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Android O Developer Preview 2

Android O Developer Preview 2

Date: May 2017
Build: OPP2.170420.019 (Nexus 5X, Nexus 6P, Nexus Player, Pixel, Pixel C, Pixel XL)
Emulator support: x86 & ARM (32/64-bit)
Google Play services: 10
API diff: DP2/25DP2/DP1

General advisories

This public beta release is for early adopters and is available for daily use, development, or compatibility testing. Please be aware of these general notes about the release:

  • This public beta release may have various stability, battery, or performance issues on supported devices.
  • Some apps may not function as expected on this public beta release. This includes Google’s apps as well as other apps.
  • This public beta release is Compatibility Test Suite (CTS) approved on supported devices. Apps that depend on CTS approved builds should work normally on these devices (Android Pay, for example).
  • This public beta release is available on these supported devices: Nexus 5X, Nexus 6P, Nexus Player, Pixel C, Pixel, and Pixel XL.
  • Android emulator system images are available for handsets, Android TV, and Android Wear.

Known issues

Performance and battery

  • System and app performance is known to be periodically slow/janky, and devices may become occasionally unresponsive. These problems may become more acute with prolonged use.
  • Battery life may be regressed in this early release for screen-on and screen-off use cases.

System UI

  • Device wallpaper changes with largest font and large display size.


  • Camera may be slow to launch.


  • Occasional audio stuttering issues.


  • Wi-Fi driver issue can prevent finding available Wi-Fi networks.
  • Notification sounds may be audible when playing YouTube videos through Cast.

External storage

  • On Nexus Player, users may be unable to explore or browse portable storage contents.

Setup wizard

  • NFC service crash observed in Set-Up Wizard.

Backup & restore

  • Wi-Fi data not restored after performing restore from another device/cloud restore.


  • Device may get stuck in Finishing touches when adding new user.


  • Unable to access Vision settings in welcome screen after navigating back from language selection list.


  • Developers using FCM/GCM with Android O should update their Google Play services SDK to version ≥ 10.2.1, which is available from the SDK manager in Android Studio.

Android Wear

  • Only the x86 emulator is currently supported.

Android TV

  • Keyboard characters are not displayed in the text field across all screens during initial set up process if talkback is on.
  • PIP window is not dismissed on playing movies from Google Play Movies and TV app.
  • Talkback stops working on selecting OK button when any non-selectable Settings sub-options are spoken out.


  • Downloading DPC (Device Policy Controller) with a Google Account doesn’t complete. The workaround for a profile owner is, download and install the DPC manually from Google Play and add the account manually in the work profile. For a Device Owner, use QR or NFC provisioning instead.
  • Tapping the managed device text in Quick Settings shows a blank Device monitoring dialog.
  • TestDPC app crashes when attempting to set a new reset-password token.
  • Device rebooted upon turning off work mode from QS panel.

Preinstalled apps

  • Dialer app may crash after boot up after build loading.
  • SMS reply for Phone does not launch Messages app.
  • YouTube app freezes after returning from PiP mode
  • After video ends, Chrome app crash observed after dismissing PIP window;


  • Google Indic Keyboard crashes on tapping ? button next to Hide keyboard button;

API changes

This section lists notable changes in features, behavior, and APIs from O DP1 to DP2. For a complete list of all API changes, see the API diff reports:


All versions of the findViewById() method now return <T extends View> T instead of View. For more information, see Android O Features and APIs.

Background execution limits

The following changes have been made to background execution limits for DP2:

  • Even for apps not targeting O, users can use the Settings screen to enable background execution limits.
  • The method NotificationManager.startServiceInForeground() (introduced in DP1) is now deprecated. To start a foreground service, useContext.startForegroundService().
  • A number of broadcasts have been exempted from, or added to, the restrictions on implicit broadcasts. Implicit Broadcast Exceptions has been updated to reflect these changes.

For more information, see Background Execution Limits.

Wi-Fi Aware

In DP1, the method for creating a method specifier is createNetworkSpecifier(). Beginning with DP2, the methods for creating a method specifier are now either createNetworkSpecifierOpen() for unencrypted connections or createNetworkSpecifierPassphrase() for encrypted connections. For more information, see WifiAwareSession and DiscoverySession. For more information, see Wi-Fi Aware.


Several classes and methods have different functionality in DP2 to account for the new Android Autofill Framework support. For more details, see Web form autofill.

App Analysis at Runtime

In Android O DP2, several classes were added to the java.lang.reflect package, which makes it easier to discover information at runtime about the parameters, methods, and constructors within your app’s logic.

For more information about Java 8 language features available in Android O, see Use Java 8 language features.

ICU4J Support

Android O updates the following ICU4J Android Framework APIs:

For the most recent information about these classes, consult their API reference documentation.

Autofill Framework

In Android O DP2, the Autofill Framework provides a View.setAutofillHints() method and android:autofillHints attribute, which you can use to provide the system with hints about the input type that is expected in each field.

For more information about this and other changes to the Autofill Framework, consult the Autofill Framework page.

Downloadable Fonts

Android O DP2 adds several classes and methods to enable your app to download fonts from a font provider. This feature is available in Android O as well as in Support Library 26 to support devices running Android API version 14 and higher.

For the most recent information about this feature, see Downloadable Fonts.

Fonts in XML

The Fonts in XML feature is now available through Support Library 26 to support devices running Android API version 14 and higher.

For the most recent information about this feature, review Fonts in XML.

Autosizing TextViews

The Autosizing TextView feature is now available through Support Library 26 to support devices running Android API version 14 and higher.

For more information about this feature, see Autosizing TextView.

Input and Navigation

The following changes have been made to Android input and navigation capabilities for DP2:

  • The View class has added an attribute and a method to allow for more fine-grained control over UI element highlighting.

For more information, see Input and navigation.

Telephony Permissions

Several new permissions related to telephony have been added in DP2.

For more information, see Permissions.

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