Android Studio 2.3（2017 年 3 月）

<h1 class="hide-from-toc">
  New
</h1>

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<ul>
  <li>Android Studio can now convert PNG, BMP, JPG, and static GIF files to
  WebP format. WebP is an image file format from Google that provides lossy
  compression (like JPEG) as well as transparency (like PNG) but can provide
  better compression than either JPEG or PNG. For more information, see
    <a href="/studio/write/convert-webp.html">Convert images to WebP in Android
    Studio</a>.
  </li>

  <li>The new <a href="/studio/write/app-link-indexing.html">App Links
  Assistant</a> simplifies the process of adding Android App Links to your app
  into a step-by-step wizard. Android App Links are HTTP URLs that bring users
  directly to specific content in your Android app.
  </li>

  <li>The Layout Editor now includes support for two new ConstraintLayout
  features:
    <ul>
      <li>Define a view size based on an aspect ratio.
      </li>
      <li>Create packed, spread, and weighted linear groups with constraint
      chains.
      </li>
    </ul>
    For more information, see <a href=
    "/training/constraint-layout/index.html">Build a Responsive UI with
    ConstraintLayout</a>.
  </li>

  <li>The Layout Editor also now lets you create a list of <a href=
  "/studio/write/layout-editor.html#edit-properties">favorite attributes</a> so
  you don't have to click <b>View all attributes</b> to access the attributes
  you use most.
  </li>

  <li>When adding a material icon using the Vector Import Dialog (<b>File &gt;
  New &gt; Vector Asset</b>), you can now filter the list of available icons by
  category or by icon name. For more information, see <a href=
  "/studio/write/vector-asset-studio.html#materialicon">Adding a material
  icon</a>.
  </li>

  <li>
    <a href="/studio/write/annotations.html#accessibility">New and updated
    annotations</a>. The new <code>@RestrictTo</code> annotation for methods,
    classes, and packages lets you restrict an API. The updated
    <code>@VisibleForTesting</code> annotation now has an optional
    <code>otherwise</code> argument that lets you designate what the visibility
    of a method should be if not for the need to make it visible for testing.
    Lint uses the <code>otherwise</code> option to enforce the intended
    visibility of the method.
  </li>

  <li>New <a href="/studio/write/lint.html#snapshot">lint baseline support</a>
  allows you to use a snapshot of your project's current set of warnings as a
  baseline for future inspection runs so only new issues are reported. The
  baseline snapshot lets you start using lint to fail the build for new issues
  without having to go back and address all existing issues first.
  </li>

  <li>New lint checks, including the following:
    <ul>
      <li>Obsolete <code>SDK_INT</code> Checks: Android Studio removes obsolete
      code that checks for SDK versions.
      </li>
      <li>Object Animator Validation: Lint analyzes your code to make sure that
      your <code>ObjectAnimator</code> calls reference valid methods with the
      right signatures and checks that those methods are annotated with <code>
        @Keep</code> to prevent ProGuard from renaming or removing them during
        release builds.
      </li>
      <li>Unnecessary Item Decorator Copy: Older versions of the
      <code>RecyclerView</code> library did not include a divider decorator
      class, but one was provided as a sample in the support demos. Recent
      versions of the library have a divider decorator class. Lint looks for
      the old sample and suggests replacing it with the new one.
      </li>
      <li>WifiManager Leak: Prior to Android 7.0 (API level 24), initializing
      the <code>WifiManager</code> with <code><a href="/reference/android/content/Context.html#getSystemService(java.lang.Class&lt;T&gt;)">Context.getSystemService()</a></code>
      can cause a memory leak if the context is not the application context.
      Lint looks for these initializations, and if it <em>cannot</em> determine
      that the context is the application context, it suggests you use <code><a href="/reference/android/content/Context.html#getApplicationContext()">Context.getApplicationContext()</a></code> to get the proper context for the
      initialization.
      </li>
      <li>Improved Resource Prefix: The existing <code>resourcePrefix</code>
      lint check had many limitations. You can now configure your project with
      a prefix, such as <code>android { resourcePrefix '<var>my_lib</var>'
      }</code>, and lint makes sure that all of your resources are using this
      prefix. You can use variations of the name for styles and themes. For
      example for the <var>my_lib</var> prefix, you can have themes named
      <code>MyLibTheme</code>, <code>myLibAttr</code>,
      <code>my_lib_layout</code>, and so on.
      </li>
      <li>Switch to WebP: This check identifies images in your project that can
      be converted to WebP format based on your project’s
      <code>minSdkVersion</code> setting. An associated quickfix can
      automatically convert the images, or you can <a href=
      "/studio/write/convert-webp.html">convert images to WebP</a> manually.
      </li>
      <li>Unsafe WebP: If your project already includes WebP images, this check
      analyzes your project to ensure that your <code>minSdkVersion</code>
      setting is high enough to support the included images. For more
      information about WebP support in Android and Android Studio, see
      <a class="external" href=
      "https://developers.google.com/speed/webp/faq#which_web_browsers_natively_support_webp">
        Which browsers natively support WebP?</a> and <a href=
        "/studio/write/convert-webp.html">Create WebP Images Using Android
        Studio</a>.
      </li>
    </ul>
  </li>
</ul>

<h1 class="hide-from-toc">
  Changes
</h1>

<ul>
  <li>A separate button to push changes with Instant Run: After deploying your
  app, you now click <b>Apply Changes</b> <img src=
  "/studio/images/buttons/toolbar-apply-changes.svg" alt="" class=
  "inline-icon"> to quickly push incremental changes to your running app using
  Instant Run. The <b>Run</b> <img src="/studio/images/buttons/toolbar-run.png"
    alt="" class="inline-icon"> and <b>Debug</b> <img src=
    "/studio/images/buttons/toolbar-debug.png" alt="" class="inline-icon">
    buttons are always available to you when you want to reliably push your
    changes and force an app restart.
    <ul>
      <li>Instant Run is supported only when deploying your app to a target
      device running Android 5.0 (API level 21) or higher.
      </li>
      <li>Instant Run is no longer disabled for projects that <a href=
      "/studio/projects/add-native-code.html">link to external native
      projects</a> using CMake or ndk-build. However, you can only use Instant
      Run to push incremental changes to your Java code, not your native code.
      </li>
      <li>Cold swaps (which you can force for a running app by clicking
      <strong>Run</strong> <img src="/studio/images/buttons/toolbar-run.png"
      alt="" class="inline-icon">) are now more reliable. Forcing a cold swap
      also fixes the issue where changes to notification and widget UIs were
      not updated on the target device.
      </li>
      <li>Includes optimizations that make app startup much faster. These
      optimizations may affect profiling, so you should temporarily <a href=
      "/studio/run/index.html#disable-ir">disable Instant Run</a> whenever
      profiling your app.
      </li>
    </ul>
  </li>

  <li>
    <p>
      The <b>AVD Manager</b> <img src=
      "/studio/images/buttons/toolbar-avd-manager.png" alt="" class=
      "inline-icon"> and <b>SDK Manager</b> <img src=
      "/studio/images/buttons/toolbar-sdk-manager.png" alt="" class=
      "inline-icon"> buttons are now included in the lean Navigation Bar as
      well as the full Toolbar. To use the lean Navigation Bar, click
      <b>View</b> to open the View menu, then ensure that <b>Navigation Bar</b>
      is selected and <b>Toolbar</b> is <em>not</em> selected.
    </p>
    <img src="/studio/images/releases/navigationbar_sdkavd_2x.png" width="757">
  </li>

  <li>The "Hybrid" debugger has been renamed to "Dual" debugger.
  </li>

  <li>In the <a href="/studio/run/rundebugconfig.html">Run/Debug
  Configurations</a> dialog, under Defaults in the left pane, the following run
  configuration names have changed with no behavior changes:
    <ul>
      <li>The JUnit name has changed to Android JUnit. If you have a project
      that uses JUnit run configurations, those configurations are transformed
      to Android JUnit run configurations the first time you open the project
      with Android Studio. A dialog appears to inform you of the name change.
      </li>
      <li>The Android Tests name has changed to Android Instrumented Tests.
      </li>
    </ul>
  </li>

  <li>The <a href="/studio/debug/am-gpu-debugger.html">GPU Debugger</a> has
  been removed from Android Studio as of version 2.3. An open-source,
  standalone version of the tool is now available on <a href=
  "https://github.com/google/gapid" class="external-link">GitHub</a>.
  </li>

  <li>The Run/Debug option is no longer available when you right-click a <code>
    *.gradle build</code> script.
  </li>

  <li>All templates now use <code>ConstraintLayout</code> as the default
  layout.
  </li>

  <li>The Widgets palette in the Layout Editor has been redesigned.
  </li>
</ul>

<p>
  This release also includes a number of bug fixes. <a href=
  "https://code.google.com/p/android/issues/list?can=1&amp;q=target%3D2.3+status%3DReleased&amp;colspec=ID+Status+Priority+Owner+Summary+Stars+Reporter+Opened&amp;cells=tiles">
  See all bug fixes in 2.3.0.</a>
</p>

<p class="note">
  <b>Known issue:</b> Some device manufacturers block apps from automatically
  launching after being installed on the device. When deploying your app to a
  physical device using Android Studio 2.3, this restriction breaks the
  intended behavior of Instant Run and causes the following error output:
  <code>Error: Not found; no service started</code>. To avoid this issue,
  either <a href="/studio/run/emulator.html">use the emulator</a> or enable
  automatic launching for your app in your device's settings. The procedure
  for doing this is different for each device, so check the instructions
  provided by the manufacturer. To learn more about this issue, see
  <a href="https://code.google.com/p/android/issues/detail?id=235879">Issue
    #235879</a>.
</p>