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Android 3.0 APIs

In this document

  1. API Overview
  2. API Level

Reference

  1. API Differences Report »

API Level: 11

For developers, the Android 3.0 platform (HONEYCOMB) is available as a downloadable component for the Android SDK. The downloadable platform includes an Android library and system image, as well as a set of emulator skins and more. The downloadable platform includes no external libraries.

For developers, the Android 3.0 platform is available as a downloadable component for the Android SDK. The downloadable platform includes an Android library and system image, as well as a set of emulator skins and more. To get started developing or testing against Android 3.0, use the Android SDK Manager to download the platform into your SDK.

API Overview

The sections below provide a technical overview of what's new for developers in Android 3.0, including new features and changes in the framework API since the previous version.

Fragments

A fragment is a new framework component that allows you to separate distinct elements of an activity into self-contained modules that define their own UI and lifecycle. To create a fragment, you must extend the Fragment class and implement several lifecycle callback methods, similar to an Activity. You can then combine multiple fragments in a single activity to build a multi-pane UI in which each pane manages its own lifecycle and user inputs.

You can also use a fragment without providing a UI and instead use the fragment as a worker for the activity, such as to manage the progress of a download that occurs only while the activity is running.

Additionally:

To manage the fragments in your activity, you must use the FragmentManager, which provides several APIs for interacting with fragments, such as finding fragments in the activity and popping fragments off the back stack to restore their previous state.

To perform a transaction, such as add or remove a fragment, you must create a FragmentTransaction. You can then call methods such as add() remove(), or replace(). Once you've applied all the changes you want to perform for the transaction, you must call commit() and the system applies the fragment transaction to the activity.

For more information about using fragments, read the Fragments documentation. Several samples are also available in the API Demos application.

Action Bar

The Action Bar is a replacement for the traditional title bar at the top of the activity window. It includes the application logo in the left corner and provides a new interface for items in the Options Menu. Additionally, the Action Bar allows you to:

The Action Bar is standard for all applications that use the new holographic theme, which is also standard when you set either the android:minSdkVersion or android:targetSdkVersion to "11".

For more information about the Action Bar, read the Action Bar documentation. Several samples are also available in the API Demos application.

System clipboard

Applications can now copy and paste data (beyond mere text) to and from the system-wide clipboard. Clipped data can be plain text, a URI, or an intent.

By providing the system access to the data you want the user to copy, through a content provider, the user can copy complex content (such as an image or data structure) from your application and paste it into another application that supports that type of content.

To start using the clipboard, get the global ClipboardManager object by calling getSystemService(CLIPBOARD_SERVICE).

To copy an item to the clipboard, you need to create a new ClipData object, which holds one or more ClipData.Item objects, each describing a single entity. To create a ClipData object containing just one ClipData.Item, you can use one of the helper methods, such as newPlainText(), newUri(), and newIntent(), which each return a ClipData object pre-loaded with the ClipData.Item you provide.

To add the ClipData to the clipboard, pass it to setPrimaryClip() for your instance of ClipboardManager.

You can then read a file from the clipboard (in order to paste it) by calling getPrimaryClip() on the ClipboardManager. Handling the ClipData you receive can be complicated and you need to be sure you can actually handle the data type in the clipboard before attempting to paste it.

The clipboard holds only one piece of clipped data (a ClipData object) at a time, but one ClipData can contain multiple ClipData.Items.

For more information, read the Copy and Paste documentation. You can also see a simple implementation of copy and paste in the API Demos sample and a more complete implementation in the Note Pad sample.

Drag and drop

New APIs simplify drag and drop operations in your application's user interface. A drag operation is the transfer of some kind of data—carried in a ClipData object—from one place to another. The start and end point for the drag operation is a View, so the APIs that directly handle the drag and drop operations are in the View class.

A drag and drop operation has a lifecycle that's defined by several drag actions—each defined by a DragEvent object—such as ACTION_DRAG_STARTED, ACTION_DRAG_ENTERED, and ACTION_DROP. Each view that wants to participate in a drag operation can listen for these actions.

To begin dragging content in your activity, call startDrag() on a View, providing a ClipData object that represents the data to drag, a View.DragShadowBuilder to facilitate the "shadow" that users see under their fingers while dragging, and an Object that can share information about the drag object with views that may receive the object.

To accept a drag object in a View (receive the "drop"), register the view with an OnDragListener by calling setOnDragListener(). When a drag event occurs on the view, the system calls onDrag() for the OnDragListener, which receives a DragEvent describing the type of drag action has occurred (such as ACTION_DRAG_STARTED, ACTION_DRAG_ENTERED, and ACTION_DROP). During a drag, the system repeatedly calls onDrag() for the view underneath the drag, to deliver a stream of drag events. The receiving view can inquire the event type delivered to onDragEvent() by calling getAction() on the DragEvent.

Note: Although a drag event may carry a ClipData object, this is not related to the system clipboard. A drag and drop operation should never put the dragged data in the system clipboard.

For more information, read the Dragging and Dropping documentation. You can also see an implementation of drag and drop in the API Demos application and the Honeycomb Gallery application.

App widgets

Android 3.0 supports several new widget classes for more interactive app widgets on the users Home screen, including: GridView, ListView, StackView, ViewFlipper, and AdapterViewFlipper.

More importantly, you can use the new RemoteViewsService to create app widgets with collections, using widgets such as GridView, ListView, and StackView that are backed by remote data, such as from a content provider.

The AppWidgetProviderInfo class (defined in XML with an <appwidget-provider> element) also supports two new fields: autoAdvanceViewId and previewImage. The autoAdvanceViewId field lets you specify the view ID of the app widget subview that should be auto-advanced by the app widget’s host. The previewImage field specifies a preview of what the app widget looks like and is shown to the user from the widget picker. If this field is not supplied, the app widget's icon is used for the preview.

To help create a preview image for your app widget (to specify in the previewImage field), the Android emulator includes an application called "Widget Preview." To create a preview image, launch this application, select the app widget for your application and set it up how you'd like your preview image to appear, then save it and place it in your application's drawable resources.

You can see an implementation of the new app widget features in the StackView App Widget and Weather List Widget applications.

Status bar notifications

The Notification APIs have been extended to support more content-rich status bar notifications, plus a new Notification.Builder class allows you to easily create Notification objects.

New features include:

Content loaders

New framework APIs facilitate asynchronous loading of data using the Loader class. You can use it in combination with UI components such as views and fragments to dynamically load data from worker threads. The CursorLoader subclass is specially designed to help you do so for data backed by a ContentProvider.

All you need to do is implement the LoaderCallbacks interface to receive callbacks when a new loader is requested or the data has changed, then call initLoader() to initialize the loader for your activity or fragment.

For more information, read the Loaders documentation. You can also see example code using loaders in the LoaderCursor and LoaderThrottle samples.

Bluetooth A2DP and headset APIs

Android now includes APIs for applications to verify the state of connected Bluetooth A2DP and headset profile devices. For example, applications can identify when a Bluetooth headset is connected for listening to music and notify the user as appropriate. Applications can also receive broadcasts for vendor specific AT commands and notify the user about the state of the connected device, such as when the connected device's battery is low.

You can initialize the respective BluetoothProfile by calling getProfileProxy() with either the A2DP or HEADSET profile constant and a BluetoothProfile.ServiceListener to receive callbacks when the Bluetooth client is connected or disconnected.

Animation framework

An all new flexible animation framework allows you to animate arbitrary properties of any object (View, Drawable, Fragment, Object, or anything else). It allows you to define several aspects of an animation, such as:

You can define these animation aspects, and others, for an object's int, float, and hexadecimal color values, by default. That is, when an object has a property field for one of these types, you can change its value over time to affect an animation. To animate any other type of value, you tell the system how to calculate the values for that given type, by implementing the TypeEvaluator interface.

There are two animators you can use to animate the values of a property: ValueAnimator and ObjectAnimator. The ValueAnimator computes the animation values, but is not aware of the specific object or property that is animated as a result. It simply performs the calculations, and you must listen for the updates and process the data with your own logic. The ObjectAnimator is a subclass of ValueAnimator and allows you to set the object and property to animate, and it handles all animation work. That is, you give the ObjectAnimator the object to animate, the property of the object to change over time, and a set of values to apply to the property over time, then start the animation.

Additionally, the LayoutTransition class enables automatic transition animations for changes you make to your activity layout. To enable transitions for part of the layout, create a LayoutTransition object and set it on any ViewGroup by calling setLayoutTransition(). This causes default animations to run whenever items are added to or removed from the group. To specify custom animations, call setAnimator() on the LayoutTransition and provide a custom Animator, such as a ValueAnimator or ObjectAnimator discussed above.

For more information, see the Property Animation documentation. You can also see several samples using the animation APIs in the API Demos application.

Extended UI framework

Graphics

Media

Keyboard support

Split touch events

Previously, only a single view could accept touch events at one time. Android 3.0 adds support for splitting touch events across views and even windows, so different views can accept simultaneous touch events.

Split touch events is enabled by default when an application targets Android 3.0. That is, when the application has set either the android:minSdkVersion or android:targetSdkVersion attribute's value to "11".

However, the following properties allow you to disable split touch events across views inside specific view groups and across windows.

WebKit

Browser

The Browser application adds the following features to support web applications:

JSON utilities

New classes, JsonReader and JsonWriter, help you read and write JSON streams. The new APIs complement the org.json classes, which manipulate a document in memory.

You can create an instance of JsonReader by calling its constructor method and passing the InputStreamReader that feeds the JSON string. Then begin reading an object by calling beginObject(), read a key name with nextName(), read the value using methods respective to the type, such as nextString() and nextInt(), and continue doing so while hasNext() is true.

You can create an instance of JsonWriter by calling its constructor and passing the appropriate OutputStreamWriter. Then write the JSON data in a manner similar to the reader, using name() to add a property name and an appropriate value() method to add the respective value.

These classes are strict by default. The setLenient() method in each class configures them to be more liberal in what they accept. This lenient parse mode is also compatible with the org.json's default parser.

New feature constants

The <uses-feature> manfest element should be used to inform external entities (such as Google Play) of the set of hardware and software features on which your application depends. In this release, Android adds the following new constants that applications can declare with this element:

New permissions

New platform technologies

API differences report

For a detailed view of all API changes in Android 3.0 (API Level 11), see the API Differences Report.

API Level

The Android 3.0 platform delivers an updated version of the framework API. The Android 3.0 API is assigned an integer identifier — 11 — that is stored in the system itself. This identifier, called the "API Level", allows the system to correctly determine whether an application is compatible with the system, prior to installing the application.

To use APIs introduced in Android 3.0 in your application, you need compile the application against the Android library that is provided in the Android 3.0 SDK platform. Depending on your needs, you might also need to add an android:minSdkVersion="11" attribute to the <uses-sdk> element in the application's manifest. If your application is designed to run only on Android 2.3 and higher, declaring the attribute prevents the application from being installed on earlier versions of the platform.

For more information, read What is API Level?

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