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.
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
in their manifest files.
Additionally, developers can request filtering on Android Market, such that their applications are not discoverable to users whose devices do not include the platform’s SIP stack and services.
To request filtering,
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
Additionally, developers can request filtering on Android Market, such that their applications are not discoverable to users whose devices do not support NFC.
To request filtering, add
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 in Android Market, such that their applications are not discoverable to users whose devices do not offer a gyroscope sensor.
To do so, add
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.
New Camera.CameraInfo class stores a camera's positional characteristics (orientation, front-facing or back-facing).
New getNumberOfCameras(), getCameraInfo(), and getNumberOfCameras() methods in the Camera class let applications query for the cameras available and open the camera that they need.
New get() method lets applications retrieve a CamcorderProfile for a specific camera.
New getJpegEncodingQualityParameter() lets applications obtain the still-image capture quality level for a specific camera.
The Camera API also adds:
New parameters for cameras, including focus distance, focus mode, and preview fps maximum/minimum. New getFocusDistances(), getPreviewFpsRange(), and getSupportedPreviewFpsRange() for getting camera parameters, as well as setPreviewFpsRange() for setting preview framerate.
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.
New android.media.audiofx package provides the API to access audio effects.
New AudioEffect is the base class for controlling audio effects provided by the Android audio framework.
New audio session ID that lets an application associate a set of audio effects with an instance of AudioTrack or MediaPlayer.
New AudioTrack class constructor that lets you create an AudioTrack with a specific session ID. New attachAuxEffect(), getAudioSessionId(), and setAuxEffectSendLevel() methods.
New attachAuxEffect(), getAudioSessionId(), setAudioSessionId(int), and setAuxEffectSendLevel() methods and supporting types.
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.
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.
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.
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
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
ActivityInfo adds new constants for managing Activity orientation: SCREEN_ORIENTATION_FULL_SENSOR, SCREEN_ORIENTATION_REVERSE_LANDSCAPE, SCREEN_ORIENTATION_REVERSE_PORTRAIT, SCREEN_ORIENTATION_SENSOR_LANDSCAPE, and SCREEN_ORIENTATION_SENSOR_PORTRAIT.
New constant IMPORTANCE_PERCEPTIBLE for the importance field in ActivityManager.RunningAppProcessInfo. The value indicates that a specific process is running something that is considered to be actively perceptible to the user. An example would be an application performing background music playback.
The setPersistent(boolean) method to mark an Activity as persistent is now deprecated and the implementation is a no-op.
Notification text and icon styles
TextAppearance.StatusBar.EventContent.Title, TextAppearance.StatusBar.Icon, and
TextAppearance.StatusBar.Title for managing notification style.
New setUseWebViewBackgroundForOverscrollBackground() method lets a WebView specify whether to use its own background for the overscroll background.
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
Adds remaining OpenGL ES 2.0 methods glDrawElements() and glVertexAttribPointer() in the android.opengl.GLES20 class.
Adds support for YV12 pixel format, a planar 4:2:0 YCrCb format.
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.
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.
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.
New constants for declaring hardware and software features. See the list in the New Feature Constants section, below.
PackageInfo adds new firstInstallTime and lastUpdateTime fields that store the time of the package installation and last update.
New getProviderInfo() method for retrieving all of the information known about a particular content provider class.
The TelephonyManager adds the constant NETWORK_TYPE_EVDO_B for specifying the CDMA EVDO Rev B network type.
New getPsc() method returns the primary scrambling code of the serving cell on a UMTS network.
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.system removes several classes that were previously deprecated.
Dalvik core libraries:
New collections: ArrayDeque, NavigableMap, ConcurrentSkipListMap, LinkedBlockingDeque
New Arrays utilities: binarySearch(), copyOf(), copyOfRange(), and others.
CookieManager for HttpURLConnection.
More complete network APIs: InterfaceAddress, NetworkInterface and IDN
File read and write controls
Normalizer and Normalizer.Form
Improved javax.net.ssl server sockets.
New manifest elements and attributes
New xlargeScreens attribute for
For details, see Supporting
New values for android:screenOrientation attribute of
"reverseLandscape" — The Activity would like to have the screen in landscape orientation, turned in the opposite direction from normal landscape.
"reversePortait" — 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).
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 Android Market.
android.hardware.audio.low_latency — The application uses a low-latency audio pipeline on the device and is sensitive to delays or lag in sound input or output.
android.hardware.camera.front — The application uses a front-facing camera on the device.
android.hardware.nfc — The application uses NFC radio features in the device.
android.hardware.sensor.barometer — The application uses the device's barometer.
android.hardware.sensor.gyroscope — The application uses the device's gyroscope sensor.
android.software.sip — The application uses the SIP API on the device.
android.software.sip.voip — The application uses a SIP-based VoIP service on the device.
android.hardware.touchscreen.multitouch.jazzhand — The application uses advanced multipoint multitouch capabilities on the device screen, for tracking five or more points fully independently.