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diff --git a/docs/html/guide/faq/framework.jd b/docs/html/guide/faq/framework.jd deleted file mode 100644 index c851e72..0000000 --- a/docs/html/guide/faq/framework.jd +++ /dev/null @@ -1,185 +0,0 @@ -page.title=Android Application Framework FAQ -excludeFromSuggestions=true -@jd:body - -<ul> - <li><a href="#1">Do all the Activities and Services of an - application run in a single process?</a></li> - <li><a href="#2">Do all Activities run in the main thread of - an application process?</a></li> - <li><a href="#3">How do I pass complicated data structures - from one Activity/Service to another?</a></li> - <li><a href="#4">How can I check if an Activity is already - running before starting it?</a></li> - <li><a href="#5">If an Activity starts a remote service, is - there any way for the Service to pass a message back to the Activity?</a></li> - <li><a href="#6">How to avoid getting the Application not - responding dialog?</a></li> - <li><a href="#7">How does an application know if a package is - added or removed?</a></li> -</ul> - - -<a name="1" id="1"></a> - -<h2>Do all the Activities and Services of an application run in a -single process?</h2> - -<p>All Activities and Services in an application run in a single process by -default. If needed, you can declare an <code>android:process</code> attribute -in your manifest file, to explicitly place a component (Activity/Service) in -another process.</p> - - - -<a name="2" id="2"></a> - -<h2>Do all Activities run in the main thread of an application -process?</h2> - -<p>By default, all of the application code in a single process runs -in the main UI thread. This is the same thread -that also handles UI events. The only exception is the code that handles -IPC calls coming in from other processes. The system maintains a -separate pool of transaction threads in each process to dispatch all -incoming IPC calls. The developer should create separate threads for any -long-running code, to avoid blocking the main UI thread.</p> - - - -<a name="3" id="3"></a> - -<h2>How do I pass data between Activities/Services within a single -application?</h2> - -<p>It depends on the type of data that you want to share:</p> - -<h3>Primitive Data Types</h3> - -<p>To share primitive data between Activities/Services in an -application, use Intent.putExtras(). For passing primitive data that -needs to persist use the -<a href="{@docRoot}guide/topics/data/data-storage.html#preferences"> -Preferences</a> storage mechanism.</p> - -<h3>Non-Persistent Objects</h3> - -<p>For sharing complex non-persistent user-defined objects for short -duration, the following approaches are recommended: -</p> - <h4>Singleton class</h4> - <p>You can take advantage of the fact that your application -components run in the same process through the use of a singleton. -This is a class that is designed to have only one instance. It -has a static method with a name such as <code>getInstance()</code> -that returns the instance; the first time this method is called, -it creates the global instance. Because all callers get the same -instance, they can use this as a point of interaction. For -example activity A may retrieve the instance and call setValue(3); -later activity B may retrieve the instance and call getValue() to -retrieve the last set value.</p> - - <h4>A public static field/method</h4> - <p>An alternate way to make data accessible across Activities/Services is to use <em>public static</em> -fields and/or methods. You can access these static fields from any other -class in your application. To share an object, the activity which creates your object sets a -static field to point to this object and any other activity that wants to use -this object just accesses this static field.</p> - - <h4>A HashMap of WeakReferences to Objects</h4> - <p>You can also use a HashMap of WeakReferences to Objects with Long -keys. When an activity wants to pass an object to another activity, it -simply puts the object in the map and sends the key (which is a unique -Long based on a counter or time stamp) to the recipient activity via -intent extras. The recipient activity retrieves the object using this -key.</p> - -<h3>Persistent Objects</h3> - -<p>Even while an application appears to continue running, the system -may choose to kill its process and restart it later. If you have data -that you need to persist from one activity invocation to the next, you -need to represent that data as state that gets saved by an activity when -it is informed that it might go away.</p> - -<p>For sharing complex persistent user-defined objects, the -following approaches are recommended: -<ul> - <li>Application Preferences</li> - <li>Files</li> - <li>contentProviders</li> - <li>SQLite DB</li> -</ul> -</p> - -<p>If the shared data needs to be retained across points where the application -process can be killed, then place that data in persistent storage like -Application Preferences, SQLite DB, Files or ContentProviders. Please refer to -the <a href="{@docRoot}guide/topics/data/data-storage.html">Data Storage</a> -for further details on how to use these components.</p> - - - - -<a name="4" id="4"></a> - -<h2>How can I check if an Activity is already running before starting -it?</h2> - -<p>The general mechanism to start a new activity if its not running— -or to bring the activity stack to the front if is already running in the -background— is the to use the NEW_TASK_LAUNCH flag in the startActivity() -call.</p> - - - -<a name="5" id="5"></a> - -<h2>If an Activity starts a remote service, is there any way for the -Service to pass a message back to the Activity?</h2> - -<p>See the {@link android.app.Service} documentation's for examples of -how clients can interact with a service. You can take advantage of the -fact that your components run in the same process to greatly simplify -service interaction from the generic remote case, as shown by the "Local -Service Sample". In some cases techniques like singletons may also make sense. - - -<a name="6" id="6"></a> - -<h2>How to avoid getting the Application not responding dialog?</h2> - -<p>Please read the <a href="{@docRoot}guide/practices/design/responsiveness.html">Designing for Responsiveness</a> -document.</p> - - - - -<a name="7" id="7"></a> - -<h2>How does an application know if a package is added or removed? -</h2> - -<p>Whenever a package is added, an intent with PACKAGE_ADDED action -is broadcast by the system. Similarly when a package is removed, an -intent with PACKAGE_REMOVED action is broadcast. To receive these -intents, you should write something like this: -<pre> - <receiver android:name ="com.android.samples.app.PackageReceiver"> - <intent-filter> - <action android:name="android.intent.action.PACKAGE_ADDED"/> - <action android:name="android.intent.action.PACKAGE_REMOVED"/> - - <data android:scheme="package" /> - </intent-filter> - </receiver> - </pre> - <br> -Here PackageReceiver is a BroadcastReceiver class.Its onReceive() -method is invoked, every time an application package is installed or -removed. - -</p> - - - |