page.title=Android 2.2 APIs excludeFromSuggestions=true sdk.platform.version=2.2 sdk.platform.apiLevel=8 sdk.platform.majorMinor=minor @jd:body
API Level: {@sdkPlatformApiLevel}
Android {@sdkPlatformVersion} is a {@sdkPlatformMajorMinor} platform release including user features, developer features, API changes, and bug fixes. For information on developer features and API changes, see the Framework API section.
For developers, the Android {@sdkPlatformVersion} 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 {@sdkPlatformVersion}, use the Android SDK Manager to download the platform into your SDK.
For a list of new user features and platform highlights, see the Android 2.2 Platform Highlights document.
The Android {@sdkPlatformVersion} platform delivers an updated version of the framework API. The Android {@sdkPlatformVersion} API is assigned an integer identifier — {@sdkPlatformApiLevel} — 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 {@sdkPlatformVersion} in your
application, you need to set the proper value, "{@sdkPlatformApiLevel}", in the
android:minSdkVersion
attributes of the <uses-sdk>
element in your application's manifest.
For more information about how to use API Level, see the API Levels document.
The sections below provide information about changes made to the application framework API provided by the Android {@sdkPlatformVersion} platform.
The Android platform now allows applications to request installation onto the device's external storage media (such as the SD card), as an alternative to installation onto the device's internal memory.
Application developers can express the preferred installation location for
their applications by means of a new attribute of <manifest>
in the manifest file,
android:installLocation
. The attribute supports three values:
"internalOnly"
, "preferExternal"
, and
"auto"
. At install time, the system checks the value of
android:installLocation
and installs the application
.apk
according to the preferred location, if possible. If the
application has requested external installation, the system installs it into a
private, encrypted partition in the external media. Once an application .apk is
installed externally, the system lets the user change the storage location of
the .apk and move it onto the device's internal memory if needed (and vice
versa), through Manage Applications in the user settings.
By default, the system installs all applications onto the device's internal
memory, except for those that explicitly request external installation. This
means that the system will always install legacy applications onto internal
memory, since they do not have access to the
android:installLocation
attribute. However, it is possible to
configure and compile a legacy application such that it is installed internally
on older versions of the platform and externally on Android 2.2 and later
platforms, if necessary.
Note that requesting installation onto the device's external media is not suitable for all applications, particularly because the external media may be removable and unmounting/remounting may disrupt the user experience and system settings.
For more information about setting a preferred install location for your application, including a discussion of what types of applications should and should not request external installation, please read the App Install Location document.
The platform now provides a generalized backup service that applications can use to backup and restore user data, to ensure that users can maintain their data when switching devices or reinstalling the application. The Backup Manager handles the work of transporting the application data to and from the backup storage area in the cloud. The Backup Manager can store any type of data, from arbitrary data to files, and manages backup and restore operations in an atomic manner. For more information, see Data Backup.
New device policy management APIs allow developers to write "device administrator" applications that can control security features of the device, such as the minimum password strength, data wipe, and so on. Users can select the administrators that are enabled on their devices. For more information, see the {@link android.app.admin android.app.admin} classees or the example application code in DeviceAdminSample.java.
fill_parent
is renamed to match_parent
. This affects both XML and Java code (see {@link android.view.ViewGroup.LayoutParams}). Note that the platform will continue to honor uses of fill_parent
in legacy applications. android:installLocation
attribute of the <manifest>
element. Specifies the default install location defined by an application.android:backupAgent
attribute of the
<application>
element. Specifies the component name of the
BackupAgent subclass provided by the application to handle backup/restore
operations, if any.android:restoreAnyVersion
attribute of the
<application>
element. Boolean value that indicates whether
the application is prepared to attempt a restore of any backed-up dataset, even
if the backup is apparently from a newer version of the application than is
currently installed on the device.android:vmSafeMode
attribute of the <application>
element. Boolean value that specifies whether to disable JIT compiler optimizations when running the application.android.permission.BIND_DEVICE_ADMIN
— Any device administration broadcast receiver must require this permission, to ensure that only the system can interact with it.android.permission.KILL_BACKGROUND_PROCESSES
— Allows an application to call {@link android.app.ActivityManager#killBackgroundProcesses(String)}.
android.permission.BIND_WALLPAPER
— Any {@link android.service.wallpaper.WallpaperService} must require this permission, to ensure that only the system can interact with it.android.permission.SET_TIME
— Allows an application to set the system time.For a detailed view of all API changes in Android {@sdkPlatformVersion} (API Level {@sdkPlatformApiLevel}), see the API Differences Report.