need to start a specific +component in your app, you should specify the component name.</p> + +<p class="note"><strong>Note:</strong> When starting a {@link android.app.Service}, you should +<strong>always specify the component name</strong>. Otherwise, you cannot be certain what service +will respond to the intent, and the user cannot see which service starts.</p> + +<p>This field of the {@link android.content.Intent} is a +{@link android.content.ComponentName} object, which you can specify using a fully +qualified class name of the target component, including the package name of the app. For example, +{@code com.example.ExampleActivity}. You can set the component name with {@link +android.content.Intent#setComponent setComponent()}, {@link android.content.Intent#setClass +setClass()}, {@link android.content.Intent#setClassName(String, String) setClassName()}, or with the +{@link android.content.Intent} constructor.</p> -<p> -The component name is set by <code>{@link android.content.Intent#setComponent -setComponent()}</code>, <code>{@link android.content.Intent#setClass -setClass()}</code>, or <code>{@link android.content.Intent#setClassName(String, String) -setClassName()}</code> and read by <code>{@link android.content.Intent#getComponent -getComponent()}</code>. -</p> </dd> <p><dt><b>Action</b></dt> -<dd>A string naming the action to be performed — or, in the case of broadcast -intents, the action that took place and is being reported. The Intent class defines -a number of action constants, including these: -</p> +<dd>A string that specifies the generic action to perform (such as <em>view</em> or <em>pick</em>). -<table> -<tr> - <th>Constant</th> - <th>Target component</th> - <th>Action</th> -</tr><tr> - <td>{@code ACTION_CALL} - <td>activity - <td>Initiate a phone call. -</tr><tr> - <td>{@code ACTION_EDIT} - <td>activity - <td>Display data for the user to edit. -</tr><tr> - <td>{@code ACTION_MAIN} - <td>activity - <td>Start up as the initial activity of a task, with no data input and no returned output. -</tr><tr> - <td>{@code ACTION_SYNC} - <td>activity - <td>Synchronize data on a server with data on the mobile device. -</tr><tr> - <td>{@code ACTION_BATTERY_LOW} - <td>broadcast receiver - <td>A warning that the battery is low. -</tr><tr> - <td>{@code ACTION_HEADSET_PLUG} - <td>broadcast receiver - <td>A headset has been plugged into the device, or unplugged from it. -</tr><tr> - <td>{@code ACTION_SCREEN_ON} - <td>broadcast receiver - <td>The screen has been turned on. -</tr><tr> - <td>{@code ACTION_TIMEZONE_CHANGED} - <td>broadcast receiver - <td>The setting for the time zone has changed. -</tr> -</table> +<p>In the case of a broadcast intent, this is the action that took place and is being reported. +The action largely determines how the rest of the intent is structured—particularly +what is contained in the data and extras. -<p> -See the {@link android.content.Intent} class description for a list of -pre-defined constants for generic actions. Other actions are defined -elsewhere in the Android API. -You can also define your own action strings for activating the components -in your application. Those you invent should include the application -package as a prefix — for example: -"<code>com.example.project.SHOW_COLOR</code>". -</p> +<p>You can specify your own actions for use by intents within your app (or for use by other +apps to invoke components in your app), but you should usually use action constants +defined by the {@link android.content.Intent} class or other framework classes. Here are some +common actions for starting an activity:</p> -<p> -The action largely determines how the rest of the intent is structured -— particularly the <a href="#data">data</a> and -<a href="#extras">extras</a> fields — -much as a method name determines a set of arguments and a return value. -For this reason, it's a good idea to use action names that are -as specific as possible, and to couple them tightly to the other fields of -the intent. In other words, instead of defining an action in isolation, -define an entire protocol for the Intent objects your components can handle. -</p> +<dl> +<dt>{@link android.content.Intent#ACTION_VIEW}</dt> + <dd>Use this action in an intent with {@link + android.content.Context#startActivity startActivity()} when you have some information that + an activity can show to the user, such as a photo to view in a gallery app, or an address to + view in a map app.</dd> + +<dt>{@link android.content.Intent#ACTION_SEND}</dt> + <dd>Also known as the "share" intent, you should use this in an intent with {@link + android.content.Context#startActivity startActivity()} when you have some data that the user can + share through another app, such as an email app or social sharing app.</dd> +</dl> -<p> -The action in an Intent object is set by the -<code>{@link android.content.Intent#setAction setAction()}</code> -method and read by -<code>{@link android.content.Intent#getAction getAction()}</code>. -</p> -</dd> +<p>See the {@link android.content.Intent} class reference for more +constants that define generic actions. Other actions are defined +elsewhere in the Android framework, such as in {@link android.provider.Settings} for actions +that open specific screens in the system's Settings app.</p> -<p><dt><b>Data</b><a name="data"></a></dt> -<dd>The URI of the data to be acted on and the MIME type of that data. Different -actions are paired with different kinds of data specifications. For example, if -the action field is {@code ACTION_EDIT}, -the data field would contain the URI of the document to be displayed for editing. -If the action is {@code ACTION_CALL}, the data field would be a {@code tel:} URI -with the number to call. Similarly, if the action is {@code ACTION_VIEW} and the -data field is an {@code http:} URI, the receiving activity would be called upon -to download and display whatever data the URI refers to. +<p>You can specify the action for an intent with {@link android.content.Intent#setAction +setAction()} or with an {@link android.content.Intent} constructor.</p> -<p> -When matching an intent to a component that is capable of handling the data, -it's often important to know the type of data (its MIME type) in addition to its URI. -For example, a component able to display image data should not be called -upon to play an audio file. -</p> +<p>If you define your own actions, be sure to include your app's package name +as a prefix. For example:</p> +<pre>static final String ACTION_TIMETRAVEL = "com.example.action.TIMETRAVEL";</pre> +</dd> -<p> -In many cases, the data type can be inferred from the URI — particularly -{@code content:} URIs, which indicate that the data is located on the device and -controlled by a content provider (see the -<a href="{@docRoot}guide/topics/providers/content-providers.html">separate -discussion on content providers</a>). But the type can also be explicitly set -in the Intent object. -The <code>{@link android.content.Intent#setData setData()}</code> method specifies -data only as a URI, <code>{@link android.content.Intent#setType setType()}</code> -specifies it only as a MIME type, and <code>{@link -android.content.Intent#setDataAndType setDataAndType()}</code> specifies it as both -a URI and a MIME type. The URI is read by <code>{@link -android.content.Intent#getData getData()}</code> and the type by <code>{@link -android.content.Intent#getType getType()}</code>. -</p> +<dt><b>Data</b></dt> +<dd>The URI (a {@link android.net.Uri} object) that references the data to be acted on and/or the +MIME type of that data. The type of data supplied is generally dictated by the intent's action. For +example, if the action is {@link android.content.Intent#ACTION_EDIT}, the data should contain the +URI of the document to edit. + +<p>When creating an intent, +it's often important to specify the type of data (its MIME type) in addition to its URI. +For example, an activity that's able to display images probably won't be able +to play an audio file, even though the URI formats could be similar. +So specifying the MIME type of your data helps the Android +system find the best component to receive your intent. +However, the MIME type can sometimes be inferred from the URI—particularly when the data is a +{@code content:} URI, which indicates the data is located on the device and controlled by a +{@link android.content.ContentProvider}, which makes the data MIME type visible to the system.</p> + +<p>To set only the data URI, call {@link android.content.Intent#setData setData()}. +To set only the MIME type, call {@link android.content.Intent#setType setType()}. If necessary, you +can set both explicitly with {@link +android.content.Intent#setDataAndType setDataAndType()}.</p> + +<p class="caution"><strong>Caution:</strong> If you want to set both the URI and MIME type, +<strong>do not</strong> call {@link android.content.Intent#setData setData()} and +{@link android.content.Intent#setType setType()} because they each nullify the value of the other. +Always use {@link android.content.Intent#setDataAndType setDataAndType()} to set both +URI and MIME type.</p> </dd> <p><dt><b>Category</b></dt> -<dd>A string containing additional information about the kind of component -that should handle the intent. Any number of category descriptions can be -placed in an Intent object. As it does for actions, the Intent class defines -several category constants, including these: - -<table> -<tr> - <th>Constant</th> - <th>Meaning</th> -</tr><tr> - <td>{@code CATEGORY_BROWSABLE} - <td>The target activity can be safely invoked by the browser to display data - referenced by a link — for example, an image or an e-mail message. -</tr><tr> - <td>{@code CATEGORY_GADGET} - <td>The activity can be embedded inside of another activity that hosts gadgets. -</tr><tr> - <td>{@code CATEGORY_HOME} - <td>The activity displays the home screen, the first screen the user sees when - the device is turned on or when the <em>Home</em> button is pressed. -</tr><tr> - <td>{@code CATEGORY_LAUNCHER} - <td>The activity can be the initial activity of a task and is listed in - the top-level application launcher. -</tr><tr> - <td>{@code CATEGORY_PREFERENCE} - <td>The target activity is a preference panel. -</tr> -</table> +<dd>A string containing additional information about the kind of component +that should handle the intent. Any number of category descriptions can be +placed in an intent, but most intents do not require a category. +Here are some common categories: -<p> -See the {@link android.content.Intent} class description for the full list of -categories. -</p> +<dl> +<dt>{@link android.content.Intent#CATEGORY_BROWSABLE}</dt> + <dd>The target activity allows itself to be started by a web browser to display data + referenced by a link—such as an image or an e-mail message. + </dd> +<dt>{@link android.content.Intent#CATEGORY_LAUNCHER}</dt> + <dd>The activity is the initial activity of a task and is listed in + the system's application launcher. + </dd> +</dl> -<p> -The <code>{@link android.content.Intent#addCategory addCategory()}</code> method -places a category in an Intent object, <code>{@link android.content.Intent#removeCategory -removeCategory()}</code> deletes a category previously added, and <code>{@link android.content.Intent#getCategories getCategories()}</code> gets the set of all -categories currently in the object. -</p> +<p>See the {@link android.content.Intent} class description for the full list of +categories.</p> + +<p>You can specify a category with {@link android.content.Intent#addCategory addCategory()}.</p> </dd> +</dl> -<p><dt><b>Extras</b><a name="extras"></a></dt> -<dd>Key-value pairs for additional information that should be delivered to the -component handling the intent. Just as some actions are paired with particular -kinds of data URIs, some are paired with particular extras. For example, an -{@code ACTION_TIMEZONE_CHANGED} intent has a "{@code time-zone}" extra that -identifies the new time zone, and {@code ACTION_HEADSET_PLUG} has a -"{@code state}" extra indicating whether the headset is now plugged in or -unplugged, as well as a "{@code name}" extra for the type of headset. -If you were to invent a {@code SHOW_COLOR} action, the color value would -be set in an extra key-value pair. -<p> -The Intent object has a series of {@code put...()} methods for inserting various -types of extra data and a similar set of {@code get...()} methods for reading -the data. These methods parallel those for {@link android.os.Bundle} objects. -In fact, the extras can be installed and read as a Bundle using the <code>{@link -android.content.Intent#putExtras putExtras()}</code> and <code>{@link -android.content.Intent#getExtras getExtras()}</code> methods. -</p> +<p>These properties listed above (component name, action, data, and category) represent the +defining characteristics of an intent. By reading these properties, the Android system +is able to resolve which app component it should start.</p> + +<p>However, an intent can carry additional information that does not affect +how it is resolved to an app component. An intent can also supply:</p> + +<dl> +<dt><b>Extras</b></dt> +<dd>Key-value pairs that carry additional information required to accomplish the requested action. +Just as some actions use particular kinds of data URIs, some actions also use particular extras. + +<p>You can add extra data with various {@link android.content.Intent#putExtra putExtra()} methods, +each accepting two parameters: the key name and the value. +You can also create a {@link android.os.Bundle} object with all the extra data, then insert +the {@link android.os.Bundle} in the {@link android.content.Intent} with {@link +android.content.Intent#putExtras putExtras()}.</p> + +<p>For example, when creating an intent to send an email with +{@link android.content.Intent#ACTION_SEND}, you can specify the "to" recipient with the +{@link android.content.Intent#EXTRA_EMAIL} key, and specify the "subject" with the +{@link android.content.Intent#EXTRA_SUBJECT} key.</p> + +<p>The {@link android.content.Intent} class specifies many {@code EXTRA_*} constants +for standardized data types. If you need to declare your own extra keys (for intents that +your app receives), be sure to include your app's package name +as a prefix. For example:</p> +<pre>static final String EXTRA_GIGAWATTS = "com.example.EXTRA_GIGAWATTS";</pre> </dd> -<p><dt><b>Flags</b></dt> -<dd>Flags of various sorts. Many instruct the Android system how to launch an -activity (for example, which task the activity should belong to) and how to treat -it after it's launched (for example, whether it belongs in the list of recent -activities). All these flags are defined in the Intent class. +<dt><b>Flags</b></dt> +<dd>Flags defined in the {@link android.content.Intent} class that function as metadata for the +intent. The flags may instruct the Android system how to launch an activity (for example, which +<a href="{@docRoot}guide/components/tasks-and-back-stack.html">task</a> the activity should belong +to) and how to treat it after it's launched (for example, whether it belongs in the list of recent +activities). + +<p>For more information, see the {@link android.content.Intent#setFlags setFlags()} method.</p> </dd> </dl> -<p> -The Android system and the applications that come with the platform employ -Intent objects both to send out system-originated broadcasts and to activate -system-defined components. To see how to structure an intent to activate a -system component, consult the -<a href="{@docRoot}guide/appendix/g-app-intents.html">list of intents</a> -in the reference. -</p> -<h2><a name="ires"></a>Intent Resolution</h2> -<p> -Intents can be divided into two groups: -</p> +<h3 id="ExampleExplicit">Example explicit intent</h3> -<ul> -<li><i>Explicit intents</i> designate the target component by its -name (the <a href="#cname">component name field</a>, mentioned earlier, -has a value set). Since component names would generally not be known to -developers of other applications, explicit intents are typically used -for application-internal messages — such as an activity starting -a subordinate service or launching a sister activity.</li> - -<li><p><i>Implicit intents</i> do not name a target (the field for -the component name is blank). Implicit intents are often used to -activate components in other applications.</p></li> -</ul> +<p>An explicit intent is one that you use to launch a specific app component, such as +a particular activity or service in your app. To create an explicit intent, define +the component name for the {@link android.content.Intent} object—all +other intent properties are optional.</p> -<p> -Android delivers an explicit intent to an instance of the designated -target class. Nothing in the Intent object other than the component -name matters for determining which component should get the intent. -</p> +<p>For example, if you built a service in your app, named {@code DownloadService}, +designed to download a file from the web, you can start it with the following code:</p> -<p> -A different strategy is needed for implicit intents. In the absence of a -designated target, the Android system must find the best component (or -components) to handle the intent — a single activity or service to -perform the requested action or the set of broadcast receivers to respond -to the broadcast announcement. It does so by comparing the contents of -the Intent object to <i>intent filters</i>, structures associated with -components that can potentially receive intents. Filters advertise the -capabilities of a component and delimit the intents it can handle. They -open the component to the possibility of receiving implicit intents of -the advertised type. If a component does not have any intent filters, -it can receive only explicit intents. A component with filters can -receive both explicit and implicit intents. -</p> +<pre> +// Executed in an Activity, so 'this' is the {@link android.content.Context} +// The fileUrl is a string URL, such as "http://www.example.com/image.png" +Intent downloadIntent = new Intent(this, DownloadService.class); +downloadIntent.setData({@link android.net.Uri#parse Uri.parse}(fileUrl)); +startService(downloadIntent); +</pre> -<p> -Only three aspects of an Intent object are consulted when the object -is tested against an intent filter: -</p> +<p>The {@link android.content.Intent#Intent(Context,Class)} +constructor supplies the app {@link android.content.Context} and the +component a {@link java.lang.Class} object. As such, +this intent explicitly starts the {@code DownloadService} class in the app.</p> -<p style="margin-left: 2em">action -<br/>data (both URI and data type) -<br/>category</p> +<p>For more information about building and starting a service, see the +<a href="{@docRoot}guide/components/services.html">Services</a> guide.</p> -<p> -The extras and flags play no part in resolving which component receives -an intent. -</p> -<h3><a name="ifs"></a>Intent filters</h3> -<p> -To inform the system which implicit intents they can handle, activities, -services, and broadcast receivers can have one or more intent filters. -Each filter describes a capability of the component, a set of intents that -the component is willing to receive. It, in effect, filters in -intents of a desired type, while filtering out unwanted -intents — but only unwanted implicit intents (those that don't name -a target class). An explicit intent is always delivered to its target, -no matter what it contains; the filter is not consulted. But an implicit -intent is delivered to a component only if it can pass through one of the -component's filters. -</p> +<h3 id="ExampleSend">Example implicit intent</h3> -<p> -A component has separate filters for each job it can do, each face it can -present to the user. For example, the NoteEditor activity of the sample -Note Pad application has two filters — one for starting up with a -specific note that the user can view or edit, and another for starting -with a new, blank note that the user can fill in and save. (All of Note -Pad's filters are described in the <a href="#npex">Note Pad Example</a> -section, later.) -</p> +<p>An implicit intent specifies an action that can invoke any app on the device able +to perform the action. Using an implicit intent is useful when your app cannot perform the +action, but other apps probably can and you'd like the user to pick which app to use.</p> -<div class="sidebox-wrapper"> -<div class="sidebox"> -<h2>Filters and security</h2> -<p>An intent filter cannot be relied on for security. While it opens a -component to receiving only certain kinds of implicit intents, it does -nothing to prevent explicit intents from targeting the component. Even -though a filter restricts the intents a component will be asked to handle -to certain actions and data sources, someone could always put -together an explicit intent with a different action and data source, and -name the component as the target. -</p> +<p>For example, if you have content you want the user to share with other people, create an intent +with the {@link android.content.Intent#ACTION_SEND} action +and add extras that specify the content to share. When you call +{@link android.content.Context#startActivity startActivity()} with that intent, the user can +pick an app through which to share the content.</p> + +<p class="caution"><strong>Caution:</strong> It's possible that a user won't have <em>any</em> +apps that handle the implicit intent you send to {@link android.content.Context#startActivity +startActivity()}. If that happens, the call will fail and your app will crash. To verify +that an activity will receive the intent, call {@link android.content.Intent#resolveActivity +resolveActivity()} on your {@link android.content.Intent} object. If the result is non-null, +then there is at least one app that can handle the intent and it's safe to call +{@link android.content.Context#startActivity startActivity()}. If the result is null, +you should not use the intent and, if possible, you should disable the feature that issues +the intent.</p> + + +<pre> +// Create the text message with a string +Intent sendIntent = new Intent(); +sendIntent.setAction(Intent.ACTION_SEND); +sendIntent.putExtra(Intent.EXTRA_TEXT, textMessage); +sendIntent.setType({@link + org.apache.http.protocol.HTTP#PLAIN_TEXT_TYPE + HTTP.PLAIN_TEXT_TYPE}); // "text/plain" MIME type + +// Verify that the intent will resolve to an activity +if (sendIntent.resolveActivity(getPackageManager()) != null) { + startActivity(sendIntent); +} +</pre> + +<p class="note"><strong>Note:</strong> In this case, a URI is not used, but the intent's data type +is declared to specify the content carried by the extras.</p> + + +<p>When {@link android.content.Context#startActivity startActivity()} is called, the system +examines all of the installed apps to determine which ones can handle this kind of intent (an +intent with the {@link android.content.Intent#ACTION_SEND} action and that carries "text/plain" +data). If there's only one app that can handle it, that app opens immediately and is given the +intent. If multiple activities accept the intent, the system +displays a dialog so the user can pick which app to use..</p> + + +<div class="figure" style="width:200px"> + <img src="{@docRoot}images/training/basics/intent-chooser.png" alt=""> + <p class="img-caption"><strong>Figure 2.</strong> A chooser dialog.</p> </div> -</div> -<p> -An intent filter is an instance of the {@link android.content.IntentFilter} class. -However, since the Android system must know about the capabilities of a component -before it can launch that component, intent filters are generally not set up in -Java code, but in the application's manifest file (AndroidManifest.xml) as -<code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html"><intent-filter></a></code> -elements. (The one exception would be filters for -broadcast receivers that are registered dynamically by calling <code>{@link android.content.Context#registerReceiver(BroadcastReceiver, IntentFilter, String, -Handler) Context.registerReceiver()}</code>; they are directly created as -IntentFilter objects.) -</p> +<h3 id="ForceChooser">Forcing an app chooser</h3> -<p> -A filter has fields that parallel the action, data, and category fields of an -Intent object. An implicit intent is tested against the filter in all three areas. -To be delivered to the component that owns the filter, it must pass all three tests. -If it fails even one of them, the Android system won't deliver it to the -component — at least not on the basis of that filter. However, since a -component can have multiple intent filters, an intent that does not pass -through one of a component's filters might make it through on another. -</p> +<p>When there is more than one app that responds to your implicit intent, +the user can select which app to use and make that app the default choice for the +action. This is nice when performing an action for which the user +probably wants to use the same app from now on, such as when opening a web page (users +often prefer just one web browser) .</p> -<p> -Each of the three tests is described in detail below: -</p> +<p>However, if multiple apps can respond to the intent and the user might want to use a different +app each time, you should explicitly show a chooser dialog. The chooser dialog asks the +user to select which app to use for the action every time (the user cannot select a default app for +the action). For example, when your app performs "share" with the {@link +android.content.Intent#ACTION_SEND} action, users may want to share using a different app depending +on their current situation, so you should always use the chooser dialog, as shown in figure 2.</p> -<dl> -<dt><b>Action test</b></dt> -<dd>An -<code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html"><intent-filter></a></code> -element in the manifest file lists actions as -<code><a href="{@docRoot}guide/topics/manifest/action-element.html"><action></a></code> -subelements. For example: - -<pre><intent-filter . . . > - <action android:name="com.example.project.SHOW_CURRENT" /> - <action android:name="com.example.project.SHOW_RECENT" /> - <action android:name="com.example.project.SHOW_PENDING" /> - . . . -</intent-filter></pre> -<p> -As the example shows, while an Intent object names just a single action, -a filter may list more than one. The list cannot be empty; a filter must -contain at least one {@code <action>} element, or it -will block all intents. -</p> -<p> -To pass this test, the action specified in the Intent object must match -one of the actions listed in the filter. If the object or the filter -does not specify an action, the results are as follows: -</p> +<p>To show the chooser, create an {@link android.content.Intent} using {@link +android.content.Intent#createChooser createChooser()} and pass it to {@link +android.app.Activity#startActivity startActivity()}. For example:</p> -<ul> -<li>If the filter fails to list any actions, there is nothing for an -intent to match, so all intents fail the test. No intents can get -through the filter.</li> - -<li><p>On the other hand, an Intent object that doesn't specify an -action automatically passes the test — as long as the filter -contains at least one action.</p></li> -</ul -</dd> +<pre> +Intent intent = new Intent(Intent.ACTION_SEND); +... -<dt><b>Category test</b></dt> -<dd>An -<code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html"><intent-filter></a></code> -element also lists categories as subelements. For example: +// Always use string resources for UI text. +// This says something like "Share this photo with" +String title = getResources().getString(R.string.chooser_title); +// Create intent to show chooser +Intent chooser = Intent.createChooser(intent, title); -<pre><intent-filter . . . > - <category android:name="android.intent.category.DEFAULT" /> - <category android:name="android.intent.category.BROWSABLE" /> - . . . -</intent-filter></pre> +// Verify the intent will resolve to at least one activity +if (sendIntent.resolveActivity(getPackageManager()) != null) { + startActivity(sendIntent); +} +</pre> -<p> -Note that the constants described earlier for actions and categories are not -used in the manifest file. The full string values are used instead. For -instance, the "{@code android.intent.category.BROWSABLE}" string in the example -above corresponds to the {@code CATEGORY_BROWSABLE} constant mentioned earlier -in this document. Similarly, the string "{@code android.intent.action.EDIT}" -corresponds to the {@code ACTION_EDIT} constant. -</p> +<p>This displays a dialog with a list of apps that respond to the intent passed to the {@link +android.content.Intent#createChooser createChooser()} method and uses the supplied text as the +dialog title.</p> -<p> -For an intent to pass the category test, every category in the Intent object -must match a category in the filter. The filter can list additional categories, -but it cannot omit any that are in the intent. -</p> -<p> -In principle, therefore, an Intent object with no categories should always pass -this test, regardless of what's in the filter. That's mostly true. However, -with one exception, Android treats all implicit intents passed to {@link -android.content.Context#startActivity startActivity()} as if they contained -at least one category: "{@code android.intent.category.DEFAULT}" (the -{@code CATEGORY_DEFAULT} constant). -Therefore, activities that are willing to receive implicit intents must -include "{@code android.intent.category.DEFAULT}" in their intent filters. -(Filters with "{@code android.intent.action.MAIN}" and -"{@code android.intent.category.LAUNCHER}" settings are the exception. -They mark activities that begin new tasks and that are represented on the -launcher screen. They can include "{@code android.intent.category.DEFAULT}" -in the list of categories, but don't need to.) See <a href="#imatch">Using -intent matching</a>, later, for more on these filters.) -</p> -<dd> -<dt><b>Data test</b></dt> -<dd>Like the action and categories, the data specification for an intent filter -is contained in a subelement. And, as in those cases, the subelement can appear -multiple times, or not at all. For example: -<pre><intent-filter . . . > - <data android:mimeType="video/mpeg" android:scheme="http" . . . /> - <data android:mimeType="audio/mpeg" android:scheme="http" . . . /> - . . . -</intent-filter></pre> -<p> -Each -<code><a href="{@docRoot}guide/topics/manifest/data-element.html"><data></a></code> -element can specify a URI and a data type (MIME media type). There are separate -attributes — {@code scheme}, {@code host}, {@code port}, -and {@code path} — for each part of the URI: -</p> -<p style="margin-left: 2em">{@code scheme://host:port/path}</p> -<p> -For example, in the following URI, -</p> -<p style="margin-left: 2em">{@code content://com.example.project:200/folder/subfolder/etc}</p> -<p> the scheme is "{@code content}", the host is "{@code com.example.project}", -the port is "{@code 200}", and the path is "{@code folder/subfolder/etc}". -The host and port together constitute the URI <i>authority</i>; if a host is -not specified, the port is ignored. -</p> +<h2 id="Receiving">Receiving an Implicit Intent</h2> -<p> -Each of these attributes is optional, but they are not independent of each other: -For an authority to be meaningful, a scheme must also be specified. -For a path to be meaningful, both a scheme and an authority must be specified. -</p> +<p>To advertise which implicit intents your app can receive, declare one or more intent filters for +each of your app components with an <a href= +"{@docRoot}guide/topics/manifest/intent-filter-element.html">{@code <intent-filter>}</a> +element in your <a href="{@docRoot}guide/topics/manifest/manifest-intro.html">manifest file</a>. +Each intent filter specifies the type of intents it accepts based on the intent's action, +data, and category. The system will deliver an implicit intent to your app component only if the +intent can pass through one of your intent filters.</p> -<p> -When the URI in an Intent object is compared to a URI specification in a filter, -it's compared only to the parts of the URI actually mentioned in the filter. -For example, if a filter specifies only a scheme, all URIs with that scheme match -the filter. If a filter specifies a scheme and an authority but no path, all URIs -with the same scheme and authority match, regardless of their paths. If a filter -specifies a scheme, an authority, and a path, only URIs with the same scheme, -authority, and path match. However, a path specification in the filter can -contain wildcards to require only a partial match of the path. -</p> +<p class="note"><strong>Note:</strong> An explicit intent is always delivered to its target, +regardless of any intent filters the component declares.</p> -<p> -The {@code type} attribute of a {@code <data>} element specifies the MIME type -of the data. It's more common in filters than a URI. Both the Intent object and -the filter can use a "*" wildcard for the subtype field — for example, -"{@code text/*}" or "{@code audio/*}" — indicating any subtype matches. -</p> +<p>An app component should declare separate filters for each unique job it can do. +For example, one activity in an image gallery app may have two filters: one filter +to view an image, and another filter to edit an image. When the activity starts, +it inspects the {@link android.content.Intent} and decides how to behave based on the information +in the {@link android.content.Intent} (such as to show the editor controls or not).</p> -<p> -The data test compares both the URI and the data type in the Intent object to a URI -and data type specified in the filter. The rules are as follows: -</p> +<p>Each intent filter is defined by an <a +href="{@docRoot}guide/topics/manifest/intent-filter-element.html">{@code <intent-filter>}</a> +element in the app's manifest file, nested in the corresponding app component (such +as an <a href="{@docRoot}guide/topics/manifest/activity-element.html">{@code <activity>}</a> +element). Inside the <a +href="{@docRoot}guide/topics/manifest/intent-filter-element.html">{@code <intent-filter>}</a>, +you can specify the type of intents to accept using one or more +of these three elements:</p> -<ol type="a"> -<li>An Intent object that contains neither a URI nor a data type passes the -test only if the filter likewise does not specify any URIs or data types.</li> - -<li><p>An Intent object that contains a URI but no data type (and a type cannot -be inferred from the URI) passes the test only if its URI matches a URI in the -filter and the filter likewise does not specify a type. This will be the case -only for URIs like {@code mailto:} and {@code tel:} that do not refer to actual data.</p></li> - -<li><p>An Intent object that contains a data type but not a URI passes the test -only if the filter lists the same data type and similarly does not specify a URI.</p></li> - -<li><p>An Intent object that contains both a URI and a data type (or a data type -can be inferred from the URI) passes the data type part of the test only if its -type matches a type listed in the filter. It passes the URI part of the test -either if its URI matches a URI in the filter or if it has a {@code content:} -or {@code file:} URI and the filter does not specify a URI. In other words, -a component is presumed to support {@code content:} and {@code file:} data if -its filter lists only a data type.</p></li> -</ol> +<dl> +<dt><a href="{@docRoot}guide/topics/manifest/action-element.html">{@code <action>}</a></dt> + <dd>Declares the intent action accepted, in the {@code name} attribute. The value + must be the literal string value of an action, not the class constant.</dd> +<dt><a href="{@docRoot}guide/topics/manifest/data-element.html">{@code <data>}</a></dt> + <dd>Declares the type of data accepted, using one or more attributes that specify various + aspects of the data URI (<code>scheme</code>, <code>host</code>, <code>port</code>, + <code>path</code>, etc.) and MIME type.</dd> +<dt><a href="{@docRoot}guide/topics/manifest/category-element.html">{@code <category>}</a></dt> + <dd>Declares the intent category accepted, in the {@code name} attribute. The value + must be the literal string value of an action, not the class constant. + + <p class="note"><strong>Note:</strong> In order to receive implicit intents, you + <strong>must include</strong> the + {@link android.content.Intent#CATEGORY_DEFAULT} category in the intent filter. The methods + {@link android.app.Activity#startActivity startActivity()} and + {@link android.app.Activity#startActivityForResult startActivityForResult()} treat all intents + as if they declared the {@link android.content.Intent#CATEGORY_DEFAULT} category. + If you do not declare this category in your intent filter, no implicit intents will resolve to + your activity.</p> + </dd> </dl> -<p> -If an intent can pass through the filters of more than one activity or service, -the user may be asked which component to activate. An exception is raised if -no target can be found. -</p> +<p>For example, here's an activity declaration with an intent filter to receive an +{@link android.content.Intent#ACTION_SEND} intent when the data type is text:</p> +<pre> +<activity android:name="ShareActivity"> + <intent-filter> + <action android:name="android.intent.action.SEND"/> + <category android:name="android.intent.category.DEFAULT"/> + <data android:mimeType="text/plain"/> + </intent-filter> +</activity> +</pre> -<h3><a name="ccases"></a>Common cases</h3> +<p>It's okay to create a filter that includes more than one instance of +<a href="{@docRoot}guide/topics/manifest/action-element.html">{@code <action>}</a>, +<a href="{@docRoot}guide/topics/manifest/data-element.html">{@code <data>}</a>, or +<a href="{@docRoot}guide/topics/manifest/category-element.html">{@code <category>}</a>. +If you do, you simply need to be certain that the component can handle any and all combinations +of those filter elements.</p> -<p> -The last rule shown above for the data test, rule (d), reflects the expectation -that components are able to get local data from a file or content provider. -Therefore, their filters can list just a data type and do not need to explicitly -name the {@code content:} and {@code file:} schemes. -This is a typical case. A {@code <data>} element like the following, -for example, tells Android that the component can get image data from a content -provider and display it: -</p> +<p>When you want to handle multiple kinds of intents, but only in specific combinations of +action, data, and category type, then you need to create multiple intent filters.</p> -<pre><data android:mimeType="image/*" /></pre> -<p> -Since most available data is dispensed by content providers, filters that -specify a data type but not a URI are perhaps the most common. +<div class="sidebox-wrapper"> +<div class="sidebox"> +<h2>Restricting access to components</h2> +<p>Using an intent filter is not a secure way to prevent other apps from starting +your components. Although intent filters restrict a component to respond to only +certain kinds of implicit intents, another app can potentially start your app component +by using an explicit intent if the developer determines your component names. +If it's important that <em>only your own app</em> is able to start one of your components, +set the <a href="{@docRoot}guide/topics/manifest/activity-element.html#exported">{@code +exported}</a> attribute to {@code "false"} for that component. </p> +</div> +</div> -<p> -Another common configuration is filters with a scheme and a data type. For -example, a {@code <data>} element like the following tells Android that -the component can get video data from the network and display it: -</p> +<p>An implicit intent is tested against a filter by comparing the intent to each of the +three elements. To be delivered to the component, the intent must pass all three tests. +If it fails to match even one of them, the Android system won't deliver the intent to the +component. However, because a component may have multiple intent filters, an intent that does +not pass through one of a component's filters might make it through on another filter. +More information about how the system resolves intents is provided in the section below +about <a href="#Resolution">Intent Resolution</a>.</p> + +<p class="caution"><strong>Caution:</strong> To avoid inadvertently running a different app's +{@link android.app.Service}, always use an explicit intent to start your own service and do not +declare intent filters for your service.</p> + +<p class="note"><strong>Note:</strong> +For all activities, you must declare your intent filters in the manifest file. +However, filters for broadcast receivers can be registered dynamically by calling +{@link android.content.Context#registerReceiver(BroadcastReceiver, IntentFilter, String, +Handler) registerReceiver()}. You can then unregister the receiver with {@link +android.content.Context#unregisterReceiver unregisterReceiver()}. Doing so allows your app +to listen for specific broadcasts during only a specified period of time while your app +is running.</p> + + + + + + + +<h3 id="ExampleFilters">Example filters</h3> + +<p>To better understand some of the intent filter behaviors, look at the following snippet +from the manifest file of a social-sharing app.</p> + +<pre> +<activity android:name="MainActivity"> + <!-- This activity is the main entry, should appear in app launcher --> + <intent-filter> + <action android:name="android.intent.action.MAIN" /> + <category android:name="android.intent.category.LAUNCHER" /> + </intent-filter> +</activity> + +<activity android:name="ShareActivity"> + <!-- This activity handles "SEND" actions with text data --> + <intent-filter> + <action android:name="android.intent.action.SEND"/> + <category android:name="android.intent.category.DEFAULT"/> + <data android:mimeType="text/plain"/> + </intent-filter> + <!-- This activity also handles "SEND" and "SEND_MULTIPLE" with media data --> + <intent-filter> + <action android:name="android.intent.action.SEND"/> + <action android:name="android.intent.action.SEND_MULTIPLE"/> + <category android:name="android.intent.category.DEFAULT"/> + <data android:mimeType="application/vnd.google.panorama360+jpg"/> + <data android:mimeType="image/*"/> + <data android:mimeType="video/*"/> + </intent-filter> +</activity> +</pre> + +<p>The first activity, {@code MainActivity}, is the app's main entry point—the activity that +opens when the user initially launches the app with the launcher icon:</p> +<ul> + <li>The {@link android.content.Intent#ACTION_MAIN} action + indicates this is the main entry point and does not expect any intent data.</li> + <li>The {@link android.content.Intent#CATEGORY_LAUNCHER} category indicates that this activity's + icon should be placed in the system's app launcher. If the <a + href="{@docRoot}guide/topics/manifest/activity-element.html">{@code <activity>}</a> element + does not specify an icon with {@code icon}, then the system uses the icon from the <a + href="{@docRoot}guide/topics/manifest/application-element.html">{@code <application>}</a> + element.</li> +</ul> +<p>These two must be paired together in order for the activity to appear in the app launcher.</p> -<pre><data android:scheme="http" android:type="video/*" /></pre> +<p>The second activity, {@code ShareActivity}, is intended to facilitate sharing text and media +content. Although users might enter this activity by navigating to it from {@code MainActivity}, +they can also enter {@code ShareActivity} directly from another app that issues an implicit +intent matching one of the two intent filters.</p> -<p> -Consider, for example, what the browser application does when -the user follows a link on a web page. It first tries to display the data -(as it could if the link was to an HTML page). If it can't display the data, -it puts together an implicit intent with the scheme and data type and tries -to start an activity that can do the job. If there are no takers, it asks the -download manager to download the data. That puts it under the control -of a content provider, so a potentially larger pool of activities -(those with filters that just name a data type) can respond. -</p> +<p class="note"><strong>Note:</strong> The MIME type, +<a href="https://developers.google.com/panorama/android/">{@code +application/vnd.google.panorama360+jpg}</a>, is a special data type that specifies +panoramic photos, which you can handle with the <a +href="{@docRoot}reference/com/google/android/gms/panorama/package-summary.html">Google +panorama</a> APIs.</p> -<p> -Most applications also have a way to start fresh, without a reference -to any particular data. Activities that can initiate applications -have filters with "{@code android.intent.action.MAIN}" specified as -the action. If they are to be represented in the application launcher, -they also specify the "{@code android.intent.category.LAUNCHER}" -category: -</p> -<pre><intent-filter . . . > - <action android:name="android.intent.action.MAIN" /> - <category android:name="android.intent.category.LAUNCHER" /> -</intent-filter></pre> -<h3><a name="imatch"></a>Using intent matching</h3> -<p> -Intents are matched against intent filters not only to discover a target -component to activate, but also to discover something about the set of -components on the device. For example, the Android system populates the -application launcher, the top-level screen that shows the applications -that are available for the user to launch, by finding all the activities - with intent filters that specify the "{@code android.intent.action.MAIN}" -action and "{@code android.intent.category.LAUNCHER}" category -(as illustrated in the previous section). It then displays the icons and -labels of those activities in the launcher. Similarly, it discovers the -home screen by looking for the activity with -"{@code android.intent.category.HOME}" in its filter. -</p> -<p> -Your application can use intent matching is a similar way. -The {@link android.content.pm.PackageManager} has a set of {@code query...()} -methods that return all components that can accept a particular intent, and -a similar series of {@code resolve...()} methods that determine the best -component to respond to an intent. For example, -{@link android.content.pm.PackageManager#queryIntentActivities -queryIntentActivities()} returns a list of all activities that can perform -the intent passed as an argument, and {@link -android.content.pm.PackageManager#queryIntentServices -queryIntentServices()} returns a similar list of services. -Neither method activates the components; they just list the ones that -can respond. There's a similar method, -{@link android.content.pm.PackageManager#queryBroadcastReceivers -queryBroadcastReceivers()}, for broadcast receivers. -</p> -<h2 id="npex">Note Pad Example</h2> -<p> -The Note Pad sample application enables users to browse through a list -of notes, view details about individual items in the list, edit the items, -and add a new item to the list. This section looks at the intent filters -declared in its manifest file. (If you're working offline in the SDK, you -can find all the source files for this sample application, including its -manifest file, at {@code <sdk>/samples/NotePad/index.html}. -If you're viewing the documentation online, the source files are in the -<a href="{@docRoot}resources/samples/index.html">Tutorials and Sample Code</a> -section <a href="{@docRoot}resources/samples/NotePad/index.html">here</a>.) -</p> -<p> -In its manifest file, the Note Pad application declares three activities, -each with at least one intent filter. It also declares a content provider -that manages the note data. Here is the manifest file in its entirety: -</p> -<pre><manifest xmlns:android="http://schemas.android.com/apk/res/android" - package="com.example.android.notepad"> - <application android:icon="@drawable/app_notes" - android:label="@string/app_name" > - - <provider android:name="NotePadProvider" - android:authorities="com.google.provider.NotePad" /> - - <activity android:name="NotesList" android:label="@string/title_notes_list"> - <intent-filter> - <action android:name="android.intent.action.MAIN" /> - <category android:name="android.intent.category.LAUNCHER" /> - </intent-filter> - <intent-filter> - <action android:name="android.intent.action.VIEW" /> - <action android:name="android.intent.action.EDIT" /> - <action android:name="android.intent.action.PICK" /> - <category android:name="android.intent.category.DEFAULT" /> - <data android:mimeType="vnd.android.cursor.dir/vnd.google.note" /> - </intent-filter> - <intent-filter> - <action android:name="android.intent.action.GET_CONTENT" /> - <category android:name="android.intent.category.DEFAULT" /> - <data android:mimeType="vnd.android.cursor.item/vnd.google.note" /> - </intent-filter> - </activity> - - <activity android:name="NoteEditor" - android:theme="@android:style/Theme.Light" - android:label="@string/title_note" > - <intent-filter android:label="@string/resolve_edit"> - <action android:name="android.intent.action.VIEW" /> - <action android:name="android.intent.action.EDIT" /> - <action android:name="com.android.notepad.action.EDIT_NOTE" /> - <category android:name="android.intent.category.DEFAULT" /> - <data android:mimeType="vnd.android.cursor.item/vnd.google.note" /> - </intent-filter> - <intent-filter> - <action android:name="android.intent.action.INSERT" /> - <category android:name="android.intent.category.DEFAULT" /> - <data android:mimeType="vnd.android.cursor.dir/vnd.google.note" /> - </intent-filter> - </activity> - - <activity android:name="TitleEditor" - android:label="@string/title_edit_title" - android:theme="@android:style/Theme.Dialog"> - <intent-filter android:label="@string/resolve_title"> - <action android:name="com.android.notepad.action.EDIT_TITLE" /> - <category android:name="android.intent.category.DEFAULT" /> - <category android:name="android.intent.category.ALTERNATIVE" /> - <category android:name="android.intent.category.SELECTED_ALTERNATIVE" /> - <data android:mimeType="vnd.android.cursor.item/vnd.google.note" /> - </intent-filter> - </activity> - - </application> -</manifest></pre> -<p> -The first activity, NotesList, is -distinguished from the other activities by the fact that it operates -on a directory of notes (the note list) rather than on a single note. -It would generally serve as the initial user interface into the -application. It can do three things as described by its three intent -filters: -</p> -<ol> -<li><pre><intent-filter> - <action android:name="android.intent.action.MAIN" /> - <category android:name="android.intent.category.LAUNCHER" /> -</intent-filter></pre> -<p> -This filter declares the main entry point into the Note Pad application. -The standard {@code MAIN} action is an entry point that does not require -any other information in the Intent (no data specification, for example), -and the {@code LAUNCHER} category says that this entry point should be -listed in the application launcher. -</p></li> - -<li><pre><intent-filter> - <action android:name="android.intent.action.VIEW" /> - <action android:name="android.intent.action.EDIT" /> - <action android:name="android.intent.action.PICK" /> - <category android:name="android.intent.category.DEFAULT" /> - <data android:mimeType="vnd.android.cursor.dir/vnd.google.note" /> -</intent-filter></pre> +<h2 id="PendingIntent">Using a Pending Intent</h2> -<p> -This filter declares the things that the activity can do on a directory -of notes. It can allow the user to view or edit the directory (via -the {@code VIEW} and {@code EDIT} actions), or to pick a particular note -from the directory (via the {@code PICK} action). -</p> +<p>A {@link android.app.PendingIntent} object is a wrapper around an {@link +android.content.Intent} object. The primary purpose of a {@link android.app.PendingIntent} +is to grant permission to a foreign application +to use the contained {@link android.content.Intent} as if it were executed from your +app's own process.</p> -<p> -The {@code mimeType} attribute of the -<code><a href="{@docRoot}guide/topics/manifest/data-element.html"><data></a></code> -element specifies the kind of data that these actions operate on. It -indicates that the activity can get a Cursor over zero or more items -({@code vnd.android.cursor.dir}) from a content provider that holds -Note Pad data ({@code vnd.google.note}). The Intent object that launches -the activity would include a {@code content:} URI specifying the exact -data of this type that the activity should open. -</p> +<p>Major use cases for a pending intent include:</p> +<ul> + <li>Declare an intent to be executed when the user performs an action with your <a + href="{@docRoot}guide/topics/ui/notifiers/notifications.html">Notification</a> + (the Android system's {@link android.app.NotificationManager} + executes the {@link android.content.Intent}). + <li>Declare an intent to be executed when the user performs an action with your + <a href="{@docRoot}guide/topics/appwidgets/index.html">App Widget</a> + (the Home screen app executes the {@link android.content.Intent}). + <li>Declare an intent to be executed at a specified time in the future (the Android + system's {@link android.app.AlarmManager} executes the {@link android.content.Intent}). +</ul> -<p> -Note also the {@code DEFAULT} category supplied in this filter. It's -there because the <code>{@link android.content.Context#startActivity -Context.startActivity()}</code> and -<code>{@link android.app.Activity#startActivityForResult -Activity.startActivityForResult()}</code> methods treat all intents -as if they contained the {@code DEFAULT} category — with just -two exceptions: -</p> +<p>Because each {@link android.content.Intent} object is designed to be handled by a specific +type of app component (either an {@link android.app.Activity}, a {@link android.app.Service}, or +a {@link android.content.BroadcastReceiver}), so too must a {@link android.app.PendingIntent} be +created with the same consideration. When using a pending intent, your app will not +execute the intent with a call such as {@link android.content.Context#startActivity +startActivity()}. You must instead declare the intended component type when you create the +{@link android.app.PendingIntent} by calling the respective creator method:</p> <ul> -<li>Intents that explicitly name the target activity</li> -<li>Intents consisting of the {@code MAIN} action and {@code LAUNCHER} -category</li> + <li>{@link android.app.PendingIntent#getActivity PendingIntent.getActivity()} for an + {@link android.content.Intent} that starts an {@link android.app.Activity}.</li> + <li>{@link android.app.PendingIntent#getService PendingIntent.getService()} for an + {@link android.content.Intent} that starts a {@link android.app.Service}.</li> + <li>{@link android.app.PendingIntent#getBroadcast PendingIntent.getBroadcast()} for a + {@link android.content.Intent} that starts an {@link android.content.BroadcastReceiver}.</li> </ul> -<p> -Therefore, the {@code DEFAULT} category is <em>required</em> for all -filters — except for those with the {@code MAIN} action and -{@code LAUNCHER} category. (Intent filters are not consulted for -explicit intents.) -</p></li> - -<li><pre><intent-filter> - <action android:name="android.intent.action.GET_CONTENT" /> - <category android:name="android.intent.category.DEFAULT" /> - <data android:mimeType="vnd.android.cursor.item/vnd.google.note" /> -</intent-filter></pre> +<p>Unless your app is <em>receiving</em> pending intents from other apps, +the above methods to create a {@link android.app.PendingIntent} are the only +{@link android.app.PendingIntent} methods you'll probably ever need.</p> -<p> -This filter describes the activity's ability to return a note selected by -the user without requiring any specification of the directory the user should -choose from. The {@code GET_CONTENT} action is similar to the {@code PICK} -action. In both cases, the activity returns the URI for a note selected by -the user. (In each case, it's returned to the activity that called -<code>{@link android.app.Activity#startActivityForResult -startActivityForResult()}</code> to start the NoteList activity.) Here, -however, the caller specifies the type of data desired instead of the -directory of data the user will be picking from. -</p> +<p>Each method takes the current app {@link android.content.Context}, the +{@link android.content.Intent} you want to wrap, and one or more flags that specify +how the intent should be used (such as whether the intent can be used more than once).</p> -<p> -The data type, <code>vnd.android.cursor.item/vnd.google.note</code>, -indicates the type of data the activity can return — a URI for -a single note. From the returned URI, the caller can get a Cursor for -exactly one item ({@code vnd.android.cursor.item}) from the content -provider that holds Note Pad data ({@code vnd.google.note}). -</p> +<p>More information about using pending intents is provided with the documentation for each +of the respective use cases, such as in the <a +href="{@docRoot}guide/topics/ui/notifiers/notifications.html">Notifications</a> +and <a href="{@docRoot}guide/topics/appwidgets/index.html">App Widgets</a> API guides.</p> -<p> -In other words, for the {@code PICK} action in the previous filter, -the data type indicates the type of data the activity could display to the -user. For the {@code GET_CONTENT} filter, it indicates the type of data -the activity can return to the caller. -</p></li> -</ol> -<p> -Given these capabilities, the following intents will resolve to the -NotesList activity: -</p> -<dl style="margin-left: 2em"> -<dt>action: <code>android.intent.action.MAIN</code></dt> -<dd>Launches the activity with no data specified.</dd> - -<dt>action: <code>android.intent.action.MAIN</code> -<br/>category: <code>android.intent.category.LAUNCHER</code></dt> -<dd> Launches the activity with no data selected specified. -This is the actual intent used by the Launcher to populate its top-level -list. All activities with filters that match this action and category -are added to the list.</dd> - -<dt>action: <code>android.intent.action.VIEW</code> -<br/>data: <code>content://com.google.provider.NotePad/notes</code></dt> -<dd>Asks the activity to display a list of all the notes under -<code>content://com.google.provider.NotePad/notes</code>. The user can then -browse through the list and get information about the items in it.</dd> - -<dt>action: <code>android.intent.action.PICK</code> -<br/>data: <code>content://com.google.provider.NotePad/notes</code></dt> -<dd>Asks the activity to display a list of the notes under -<code>content://com.google.provider.NotePad/notes</code>. -The user can then pick a note from the list, and the activity will return -the URI for that item back to the activity that started the NoteList activity.</dd> - -<dt>action: <code>android.intent.action.GET_CONTENT</code> -<br/>data type: <code>vnd.android.cursor.item/vnd.google.note</code></dt> -<dd>Asks the activity to supply a single item of Note Pad data.</dd> -</dl> -<p> -The second activity, NoteEditor, shows -users a single note entry and allows them to edit it. It can do two things -as described by its two intent filters: -<ol> -<li><pre><intent-filter android:label="@string/resolve_edit"> - <action android:name="android.intent.action.VIEW" /> + + +<h2 id="Resolution">Intent Resolution</h2> + + +<p>When the system receives an implicit intent to start an activity, it searches for the +best activity for the intent by comparing the intent to intent filters based on three aspects:</p> + +<ul> + <li>The intent action + <li>The intent data (both URI and data type) + <li>The intent category +</ul> + +<p>The following sections describe how an intents are matched to the appropriate component(s) +in terms of how the intent filter is declared in an app's manifest file.</p> + + +<h3 id="ActionTest">Action test</h3> + +<p>To specify accepted intent actions, an intent filter can declare zero or more +<a href="{@docRoot}guide/topics/manifest/action-element.html">{@code +<action>}</a> elements. For example:</p> + +<pre> +<intent-filter> <action android:name="android.intent.action.EDIT" /> - <action android:name="com.android.notepad.action.EDIT_NOTE" /> - <category android:name="android.intent.category.DEFAULT" /> - <data android:mimeType="vnd.android.cursor.item/vnd.google.note" /> -</intent-filter></pre> + <action android:name="android.intent.action.VIEW" /> + ... +</intent-filter> +</pre> -<p> -The first, primary, purpose of this activity is to enable the user to -interact with a single note — to either {@code VIEW} the note or -{@code EDIT} it. (The {@code EDIT_NOTE} category is a synonym for -{@code EDIT}.) The intent would contain the URI for data matching the -MIME type <code>vnd.android.cursor.item/vnd.google.note</code> — -that is, the URI for a single, specific note. It would typically be a -URI that was returned by the {@code PICK} or {@code GET_CONTENT} -actions of the NoteList activity. -</p> +<p>To get through this filter, the action specified in the {@link android.content.Intent} + must match one of the actions listed in the filter.</p> -<p> -As before, this filter lists the {@code DEFAULT} category so that the -activity can be launched by intents that don't explicitly specify the -NoteEditor class. -</p></li> +<p>If the filter does not list any actions, there is nothing for an +intent to match, so all intents fail the test. However, if an {@link android.content.Intent} +does not specify an action, it will pass the test (as long as the filter +contains at least one action).</p> + + + +<h3 id="CategoryTest">Category test</h3> + +<p>To specify accepted intent categories, an intent filter can declare zero or more +<a href="{@docRoot}guide/topics/manifest/category-element.html">{@code +<category>}</a> elements. For example:</p> -<li><pre><intent-filter> - <action android:name="android.intent.action.INSERT" /> +<pre> +<intent-filter> <category android:name="android.intent.category.DEFAULT" /> - <data android:mimeType="vnd.android.cursor.dir/vnd.google.note" /> -</intent-filter></pre> + <category android:name="android.intent.category.BROWSABLE" /> + ... +</intent-filter> +</pre> -<p> -The secondary purpose of this activity is to enable the user to create a new -note, which it will {@code INSERT} into an existing directory of notes. The -intent would contain the URI for data matching the MIME type -<code>vnd.android.cursor.dir/vnd.google.note</code> — that -is, the URI for the directory where the note should be placed. -</p></li> -</ol> +<p>For an intent to pass the category test, every category in the {@link android.content.Intent} +must match a category in the filter. The reverse is not necessary—the intent filter may +declare more categories than are specified in the {@link android.content.Intent} and the +{@link android.content.Intent} will still pass. Therefore, an intent with no categories should +always pass this test, regardless of what categories are declared in the filter.</p> + +<p class="note"><strong>Note:</strong> +Android automatically applies the the {@link android.content.Intent#CATEGORY_DEFAULT} category +to all implicit intents passed to {@link +android.content.Context#startActivity startActivity()} and {@link +android.app.Activity#startActivityForResult startActivityForResult()}. +So if you want your activity to receive implicit intents, it must +include a category for {@code "android.intent.category.DEFAULT"} in its intent filters (as +shown in the previous {@code <intent-filter>} example.</p> + + + +<h3 id="DataTest">Data test</h3> + +<p>To specify accepted intent data, an intent filter can declare zero or more +<a href="{@docRoot}guide/topics/manifest/data-element.html">{@code +<data>}</a> elements. For example:</p> + +<pre> +<intent-filter> + <data android:mimeType="video/mpeg" android:scheme="http" ... /> + <data android:mimeType="audio/mpeg" android:scheme="http" ... /> + ... +</intent-filter> +</pre> + +<p>Each <code><a href="{@docRoot}guide/topics/manifest/data-element.html"><data></a></code> +element can specify a URI structure and a data type (MIME media type). There are separate +attributes — {@code scheme}, {@code host}, {@code port}, +and {@code path} — for each part of the URI: +</p> + +<p style="margin-left: 2em">{@code <scheme>://<host>:<port>/<path>}</p> <p> -Given these capabilities, the following intents will resolve to the -NoteEditor activity: +For example: </p> -<dl style:"margin-left: 2em"> -<dt>action: <code>android.intent.action.VIEW</code> -<br/>data: <code>content://com.google.provider.NotePad/notes/<var>ID</var></code></dt> -<dd>Asks the activity to display the content of the note identified -by {@code <var>ID</var>}. (For details on how {@code content:} URIs -specify individual members of a group, see -<a href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a>.) - -<dt>action: <code>android.intent.action.EDIT</code> -<br/>data: <code>content://com.google.provider.NotePad/notes/<var>ID</var></code></dt> -<dd>Asks the activity to display the content of the note identified -by {@code <var>ID</var>}, and to let the user edit it. If the user -saves the changes, the activity updates the data for the note in the -content provider.</dd> - -<dt>action: <code>android.intent.action.INSERT</code> -<br/>data: <code>content://com.google.provider.NotePad/notes</code></dt> -<dd>Asks the activity to create a new, empty note in the notes list at -<code>content://com.google.provider.NotePad/notes</code> -and allow the user to edit it. If the user saves the note, its URI -is returned to the caller. -</dd> -</dl> +<p style="margin-left: 2em">{@code content://com.example.project:200/folder/subfolder/etc}</p> -<p>The last activity, TitleEditor, -enables the user to edit the title of a note. This could be implemented -by directly invoking the activity (by explicitly setting its component -name in the Intent), without using an intent filter. But here we take -the opportunity to show how to publish alternative operations on existing -data: +<p>In this URI, the scheme is {@code content}, the host is {@code com.example.project}, +the port is {@code 200}, and the path is {@code folder/subfolder/etc}. </p> -<pre><intent-filter android:label="@string/resolve_title"> - <action android:name="com.android.notepad.action.EDIT_TITLE" /> - <category android:name="android.intent.category.DEFAULT" /> - <category android:name="android.intent.category.ALTERNATIVE" /> - <category android:name="android.intent.category.SELECTED_ALTERNATIVE" /> - <data android:mimeType="vnd.android.cursor.item/vnd.google.note" /> -</intent-filter></pre> +<p>Each of these attributes is optional in a <a +href="{@docRoot}guide/topics/manifest/data-element.html">{@code <data>}</a> element, +but there are linear dependencies:</p> +<ul> + <li>If a scheme is not specified, the host is ignored.</li> + <li>If a host is not specified, the port is ignored.</li> + <li>If both the scheme and host are not specified, the path is ignored.</li> +</ul> -<p> -The single intent filter for this activity uses a custom action called -"<code>com.android.notepad.action.EDIT_TITLE</code>". It must be invoked on -a specific note (data type <code>vnd.android.cursor.item/vnd.google.note</code>), -like the previous {@code VIEW} and {@code EDIT} actions. However, here the -activity displays the title contained in the note data, not the content of -the note itself. +<p>When the URI in an intent is compared to a URI specification in a filter, +it's compared only to the parts of the URI included in the filter. For example:</p> +<ul> + <li>If a filter specifies only a scheme, all URIs with that scheme match +the filter.</li> + <li>If a filter specifies a scheme and an authority but no path, all URIs +with the same scheme and authority pass the filter, regardless of their paths.</li> + <li>If a filter specifies a scheme, an authority, and a path, only URIs with the same scheme, +authority, and path pass the filter.</li> +</ul> + +<p class="note"><strong>Note:</strong> A path specification can +contain a wildcard asterisk (*) to require only a partial match of the path name.</p> + +<p>The data test compares both the URI and the MIME type in the intent to a URI +and MIME type specified in the filter. The rules are as follows: </p> +<ol type="a"> +<li>An intent that contains neither a URI nor a MIME type passes the +test only if the filter does not specify any URIs or MIME types.</li> + +<li>An intent that contains a URI but no MIME type (neither explicit nor inferable from the +URI) passes the test only if its URI matches the filter's URI format +and the filter likewise does not specify a MIME type.</li> + +<li>An intent that contains a MIME type but not a URI passes the test +only if the filter lists the same MIME type and does not specify a URI format.</li> + +<li>An intent that contains both a URI and a MIME type (either explicit or inferable from the +URI) passes the MIME type part of the test only if that +type matches a type listed in the filter. It passes the URI part of the test +either if its URI matches a URI in the filter or if it has a {@code content:} +or {@code file:} URI and the filter does not specify a URI. In other words, +a component is presumed to support {@code content:} and {@code file:} data if +its filter lists <em>only</em> a MIME type.</p></li> +</ol> + <p> -In addition to supporting the usual {@code DEFAULT} category, the title -editor also supports two other standard categories: -<code>{@link android.content.Intent#CATEGORY_ALTERNATIVE ALTERNATIVE}</code> -and <code>{@link android.content.Intent#CATEGORY_SELECTED_ALTERNATIVE -SELECTED_ALTERNATIVE}</code>. -These categories identify activities that can be presented to users in -a menu of options (much as the {@code LAUNCHER} category identifies -activities that should be presented to user in the application launcher). -Note that the filter also supplies an explicit label (via -<code>android:label="@string/resolve_title"</code>) to better control -what users see when presented with this activity as an alternative -action to the data they are currently viewing. (For more information -on these categories and building options menus, see the -<code>{@link android.content.pm.PackageManager#queryIntentActivityOptions -PackageManager.queryIntentActivityOptions()}</code> and -<code>{@link android.view.Menu#addIntentOptions Menu.addIntentOptions()}</code> -methods.) +This last rule, rule (d), reflects the expectation +that components are able to get local data from a file or content provider. +Therefore, their filters can list just a data type and do not need to explicitly +name the {@code content:} and {@code file:} schemes. +This is a typical case. A <a +href="{@docRoot}guide/topics/manifest/data-element.html">{@code <data>}</a> element +like the following, for example, tells Android that the component can get image data from a content +provider and display it: </p> +<pre> +<intent-filter> + <data android:mimeType="image/*" /> + ... +</intent-filter></pre> + <p> -Given these capabilities, the following intent will resolve to the -TitleEditor activity: +Because most available data is dispensed by content providers, filters that +specify a data type but not a URI are perhaps the most common. </p> -<dl style="margin-left: 2em"> -<dt>action: <code>com.android.notepad.action.EDIT_TITLE</code> -<br/>data: <code>content://com.google.provider.NotePad/notes/<var>ID</var></code></dt> -<dd>Asks the activity to display the title associated with note <var>ID</var>, and -allow the user to edit the title.</dd> -</dl> +<p> +Another common configuration is filters with a scheme and a data type. For +example, a <a +href="{@docRoot}guide/topics/manifest/data-element.html">{@code <data>}</a> +element like the following tells Android that +the component can retrieve video data from the network in order to perform the action: +</p> +<pre> +<intent-filter> + <data android:scheme="http" android:type="video/*" /> + ... +</intent-filter></pre> +<h3 id="imatch">Intent matching</h3> +<p>Intents are matched against intent filters not only to discover a target +component to activate, but also to discover something about the set of +components on the device. For example, the Home app populates the app launcher +by finding all the activities with intent filters that specify the +{@link android.content.Intent#ACTION_MAIN} action and +{@link android.content.Intent#CATEGORY_LAUNCHER} category.</p> - +<p>Your application can use intent matching in a similar way. +The {@link android.content.pm.PackageManager} has a set of {@code query...()} +methods that return all components that can accept a particular intent, and +a similar series of {@code resolve...()} methods that determine the best +component to respond to an intent. For example, +{@link android.content.pm.PackageManager#queryIntentActivities +queryIntentActivities()} returns a list of all activities that can perform +the intent passed as an argument, and {@link +android.content.pm.PackageManager#queryIntentServices +queryIntentServices()} returns a similar list of services. +Neither method activates the components; they just list the ones that +can respond. There's a similar method, +{@link android.content.pm.PackageManager#queryBroadcastReceivers +queryBroadcastReceivers()}, for broadcast receivers. +</p> diff --git a/docs/html/guide/components/services.jd b/docs/html/guide/components/services.jd index 30da33a..da01d2c 100644 --- a/docs/html/guide/components/services.jd +++ b/docs/html/guide/components/services.jd @@ -212,41 +212,35 @@ element. For example:</p> </manifest> </pre> +<p>See the <a +href="{@docRoot}guide/topics/manifest/service-element.html">{@code <service>}</a> element +reference for more information about declaring your service in the manifest.</p> + <p>There are other attributes you can include in the <a href="{@docRoot}guide/topics/manifest/service-element.html">{@code <service>}</a> element to define properties such as permissions required to start the service and the process in which the service should run. The <a href="{@docRoot}guide/topics/manifest/service-element.html#nm">{@code android:name}</a> attribute is the only required attribute—it specifies the class name of the service. Once -you publish your application, you should not change this name, because if you do, you might break -some functionality where explicit intents are used to reference your service (read the blog post, <a +you publish your application, you should not change this name, because if you do, you risk breaking +code due to dependence on explicit intents to start or bind the service (read the blog post, <a href="http://android-developers.blogspot.com/2011/06/things-that-cannot-change.html">Things That Cannot Change</a>). -<p>See the <a -href="{@docRoot}guide/topics/manifest/service-element.html">{@code <service>}</a> element -reference for more information about declaring your service in the manifest.</p> - -<p>Just like an activity, a service can define intent filters that allow other components to -invoke the service using implicit intents. By declaring intent filters, components -from any application installed on the user's device can potentially start your service if your -service declares an intent filter that matches the intent another application passes to {@link -android.content.Context#startService startService()}.</p> - -<p>If you plan on using your service only locally (other applications do not use it), then you -don't need to (and should not) supply any intent filters. Without any intent filters, you must -start the service using an intent that explicitly names the service class. More information -about <a href="#StartingAService">starting a service</a> is discussed below.</p> +<p>To ensure your app is secure, <strong>always use an explicit intent when starting or binding +your {@link android.app.Service}</strong> and do not declare intent filters for the service. If +it's critical that you allow for some amount of ambiguity as to which service starts, you can +supply intent filters for your services and exclude the component name from the {@link +android.content.Intent}, but you then must set the package for the intent with {@link +android.content.Intent#setPackage setPackage()}, which provides sufficient disambiguation for the +target service.</p> -<p>Additionally, you can ensure that your service is private to your application only if -you include the <a +<p>Additionally, you can ensure that your service is available to only your app by +including the <a href="{@docRoot}guide/topics/manifest/service-element.html#exported">{@code android:exported}</a> -attribute and set it to {@code "false"}. This is effective even if your service supplies intent -filters.</p> +attribute and setting it to {@code "false"}. This effectively stops other apps from starting your +service, even when using an explicit intent.</p> -<p>For more information about creating intent filters for your service, see the <a -href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filters</a> -document.</p> @@ -333,7 +327,7 @@ client. (Though, you also need to provide a small constructor for the service.)< <pre> public class HelloIntentService extends IntentService { - /** + /** * A constructor is required, and must call the super {@link android.app.IntentService#IntentService} * constructor with a name for the worker thread. */ @@ -443,8 +437,8 @@ public class HelloService extends Service { HandlerThread thread = new HandlerThread("ServiceStartArguments", Process.THREAD_PRIORITY_BACKGROUND); thread.start(); - - // Get the HandlerThread's Looper and use it for our Handler + + // Get the HandlerThread's Looper and use it for our Handler mServiceLooper = thread.getLooper(); mServiceHandler = new ServiceHandler(mServiceLooper); } @@ -458,7 +452,7 @@ public class HelloService extends Service { Message msg = mServiceHandler.obtainMessage(); msg.arg1 = startId; mServiceHandler.sendMessage(msg); - + // If we get killed, after returning from here, restart return START_STICKY; } @@ -468,10 +462,10 @@ public class HelloService extends Service { // We don't provide binding, so return null return null; } - + @Override public void onDestroy() { - Toast.makeText(this, "service done", Toast.LENGTH_SHORT).show(); + Toast.makeText(this, "service done", Toast.LENGTH_SHORT).show(); } } </pre> @@ -652,7 +646,7 @@ developer guides for more information.</p> <h2 id="Foreground">Running a Service in the Foreground</h2> <p>A foreground service is a service that's considered to be something the -user is actively aware of and thus not a candidate for the system to kill when low on memory. A +user is actively aware of and thus not a candidate for the system to kill when low on memory. A foreground service must provide a notification for the status bar, which is placed under the "Ongoing" heading, which means that the notification cannot be dismissed unless the service is either stopped or removed from the foreground.</p> |