android_frameworks_base/docs/html/about/versions/android-5.0-changes.jd

page.title=Android 5.0 Changes
excludeFromSuggestions=true
sdk.platform.version=5.0
sdk.platform.apiLevel=21
@jd:body


<div id="qv-wrapper">
<div id="qv">

<h2>In this document</h2>

<ol id="toc44" class="hide-nested">
  <li><a href="#UI"><a href="#ART">ART Runtime</a></a></li>
  <li><a href="#BehaviorNotifications">Notifications</a></li>
  <li><a href="#BehaviorMediaControl">Media Controls</a></li>
  <li><a href="#BehaviorGetRecentTasks">getRecentTasks()</a></li>
  <li><a href="#64BitSupport">64-Bit Android NDK</a></li>
  <li><a href="#BindService">Binding to a Service</a></li>
  <li><a href="#Power"><a href="#BehaviorWebView">WebView</a></a></li>
  <li><a href="#custom_permissions">Custom Permissions</a></li>
  <li><a href="#ssl">TLS/SSL Configuration</a></li>
</ol>

<h2>API Differences</h2>
<ol>
<li><a href="{@docRoot}sdk/api_diff/21/changes.html">API level 20 to 21 &raquo;</a> </li>
<li><a href="{@docRoot}sdk/api_diff/preview-21/changes.html">L Developer Preview to 21 &raquo;</a> </li>
</ol>


<h2>See Also</h2>
<ol>
<li><a href="{@docRoot}about/versions/lollipop.html">Android Lollipop Highlights</a> </li>
<li><a href="{@docRoot}about/versions/android-5.0.html">Android 5.0 API Overview</a> </li>
</ol>


</div>
</div>

<p>API Level: {@sdkPlatformApiLevel}</p>
<p>Along with new features and capabilities, Android 5.0 includes a variety of changes
API changes,
behavior changes, system enhancements, and bug fixes. This document highlights
some of the key changes that you should be understand and account for in your apps.</p>

<p>If you have previously published an app for Android, be aware that your app
  might be affected by these changes in Android 5.0.</p>


<p>For a high-level look at the new platform features, instead
see the
<a href="{@docRoot}about/versions/lollipop.html">Android Lollipop
highlights</a>.</p>



<h2 id="ART">Android Runtime (ART)</h2>

<p>In Android 5.0 the ART runtime replaces Dalvik as the platform default. The ART runtime was
introduced in Android 4.4 on an experimental basis.</p>

<p>For an overview of ART's new features, see
<a href="https://source.android.com/devices/tech/dalvik/art.html">Introducing
ART</a>. Some of the major new features are:</p>

<ul>
  <li>Ahead-of-time (AOT) compilation</li>
  <li>Improved garbage collection (GC)</li>
  <li>Improved debugging support</li>
</ul>

<p>Most Android apps should just work without any changes under ART. However, some
techniques that work on Dalvik do not work on ART. For information about the
most important issues, see
<a href="{@docRoot}guide/practices/verifying-apps-art.html">Verifying App
Behavior on the Android Runtime (ART)</a>. Pay particular attention if:</p>

<ul>
  <li>Your app uses Java Native Interface (JNI) to run C/C++ code.</li>
  <li>You use development tools that generate non-standard code (such as some
      obfuscators).</li>
  <li>You use techniques that are incompatible with compacting garbage
      collection.</li>
</ul>


<h2 id="BehaviorNotifications">Notifications</h2>

<p>Make sure your notifications take these Android 5.0 changes into account.
 To learn more about designing your notifications for Android 5.0 and higher,
 see the <a href="{@docRoot}design/patterns/notifications.html">notifications design guide</a>.
</p>

<h3 id="NotificationsMaterialDesignStyle">Material design style</h3>
<p>Notifications are drawn with dark text atop white (or very light) backgrounds
  to match the new material design widgets. Make sure that all your
  notifications look right with the new color scheme. If your notifications
look wrong, fix them:</p>

<ul>
  <li>Use {@link android.app.Notification.Builder#setColor(int) setColor()}
    to set an accent color in a circle behind your icon image. </li>
  <li>Update or remove assets that involve color. The system ignores all
    non-alpha channels in action icons and in the main notification icon. You
    should assume that these icons will be alpha-only. The system draws
    notification icons in white and action icons in dark gray.</li>
</ul>

<h3 id="NotificationsSoundVibration">Sound and vibration</h3>
<p>If you are currently adding sounds and vibrations to your notifications by
using the {@link android.media.Ringtone}, {@link android.media.MediaPlayer},
or {@link android.os.Vibrator} classes, remove this code so that
the system can present notifications correctly in
<em>priority</em> mode. Instead, use
{@link android.app.Notification.Builder} methods to add sounds and
vibration.</p>

<p>Setting the device to
{@link android.media.AudioManager#RINGER_MODE_SILENT RINGER_MODE_SILENT} causes
the device to enter the new priority mode. The device leaves priority
mode if you set it to
{@link android.media.AudioManager#RINGER_MODE_NORMAL RINGER_MODE_NORMAL} or
{@link android.media.AudioManager#RINGER_MODE_NORMAL RINGER_MODE_VIBRATE}.</p>

<p>Previously, Android used {@link android.media.AudioManager#STREAM_MUSIC STREAM_MUSIC}
as the master stream to control volume on tablet devices. In Android 5.0, the
master volume stream for both phone and tablet devices is now unified, and
is controlled by {@link android.media.AudioManager#STREAM_RING STREAM_RING} or
{@link android.media.AudioManager#STREAM_NOTIFICATION STREAM_NOTIFICATION}.</p>

<h3 id="NotificationsLockscreenVisibility">Lock screen visibility</h3>
<p>By default, notifications now appear on the user's lock screen in Android 5.0.
Users can choose to protect sensitive information from being exposed, in which
case the system automatically redacts the text displayed by the notification. To
customize this redacted notification, use
{@link android.app.Notification.Builder#setPublicVersion(android.app.Notification)
  setPublicVersion()}.</p>
<p>If the notification does not contain personal information, or if you want to
allow media playback control on the notification, call the
{@link android.app.Notification.Builder#setVisibility(int) setVisibility()}
method and set the notification's visibility level to
{@link android.app.Notification#VISIBILITY_PUBLIC VISIBILITY_PUBLIC}.
</p>

<h3 id="NotificationsMediaPlayback">Media playback</h3>
<p>If you are implementing notifications that present media playback
status or transport controls, consider using the new
{@link android.app.Notification.MediaStyle} template instead of a custom
{@link android.widget.RemoteViews.RemoteView} object. Whichever approach you
choose, make sure to set the notification's visibility to
{@link android.app.Notification#VISIBILITY_PUBLIC VISIBILITY_PUBLIC} so that
your controls are accessible from the lock screen. Note that beginning in
Android 5.0, the system no longer shows
{@link android.media.RemoteControlClient} objects on the lock screen. For more
information, see
<a href="#BehaviorMediaControl">If your app uses RemoteControlClient</a>.</p>

<h3 id="NotificationsHeadsup">Heads-up notification</h3>
<p>Notifications may now appear in a small floating window (also called a
  heads-up notification) when the device is active (that is, the device is
  unlocked and its screen is on). These notifications appear similar to the
  compact form of your notification, except that the heads-up notification also
  shows action buttons. Users can act on, or dismiss, a heads-up notification
  without leaving the current app.</p>

<p>Examples of conditions that may trigger heads-up notifications include:</p>

<ul>
  <li>The user's activity is in fullscreen mode (the app uses
{@link android.app.Notification#fullScreenIntent})</li>
  <li>The notification has high priority and uses ringtones or vibrations</li>
</ul>

<p>If your app implements notifications under any of those scenarios, make sure
that heads-up notifications are presented correctly.</p>

<h2 id="BehaviorMediaControl">Media Controls and RemoteControlClient</h2>
<p>The {@link android.media.RemoteControlClient} class is now deprecated. Switch
  to the new {@link android.media.session.MediaSession} API as
  soon as possible.</p>

<p>Lock screens in Android 5.0 do not show transport controls for
your {@link android.media.session.MediaSession} or
{@link android.media.RemoteControlClient}. Instead, your app can provide
media playback control from the lock screen through a notification. This
gives your app more control over the presentation of media buttons, while
providing a consistent experience for users across locked and
unlocked devices.</p>

<p>Android 5.0 introduces a new
{@link android.app.Notification.MediaStyle} template for this purpose.
{@link android.app.Notification.MediaStyle} converts notification
actions that you added with
{@link android.app.Notification.Builder#addAction(int, java.lang.CharSequence,
  android.app.PendingIntent)
Notification.Builder.addAction()} into compact buttons embedded in your app's
media playback notifications. Pass your session token to the
{@link android.app.Notification.MediaStyle#setMediaSession(android.media.session.MediaSession.Token)
  setSession()} method to inform the system that this notification controls an
  ongoing media session.</p>

<p>Make sure to set the notification's visibility to
  {@link android.app.Notification#VISIBILITY_PUBLIC VISIBILITY_PUBLIC}
  to mark the notification as safe to show on any lock screen (secure or
  otherwise). For more information, see
  <a href="#LockscreenNotifications">Lock screen notifications</a>.</p>

<p>To display media playback controls if your app is running on the
Android <a href="{@docRoot}tv/index.html">TV</a> or
<a href="{@docRoot}wear/index.html">Wear</a> platform, implement the
{@link android.media.session.MediaSession} class. You should also implement
{@link android.media.session.MediaSession} if your app needs to receive media
button events on Android devices.</p>

<h2 id="BehaviorGetRecentTasks">getRecentTasks()</h2>

<p>With the introduction of the new <em>concurrent documents and activities
tasks</em> feature in Android 5.0 (see <a href="#Recents">Concurrent
documents and activities in the recents screen</a> below),
the {@link android.app.ActivityManager#getRecentTasks
ActivityManager.getRecentTasks()} method is now deprecated to improve user
privacy. For backward compatibility, this method still returns a small subset of
its data, including the calling application’s own tasks and possibly some other
non-sensitive tasks (such as Home). If your app is using this method to retrieve
its own tasks, use {@link android.app.ActivityManager#getAppTasks() getAppTasks()}
instead to retrieve that information.</p>

<h2 id="64BitSupport">64-Bit Support in the Android NDK</h2>

<p>Android 5.0 introduces support for 64-bit systems. The 64-bit enhancement
  increases address space and improves performance, while still supporting
  existing 32-bit apps fully. The 64-bit support also improves the performance of
  OpenSSL for cryptography. In addition, this release introduces new native
  media NDK APIs, as well as native OpenGL ES (GLES) 3.1 support.</p>

<p>To use the 64-bit support provided in Android 5.0, download and install NDK
  Revision 10c from the
<a href="{@docRoot}tools/sdk/ndk/index.html">Android NDK page</a>. Refer to the
Revision 10c <a href="{@docRoot}tools/sdk/ndk/index.html#Revisions">release notes</a>
for more information about important changes and bug fixes to the NDK.</p>

<h2 id="BindService">Binding to a Service</h2>

<p>The
  {@link android.content.Context#bindService(android.content.Intent, android.content.ServiceConnection, int) Context.bindService()}
  method now requires an explicit {@link android.content.Intent},
and throws an exception if given an implicit intent.
To ensure your app is secure, use an explicit intent when starting or binding
your {@link android.app.Service}, and do not declare intent filters for the service.</p>

<h2 id="BehaviorWebView">WebView</h2>

<p>Android 5.0 changes the default behavior for your app.</p>
<ul>
<li><strong>If your app targets API level 21 or higher:</strong>
  <ul>
    <li>The system
  blocks <a href="https://developer.mozilla.org/en-US/docs/Security/MixedContent"
  class="external-link">mixed content</a> and third party cookies by default. To allow mixed
  content and third party cookies, use the
  {@link android.webkit.WebSettings#setMixedContentMode(int) setMixedContentMode()}
and {@link android.webkit.CookieManager#setAcceptThirdPartyCookies(android.webkit.WebView, boolean) setAcceptThirdPartyCookies()}
methods respectively.</li>
    <li>The system now intelligently chooses portions of the HTML
      document to draw. This new default behavior helps to reduce memory
      footprint and increase performance. If you want to
      render the whole document at once, disable this optimization by calling
      {@link android.webkit.WebView#enableSlowWholeDocumentDraw()}.</li>
  </ul>
</li>
<li><strong>If your app targets API levels lower than 21:</strong> The system
  allows mixed content and third party cookies, and always renders the whole
  document at once.</li>
</ul>

<h2 id="custom_permissions">Uniqueness Requirement for Custom Permissions</h2>

<p>
  As documented in the <a href=
  "{@docRoot}guide/topics/manifest/manifest-intro.html#perms">Permissions</a>
  overview, Android apps can define custom permissions as a means of managing
  access to components in a proprietary way, without using the platform’s
  pre-defined system permissions. Apps define custom permissions in <a href=
  "http://developer.android.com/guide/topics/manifest/permission-element.html"><code>
  &lt;permission&gt;</code></a> elements declared in their manifest files.
</p>

<p>
  There are a small number of scenarios where defining custom permissions is a
  legitimate and secure approach. However, creating custom permissions is
  sometimes unnecessary and can even introduce potential risk to an app,
  depending on the protection level assigned to the permissions.
</p>

<p>
  Android 5.0 includes a behavior change to ensure
  that only one app can define a given custom permission, unless signed with the 
  same key as other apps defining the permission. 
</p>

<h3>
  Apps using duplicate custom permissions
</h3>

<p>
  Any app can define any custom permission it wants, so it can happen
  that multiple apps might <strong>define the same custom permission</strong>.
  For example, if two apps offer a similar capability, they might derive the
  same logical name for their custom permissions. Apps might also incorporate
  common public libraries or code examples that themselves include the same
  custom permission definitions.
</p>

<p>
  In Android 4.4 and earlier, users were able to install multiple such
  apps on a given device, although the system assigned the protection level
  specified by the first-installed app. 
</p>

<p>
  Starting in Android 5.0, the system enforces a new
  <strong>uniqueness restriction on custom permissions</strong> for
  apps that are signed with different keys. Now only one app on a device can
  define a given custom permission (as determined by its name), unless the
  other app defining the permission is signed with the same key. If the user
  tries to install an app with a duplicate custom permission and is not signed
  with the same key as the resident app that defines the permission, the system
  blocks the installation.
</p>

<h3>
  Considerations for your app
</h3>

<p>
  In Android 5.0 and later, apps can continue to define their own custom
  permissions just as before and to request custom permissions from other apps
  through the <code>&lt;uses-permission&gt;</code> mechanism. However with the
  new requirement introduced in Android 5.0, you should carefully assess
  possible impacts on your app.
</p>

<p>
  Here are some points to consider:
</p>

<ul>
  <li>Does your app declare any <a href=
  "http://developer.android.com/guide/topics/manifest/permission-element.html">
    <code>&lt;permission&gt;</code></a> elements in its manifest? If so, are
    they actually necessary to the proper function of your app or service? Or
    could you use a system default permission instead?
  </li>

  <li>If you have <a href=
  "http://developer.android.com/guide/topics/manifest/permission-element.html">
    <code>&lt;permission&gt;</code></a> elements in your app, do you know where
    they came from?
  </li>

  <li>Do you actually intend for other apps to request your custom permissions
  through <a href=
  "http://developer.android.com/guide/topics/manifest/uses-permission-element.html">
    <code>&lt;uses-permission&gt;</code></a>?
  </li>

  <li>Are you using boilerplate or example code in your app that includes
  <a href=
  "http://developer.android.com/guide/topics/manifest/permission-element.html">
    <code>&lt;permission&gt;</code></a> elements? Are those permission elements
    actually necessary?
  </li>

  <li>Do your custom permissions use names that are simple or based on common
  terms that other apps might share?
  </li>
</ul>

<h3>
  New installs and updates
</h3>

<p>
  As mentioned above, for new installs and updates of your app on devices
  running Android 4.4 or earlier are unaffected and there is no change in
  behavior. For new installs and updates on devices running Android 5.0 or
  later, the system <strong>prevents installation of your app</strong> if it
  defines a custom permission that is already defined by an existing resident
  app.
</p>

<h3>
  Existing installs with Android 5.0 system update
</h3>

<p>
  If your app uses custom permissions and is widely distributed and installed,
  there’s a chance that it will be affected when users receive update their
  devices to Android 5.0. After the system update is installed, the system
  revalidates installed apps, including a check of their custom permissions. If
  your app defines a custom permission that is already defined by another app
  that has already been validated, and your app is not signed with the same key
  as the other app, the system <strong>does not re-install your app</strong>.
</p>

<h3>
  Recommendations
</h3>

<p>
  On devices running Android 5.0 or later, we recommend that you examine your
  app immediately, make any adjustments needed, and publish the updated version
  as soon as possible to your users.
</p>

<ul>
  <li>If you are using custom permissions in your app, consider their origin
  and whether you actually need them. Remove all <a href=
  "http://developer.android.com/guide/topics/manifest/permission-element.html">
    <code>&lt;permission&gt;</code></a> elements from your app, unless you are
    certain that they are required for proper function of your app.
  </li>

  <li>Consider replacing your custom permissions with system default
  permissions where possible.
  </li>

  <li>If your app requires custom permissions, rename your custom permissions
  to be unique to your app, such as by appending them to the full package name
  of your app.
  </li>

  <li>If you have a suite of apps <em>signed with different keys</em> and the apps
  access a shared component by means of a custom permission, make sure that the
  custom permission is only defined once, in the shared component. Apps that
  use the shared component should not define the custom permission themselves,
  but should instead request access through the <a href=
  "{@docRoot}guide/topics/manifest/uses-permission-element.html">
    <code>&lt;uses-permission&gt;</code></a> mechanism.
  </li>

  <li>If you have a suite of apps are <em>signed with the same key</em>,
  each app can define the same custom permission(s) as <span style="white-space:nowrap;">needed
  &mdash; the</span> system allows the apps to be installed in the usual way.
  </li>

</ul>


<h2 id="ssl">
  TLS/SSL Default Configuration Changes
</h2>

<p>
  Android 5.0 introduces changes the default TLS/SSL configuration used by apps
  for HTTPS and other TLS/SSL traffic:
</p>

<ul>
  <li>TLSv1.2 and TLSv1.1 protocols are now enabled,</li>
  <li>AES-GCM (AEAD) cipher suites are now enabled,</li>
  <li>MD5, 3DES, export, and static key ECDH cipher suites are now disabled,</li>
  <li>Forward Secrecy cipher suites (ECDHE and DHE) are preferred.</li>
</ul>

<p>
  These changes may lead to breakages in HTTPS or TLS/SSL connectivity in a
  small number of cases listed below.
</p>

<p>
  Note that the security ProviderInstaller from Google Play services already
  offers these changes across Android platform versions back to Android 2.3.
</p>

<h3>
  Server does not support any of the enabled ciphers suites
</h3>

<p>
  For example, a server might support only 3DES or MD5 cipher suites. The
  preferred fix is to improve the server’s configuration to enable stronger and
  more modern cipher suites and protocols. Ideally, TLSv1.2 and AES-GCM should
  be enabled, and Forward Secrecy cipher suites (ECDHE, DHE) should be enabled
  and preferred.
</p>

<p>
  An alternative is to modify the app to use a custom SSLSocketFactory to
  communicate with the server. The factory should be designed to create
  SSLSocket instances which have some of the cipher suites required by the
  server enabled in addition to default cipher suites.
</p>

<h3>
  App is making wrong assumptions about cipher suites used to connect to server
</h3>

<p>
  For example, some apps contain a custom X509TrustManager that breaks because
  it expects the authType parameter to be RSA but encounters ECDHE_RSA or
  DHE_RSA.
</p>

<h3>
  Server is intolerant to TLSv1.1, TLSv1.2 or new TLS extensions
</h3>

<p>
  For example, the TLS/SSL handshake with a server is erroneously rejected or
  stalls. The preferred fix is to upgrade the server to comply with the TLS/SSL
  protocol. This will make the server successfully negotiate these newer
  protocols or negotiate TLSv1 or older protocols and ignore TLS extensions it
  does not understand. In some cases disabling TLSv1.1 and TLSv1.2 on the
  server may work as a stopgap measure until the server software is upgraded.
</p>

<p>
  An alternative is to modify the app to use a custom SSLSocketFactory to
  communicate with the server. The factory should be designed to create
  SSLSocket instances with only those protocols enabled which are correctly
  supported by the server.
</p>