Android 2.3 APIs

In this document

  1. API Overview
  2. API Level

Reference

  1. API Differences Report »

API Level: 9

For developers, the Android 2.3 (GINGERBREAD)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 2.3, 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 2.3, including new features and changes in the framework API since the previous version.

SIP-based VoIP

The platform now includes a SIP protocol stack and framework API that lets developers build internet telephony applications. Using the API, applications can offer voice calling features without having to manage sessions, transport-level communication, or audio — these are handled transparently by the platform's SIP API and services.

The SIP API is available in the android.net.sip package. The key class is SipManager, which applications use to set up and manage SIP profiles, then initiate audio calls and receive audio calls. Once an audio call is established, applications can mute calls, turn on speaker mode, send DTMF tones, and more. Applications can also use the SipManager to create generic SIP connections.

The platform’s underlying SIP stack and services are available on devices at the discretion of the manufacturer and associated carrier. For this reason, applications should use the isApiSupported() method to check whether SIP support is available, before exposing calling functionality to users.

To use the SIP API, applications must request permission from the user by declaring <uses-permission android:name="android.permission.INTERNET"> and <uses-permission android:name="android.permission.USE_SIP"> in their manifest files.

Additionally, developers can request filtering on Google Play, such that their applications are not discoverable to users whose devices do not include the platform’s SIP stack and services. To request filtering, add <uses-feature android:name="android.software.sip" android:required="true"> and <uses-feature android:name="android.software.sip.voip"> to the application manifest.

For more information, read the SIP developer guide.

Near Field Communications (NFC)

Android 2.3 includes an NFC stack and framework API that lets developers read NDEF tags that are discovered as a user touches an NFC-enabled device to tag elements embedded in stickers, smart posters, and even other devices.

The platform provides the underlying NFC services that work with the device hardware to discover tags when they come into range. On discovering a tag, the platform notifies applications by broadcasting an Intent, appending the tag's NDEF messages to the Intent as extras. Applications can create Intent filters to recognize and handle targeted tags and messages. For example, after receiving a tag by Intent, applications extract the NDEF messages, store them, alert the user, or handle them in other ways.

The NFC API is available in the android.nfc package. The key classes are:

  • NfcAdapter, which represents the NFC hardware on the device.
  • NdefMessage, which represents an NDEF data message, the standard format in which "records" carrying data are transmitted between devices and tags. Applications can receive these messages from ACTION_TAG_DISCOVERED Intents.
  • NdefRecord, delivered in an NdefMessage, which describes the type of data being shared and carries the data itself.

NFC communication relies on wireless technology in the device hardware, so support for the platform's NFC features on specific devices is determined by their manufacturers. To determine the NFC support on the current device, applications can call isEnabled() to query the NfcAdapter. The NFC API is always present, however, regardless of underlying hardware support.

To use the NFC API, applications must request permission from the user by declaring <uses-permission android:name="android.permission.NFC"> in their manifest files.

Additionally, developers can request filtering on Google Play, such that their applications are not discoverable to users whose devices do not support NFC. To request filtering, add <uses-feature android:name="android.hardware.nfc" android:required="true"> to the application's manifest.

To look at a sample application that uses the NFC API, see NFCDemo.

Gyroscope and other sensors

Android 2.3 adds platform and API support for several new sensor reading types — gyroscope, rotation vector, linear acceleration, gravity, and barometer. Developers can use the new sensor readings to create applications that respond quickly and smoothly to precise changes in device position and motion. The Sensor API reports gyroscope and other sensor changes to interested applications, whether they are running on the application framework or in native code.

Note that the specific set of hardware sensors available on any given device varies at the discretion of the device manufacturer.

Developers can request filtering on Google Play, such that their applications are not discoverable to users whose devices do not offer a gyroscope sensor. To do so, add <uses-feature android:name="android.hardware.sensor.gyroscope" android:required="true"> to the application manifest.

For API details, see Sensor.

Multiple cameras support

Applications can now make use of any cameras that are available on a device, for either photo or video capture. The Camera lets applications query for the number of cameras available and the unique characteristics of each.

To look at sample code for accessing a front-facing camera, see CameraPreview.java in the ApiDemos sample application.

The Camera API also adds:

Mixable audio effects

The platform's media framework adds support for new per-track or global audio effects, including bass boost, headphone virtualization, equalization, and reverb.

To look at sample code for audio effects, see AudioFxDemo.java in the ApiDemos sample application.

The media framework also adds:

  • New support for altitude tag in EXIF metadata for JPEG files. New method getAltitude() method to retrieve the value of the EXIF altitude tag.
  • New setOrientationHint() method lets an application tell MediaRecorder of the orientation during video capture.

Download manager

The platform includes a new DownloadManager system service that handles long-running HTTP downloads. Applications can request that a URI be downloaded to a particular destination file. The DownloadManager will conduct the download in the background, taking care of HTTP interactions and retrying downloads after failures or across connectivity changes and system reboots.

  • Applications can obtain an instance of the DownloadManager class by calling getSystemService(String) and passing DOWNLOAD_SERVICE. Applications that request downloads through this API should register a broadcast receiver for ACTION_NOTIFICATION_CLICKED, to appropriately handle when the user clicks on a running download in a notification or from the Downloads UI.
  • The DownloadManager.Request class lets an application provide all the information necessary to request a new download, such as request URI and download destination. A request URI is the only required parameter. Note that the default download destination is a shared volume where the system can delete your file if it needs to reclaim space for system use. For persistent storage of a download, specify a download destination on external storage (see setDestinationUri(Uri)).
  • The DownloadManager.Query class provides methods that let an application query for and filter active downloads.

StrictMode

To help developers monitor and improve the performance of their applications, the platform offers a new system facility called StrictMode. When implemented in an application, StrictMode catches and notifies the developer of accidental disk or network activity that could degrade application performance, such as activity taking place on the application's main thread (where UI operations are received and animations are also taking place). Developers can evaluate the network and disk usages issues raised in StrictMode and correct them if needed, keeping the main thread more responsive and preventing ANR dialogs from being shown to users.

  • StrictMode is the core class and is the main integration point with the system and VM. The class provides convenience methods for managing the thread and VM policies that apply to the instance.
  • StrictMode.ThreadPolicy and StrictMode.VmPolicy hold the policies that you define and apply to thread and VM instances.

For more information about how to use StrictMode to optimize your application, see the class documentation and sample code at android.os.StrictMode.

UI Framework

  • Support for overscroll
    • New support for overscroll in Views and Widgets. In Views, applications can enable/disable overscroll for a given view, set the overscoll mode, control the overscroll distance, and handle the results of overscrolling.
    • In Widgets, applications can control overscroll characteristics such as animation, springback, and overscroll distance. For more information, see android.view.View and android.widget.OverScroller.
    • ViewConfiguration also provides methods getScaledOverflingDistance() and getScaledOverscrollDistance().
    • New overScrollMode, overScrollFooter, and overScrollHeader attributes for <ListView> elements, for controlling overscroll behavior.
  • Support for touch filtering
    • New support for touch filtering, which lets an application improve the security of Views that provide access to sensitive functionality. For example, touch filtering is appropriate to ensure the security of user actions such as granting a permission request, making a purchase, or clicking on an advertisement. For details, see the View class documentation.
    • New filterTouchesWhenObscured attribute for view elements, which declares whether to filter touches when the view's window is obscured by another visible window. When set to "true", the view will not receive touches whenever a toast, dialog or other window appears above the view's window. Refer to View security documentation for details.

    To look at sample code for touch filtering, see SecureView.java in the ApiDemos sample application.

  • Improved event management
    • New base class for input events, InputEvent. The class provides methods that let applications determine the meaning of the event, such as by querying for the InputDevice from which the event orginated. The KeyEvent and MotionEvent are subclasses of InputEvent.
    • New base class for input devices, InputDevice. The class stores information about the capabilities of a particular input device and provides methods that let applications determine how to interpret events from an input device.
  • Improved motion events
    • The MotionEvent API is extended to include "pointer ID" information, which lets applications to keep track of individual fingers as they move up and down. The class adds a variety of methods that let an application work efficiently with motion events.
    • The input system now has logic to generate motion events with the new pointer ID information, synthesizing identifiers as new pointers are down. The system tracks multiple pointer IDs separately during a motion event, and ensures proper continuity of pointers by evaluating at the distance between the last and next set of pointers.
  • Text selection controls
    • A new setComposingRegion method lets an application mark a region of text as composing text, maintaining the current styling. A getSelectedText method returns the selected text to the application. The methods are available in BaseInputConnection, InputConnection, and InputConnectionWrapper.
    • New textSelectHandle, textSelectHandleLeft, textSelectHandleRight, and textSelectHandleWindowStyle attributes for <TextView>, for referencing drawables that will be used to display text-selection anchors and the style for the containing window.
  • Activity controls
  • Notification text and icon styles

    • Extra Large Screens

    The platform now supports extra large screen sizes, such as those that might be found on tablet devices. Developers can indicate that their applications are designed to support extra large screen sizes by adding a <supports screens ... android:xlargeScreens="true"> element to their manifest files. Applications can use a new resource qualifier, xlarge, to tag resources that are specific to extra large screens. For details on how to support extra large and other screen sizes, see Supporting Multiple Screens.

    Graphics

    Content Providers

    • New AlarmClock provider class for setting an alarm or handling an alarm. The provider contains a ACTION_SET_ALARM Intent action and extras that can be used to start an Activity to set a new alarm in an alarm clock application. Applications that wish to receive the SET_ALARM Intent should create an activity that requires the the SET_ALARM permission. Applications that wish to create a new alarm should use Context.startActivity(), so that the user has the option of choosing which alarm clock application to use.
    • MediaStore supports a new Intent action, PLAY_FROM_SEARCH, that lets an application search for music media and automatically play content from the result when possible. For example, an application could fire this Intent as the result of a voice recognition command to listen to music.
    • MediaStore also adds a new MEDIA_IGNORE_FILENAME flag that tells the media scanner to ignore media in the containing directory and its subdirectories. Developers can use this to avoid having graphics appear in the Gallery and likewise prevent application sounds and music from showing up in the Music app.
    • The Settings provider adds the new Activity actions APPLICATION_DETAILS_SETTINGS and MANAGE_ALL_APPLICATIONS_SETTINGS, which let an application show the details screen for a specific application or show the Manage Applications screen.
    • The ContactsContract provider adds the ContactsContract.CommonDataKinds.SipAddress data kind, for storing a contact's SIP (Internet telephony) address.

    Location

    • The LocationManager now tracks application requests that result in wake locks or wifi locks according to WorkSource, a system-managed class that identifies the application.

      The LocationManager keeps track of all clients requesting periodic updates, and tells its providers about them as a WorkSource parameter, when setting their minimum update times. The network location provider uses WorkSource to track the wake and wifi locks initiated by an application and adds it to the application's battery usage reported in Manage Applications.

    • The LocationManager adds several new methods that let an Activity register to receive periodic or one-time location updates based on specified criteria (see below).
    • A new Criteria class lets an application specify a set of criteria for selecting a location provider. For example, providers may be ordered according to accuracy, power usage, ability to report altitude, speed, and bearing, and monetary cost.

    Storage

    • Android 2.3 adds a new StorageManager that supports OBB (Opaque Binary Blob) files. Although platform support for OBB is available in Android 2.3, development tools for creating and managing OBB files will not be availble until early 2011.
    • The Android 2.3 platform adds official support for devices that do not include SD cards (although it provides virtual SD Card partition, when no physical SD card is available). A convenience method, isExternalStorageRemovable(), lets applications determine whether a physical SD card is present.

    Package Manager

    Telephony

    Native access to Activity lifecycle, windows

    Android 2.3 exposes a broad set of APIs to applications that use native code. Framework classes of interest to such applications include:

    • NativeActivity is a new type of Activity class, whose lifecycle callbacks are implemented directly in native code. A NativeActivity and its underlying native code run in the system just as do other Activities — specifically they run in the Android application's system process and execute on the application's main UI thread, and they receive the same lifecycle callbacks as do other Activities.
    • New InputQueue class and callback interface lets native code manage event queueing.
    • New SurfaceHolder.Callback2 interface lets native code manage a SurfaceHolder.
    • New takeInputQueue and takeSurface() methods in Window let native code manage events and surfaces.

    For full information on working with native code or to download the NDK, see the Android NDK page.

    Dalvik Runtime

    New manifest elements and attributes

    • New xlargeScreens attribute for <supports-screens> element, to indicate whether the application supports extra large screen form-factors. For details, see Supporting Multiple Screens.
    • New values for android:screenOrientation attribute of <activity> element:
      • "reverseLandscape" — The Activity would like to have the screen in landscape orientation, turned in the opposite direction from normal landscape.
      • "reversePortrait" — The Activity would like to have the screen in portrait orientation, turned in the opposite direction from normal portrait.
      • "sensorLandscape" — The Activity would like to have the screen in landscape orientation, but can use the sensor to change which direction the screen is facing.
      • "sensorPortrait" — The Activity would like to have the screen in portrait orientation, but can use the sensor to change which direction the screen is facing.
      • "fullSensor" — Orientation is determined by a physical orientation sensor: the display will rotate based on how the user moves the device. This allows any of the 4 possible rotations, regardless of what the device will normally do (for example some devices won't normally use 180 degree rotation).

    New Permissions

    • com.android.permission.SET_ALARM — Allows an application to broadcast an Intent to set an alarm for the user. An Activity that handles the SET_ALARM Intent action should require this permission.
    • android.permission.USE_SIP — Allows an application to use the SIP API to make or receive internet calls.
    • android.permission.NFC — Allows an application to use the NFC API to read NFC tags.

    New Feature Constants

    The platform adds several new hardware features that developers can declare in their application manifests as being required by their applications. This lets developers control how their application is filtered, when published on Google Play.

    For full information about how to declare features and use them for filtering, see the documentation for <uses-feature>.

    API differences report

    For a detailed view of all API changes in Android 2.3 (API Level 9), see the API Differences Report.

    API Level

    The Android 2.3 platform delivers an updated version of the framework API. The Android 2.3 API is assigned an integer identifier — 9 — 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 2.3 in your application, you need compile the application against the Android library that is provided in the Android 2.3 SDK platform. Depending on your needs, you might also need to add an android:minSdkVersion="9" 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?