am 7350ff3d: Merge change 24631 into donut

<li>It lets applications describe the framework API revision that they

require</li>

<li>It lets the system negotiate the installation of applications on the user's

device, such that version-incompatible applications are not installed on a

user's device</li>

device, such that version-incompatible applications are not installed.</li>

</ul>

<p>Each Android platform version stores its API Level identifier internally, in

the system assumes that the application requires API Level 1. </li>

<li>If a <code>android:maxSdkVersion</code> attribute is declared, its value

must be equal to or greater than the system's API Level integer. 

in the system itself. If not declared, the system assumes that the application

If not declared, the system assumes that the application

has no maximum API Level. </li>

</ul>

<code>android:minSdkVersion</code> is to tell the Android system that it is

using APIs that were <em>introduced</em> in the API Level specified. If the

application were to be somehow installed on a platform with a lower API Level,

then it would crash at run-time when it tries to access APIs that don't exist.

then it would crash at run-time when it tried to access APIs that don't exist.

The system prevents such an outcome by not allowing the application to be

installed if the lowest API Level it requires is higher than that of the

platform version on the target device.</p>

application and use it successfully, then later receive an OTA update to a new

version of the Android platform. Once the update is installed, your application

will run in a new run-time version of the environment, but one that has the API

and system capabilities that it depends on. </p>

and system capabilities that your application depends on. </p>

<p>In some cases, changes <em>below</em> the API, such those in the underlying

system itself, may affect your application when it is run in the new

<p>Although it's unlikely that an Android-powered device would be downgraded to

a previous version of the platform, it's important to realize that there are

likely to be many devices in the field that run earlier versions of the

platform. Even among devices that receive OTA updates, some might lag and not

receive an update for a significant amount of time. </p>

platform. Even among devices that receive OTA updates, some might lag and

might not receive an update for a significant amount of time. </p>

<h3 id="platform">Selecting a platform version and API Level</h3>

of the Android platform it runs. See the table at the top of this document for

a list of platform versions and their API Levels. </p>

<!--

The Framework API makeup: the API available in a specific platform version is

made up of API parts introduced in previous versions, plus some parts that are

new.

-->

<h2 id="filtering">Filtering the Reference Documentation by API Level</h2>

<p>Reference documentation pages on the Android Developers site offer a "Filter

by API Level" control in the top-right area of each page. </p>

<p>The "Filter by API Level" lets you show documentation only for parts of the

API that are actually accessible to your application, based on the API Level

that it specifies in the <code>minSdkVersion</code> attribute in its manifest 

file </p>

<p>When you filter the reference documentation by an API level, only the APIs

available at that API level are shown. APIs introduced in a later API level are

grayed out and their content is masked, since they would not be accessible to

your application. </p>

<p>Note that filtering by API Level in the documentation does not provide a view

of what is new or introduced in each API Level. Filtering simply provides a way

by API Level" control in the top-right area of each page. You can use the 

control to show documentation only for parts of the API that are actually 

accessible to your application, based on the API Level that it specifies in 

the <code>android:minSdkVersion</code> attribute of its manifest file. </p>

<p>To use filtering, set the control to the same API Level as that specified

by your application. Notice that APIs introduced in a later API Level are 

then grayed out and their content is masked, since they would not be

accessible to your application. </p>

<p>Filtering by API Level in the documentation does not provide a view

of what is new or introduced in each API Level — it simply provides a way

to view the entire API associated with a given API Level, while excluding API

elements introduced in later API Levels.</p>

<p>By default, API Level filtering is enabled and set to show the latest API

Level. If you do not want to use filtering reference documentation, select the

highest available API Level.</p>

<p>Note that the reference documentation for API elements also specifies the API

Level at which the element was introduced. The API Level for packages and

classes is specified as "Since <api level>" at the top-right corner of the

content area on each documentation page. The API Level for each class member is

specified in the member's detailed description section header, at the right

margin. </p>

Level. If you do not want to use filtering reference documentation, 

simply select the highest available API Level. </p>

<p>Also note that the reference documentation for individual API elements

specifies the API Level at which the elements were introduced. The API Level 

for packages and classes is specified as "Since <api level>" at the 

top-right corner of the content area on each documentation page. The API Level 

for class members is specified in their detailed description headers, 

at the right margin. </p>

<ul>

  <li>Windows XP (32-bit) or Vista (32- or 64-bit)</li>

  <li>Mac OS X 10.4.8 or later (x86 only)</li>

  <li>Linux (tested on Linux Ubuntu Dapper Drake)</li>

  <li>Linux (tested on Linux Ubuntu Hardy Heron)</li>

</ul>

<h3>Supported Development Environments</h3>

building in alternate support or graceful degradation, or you can specify them 

as hardware requirements in a 

<a href="{@docRoot}guide/topics/manifest/uses-configuration-element.html"><code>&lt;uses-configuration&gt;</code>.</a>

element in the application's manifest file. Also see the <a href="{@docRoot}guide/topics/manifest/uses-feature-element.html"><code>&lt;uses-feature&gt;</code>

element in the application's manifest file. Also see the <a href="{@docRoot}guide/topics/manifest/uses-feature-element.html"><code>&lt;uses-feature&gt;</code></a>

manifest element, which lets your application declare a requirement for 

specific features, such as an OpenGL ES version or a camera that has 

autofocus capability.

starting with Android 1.6, the platform provides a Compatibility Mode that

automatically scales the UI of applications if they do not explicitly indicate

support for the current screen in the 

<a href="{@docRoot}guide/topics/manifest/supports-screen-element.html"><code>&lt;supports-screen&gt;</code>

<a href="{@docRoot}guide/topics/manifest/supports-screen-element.html"><code>&lt;supports-screen&gt;</code></a>

element in their manifest files. As part of testing, you should evaluate how

your application is displayed in Compatibility Mode on different screens. </p>

  </li>