page.title=Android 2.1 Platform
sdk.platform.version=2.1
sdk.platform.apiLevel=7
sdk.platform.majorMinor=minor

@jd:body

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

<h2>In this document</h2>
<ol>
  <li><a href="#features">Platform Highlights</a></li>
  <li><a href="#relnotes">Revisions</a></li>
  <li><a href="#api-level">API Level</a></li>
  <li><a href="#api">Framework API Changes</a>
  <li><a href="#apps">Built-in Applications</a></li>
  <li><a href="#locs">Locales</a></li>
  <li><a href="#skins">Emulator Skins</a></li>

    </ol>
  </li>
</ol>

<h2>Reference</h2>
<ol>
<li><a
href="{@docRoot}sdk/api_diff/{@sdkPlatformApiLevel}/changes.html">API
Differences Report &raquo;</a> </li>
</ol>

<h2>See Also</h2>
<ol>
  <li><a href="{@docRoot}sdk/exploring.html">Exploring the SDK</a></li>
</ol>

</div>
</div>

<p>
<em>API Level:</em>&nbsp;<strong>{@sdkPlatformApiLevel}</strong></p>

<p>Android {@sdkPlatformVersion} is a {@sdkPlatformMajorMinor} platform release
deployable to Android-powered handsets starting in January 2010.
This release includes new API
changes and bug fixes. For information on changes, see the <a href="#api">Framework API</a>
section.</p>

<p>For developers, the Android {@sdkPlatformVersion} platform is available as a
downloadable component for the Android SDK. The downloadable platform includes a
fully compliant Android library and system image, as well as a set of emulator
skins, sample applications, and more. The downloadable platform
includes no external libraries. </p>

<p>To get started developing or testing against the Android
{@sdkPlatformVersion} platform, use the Android SDK and AVD Manager tool to
download the platform into your SDK. For more information,
see <a href="{@docRoot}sdk/exploring.html">Exploring the
SDK</a>.</p>


<h2 id="features">Platform Highlights</h2>

<p>Android {@sdkPlatformVersion} does not add significant user features, see the <a
href="http://developer.android.com/about/versions/android-2.0-highlights.html">Android
2.0 Platform Highlights</a> document for the latest user features.</p>

<h2 id="relnotes">Revisions</h2>

<p>The sections below provide notes about successive releases of
the Android {@sdkPlatformVersion} platform component for the Android SDK, as denoted by
revision number. To determine what revision(s) of the Android
{@sdkPlatformVersion} platforms are installed in your SDK environment, refer to
the "Installed Packages" listing in the Android SDK and AVD Manager.</p>


<div class="toggle-content opened" style="padding-left:1em;">

<p><a href="#" onclick="return toggleContent(this)">
  <img src="{@docRoot}assets/images/triangle-opened.png"
class="toggle-content-img" alt="" />
  Android {@sdkPlatformVersion}, Revision 3</a> <em>(July 2011)</em>
</a></p>

<div class="toggle-content-toggleme" style="padding-left:2em;">

<dl>
<dt>Dependencies:</dt>
<dd>
<p>Requires <a href="{@docRoot}tools/sdk/tools-notes.html">SDK Tools r12</a> or
higher.</p>
</dd>
<dt>Notes:</dt>
<dd>
<p>Improvements to the platform's rendering library to support the visual layout editor in the ADT
Eclipse plugin. This revision allows for more drawing features in ADT and fixes several
bugs in the previous rendering library. It also unlocks several editor features that were added in
ADT 12.</p>
</dd>
</dl>

</div>
</div>

<div class="toggle-content closed" style="padding-left:1em;">

<p><a href="#" onclick="return toggleContent(this)">
  <img src="{@docRoot}assets/images/triangle-closed.png"
class="toggle-content-img" alt="" />
  Android {@sdkPlatformVersion}, Revision 2</a> <em>(May 2010)</em>
</a></p>

<div class="toggle-content-toggleme" style="padding-left:2em;">
<dl>
<dt>Dependencies:</dt>
<dd>
<p>Requires SDK Tools r6 or higher.</p>
</dd>

<dt>Tools:</dt>
<dd>
<ul> 
<li>Adds support for library projects in the Ant build system.</li>
<li>Adds improved layout rendering in ADT’s visual layout editor.</li>
</ul> 
</dd>

</dl>
 </div>
</div>

<div class="toggle-content closed" style="padding-left:1em;">

<p><a href="#" onclick="return toggleContent(this)">
  <img src="{@docRoot}assets/images/triangle-closed.png"
class="toggle-content-img" alt="" />
  Android {@sdkPlatformVersion}, Revision 1</a> <em>(January 2010)</em>
</a></p>

<div class="toggle-content-toggleme" style="padding-left:2em;">
<dl>
<dt>Dependencies:</dt>
<dd>
<p>Requires SDK Tools r4 or higher.</p>
</dd>
</dl>
 </div>
</div>


<h2 id="api-level">API Level</h2>

<p>The Android {@sdkPlatformVersion} platform delivers an updated version of
the framework API. The Android {@sdkPlatformVersion} API
is assigned an integer identifier &mdash;
<strong>{@sdkPlatformApiLevel}</strong> &mdash; that is
stored in the system itself. This identifier, called the "API Level", allows the
system to correctly determine whether an application is compatible with
the system, prior to installing the application. </p>

<p>To use APIs introduced in Android {@sdkPlatformVersion} in your
application, you need to set the proper value, "{@sdkPlatformApiLevel}", in the
<code>android:minSdkVersion</code> attributes of the <code>&lt;uses-sdk&gt;</code>
element in your application's manifest. </p>

<p>For more information about how to use API Level, see the <a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Levels</a> document. </p>


<h2 id="api">Framework API Changes</h2>

<p>The sections below provide information about changes made to the application
framework API provided by the Android {@sdkPlatformVersion} platform.</p>

<h3>Live Wallpapers</h3>

<p>The following additions provide APIs for you to develop animated wallpapers:</p>
<ul>
<li>New {@link android.service.wallpaper} package.</li>
<li>New {@link android.app.WallpaperInfo} class.</li>
<li>Updated {@link android.app.WallpaperManager}.</li>
</ul>

<p>Additionally, if your application uses or provides Live Wallpapers, you must
remember to add a <a
href="{@docRoot}guide/topics/manifest/uses-feature-element.html"><code>&lt;uses-feature></code></a>
 element to the application's manifest, declaring the attribute
<code>android:name="android.software.live_wallpaper"</code>. For example:</p>

<pre class="no-pretty-print">
&lt;uses-feature android:name="android.software.live_wallpaper" />
</pre>

<p>When you've published your application, Google Play checks for the
presence of this element and uses it as a filter, ensuring that your application
is not made available to users whose devices do not support Live Wallpapers.
</p>

<h3>Telephony</h3>

<ul>
<li>New {@link android.telephony.SignalStrength} class provides information
about the device's current network signal. This can be acquired from the
new {@link
android.telephony.PhoneStateListener#onSignalStrengthsChanged(SignalStrength)}
callback.</li>

<li>New {@link
android.telephony.PhoneStateListener#onDataConnectionStateChanged(int,int)}
callback.</li>
</ul>

<h3>Views</h3>

<ul>
<li>New {@link android.view.View} methods {@link android.view.View#isOpaque()}
and {@link android.view.View#onDrawScrollBars(Canvas)}.</li>

<li>New {@link android.widget.RemoteViews} methods {@link
android.widget.RemoteViews#addView(int,RemoteViews)} and {@link
android.widget.RemoteViews#removeAllViews(int)}.</li>

<li>New {@link android.view.ViewGroup} methods {@link
android.view.ViewGroup#isChildrenDrawingOrderEnabled()} and {@link
android.view.ViewGroup#setChildrenDrawingOrderEnabled(boolean)}.</li>
</ul>

<h3>WebKit</h3>

<ul>
<li>New {@link android.webkit.WebStorage} methods to manipulate web
storage databases.</li>

<li>New {@link android.webkit.GeolocationPermissions} methods to
get Geolocation permissions from, and set them on the WebView.</li>

<li>New {@link android.webkit.WebSettings} methods to manage settings for
app cache, web storage, and zooming based on screen density.</li>

<li>New {@link android.webkit.WebChromeClient} methods for handling video,
browsing history, custom Views, app cache limits, and more.</li>
</ul>

</ul>

<!--
<h3 id="behavior-changes">Behavior changes</h3>

<h3 id="bug-fixes">Bug fixes</h3>
-->

<h3 id="api-diff">API differences report</h3>

<p>For a detailed view of all API changes in Android {@sdkPlatformVersion} (API
Level {@sdkPlatformApiLevel}), as compared to API Level 6, see the <a
href="{@docRoot}sdk/api_diff/{@sdkPlatformApiLevel}/changes.html">API
Differences Report</a>.</p>

<h2 id="apps">Built-in Applications</h2>

<p>The system image included in the downloadable platform provides these
built-in applications:</p>

<table style="border:0;padding-bottom:0;margin-bottom:0;">
<tr>
<td style="border:0;padding-bottom:0;margin-bottom:0;">
	<ul>
	<li>Alarm Clock</li>
	<li>Browser</li>
	<li>Calculator</li>
	<li>Camera</li>
	<li>Contacts</li>
	<li>Custom Locale (developer app)</li>
	<li>Dev Tools (developer app)</li>
    <li>Email</li>
	</ul>
</td>
<td style="border:0;padding-bottom:0;margin-bottom:0;padding-left:5em;">
	<ul>

	<li>Gallery</li>
	<li>IMEs for Japanese, Chinese, and Latin text input</li>
	<li>Messaging</li>
	<li>Music</li>
	<li>Phone</li>
	<li>Settings</li>
	<li>Spare Parts (developer app)</li>
	</ul>
</td>
</tr>
</table>


<h2 id="locs" style="margin-top:.75em;">Locales</h2>

<p>The system image included in the downloadable platform provides a variety of
built-in locales. In some cases, region-specific strings are available for the
locales. In other cases, a default version of the language is used. The
languages that are available in the Android {@sdkPlatformVersion} system
image are listed below (with <em>language</em>_<em>country/region</em> locale
descriptor).</p>

<table style="border:0;padding-bottom:0;margin-bottom:0;">
<tr>
<td style="border:0;padding-bottom:0;margin-bottom:0;">
<ul>
<li>Chinese, PRC (zh_CN)</li>
<li>Chinese, Taiwan (zh_TW)</li>
<li>Czech (cs_CZ)</li>
<li>Dutch, Netherlands (nl_NL)</li>
<li>Dutch, Belgium (nl_BE)</li>
<li>English, US (en_US)</li>
<li>English, Britain (en_GB)</li>
<li>English, Canada (en_CA)</li>
<li>English, Australia (en_AU)</li>
<li>English, New Zealand (en_NZ)</li>
<li>English, Singapore(en_SG)</li>
<li>French, France (fr_FR)</li>
<li>French, Belgium (fr_BE)</li>
</ul>
</td>
<td style="border:0;padding-bottom:0;margin-bottom:0;padding-left:5em;">
<li>French, Canada (fr_CA)</li>
<li>French, Switzerland (fr_CH)</li>
<li>German, Germany (de_DE)</li>
<li>German, Austria (de_AT)</li>
<li>German, Switzerland (de_CH)</li>
<li>German, Liechtenstein (de_LI)</li>
<li>Italian, Italy (it_IT)</li>
<li>Italian, Switzerland (it_CH)</li>
<li>Japanese (ja_JP)</li>
<li>Korean (ko_KR)</li>
<li>Polish (pl_PL)</li>
<li>Russian (ru_RU)</li>
<li>Spanish (es_ES)</li>
</td>
</tr>
</table>

<p>Localized UI strings match the locales that are accessible
through Settings.</p>

<h2 id="skins">Emulator Skins</h2>

<p>The downloadable platform includes a set of emulator skins that you can use
for modeling your application in different screen sizes and resolutions. The
emulator skins are:</p>

<ul>
  <li>
    QVGA (240x320, low density, small screen)
  </li>
  <li>
    WQVGA (240x400, low density, normal screen)
  </li>
  <li>
    FWQVGA (240x432, low density, normal screen)
  </li>
  <li>
    HVGA (320x480, medium density, normal screen)
  </li>
  <li>
    WVGA800 (480x800, high density, normal screen)
  </li>
  <li>
    WVGA854 (480x854 high density, normal screen)
  </li>
</ul>

<p>For more information about how to develop an application that displays
and functions properly on all Android-powered devices, see <a
href="{@docRoot}guide/practices/screens_support.html">Supporting Multiple
Screens</a>.</p>