If you are developing in Eclipse with ADT, note that the SDK Tools r9 is designed for use with ADT 9.0.0 and later. After installing SDK Tools r9, we highly recommend updating your ADT Plugin to 9.0.0.

If you are developing outside Eclipse, you must have Apache Ant 1.8 or later.

If you are upgrading to SDK Tools r9 from SDK Tools r7 or earlier, the default installed location for the adb tool has changed from <SDK>/tools/adb to<SDK>/platform-tools/adb. This means that you should add the new location to your PATH and modify any custom build scripts to reference the new location. Copying the adb executable from the new location to the old is not recommended, since subsequent updates to the SDK Tools will delete the file.

• The default ProGuard configuration, proguard.cfg, now ignores the following classes:
  • classes that extend Preference
  • classes that extend BackupAgentHelper
• Ant lib rules now allow you to override java.encoding, java.source, and java.target properties.
• The default encoding for the javac Ant task is now UTF-8.
• The LogCat view in DDMS now properly displays UTF-8 characters.
• The SDK Manager is more reliable on Windows. For details on the improvements, see the Android Tools Project Site.
• If you enabled snapshots for an AVD, they are automatically captured. The emulator also now restores to the state when it last closed almost instantly.
• Fixed the missing JAR file error that prevented draw9patch from running.
• Fixed the Windows launch scripts hierarchyviewer and ddms to support the new location of adb.
• Known issues with emulator performance: Because the Android emulator must simulate the ARM instruction set architecture on your computer, emulator performance is slow. We're working hard to resolve the performance issues and it will improve in future releases.

• "Go To Declaration" hyperlink support: You can jump directly from code references (such as R.id.main) to the corresponding XML declaration, or from XML attributes (such as @string) to the corresponding resource definition, or from manifest XML registrations to activities and services.
• Improvements were made to name refactoring.
• AVDs now automatically save their state, so they can restart almost instantly. You can enable this feature when creating an AVD or by editing an AVD with the AVD Manager.
• Improvements to the Visual Layout Editor:
  • Support for rendering targets: You can now choose an arbitrary Android platform to render the current page, regardless of the project's minimum platform. This makes it easy to verify the layout and appearance of your activity on different versions of the platform.
  • Improved support for empty and nested layouts: Dragging items over nested and invisible layouts automatically enlarges and highlights these layouts, so that they can receive drops.
  • XML formatting improvements: The editor generates cleaner XML and you can now enable XML auto-formatting in the Preferences menu.
  • Improved Outline labels: The Outline tab now displays additional information about each View. Textual Views display a snippet of the actual text. Views with a source (such as ImageView) displays the resource name. Included Views display the name of the View.
  • When you right click a View in the Layout Editor, the context menu now contains Edit ID... and Edit Text... items. The Properties... context menus now list all of the properties and provide a way to edit them (Details).
  • The layout editor now properly handles <include> and <merge> tags (Details).
  • "Extract as Include" refactoring: The Layout Editor has a new refactoring that allows you to select one or more views in a layout, and extract it into a separate layout (Details).
  • Improved diagnostics for class loading and rendering errors: Class loading and rendering error messages are more useful and provide better information about the root cause of the error.
  • Improved error handling to prevent drag and reordering operations from adding children into an AdapterView.
  • Outline reordering: Reordering your views in the Outline tab is much easier (Details).
  • Fix for keybinding bug where keyboard shortcuts did not work (Issues 13231 and 13134).
  • Fix for problems with Custom layout attribute menu (Issue 13134).
  • Automatic configuration for various view types: Certain views have properties configured by default. For example, the width of an EditText object is set to match_parent when added to a vertical LinearLayout or a default image is added to an ImageButton.
  • Previews during dragging: Dragging from the palette or dragging within the layout editor now shows live previews of the dragged item.
  • Navigation improvements: In the Layout Editor, double-clicking Views jumps to the corresponding XML element. In the Outline view, double-clicking opens the Properties view.
  • The editor has Honeycomb style animation preview support.
  • Improved rendering support for various Views (such as TabHosts and SlidingDrawers) in Honeycomb (Issues 3162 and 13092).
  • Included layouts can be rendered and edited in the context of the layouts that include them. From a layout using an <include> tag, double-clicking on the <include> element edits the referenced layout in the context of the current layout. Additionally, when editing a layout that is included by other layouts, you can quickly change between context layouts, by right clicking in the editor and choosing Show included in.... This feature is only available in Honeycomb.
• This release fixes many other bugs, but the most important ones are listed below:
  • Fixed issue that prevented launching debug builds on productions devices when debuggable=true was not set in the Android manifest.
  • The LogCat view in DDMS properly handles UTF-8 characters.
  • The SDK Manager is more reliable on Windows (Details).
  • A JUnit initialization bug that prevented you from working with JUnit tests was fixed (Issue 12411).