Setting up the emulator is fast and convenient and allows you to emulate various screen sizes and device characteristics. Be sure to select a Pixel 2, 3, 3a, 4, or 4a device definition and an Android 11 API level 30 system image. If you don't already have an Android 11 system image installed that matches your device definition, click Download next to the Release Name to get it. When you return to the list of virtual devices in the AVD Manager, double-click your new virtual device to launch it.
Android Generic System Image GSI binaries are available to developers for app testing and validation purposes on supported Treble-compliant devices. Good examples of clusters include: side panels, navigation bars, main content areas, and elements that could contain many child elements.
Note: Clusters cannot be nested, although non-nested clusters may appear at different levels of the hierarchy. If you attempt to nest clusters, the framework treats only the top-most ViewGroup element as a cluster.
On devices that have touchscreens, you can set a cluster-designated ViewGroup object's android:touchscreenBlocksFocus element to true to allow cluster-only navigation into and out of that cluster.
If you apply this configuration to a cluster, users cannot use the Tab key or arrow keys to navigate into or out of the cluster; they must press the cluster navigation keyboard combination instead. Activities and services can use instances of TextToSpeech to dictate and pronounce content. As of Android 8. You can use this functionality to call attention to specific words as the text-to-speech engine speaks them.
To use these text-to-speech engine improvements in your app, register an instance of UtteranceProgressListener. As part of the registration process, include a handler for the onRangeStart method. The text-to-speech engine calls rangeStart to record the point in time at which it expects audio playback of a specific range of text to start.
When the audio for that text range starts playback, your app's onRangeStart method executes. Your app can then respond to this callback, such as by highlighting the text range that's associated with the utterance. For more information about tracking the playback progress of a text-to-speech engine, see the UtteranceProgressListener class reference. When the system needs to free up disk space, it will start by deleting cached files from apps that are the most over their allocated quota.
Thus, if you keep your cached data under your allocated quota, your cached files will be some of the last on the system to be cleared when necessary. When the system is deciding what cached files to delete inside your app, it will consider the oldest files first as determined by modified time.
There are also two new behaviors that you can enable on a per-directory basis to control how the system frees up your cached data:. Finally, when you need to allocate disk space for large files, consider using the new allocateBytes FileDescriptor, long API, which will automatically clear cached files belonging to other apps as needed to meet your request. When deciding if the device has enough disk space to hold your new data, call getAllocatableBytes UUID instead of using getUsableSpace , since the former will consider any cached data that the system is willing to clear on your behalf.
We've updated content providers to include support for loading a large dataset one page at a time. For example, a photo app with many thousands of images can query for a subset of the data to present in a page. Each page of results returned by a content provider is represented by a single Cursor object. Both a client and a provider must implement paging to make use of this feature. For detailed information about the changes to content providers, see ContentProvider and ContentProviderClient.
The ContentProvider and ContentResolver classes now each include a refresh method, making it easier for clients to know whether the information they request is up-to-date. You can add custom content refreshing logic by extending ContentProvider. Make sure that you override the refresh method to return true , indicating to your provider's clients that you've attempted to refresh the data yourself.
Your client app can explicitly request refreshed content by calling a different method, also called refresh. When calling this method, pass in the URI of the data to refresh. Note: Because you may be requesting data over a network, you should invoke refresh from the client side only when there's a strong indication that the content is stale. The most common reason to perform this type of content refresh is in response to a swipe-to-refresh gesture, explicitly requesting the current UI to display up-to-date content.
These improvements make it easier for your app to comply with the new background execution limits , since you can generally use scheduled jobs to replace the now-restricted background services or implicit broadcast receivers. Updates to JobScheduler include:.
For more information about implementing the data store, refer to Custom Data Store. There is a new VolumeShaper class. Use it to perform short automated volume transitions like fade-ins, fade-outs, and cross fades. See Controlling Amplitude with VolumeShaper to learn more. Audio apps share the audio output on a device by requesting and abandoning audio focus.
An app handles changes in focus by starting or stopping playback, or ducking its volume. There is a new AudioFocusRequest class. Using this class as the parameter of requestAudioFocus , apps have new capabilites when handling changes in audio focus: automatic ducking and delayed focus gain.
A new getMetrics method returns a PersistableBundle object containing configuration and performance information, expressed as a map of attributes and values. The getMetrics method is defined for these media classes:. Metrics are collected separately for each instance and persist for the lifetime of the instance. If no metrics are available the method returns null. The actual metrics returned depend on the class.
It includes a second parameter that specifies a seek mode:. Autofill services can use the string representation to appropriately fill out the views that require the data. Additionally, the AutofillManager class includes the notifyViewVisibilityChanged View, int, boolean method that you can call to notify the framework about changes in the visibility of a view in a virtual structure.
There's also an overload of the method for non virtual structures. However, non virtual structures usually don't require you to explicitly notify the framework because the method is already called by the View class. Custom descriptions are useful to help the autofill service clarify what is being saved; for example, when the screen contains a credit card, it could display a logo of the credit card bank, the last four digits of the credit card number, and its expiration number.
To learn more, see the CustomDescription class. Validator objects are used to avoid displaying the autofill save UI when the Validator condition isn't satisfied. This change is backward-compatible, as Editable implements CharSequence. The Editable interface provides valuable additional functionality. For example, because Editable also implements the Spannable interface, you can apply markup to content within an instance of EditText. By default, the WebView shows an interstitial that warns users of the known threat.
This screen gives users the option to load the URL anyway or return to a previous page that's safe.
Note: For optimal protection against known threats, wait until you've initialized Safe Browsing before you invoke a WebView object's loadUrl method.
The following code snippets show how you can instruct your app's instances of WebView to always go back to safety after encountering a known threat:. Note: Many Kotlin reference topics are derived from Java-based source code. This means that some Kotlin reference topics might contain Java code snippets. These additional libraries make it easy to add additional functionality and features to your app. Content and code samples on this page are subject to the licenses described in the Content License.
Android API Reference.
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