API Level: M
Along with new features and capabilities, M includes a variety of system changes and API behavior changes. This document highlights some of the key changes that you should be understand and account for in your apps.
If you have previously published an app for Android, be aware that your app might be affected by these changes in M.
This release introduces a new runtime permissions model, where users can now directly manage their app permissions at runtime. This model gives users improved visibility and control over permissions, while streamlining the installation and auto-update processes for app developers. Users can set permissions on or off for all apps running on Android M. However, apps that don’t target M cannot request permissions at runtime.
On your apps that target M, make sure to check and request for permissions at runtime. To determine if your app has been granted a permission, call the new {@code Context.checkSelfPermission()} method. To request for a permission, call the new {@code Activity.requestPermission()} method.
For more information on supporting the new permissions model in your app, see the Android M Runtime Permissions guide.
Android is moving away from OpenSSL to the BoringSSL library. If you’re using the Android NDK in your app, don't link against cryptographic libraries that are not a part of the NDK API, such as {@code libcrypto.so} and {@code libssl.so}. These libraries are not public APIs, and may change or break without notice across releases and devices. In addition, you may expose yourself to security vulnerabilities. Instead, modify your native code to call the Java cryptography APIs via JNI or to statically link against a cryptography library of your choice.
This release introduces new power-saving optimizations for idle devices and apps.
If a device is unplugged and not used for up to an hour, it goes into doze mode where it attempts to keep the system in a sleep state. In this mode, devices may briefly resume normal operations for up to 5 minutes every few hours so that app syncing can occur and the system can perform any pending operations.
The following restrictions apply to your apps while in device doze mode:
When the system comes out of doze mode, it executes jobs and syncs that are pending.
In M, the system may determine that apps are idle when they are not in active use by the user. Your app goes into app standby mode after two days unless the system detects any of these signals:
If the system is running on battery power, apps that are in standby mode will have their network access disabled and their syncs and jobs suspended. When the system is plugged into a power supply, it brings an app out of standby mode and executes any jobs and syncs that are pending.
Apps that use Google Cloud Messaging will continue to receive messages even if they are idle. When the system is plugged into a power supply, apps resume normal operations and can run any pending syncs and jobs.
You can test this feature by connecting a device running M to your development machine and calling the following commands:
$ adb shell am broadcast -a android.os.action.DISCHARGING $ adb shell am set-idle <packageName> true $ adb shell am set-idle <packageName> false $ adb shell am get-idle <packageName>
In M, users can adopt external storage devices such as SD cards. Adopting an external storage device encrypts and formats the device to behave like internal storage. This feature allows users to move both apps and private data of those apps between storage devices. When moving apps, the system respects the {@code android:installLocation} preference in the manifest.
If your app accesses the following APIs or fields, be aware that the file paths they return will dynamically change when the app is moved between internal and external storage devices. When building file paths, it is strongly recommended that you always call these APIs dynamically. Don’t use hardcoded file paths or persist fully-qualified file paths that were built previously.
To debug this feature in the developer preview, you can enable adoption of a USB drive that is connected to an Android device through a USB On-The-Go (OTG) cable, by running these commands:
$ adb root $ sleep 2 $ adb shell setprop persist.fw.force_adoptable 1 $ adb reboot
This release removes support for the Apache HTTP client. If your app is using this client and targets Android 2.3 (API level 9) or higher, use the {@link java.net.HttpURLConnection} class instead. This API is more efficient because it reduces network use through transparent compression and response caching, and minimizes power consumption. To continue using the Apache HTTP APIs, you must first declare the following compile-time dependency in your {@code build.gradle} file:
android {
compileSdkVersion M
useLibrary 'org.apache.http.legacy'
}
Setting the volume directly or muting specific streams via the {@link android.media.AudioManager} class is no longer supported. The {@link android.media.AudioManager#setStreamSolo(int,boolean) setStreamSolo()} method is deprecated, and you should call the {@code AudioManager.requestAudioFocus()} method instead. Similarly, the {@link android.media.AudioManager#setStreamMute(int,boolean) setStreamMute()} method is deprecated; instead, call the {@code AudioManager.adjustStreamVolume()} method and pass in the direction value {@code ADJUST_MUTE} or {@code ADJUST_UNMUTE}.
When users selects text in your app, you can now display text selection actions such as Cut, Copy, and Paste in a floating toolbar. The user interaction implementation is similar to that for the contextual action bar, as described in Enabling the contextual action mode for individual views.
To implement a floating toolbar for text selection, make the following changes in your existing apps:
If you are using Android Support Library revision 22.2, be aware that floating toolbars are not backward-compatible and appcompat takes control over {@link android.view.ActionMode} objects by default. This prevents floating toolbars from being displayed in M. To enable {@link android.view.ActionMode} support in an {@link android.support.v7.app.AppCompatActivity}, call {@code android.support.v7.app.AppCompatActivity.getDelegate()}, then call {@code android.support.v7.app.AppCompatDelegate.setHandleNativeActionModesEnabled()} on the returned {@link android.support.v7.app.AppCompatDelegate} object and set the input parameter to {@code false}. This call returns control of {@link android.view.ActionMode} objects to the framework. In devices running M, that allows the framework to support {@link android.support.v7.app.ActionBar} or floating toolbar modes, while on pre-M devices, only the {@link android.support.v7.app.ActionBar} modes are supported.
Starting this release, the Android Keystore provider no longer supports DSA. ECDSA is still supported.
Keys which do not require encryption at rest will no longer be deleted when secure lock screen is disabled or reset (for example, by the user or a Device Administrator). Keys which require encryption at rest will be deleted during these events.
Theme attributes are now supported in {@link android.content.res.ColorStateList} for devices running M. The {@link android.content.res.Resources#getColorStateList(int) getColorStateList()} and {@link android.content.res.Resources#getColor(int) getColor()} methods have been deprecated. If you are calling these APIs, call the new {@code Context.getColorStateList()} or {@code Context.getColor()} methods instead. These methods are also available in the v4 appcompat library via {@link android.support.v4.content.ContextCompat}.
Support for the {@code -night} resource qualifier has been updated in M. Previously, night mode was only available when a device was docked and in car mode. Starting in M, night mode is available on all devices and is user-configurable via Settings > Display > Theme. You can adjust this setting globally using {@link android.app.UiModeManager#setNightMode(int) setNightMode()}. The Dark theme corresponds to {@link android.app.UiModeManager#MODE_NIGHT_YES}. When the device is in night mode, the resource framework will prefer resources that have the -night qualifier. To take advantage of user-configurable Dark mode in your app, extend from the {@code Theme.Material.DayNight} set of themes rather than {@code Theme.Material} or {@code Theme.Material.Light}.
The ART runtime now properly implements access rules for the {@link java.lang.reflect.Constructor#newInstance(java.lang.Object...) newInstance()} method. This change fixes a problem where Dalvik was checking access rules incorrectly in previous versions. If your app uses the {@link java.lang.reflect.Constructor#newInstance(java.lang.Object...) newInstance()} method and you want to override access checks, call the {@link java.lang.reflect.Constructor#setAccessible(boolean) setAccessible()} method with the input parameter set to {@code true}. If your app uses the v7 appcompat library or the v7 recyclerview library, you must update your app to use to the latest versions of these libraries. Otherwise, make sure that any custom classes referenced from XML are updated so that their class constructors are accessible.
The M release updates the behavior of the dynamic linker. The dynamic linker now understands the difference between a library’s {@code soname} and its path ( public bug 6670), and search by {@code soname} is now implemented. Apps which previously worked that have bad {@code DT_NEEDED} entries (usually absolute paths on the build machine’s file system) may fail when loaded on M.
The {@code dlopen(3) RTLD_LOCAL} flag is now correctly implemented in M. Note that {@code RTLD_LOCAL} is the default, so calls to {@code dlopen(3)} that didn’t explicitly use {@code RTLD_LOCAL} will be affected (unless your app explicitly used {@code RTLD_GLOBAL}). With {@code RTLD_LOCAL}, symbols will not be made available to libraries loaded by later calls to {@code dlopen(3)} (as opposed to being referenced by {@code DT_NEEDED} entries).
This release includes the following behavior changes for Android for Work: