Figure 1. Layout using clip bounds (default).
API Level: {@sdkPlatformApiLevel}
Android {@sdkPlatformVersion} ({@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR2}) is an update to the Jelly Bean release that offers new features for users and app developers. This document provides an introduction to the most notable new APIs.
As an app developer, you should download the Android {@sdkPlatformVersion} system image and SDK platform from the SDK Manager as soon as possible. If you don't have a device running Android {@sdkPlatformVersion} on which to test your app, use the Android {@sdkPlatformVersion} system image to test your app on the Android emulator. Then build your apps against the Android {@sdkPlatformVersion} platform to begin using the latest APIs.
To better optimize your app for devices running Android {@sdkPlatformVersion},
you should set your {@code targetSdkVersion} to
"{@sdkPlatformApiLevel}", install it on an Android {@sdkPlatformVersion} system image,
test it, then publish an update with this change.
You can use APIs in Android {@sdkPlatformVersion} while also supporting older versions by adding conditions to your code that check for the system API level before executing APIs not supported by your {@code minSdkVersion}. To learn more about maintaining backward compatibility, read Supporting Different Platform Versions.
Various APIs are also available in the Android Support Library that allow you to implement new features on older versions of the platform.
For more information about how API levels work, read What is API Level?
If you have previously published an app for Android, be aware that your app might be affected by changes in Android {@sdkPlatformVersion}.
Your app might misbehave in a restricted profile environment.
Users in a restricted profile environment might not have all the standard Android apps available. For example, a restricted profile might have the web browser and camera app disabled. So your app should not make assumptions about which apps are available, because if you call {@link android.app.Activity#startActivity startActivity()} without verifying whether an app is available to handle the {@link android.content.Intent}, your app might crash in a restricted profile.
When using an implicit intent, you should always verify that an app is available to handle the intent by calling {@link android.content.Intent#resolveActivity resolveActivity()} or {@link android.content.pm.PackageManager#queryIntentActivities queryIntentActivities()}. For example:
Intent intent = new Intent(Intent.ACTION_SEND);
...
if (intent.resolveActivity(getPackageManager()) != null) {
startActivity(intent);
} else {
Toast.makeText(context, R.string.app_not_available, Toast.LENGTH_LONG).show();
}
Your app might misbehave in a restricted profile environment.
Users within a restricted profile environment do not have access to user accounts by default. If your app depends on an {@link android.accounts.Account}, then your app might crash or behave unexpectedly when used in a restricted profile.
If you'd like to prevent restricted profiles from using your app entirely because your app depends on account information that's sensitive, specify the {@code android:requiredAccountType} attribute in your manifest's {@code <application>} element.
If you’d like to allow restricted profiles to continue using your app even though they can’t create their own accounts, then you can either disable your app features that require an account or allow restricted profiles to access the accounts created by the primary user. For more information, see the section below about Supporting accounts in a restricted profile.
Your video might appear smaller on Android 4.3.
On previous versions of Android, the {@link android.widget.VideoView} widget incorrectly calculated the {@code "wrap_content"} value for {@link android.R.attr#layout_height} and {@link android.R.attr#layout_width} to be the same as {@code "match_parent"}. So while using {@code "wrap_content"} for the height or width may have previously provided your desired video layout, doing so may result in a much smaller video on Android 4.3 and higher. To fix the issue, replace {@code "wrap_content"} with {@code "match_parent"} and verify your video appears as expected on Android 4.3 as well as on older versions.
On Android tablets, users can now create restricted profiles based on the primary user. When users create a restricted profile, they can enable restrictions such as which apps are available to the profile. A new set of APIs in Android 4.3 also allow you to build fine-grain restriction settings for the apps you develop. For example, by using the new APIs, you can allow users to control what type of content is available within your app when running in a restricted profile environment.
The UI for users to control the restrictions you've built is managed by the system's Settings application. To make your app's restriction settings appear to the user, you must declare the restrictions your app provides by creating a {@link android.content.BroadcastReceiver} that receives the {@link android.content.Intent#ACTION_GET_RESTRICTION_ENTRIES} intent. The system invokes this intent to query all apps for available restrictions, then builds the UI to allow the primary user to manage restrictions for each restricted profile.
In the {@link android.content.BroadcastReceiver#onReceive onReceive()} method of your {@link android.content.BroadcastReceiver}, you must create a {@link android.content.RestrictionEntry} for each restriction your app provides. Each {@link android.content.RestrictionEntry} defines a restriction title, description, and one of the following data types:
You then put all the {@link android.content.RestrictionEntry} objects into an {@link java.util.ArrayList} and put it into the broadcast receiver's result as the value for the {@link android.content.Intent#EXTRA_RESTRICTIONS_LIST} extra.
The system creates the UI for your app's restrictions in the Settings app and saves each restriction with the unique key you provided for each {@link android.content.RestrictionEntry} object. When the user opens your app, you can query for any current restrictions by calling {@link android.os.UserManager#getApplicationRestrictions getApplicationRestrictions()}. This returns a {@link android.os.Bundle} containing the key-value pairs for each restriction you defined with the {@link android.content.RestrictionEntry} objects.
If you want to provide more specific restrictions that can't be handled by boolean, single choice, and multi-choice values, then you can create an activity where the user can specify the restrictions and allow users to open that activity from the restriction settings. In your broadcast receiver, include the {@link android.content.Intent#EXTRA_RESTRICTIONS_INTENT} extra in the result {@link android.os.Bundle}. This extra must specify an {@link android.content.Intent} indicating the {@link android.app.Activity} class to launch (use the {@link android.os.Bundle#putParcelable putParcelable()} method to pass {@link android.content.Intent#EXTRA_RESTRICTIONS_INTENT} with the intent). When the primary user enters your activity to set custom restrictions, your activity must then return a result containing the restriction values in an extra using either the {@link android.content.Intent#EXTRA_RESTRICTIONS_LIST} or {@link android.content.Intent#EXTRA_RESTRICTIONS_BUNDLE} key, depending on whether you specify {@link android.content.RestrictionEntry} objects or key-value pairs, respectively.
Any accounts added to the primary user are available to a restricted profile, but the accounts are not accessible from the {@link android.accounts.AccountManager} APIs by default. If you attempt to add an account with {@link android.accounts.AccountManager} while in a restricted profile, you will get a failure result. Due to these restrictions, you have the following three options:
To get access to an account from a restricted profile, you must add the {@code android:restrictedAccountType} attribute to the <application> tag:
<application ...
android:restrictedAccountType="com.example.account.type" >
Caution: Enabling this attribute provides your app access to the primary user's accounts from restricted profiles. So you should allow this only if the information displayed by your app does not reveal personally identifiable information (PII) that’s considered sensitive. The system settings will inform the primary user that your app grants restricted profiles to their accounts, so it should be clear to the user that account access is important for your app's functionality. If possible, you should also provide adequate restriction controls for the primary user that define how much account access is allowed in your app.
If you want to use accounts, but don’t actually require them for your app’s primary functionality, you can check for account availability and disable features when not available. You should first check if there is an existing account available. If not, then query whether it’s possible to create a new account by calling {@link android.os.UserManager#getUserRestrictions()} and check the {@link android.os.UserManager#DISALLOW_MODIFY_ACCOUNTS} extra in the result. If it is {@code true}, then you should disable whatever functionality of your app requires access to accounts. For example:
UserManager um = (UserManager) context.getSystemService(Context.USER_SERVICE);
Bundle restrictions = um.getUserRestrictions();
if (restrictions.getBoolean(UserManager.DISALLOW_MODIFY_ACCOUNTS, false)) {
// cannot add accounts, disable some functionality
}
Note: In this scenario, you should not declare any new attributes in your manifest file.
If it’s instead important that your app not be available to restricted profiles because your app depends on sensitive personal information in an account (and because restricted profiles currently cannot add new accounts), add the {@code android:requiredAccountType} attribute to the <application> tag:
<application ...
android:requiredAccountType="com.example.account.type" >
For example, the Gmail app uses this attribute to disable itself for restricted profiles, because the owner's personal email should not be available to restricted profiles.
Android now supports Bluetooth Low Energy (LE) with new APIs in {@link android.bluetooth}. With the new APIs, you can build Android apps that communicate with Bluetooth Low Energy peripherals such as heart rate monitors and pedometers.
Because Bluetooth LE is a hardware feature that is not available on all Android-powered devices, you must declare in your manifest file a {@code <uses-feature>} element for {@code "android.hardware.bluetooth_le"}:
<uses-feature android:name="android.hardware.bluetooth_le" android:required="true" />
If you're already familiar with Android's Classic Bluetooth APIs, notice that using the Bluetooth LE APIs has some differences. Most importantly is that there's now a {@link android.bluetooth.BluetoothManager} class that you should use for some high level operations such as acquiring a {@link android.bluetooth.BluetoothAdapter}, getting a list of connected devices, and checking the state of a device. For example, here's how you should now get the {@link android.bluetooth.BluetoothAdapter}:
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
To discover Bluetooth LE peripherals, call {@link android.bluetooth.BluetoothAdapter#startLeScan startLeScan()} on the {@link android.bluetooth.BluetoothAdapter}, passing it an implementation of the {@link android.bluetooth.BluetoothAdapter.LeScanCallback} interface. When the Bluetooth adapter detects a Bluetooth LE peripheral, your {@link android.bluetooth.BluetoothAdapter.LeScanCallback} implementation receives a call to the {@link android.bluetooth.BluetoothAdapter.LeScanCallback#onLeScan onLeScan()} method. This method provides you with a {@link android.bluetooth.BluetoothDevice} object representing the detected device, the RSSI value for the device, and a byte array containing the device's advertisement record.
If you want to scan for only specific types of peripherals, you can instead call {@link android.bluetooth.BluetoothAdapter#startLeScan startLeScan()} and include an array of {@link java.util.UUID} objects that specify the GATT services your app supports.
Note: You can only scan for Bluetooth LE devices or scan for Classic Bluetooth devices using previous APIs. You cannot scan for both LE and Classic Bluetooth devices at once.
To then connect to a Bluetooth LE peripheral, call {@link android.bluetooth.BluetoothDevice#connectGatt connectGatt()} on the corresponding {@link android.bluetooth.BluetoothDevice} object, passing it an implementation of {@link android.bluetooth.BluetoothGattCallback}. Your implementation of {@link android.bluetooth.BluetoothGattCallback} receives callbacks regarding the connectivity state with the device and other events. It's during the {@link android.bluetooth.BluetoothGattCallback#onConnectionStateChange onConnectionStateChange()} callback that you can begin communicating with the device if the method passes {@link android.bluetooth.BluetoothProfile#STATE_CONNECTED} as the new state.
Accessing Bluetooth features on a device also requires that your app request certain Bluetooth user permissions. For more information, see the Bluetooth Low Energy API guide.
When attempting to identify the user's location, Android may use Wi-Fi to help determine the location by scanning nearby access points. However, users often keep Wi-Fi turned off to conserve battery, resulting in location data that's less accurate. Android now includes a scan-only mode that allows the device Wi-Fi to scan access points to help obtain the location without connecting to an access point, thus greatly reducing battery usage.
If you want to acquire the user's location but Wi-Fi is currently off, you can request the user to enable Wi-Fi scan-only mode by calling {@link android.content.Context#startActivity startActivity()} with the action {@link android.net.wifi.WifiManager#ACTION_REQUEST_SCAN_ALWAYS_AVAILABLE}.
New {@link android.net.wifi.WifiEnterpriseConfig} APIs allow enterprise-oriented services to automate Wi-Fi configuration for managed devices.
Since Android 4.0, a feature called "Quick response" allows users to respond to incoming calls with an immediate text message without needing to pick up the call or unlock the device. Until now, these quick messages were always handled by the default Messaging app. Now any app can declare its capability to handle these messages by creating a {@link android.app.Service} with an intent filter for {@link android.telephony.TelephonyManager#ACTION_RESPOND_VIA_MESSAGE}.
When the user responds to an incoming call with a quick response, the Phone app sends the {@link android.telephony.TelephonyManager#ACTION_RESPOND_VIA_MESSAGE} intent with a URI describing the recipient (the caller) and the {@link android.content.Intent#EXTRA_TEXT} extra with the message the user wants to send. When your service receives the intent, it should deliver the message and immediately stop itself (your app should not show an activity).
In order to receive this intent, you must declare the {@link android.Manifest.permission#SEND_RESPOND_VIA_MESSAGE} permission.
Android now makes it easier for you to write your own Dynamic Adaptive Streaming over HTTP (DASH) players in accordance with the ISO/IEC 23009-1 standard, using existing APIs in {@link android.media.MediaCodec} and {@link android.media.MediaExtractor}. The framework underlying these APIs has been updated to support parsing of fragmented MP4 files, but your app is still responsible for parsing the MPD metadata and passing the individual streams to {@link android.media.MediaExtractor}.
If you want to use DASH with encrypted content, notice that the {@link android.media.MediaExtractor#getSampleCryptoInfo getSampleCryptoInfo()} method returns the {@link android.media.MediaCodec.CryptoInfo} metadata describing the structure of each encrypted media sample. Also, the {@link android.media.MediaExtractor#getPsshInfo()} method has been added to {@link android.media.MediaExtractor} so you can access the PSSH metadata for your DASH media. This method returns a map of {@link java.util.UUID} objects to bytes, with the {@link java.util.UUID} specifying the crypto scheme, and the bytes being the data specific to that scheme.
The new {@link android.media.MediaDrm} class provides a modular solution for digital rights management (DRM) with your media content by separating DRM concerns from media playback. For instance, this API separation allows you to play back Widevine-encrypted content without having to use the Widevine media format. This DRM solution also supports DASH Common Encryption so you can use a variety of DRM schemes with your streaming content.
You can use {@link android.media.MediaDrm} to obtain opaque key-request messages and process key-response messages from the server for license acquisition and provisioning. Your app is responsible for handling the network communication with the servers; the {@link android.media.MediaDrm} class provides only the ability to generate and process the messages.
The {@link android.media.MediaDrm} APIs are intended to be used in conjunction with the {@link android.media.MediaCodec} APIs that were introduced in Android 4.1 (API level 16), including {@link android.media.MediaCodec} for encoding and decoding your content, {@link android.media.MediaCrypto} for handling encrypted content, and {@link android.media.MediaExtractor} for extracting and demuxing your content.
You must first construct {@link android.media.MediaExtractor} and {@link android.media.MediaCodec} objects. You can then access the DRM-scheme-identifying {@link java.util.UUID}, typically from metadata in the content, and use it to construct an instance of a {@link android.media.MediaDrm} object with its constructor.
Android 4.1 (API level 16) added the {@link android.media.MediaCodec} class for low-level encoding and decoding of media content. When encoding video, Android 4.1 required that you provide the media with a {@link java.nio.ByteBuffer} array, but Android 4.3 now allows you to use a {@link android.view.Surface} as the input to an encoder. For instance, this allows you to encode input from an existing video file or using frames generated from OpenGL ES.
To use a {@link android.view.Surface} as the input to your encoder, first call {@link android.media.MediaCodec#configure configure()} for your {@link android.media.MediaCodec}. Then call {@link android.media.MediaCodec#createInputSurface()} to receive the {@link android.view.Surface} upon which you can stream your media.
For example, you can use the given {@link android.view.Surface} as the window for an OpenGL context by passing it to {@link android.opengl.EGL14#eglCreateWindowSurface eglCreateWindowSurface()}. Then while rendering the surface, call {@link android.opengl.EGL14#eglSwapBuffers eglSwapBuffers()} to pass the frame to the {@link android.media.MediaCodec}.
To begin encoding, call {@link android.media.MediaCodec#start()} on the {@link android.media.MediaCodec}. When done, call {@link android.media.MediaCodec#signalEndOfInputStream} to terminate encoding, and call {@link android.view.Surface#release()} on the {@link android.view.Surface}.
The new {@link android.media.MediaMuxer} class enables multiplexing between one audio stream and one video stream. These APIs serve as a counterpart to the {@link android.media.MediaExtractor} class added in Android 4.2 for de-multiplexing (demuxing) media.
Supported output formats are defined in {@link android.media.MediaMuxer.OutputFormat}. Currently, MP4 is the only supported output format and {@link android.media.MediaMuxer} currently supports only one audio stream and/or one video stream at a time.
{@link android.media.MediaMuxer} is mostly designed to work with {@link android.media.MediaCodec} so you can perform video processing through {@link android.media.MediaCodec} then save the output to an MP4 file through {@link android.media.MediaMuxer}. You can also use {@link android.media.MediaMuxer} in combination with {@link android.media.MediaExtractor} to perform media editing without the need to encode or decode.
In Android 4.0 (API level 14), the {@link android.media.RemoteControlClient} was added to enable media playback controls from remote control clients such as the controls available on the lock screen. Android 4.3 now provides the ability for such controllers to display the playback position and controls for scrubbing the playback. If you've enabled remote control for your media app with the {@link android.media.RemoteControlClient} APIs, then you can allow playback scrubbing by implementing two new interfaces.
First, you must enable the {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_POSITION_UPDATE} flag by passing it to {@link android.media.RemoteControlClient#setTransportControlFlags setTransportControlsFlags()}.
Then implement the following two new interfaces:
Once you update your playback with the new position, call {@link android.media.RemoteControlClient#setPlaybackState setPlaybackState()} to indicate the new playback state, position, and speed.
With these interfaces defined, you can set them for your {@link android.media.RemoteControlClient} by calling {@link android.media.RemoteControlClient#setOnGetPlaybackPositionListener setOnGetPlaybackPositionListener()} and {@link android.media.RemoteControlClient#setPlaybackPositionUpdateListener setPlaybackPositionUpdateListener()}, respectively.
Android 4.3 adds Java interfaces and native support for OpenGL ES 3.0. Key new functionality provided in OpenGL ES 3.0 includes:
The Java interface for OpenGL ES 3.0 on Android is provided with {@link android.opengl.GLES30}. When using OpenGL ES 3.0, be sure that you declare it in your manifest file with the <uses-feature> tag and the {@code android:glEsVersion} attribute. For example:
<manifest>
<uses-feature android:glEsVersion="0x00030000" />
...
</manifest>
And remember to specify the OpenGL ES context by calling {@link android.opengl.GLSurfaceView#setEGLContextClientVersion setEGLContextClientVersion()}, passing {@code 3} as the version.
For more information about using OpenGL ES, including how to check the device's supported OpenGL ES version at runtime, see the OpenGL ES API guide.
Using a mipmap as the source for your bitmap or drawable is a simple way to provide a quality image and various image scales, which can be particularly useful if you expect your image to be scaled during an animation.
Android 4.2 (API level 17) added support for mipmaps in the {@link android.graphics.Bitmap} class—Android swaps the mip images in your {@link android.graphics.Bitmap} when you've supplied a mipmap source and have enabled {@link android.graphics.Bitmap#setHasMipMap setHasMipMap()}. Now in Android 4.3, you can enable mipmaps for a {@link android.graphics.drawable.BitmapDrawable} object as well, by providing a mipmap asset and setting the {@code android:mipMap} attribute in a bitmap resource file or by calling {@link android.graphics.drawable.BitmapDrawable#hasMipMap hasMipMap()}.
The new {@link android.view.ViewOverlay} class provides a transparent layer on top of a {@link android.view.View} on which you can add visual content and which does not affect the layout hierarchy. You can get a {@link android.view.ViewOverlay} for any {@link android.view.View} by calling {@link android.view.View#getOverlay}. The overlay always has the same size and position as its host view (the view from which it was created), allowing you to add content that appears in front of the host view, but which cannot extend the bounds of that host view.
Using a {@link android.view.ViewOverlay} is particularly useful when you want to create animations such as sliding a view outside of its container or moving items around the screen without affecting the view hierarchy. However, because the usable area of an overlay is restricted to the same area as its host view, if you want to animate a view moving outside its position in the layout, you must use an overlay from a parent view that has the desired layout bounds.
When you create an overlay for a widget view such as a {@link android.widget.Button}, you can add {@link android.graphics.drawable.Drawable} objects to the overlay by calling {@link android.view.ViewOverlay#add(Drawable)}. If you call {@link android.view.ViewGroup#getOverlay} for a layout view, such as {@link android.widget.RelativeLayout}, the object returned is a {@link android.view.ViewGroupOverlay}. The {@link android.view.ViewGroupOverlay} class is a subclass of {@link android.view.ViewOverlay} that also allows you to add {@link android.view.View} objects by calling {@link android.view.ViewGroupOverlay#add(View)}.
Note: All drawables and views that you add to an overlay are visual only. They cannot receive focus or input events.
For example, the following code animates a view sliding to the right by placing the view in the parent view's overlay, then performing a translation animation on that view:
View view = findViewById(R.id.view_to_remove); ViewGroup container = (ViewGroup) view.getParent(); container.getOverlay().add(view); ObjectAnimator anim = ObjectAnimator.ofFloat(view, "translationX", container.getRight()); anim.start();
For views that contain nine-patch background images, you can now specify that they should be aligned with neighboring views based on the "optical" bounds of the background image rather than the "clip" bounds of the view.
For example, figures 1 and 2 each show the same layout, but the version in figure 1 is using clip bounds (the default behavior), while figure 2 is using optical bounds. Because the nine-patch images used for the button and the photo frame include padding around the edges, they don’t appear to align with each other or the text when using clip bounds.
Note: The screenshot in figures 1 and 2 have the "Show layout bounds" developer setting enabled. For each view, red lines indicate the optical bounds, blue lines indicate the clip bounds, and pink indicates margins.
Mouse over to hide the layout bounds.
Figure 1. Layout using clip bounds (default).
Figure 2. Layout using optical bounds.
To align the views based on their optical bounds, set the {@code android:layoutMode} attribute to {@code "opticalBounds"} in one of the parent layouts. For example:
<LinearLayout android:layoutMode="opticalBounds" ... >
Figure 3. Zoomed view of the Holo button nine-patch with optical bounds.
For this to work, the nine-patch images applied to the background of your views must specify the optical bounds using red lines along the bottom and right-side of the nine-patch file (as shown in figure 3). The red lines indicate the region that should be subtracted from the clip bounds, leaving the optical bounds of the image.
When you enable optical bounds for a {@link android.view.ViewGroup} in your layout, all descendant views inherit the optical bounds layout mode unless you override it for a group by setting {@code android:layoutMode} to {@code "clipBounds"}. All layout elements also honor the optical bounds of their child views, adapting their own bounds based on the optical bounds of the views within them. However, layout elements (subclasses of {@link android.view.ViewGroup}) currently do not support optical bounds for nine-patch images applied to their own background.
If you create a custom view by subclassing {@link android.view.View}, {@link android.view.ViewGroup}, or any subclasses thereof, your view will inherit these optical bound behaviors.
Note: All widgets supported by the Holo theme have been updated with optical bounds, including {@link android.widget.Button}, {@link android.widget.Spinner}, {@link android.widget.EditText}, and others. So you can immediately benefit by setting the {@code android:layoutMode} attribute to {@code "opticalBounds"} if your app applies a Holo theme ({@link android.R.style#Theme_Holo Theme.Holo}, {@link android.R.style#Theme_Holo_Light Theme.Holo.Light}, etc.).
To specify optical bounds for your own nine-patch images with the Draw 9-patch tool, hold CTRL when clicking on the border pixels.
You can now animate between two {@link android.graphics.Rect} values with the new {@link android.animation.RectEvaluator}. This new class is an implementation of {@link android.animation.TypeEvaluator} that you can pass to {@link android.animation.ValueAnimator#setEvaluator ValueAnimator.setEvaluator()}.
Previously, if you wanted to listen for when your view attached/detached to the window or when its focus changed, you needed to override the {@link android.view.View} class to implement {@link android.view.View#onAttachedToWindow onAttachedToWindow()} and {@link android.view.View#onDetachedFromWindow onDetachedFromWindow()}, or {@link android.view.View#onWindowFocusChanged onWindowFocusChanged()}, respectively.
Now, to receive attach and detach events you can instead implement {@link android.view.ViewTreeObserver.OnWindowAttachListener} and set it on a view with {@link android.view.ViewTreeObserver#addOnWindowAttachListener addOnWindowAttachListener()}. And to receive focus events, you can implement {@link android.view.ViewTreeObserver.OnWindowFocusChangeListener} and set it on a view with {@link android.view.ViewTreeObserver#addOnWindowFocusChangeListener addOnWindowFocusChangeListener()}.
To be sure your app fills the entire screen on every television, you can now enable overscan for you app layout. Overscan mode is determined by the {@link android.view.WindowManager.LayoutParams#FLAG_LAYOUT_IN_OVERSCAN} flag, which you can enable with platform themes such as {@link android.R.style#Theme_DeviceDefault_NoActionBar_Overscan} or by enabling the {@link android.R.attr#windowOverscan} style in a custom theme.
The {@code <activity>} tag's {@code screenOrientation} attribute now supports additional values to honor the user's preference for auto-rotation:
Additionally, you can now also declare {@code "locked"} to lock your app's orientation into the screen's current orientation.
The new {@link android.view.WindowManager.LayoutParams#rotationAnimation} field in {@link android.view.WindowManager} allows you to select between one of three animations you want to use when the system switches screen orientations. The three animations are:
Note: These animations are available only if you've set your activity to use "fullscreen" mode, which you can enable with themes such as {@link android.R.style#Theme_Holo_NoActionBar_Fullscreen Theme.Holo.NoActionBar.Fullscreen}.
For example, here's how you can enable the "crossfade" animation:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
WindowManager.LayoutParams params = getWindow().getAttributes();
params.rotationAnimation = WindowManager.LayoutParams.ROTATION_ANIMATION_CROSSFADE;
getWindow().setAttributes(params);
...
}
The new {@link android.hardware.Sensor#TYPE_GAME_ROTATION_VECTOR} sensor allows you to detect the device's rotations without worrying about magnetic interferences. Unlike the {@link android.hardware.Sensor#TYPE_ROTATION_VECTOR} sensor, the {@link android.hardware.Sensor#TYPE_GAME_ROTATION_VECTOR} is not based on magnetic north.
The new {@link android.hardware.Sensor#TYPE_GYROSCOPE_UNCALIBRATED} and {@link android.hardware.Sensor#TYPE_MAGNETIC_FIELD_UNCALIBRATED} sensors provide raw sensor data without consideration for bias estimations. That is, the existing {@link android.hardware.Sensor#TYPE_GYROSCOPE} and {@link android.hardware.Sensor#TYPE_MAGNETIC_FIELD} sensors provide sensor data that takes into account estimated bias from gyro-drift and hard iron in the device, respectively. Whereas the new "uncalibrated" versions of these sensors instead provide the raw sensor data and offer the estimated bias values separately. These sensors allow you to provide your own custom calibration for the sensor data by enhancing the estimated bias with external data.
Android 4.3 adds a new service class, {@link android.service.notification.NotificationListenerService}, that allows your app to receive information about new notifications as they are posted by the system.
If your app currently uses the accessibility service APIs to access system notifications, you should update your app to use these APIs instead.
The new Contacts Provider query, {@link android.provider.ContactsContract.CommonDataKinds.Contactables#CONTENT_URI Contactables.CONTENT_URI}, provides an efficient way to get one {@link android.database.Cursor} that contains all email addresses and phone numbers belonging to all contacts matching the specified query.
New APIs have been added to Contacts Provider that allow you to efficiently query recent changes to the contacts data. Previously, your app could be notified when something in the contacts data changed, but you would not know exactly what changed and would need to retrieve all contacts then iterate through them to discover the change.
To track changes to inserts and updates, you can now include the {@link android.provider.ContactsContract.ContactsColumns#CONTACT_LAST_UPDATED_TIMESTAMP} parameter with your selection to query only the contacts that have changed since the last time you queried the provider.
To track which contacts have been deleted, the new table {@link android.provider.ContactsContract.DeletedContacts} provides a log of contacts that have been deleted (but each contact deleted is held in this table for a limited time). Similar to {@link android.provider.ContactsContract.ContactsColumns#CONTACT_LAST_UPDATED_TIMESTAMP}, you can use the new selection parameter, {@link android.provider.ContactsContract.DeletedContacts#CONTACT_DELETED_TIMESTAMP} to check which contacts have been deleted since the last time you queried the provider. The table also contains the constant {@link android.provider.ContactsContract.DeletedContacts#DAYS_KEPT_MILLISECONDS} containing the number of days (in milliseconds) that the log will be kept.
Additionally, the Contacts Provider now broadcasts the {@link android.provider.ContactsContract.Intents#CONTACTS_DATABASE_CREATED} action when the user clears the contacts storage through the system settings menu, effectively recreating the Contacts Provider database. It’s intended to signal apps that they need to drop all the contact information they’ve stored and reload it with a new query.
For sample code using these APIs to check for changes to the contacts, look in the ApiDemos sample available in the SDK Samples download.
Previous versions of Android support right-to-left (RTL) languages and layout, but sometimes don't properly handle mixed-direction text. So Android 4.3 adds the {@link android.text.BidiFormatter} APIs that help you properly format text with opposite-direction content without garbling any parts of it.
For example, when you want to create a sentence with a string variable, such as "Did you mean 15 Bay Street, Laurel, CA?", you normally pass a localized string resource and the variable to {@link java.lang.String#format String.format()}:
Resources res = getResources(); String suggestion = String.format(res.getString(R.string.did_you_mean), address);
However, if the locale is Hebrew, then the formatted string comes out like this:
האם התכוונת ל 15 Bay Street, Laurel, CA?
That's wrong because the "15" should be left of "Bay Street." The solution is to use {@link android.text.BidiFormatter} and its {@link android.text.BidiFormatter#unicodeWrap(String) unicodeWrap()} method. For example, the code above becomes:
Resources res = getResources();
BidiFormatter bidiFormatter = BidiFormatter.getInstance();
String suggestion = String.format(res.getString(R.string.did_you_mean),
bidiFormatter.unicodeWrap(address));
By default, {@link android.text.BidiFormatter#unicodeWrap(String) unicodeWrap()} uses the first-strong directionality estimation heuristic, which can get things wrong if the first signal for text direction does not represent the appropriate direction for the content as a whole. If necessary, you can specify a different heuristic by passing one of the {@link android.text.TextDirectionHeuristic} constants from {@link android.text.TextDirectionHeuristics} to {@link android.text.BidiFormatter#unicodeWrap(String,TextDirectionHeuristic) unicodeWrap()}.
Note: These new APIs are also available for previous versions of Android through the Android Support Library, with the {@link android.support.v4.text.BidiFormatter} class and related APIs.
An {@link android.accessibilityservice.AccessibilityService} can now receive a callback for key input events with the {@link android.accessibilityservice.AccessibilityService#onKeyEvent onKeyEvent()} callback method. This allows your accessibility service to handle input for key-based input devices such as a keyboard and translate those events to special actions that previously may have been possible only with touch input or the device's directional pad.
The {@link android.view.accessibility.AccessibilityNodeInfo} now provides APIs that allow an {@link android.accessibilityservice.AccessibilityService} to select, cut, copy, and paste text in a node.
To specify the selection of text to cut or copy, your accessibility service can use the new action, {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_SET_SELECTION}, passing with it the selection start and end position with {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_ARGUMENT_SELECTION_START_INT} and {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_ARGUMENT_SELECTION_END_INT}. Alternatively you can select text by manipulating the cursor position using the existing action, {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_NEXT_AT_MOVEMENT_GRANULARITY} (previously only for moving the cursor position), and adding the argument {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_ARGUMENT_EXTEND_SELECTION_BOOLEAN}.
You can then cut or copy with {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_CUT}, {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_COPY}, then later paste with {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_PASTE}.
Note: These new APIs are also available for previous versions of Android through the Android Support Library, with the {@link android.support.v4.view.accessibility.AccessibilityNodeInfoCompat} class.
Beginning with Android 4.3, an accessibility service must declare accessibility capabilities in its metadata file in order to use certain accessibility features. If the capability is not requested in the metadata file, then the feature will be a no-op. To declare your service's accessibility capabilities, you must use XML attributes that correspond to the various "capability" constants in the {@link android.accessibilityservice.AccessibilityServiceInfo} class.
For example, if a service does not request the {@link android.R.styleable#AccessibilityService_canRequestFilterKeyEvents flagRequestFilterKeyEvents} capability, then it will not receive key events.
The new {@link android.app.UiAutomation} class provides APIs that allow you to simulate user actions for test automation. By using the platform's {@link android.accessibilityservice.AccessibilityService} APIs, the {@link android.app.UiAutomation} APIs allow you to inspect the screen content and inject arbitrary keyboard and touch events.
To get an instance of {@link android.app.UiAutomation}, call {@link android.app.Instrumentation#getUiAutomation Instrumentation.getUiAutomation()}. In order for this to work, you must supply the {@code -w} option with the {@code instrument} command when running your {@link android.test.InstrumentationTestCase} from {@code adb shell}.
With the {@link android.app.UiAutomation} instance, you can execute arbitrary events to test your app by calling {@link android.app.UiAutomation#executeAndWaitForEvent executeAndWaitForEvent()}, passing it a {@link java.lang.Runnable} to perform, a timeout period for the operation, and an implementation of the {@link android.app.UiAutomation.AccessibilityEventFilter} interface. It's within your {@link android.app.UiAutomation.AccessibilityEventFilter} implementation that you'll receive a call that allows you to filter the events that you're interested in and determine the success or failure of a given test case.
To observe all the events during a test, create an implementation of {@link android.app.UiAutomation.OnAccessibilityEventListener} and pass it to {@link android.app.UiAutomation#setOnAccessibilityEventListener setOnAccessibilityEventListener()}. Your listener interface then receives a call to {@link android.app.UiAutomation.OnAccessibilityEventListener#onAccessibilityEvent onAccessibilityEvent()} each time an event occurs, receiving an {@link android.view.accessibility.AccessibilityEvent} object that describes the event.
There is a variety of other operations that the {@link android.app.UiAutomation} APIs expose at a very low level to encourage the development of UI test tools such as uiautomator. For instance, {@link android.app.UiAutomation} can also:
And most importantly for UI test tools, the {@link android.app.UiAutomation} APIs work across application boundaries, unlike those in {@link android.app.Instrumentation}.
Android 4.3 adds the {@link android.os.Trace} class with two static methods, {@link android.os.Trace#beginSection beginSection()} and {@link android.os.Trace#endSection()}, which allow you to define blocks of code to include with the systrace report. By creating sections of traceable code in your app, the systrace logs provide you a much more detailed analysis of where slowdown occurs within your app.
For information about using the Systrace tool, read Analyzing Display and Performance with Systrace.
Android now offers a custom Java Security Provider in the {@link java.security.KeyStore} facility, called Android Key Store, which allows you to generate and save private keys that may be seen and used by only your app. To load the Android Key Store, pass {@code "AndroidKeyStore"} to {@link java.security.KeyStore#getInstance(String) KeyStore.getInstance()}.
To manage your app's private credentials in the Android Key Store, generate a new key with {@link java.security.KeyPairGenerator} with {@link android.security.KeyPairGeneratorSpec}. First get an instance of {@link java.security.KeyPairGenerator} by calling {@link java.security.KeyPairGenerator#getInstance getInstance()}. Then call {@link java.security.KeyPairGenerator#initialize initialize()}, passing it an instance of {@link android.security.KeyPairGeneratorSpec}, which you can get using {@link android.security.KeyPairGeneratorSpec.Builder KeyPairGeneratorSpec.Builder}. Finally, get your {@link java.security.KeyPair} by calling {@link java.security.KeyPairGenerator#generateKeyPair generateKeyPair()}.
Android also now supports hardware-backed storage for your {@link android.security.KeyChain} credentials, providing more security by making the keys unavailable for extraction. That is, once keys are in a hardware-backed key store (Secure Element, TPM, or TrustZone), they can be used for cryptographic operations but the private key material cannot be exported. Even the OS kernel cannot access this key material. While not all Android-powered devices support storage on hardware, you can check at runtime if hardware-backed storage is available by calling {@link android.security.KeyChain#isBoundKeyAlgorithm KeyChain.IsBoundKeyAlgorithm()}.
The following values are now supported in the {@code <uses-feature>} element so you can ensure that your app is installed only on devices that provide the features your app needs.
<uses-feature android:name="android.software.app_widgets" android:required="true" />
<uses-feature android:name="android.software.home_screen" android:required="true" />
<uses-feature android:name="android.software.input_methods" android:required="true" />
<uses-feature android:name="android.software.bluetooth_le" android:required="true" />
The following values are now supported in the {@code <uses-permission>} to declare the permissions your app requires in order to access certain APIs.
For a detailed view of all API changes in Android 4.3, see the API Differences Report.