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      1 page.title=<uses-sdk>
      2 page.tags=api levels,sdk version,minsdkversion,targetsdkversion,maxsdkversion
      3 @jd:body
      4 
      5 
      6 <div id="qv-wrapper">
      7 <div id="qv">
      8 
      9 <h2>In this document</h2>
     10 <ol>
     11   <li><a href="#ApiLevels">What is API Level?</a></li>
     12   <li><a href="#uses">Uses of API Level in Android</a></li>
     13   <li><a href="#considerations">Development Considerations</a>
     14     <ol>
     15       <li><a href="#fc">Application forward compatibility</a></li>
     16       <li><a href="#bc">Application backward compatibility</a></li>
     17       <li><a href="#platform">Selecting a platform version and API Level</a></li>
     18       <li><a href="#apilevel">Declaring a minimum API Level</a></li>
     19       <li><a href="#testing">Testing against higher API Levels</a></li>
     20     </ol>
     21   </li>
     22   <li><a href="#filtering">Filtering the Reference Documentation by API Level</a></li>
     23 </ol>
     24 </div>
     25 </div>
     26 
     27 <div class="sidebox-wrapper">
     28 <div class="sidebox">
     29     <img src="{@docRoot}assets/images/icon_play.png" style="float:left;margin:0;padding:0;">
     30     <p style="color:#669999;padding-top:1em;">Google Play Filtering</p>
     31     <p style="padding-top:1em;">Google Play uses the <code>&lt;uses-sdk&gt;</code>
     32     attributes declared in your app manifest to filter your app from devices
     33     that do not meet it's platform version requirements. Before setting these
     34     attributes, make sure that you understand
     35     <a href="{@docRoot}google/play/filters.html">Google Play filters</a>. </p>
     36   </div>
     37 </div>
     38 
     39 <dl class="xml">
     40 <dt>syntax:</dt>
     41 <dd><pre>
     42 &lt;uses-sdk android:<a href="#min">minSdkVersion</a>="<i>integer</i>"
     43           android:<a href="#target">targetSdkVersion</a>="<i>integer</i>"
     44           android:<a href="#max">maxSdkVersion</a>="<i>integer</i>" /&gt;</pre></dd>
     45 
     46 <dt>contained in:</dt>
     47 <dd><code><a href="{@docRoot}guide/topics/manifest/manifest-element.html">&lt;manifest&gt;</a></code></dd>
     48 
     49 <dt>description:</dt>
     50 <dd itemprop="description"><p>  Lets you express an application's compatibility with one or more versions of the Android platform,
     51 by means of an API Level integer. The API Level expressed by an application will be compared to the
     52 API Level of a given Android system, which may vary among different Android devices.
     53 </p>
     54 
     55 <p>Despite its name, this element is used to specify the API Level, <em>not</em>
     56 the version number of the SDK (software development kit) or Android platform.
     57 The API Level is always a single integer. You cannot derive the API Level from
     58 its associated Android version number (for example, it is not the same as the
     59 major version or the sum of the major and minor versions).</p>
     60 
     61 <p>Also read the document about
     62 <a href="{@docRoot}tools/publishing/versioning.html">Versioning Your Applications</a>.
     63 </p></dd>
     64 
     65 <dt>attributes:</dt>
     66 
     67 <dd>
     68 <dl class="attr">
     69   <dt><a name="min"></a>{@code android:minSdkVersion}</dt>
     70   <dd>An integer designating the minimum API Level required
     71   for the application to run. The Android system will prevent the user from installing
     72   the application if the system's API Level is lower than the value specified in
     73   this attribute. You should always declare this attribute.
     74 
     75   <p class="caution"><strong>Caution:</strong> If you do not declare this
     76   attribute, the system assumes a default value of "1", which indicates that your
     77   application is compatible with all versions of Android. If your application is
     78   <em>not</em> compatible with all versions (for instance, it uses APIs introduced
     79   in API Level 3) and you have not declared the proper <code>minSdkVersion</code>,
     80   then when installed on a system with an API Level less than 3, the application
     81   will crash during runtime when attempting to access the unavailable APIs. For
     82   this reason, be certain to declare the appropriate API Level in the
     83   <code>minSdkVersion</code> attribute.</p>
     84   </dd>
     85 
     86   <dt><a name="target"></a>{@code android:targetSdkVersion}</dt>
     87   <dd>An integer designating the API Level that the application targets. If not set, the default
     88 value equals that given to {@code minSdkVersion}.
     89 
     90   <p>This attribute informs the system that you have tested against the target version and the
     91 system should not enable any compatibility behaviors to maintain your app's forward-compatibility
     92 with the target version. The application is still able to run on older versions (down to {@code
     93 minSdkVersion}).</p>
     94 
     95   <p>As Android evolves with each new version, some behaviors and even appearances might change.
     96 However, if the API level of the platform is higher than the version declared by your app's {@code
     97 targetSdkVersion}, the system may enable compatibility behaviors to ensure that your app
     98 continues to work the way you expect. You can disable such compatibility
     99 behaviors by specifying {@code targetSdkVersion} to match the API
    100 level of the platform on which it's running. For example, setting this value to "11" or higher
    101 allows the system to apply a new default theme (Holo) to your app when running on Android 3.0 or
    102 higher and also disables <a href="{@docRoot}guide/practices/screen-compat-mode.html">screen
    103 compatibility mode</a> when running on larger screens (because support for API level 11 implicitly
    104 supports larger screens).</p>
    105 
    106   <p>There are many compatibility behaviors that the system may enable based on the value you set
    107 for this attribute. Several of these behaviors are described by the corresponding platform versions
    108 in the {@link android.os.Build.VERSION_CODES} reference.</p>
    109 
    110   <p>To maintain your application along with each Android release, you should increase
    111 the value of this attribute to match the latest API level, then thoroughly test your application on
    112 the corresponding platform version.</p>
    113 
    114   <p>Introduced in: API Level 4</p>
    115   </dd>
    116 
    117   <dt><a name="max"></a>{@code android:maxSdkVersion}</dt>
    118   <dd>An integer designating the maximum API Level on which the application is
    119   designed to run.
    120 
    121   <p>In Android 1.5, 1.6, 2.0, and 2.0.1, the system checks the value of this
    122   attribute when installing an application and when re-validating the application
    123   after a system update. In either case, if the application's
    124   <code>maxSdkVersion</code> attribute is lower than the API Level used by
    125   the system itself, then the system will not allow the application to be
    126   installed. In the case of re-validation after system update, this effectively
    127   removes your application from the device.
    128 
    129   <p>To illustrate how this attribute can affect your application after system
    130   updates, consider the following example: </p>
    131 
    132   <p>An application declaring <code>maxSdkVersion="5"</code> in its
    133   manifest is published on Google Play. A user whose device is running Android
    134   1.6 (API Level 4) downloads and installs the app. After a few weeks, the user
    135   receives an over-the-air system update to Android 2.0 (API Level 5). After the
    136   update is installed, the system checks the application's
    137   <code>maxSdkVersion</code> and successfully re-validates it. The
    138   application functions as normal. However, some time later, the device receives
    139   another system update, this time to Android 2.0.1 (API Level 6). After the
    140   update, the system can no longer re-validate the application because the system's
    141   own API Level (6) is now higher than the maximum supported by the application
    142   (5). The system prevents the application from being visible to the user, in
    143   effect removing it from the device.</p>
    144 
    145   <p class="warning"><strong>Warning:</strong> Declaring this attribute is not
    146   recommended. First, there is no need to set the attribute as means of blocking
    147   deployment of your application onto new versions of the Android platform as they
    148   are released. By design, new versions of the platform are fully
    149   backward-compatible. Your application should work properly on new versions,
    150   provided it uses only standard APIs and follows development best practices.
    151   Second, note that in some cases, declaring the attribute can <strong>result in
    152   your application being removed from users' devices after a system
    153   update</strong> to a higher API Level. Most devices on which your application
    154   is likely to be installed will receive periodic system updates over the air, so
    155   you should consider their effect on your application before setting this
    156   attribute.</p>
    157 
    158   <p style="margin-bottom:1em;">Introduced in: API Level 4</p>
    159 
    160   <div class="special">Future versions of Android (beyond Android 2.0.1) will no
    161 longer check or enforce the <code>maxSdkVersion</code> attribute during
    162 installation or re-validation. Google Play will continue to use the attribute
    163 as a filter, however, when presenting users with applications available for
    164 download. </div>
    165   </dd>
    166 
    167 
    168 </dl></dd>
    169 
    170 <!-- ##api level indication## -->
    171 <dt>introduced in:</dt>
    172 <dd>API Level 1</dd>
    173 
    174 </dl>
    175 
    176 
    177 
    178 
    179 
    180 <!--- CONTENT FROM OLD API LEVEL DOC ---->
    181 
    182 
    183 
    184 
    185 <h2 id="ApiLevels">What is API Level?</h2>
    186 
    187 <p>API Level is an integer value that uniquely identifies the framework API
    188 revision offered by a version of the Android platform.</p>
    189 
    190 <p>The Android platform provides a framework API that applications can use to
    191 interact with the underlying Android system. The framework API consists of:</p>
    192 
    193 <ul>
    194 <li>A core set of packages and classes</li>
    195 <li>A set of XML elements and attributes for declaring a manifest file</li>
    196 <li>A set of XML elements and attributes for declaring and accessing resources</li>
    197 <li>A set of Intents</li>
    198 <li>A set of permissions that applications can request, as well as permission
    199 enforcements included in the system</li>
    200 </ul>
    201 
    202 <p>Each successive version of the Android platform can include updates to the
    203 Android application framework API that it delivers. </p>
    204 
    205 <p>Updates to the framework API are designed so that the new API remains
    206 compatible with earlier versions of the API. That is, most changes in the API
    207 are additive and introduce new or replacement functionality. As parts of the API
    208 are upgraded, the older replaced parts are deprecated but are not removed, so
    209 that existing applications can still use them. In a very small number of cases,
    210 parts of the API may be modified or removed, although typically such changes are
    211 only needed to ensure API robustness and application or system security. All
    212 other API parts from earlier revisions are carried forward without
    213 modification.</p>
    214 
    215 <p>The framework API that an Android platform delivers is specified using an
    216 integer identifier called "API Level". Each Android platform version supports
    217 exactly one API Level, although support is implicit for all earlier API Levels
    218 (down to API Level 1). The initial release of the Android platform provided
    219 API Level 1 and subsequent releases have incremented the API Level.</p>
    220 
    221 <p>The table below specifies the API Level supported by each version of the
    222 Android platform. For information about the relative numbers of devices that
    223 are running each version, see the <a href="{@docRoot}about/dashboards/index.html">Platform
    224 Versions dashboards page</a>.</p>
    225 
    226 <table>
    227   <tr><th>Platform Version</th><th>API Level</th><th>VERSION_CODE</th><th>Notes</th></tr>
    228 
    229     <tr><td><a href="{@docRoot}about/versions/marshmallow/android-6.0.html">Android 6.0</a></td>
    230     <td><a href="{@docRoot}sdk/api_diff/23/changes.html" title="Diff Report">23</a></td>
    231     <td>{@link android.os.Build.VERSION_CODES#M}</td>
    232     <td><a href="{@docRoot}about/versions/marshmallow/index.html">Platform Highlights</a></td></tr>
    233 
    234     <tr><td><a href="{@docRoot}about/versions/android-5.1.html">Android 5.1</a></td>
    235     <td><a href="{@docRoot}sdk/api_diff/22/changes.html" title="Diff Report">22</a></td>
    236     <td>{@link android.os.Build.VERSION_CODES#LOLLIPOP_MR1}</td>
    237     <td rowspan="2"><a href="{@docRoot}about/versions/lollipop.html">Platform
    238 Highlights</a></td></tr>
    239 
    240     <tr><td><a href="{@docRoot}about/versions/android-5.0.html">Android 5.0</a></td>
    241     <td><a href="{@docRoot}sdk/api_diff/21/changes.html" title="Diff Report">21</a></td>
    242     <td>{@link android.os.Build.VERSION_CODES#LOLLIPOP}</td>
    243     </tr>
    244 
    245     <tr><td style="color:#bbb">Android 4.4W</td>
    246     <td><a href="{@docRoot}sdk/api_diff/20/changes.html" title="Diff Report">20</a></td>
    247     <td>{@link android.os.Build.VERSION_CODES#KITKAT_WATCH}</td>
    248     <td style="color:#bbb">KitKat for Wearables Only</td></tr>
    249 
    250     <tr><td><a href="{@docRoot}about/versions/android-4.4.html">Android 4.4</a></td>
    251     <td><a href="{@docRoot}sdk/api_diff/19/changes.html" title="Diff Report">19</a></td>
    252     <td>{@link android.os.Build.VERSION_CODES#KITKAT}</td>
    253     <td><a href="{@docRoot}about/versions/kitkat.html">Platform
    254 Highlights</a></td></tr>
    255 
    256     <tr><td><a href="{@docRoot}about/versions/android-4.3.html">Android 4.3</a></td>
    257     <td><a href="{@docRoot}sdk/api_diff/18/changes.html" title="Diff Report">18</a></td>
    258     <td>{@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR2}</td>
    259     <td><a href="{@docRoot}about/versions/jelly-bean.html">Platform
    260 Highlights</a></td></tr>
    261 
    262     <tr><td><a href="{@docRoot}about/versions/android-4.2.html">Android 4.2, 4.2.2</a></td>
    263     <td><a href="{@docRoot}sdk/api_diff/17/changes.html" title="Diff Report">17</a></td>
    264     <td>{@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}</td>
    265     <td><a href="{@docRoot}about/versions/jelly-bean.html#android-42">Platform
    266 Highlights</a></td></tr>
    267 
    268     <tr><td><a href="{@docRoot}about/versions/android-4.1.html">Android 4.1, 4.1.1</a></td>
    269     <td><a href="{@docRoot}sdk/api_diff/16/changes.html" title="Diff Report">16</a></td>
    270     <td>{@link android.os.Build.VERSION_CODES#JELLY_BEAN}</td>
    271     <td><a href="{@docRoot}about/versions/jelly-bean.html#android-41">Platform
    272 Highlights</a></td></tr>
    273 
    274     <tr><td><a href="{@docRoot}about/versions/android-4.0.3.html">Android 4.0.3, 4.0.4</a></td>
    275     <td><a href="{@docRoot}sdk/api_diff/15/changes.html" title="Diff Report">15</a></td>
    276     <td>{@link android.os.Build.VERSION_CODES#ICE_CREAM_SANDWICH_MR1}</td>
    277     <td rowspan="2"><a href="{@docRoot}about/versions/android-4.0-highlights.html">Platform
    278 Highlights</a></td></tr>
    279 
    280     <tr><td><a href="{@docRoot}about/versions/android-4.0.html">Android 4.0, 4.0.1, 4.0.2</a></td>
    281     <td><a href="{@docRoot}sdk/api_diff/14/changes.html" title="Diff Report">14</a></td>
    282     <td>{@link android.os.Build.VERSION_CODES#ICE_CREAM_SANDWICH}</td>
    283     </tr>
    284 
    285     <tr><td><a href="{@docRoot}about/versions/android-3.2.html">Android 3.2</a></td>
    286     <td><a href="{@docRoot}sdk/api_diff/13/changes.html" title="Diff Report">13</a></td>
    287     <td>{@link android.os.Build.VERSION_CODES#HONEYCOMB_MR2}</td>
    288     <td><!-- <a href="{@docRoot}about/versions/android-3.2-highlights.html">Platform
    289 Highlights</a>--></td></tr>
    290 
    291   <tr><td><a href="{@docRoot}about/versions/android-3.1.html">Android 3.1.x</a></td>
    292     <td><a href="{@docRoot}sdk/api_diff/12/changes.html" title="Diff Report">12</a></td>
    293     <td>{@link android.os.Build.VERSION_CODES#HONEYCOMB_MR1}</td>
    294     <td><a href="{@docRoot}about/versions/android-3.1-highlights.html">Platform Highlights</a></td></tr>
    295 
    296   <tr><td><a href="{@docRoot}about/versions/android-3.0.html">Android 3.0.x</a></td>
    297     <td><a href="{@docRoot}sdk/api_diff/11/changes.html" title="Diff Report">11</a></td>
    298     <td>{@link android.os.Build.VERSION_CODES#HONEYCOMB}</td>
    299     <td><a href="{@docRoot}about/versions/android-3.0-highlights.html">Platform Highlights</a></td></tr>
    300 
    301   <tr><td><a href="{@docRoot}about/versions/android-2.3.3.html">Android 2.3.4<br>Android 2.3.3</a></td>
    302     <td><a href="{@docRoot}sdk/api_diff/10/changes.html" title="Diff Report">10</a></td>
    303     <td>{@link android.os.Build.VERSION_CODES#GINGERBREAD_MR1}</td>
    304     <td rowspan="2"><a href="{@docRoot}about/versions/android-2.3-highlights.html">Platform
    305 Highlights</a></td></tr>
    306 
    307   <tr><td><a href="{@docRoot}about/versions/android-2.3.html">Android 2.3.2<br>Android 2.3.1<br>
    308   Android 2.3</a></td>
    309     <td><a href="{@docRoot}sdk/api_diff/9/changes.html" title="Diff Report">9</a></td>
    310     <td>{@link android.os.Build.VERSION_CODES#GINGERBREAD}</td>
    311     </tr>
    312 
    313   <tr><td><a href="{@docRoot}about/versions/android-2.2.html">Android 2.2.x</a></td>
    314     <td ><a href="{@docRoot}sdk/api_diff/8/changes.html" title="Diff Report">8</a></td>
    315     <td>{@link android.os.Build.VERSION_CODES#FROYO}</td>
    316     <td><a href="{@docRoot}about/versions/android-2.2-highlights.html">Platform Highlights</a></td></tr>
    317 
    318   <tr><td><a href="{@docRoot}about/versions/android-2.1.html">Android 2.1.x</a></td>
    319     <td><a href="{@docRoot}sdk/api_diff/7/changes.html" title="Diff Report">7</a></td>
    320     <td>{@link android.os.Build.VERSION_CODES#ECLAIR_MR1}</td>
    321     <td rowspan="3" ><a href="{@docRoot}about/versions/android-2.0-highlights.html">Platform
    322 Highlights</a></td></tr>
    323 
    324   <tr><td><a href="{@docRoot}about/versions/android-2.0.1.html">Android 2.0.1</a></td>
    325     <td><a href="{@docRoot}sdk/api_diff/6/changes.html" title="Diff Report">6</a></td>
    326     <td>{@link android.os.Build.VERSION_CODES#ECLAIR_0_1}</td>
    327     </tr>
    328 
    329   <tr><td><a href="{@docRoot}about/versions/android-2.0.html">Android 2.0</a></td>
    330     <td><a href="{@docRoot}sdk/api_diff/5/changes.html" title="Diff Report">5</a></td>
    331     <td>{@link android.os.Build.VERSION_CODES#ECLAIR}</td>
    332     </tr>
    333 
    334   <tr><td><a href="{@docRoot}about/versions/android-1.6.html">Android 1.6</a></td>
    335     <td><a href="{@docRoot}sdk/api_diff/4/changes.html" title="Diff Report">4</a></td>
    336     <td>{@link android.os.Build.VERSION_CODES#DONUT}</td>
    337     <td><a href="{@docRoot}about/versions/android-1.6-highlights.html">Platform Highlights</a></td></tr>
    338 
    339   <tr><td><a href="{@docRoot}about/versions/android-1.5.html">Android 1.5</a></td>
    340     <td><a href="{@docRoot}sdk/api_diff/3/changes.html" title="Diff Report">3</a></td>
    341     <td>{@link android.os.Build.VERSION_CODES#CUPCAKE}</td>
    342     <td><a href="{@docRoot}about/versions/android-1.5-highlights.html">Platform Highlights</a></td></tr>
    343 
    344   <tr><td><a href="{@docRoot}about/versions/android-1.1.html">Android 1.1</a></td>
    345     <td>2</td>
    346     <td>{@link android.os.Build.VERSION_CODES#BASE_1_1}</td><td></td></tr>
    347 
    348   <tr><td>Android 1.0</td>
    349     <td>1</td>
    350     <td>{@link android.os.Build.VERSION_CODES#BASE}</td>
    351     <td></td></tr>
    352 </table>
    353 
    354 
    355 <h2 id="uses">Uses of API Level in Android</h2>
    356 
    357 <p>The API Level identifier serves a key role in ensuring the best possible
    358 experience for users and application developers:
    359 
    360 <ul>
    361 <li>It lets the Android platform describe the maximum framework API revision
    362 that it supports</li>
    363 <li>It lets applications describe the framework API revision that they
    364 require</li>
    365 <li>It lets the system negotiate the installation of applications on the user's
    366 device, such that version-incompatible applications are not installed.</li>
    367 </ul>
    368 
    369 <p>Each Android platform version stores its API Level identifier internally, in
    370 the Android system itself. </p>
    371 
    372 <p>Applications can use a manifest element provided by the framework API &mdash;
    373 <code>&lt;uses-sdk&gt;</code> &mdash; to describe the minimum and maximum API
    374 Levels under which they are able to run, as well as the preferred API Level that
    375 they are designed to support. The element offers three key attributes:</p>
    376 
    377 <ul>
    378 <li><code>android:minSdkVersion</code> &mdash; Specifies the minimum API Level
    379 on which the application is able to run. The default value is "1".</li>
    380 <li><code>android:targetSdkVersion</code> &mdash; Specifies the API Level
    381 on which the application is designed to run. In some cases, this allows the
    382 application to use manifest elements or behaviors defined in the target
    383 API Level, rather than being restricted to using only those defined
    384 for the minimum API Level.</li>
    385 <li><code>android:maxSdkVersion</code> &mdash; Specifies the maximum API Level
    386 on which the application is able to run. <strong>Important:</strong> Please read the <a
    387 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><code>&lt;uses-sdk&gt;</code></a>
    388 documentation before using this attribute.  </li>
    389 </ul>
    390 
    391 <p>For example, to specify the minimum system API Level that an application
    392 requires in order to run, the application would include in its manifest a
    393 <code>&lt;uses-sdk&gt;</code> element with a <code>android:minSdkVersion</code>
    394 attribute. The value of <code>android:minSdkVersion</code> would be the integer
    395 corresponding to the API Level of the earliest version of the Android platform
    396 under which the application can run. </p>
    397 
    398 <p>When the user attempts to install an application, or when revalidating an
    399 appplication after a system update, the Android system first checks the
    400 <code>&lt;uses-sdk&gt;</code> attributes in the application's manifest and
    401 compares the values against its own internal API Level. The system allows the
    402 installation to begin only if these conditions are met:</p>
    403 
    404 <ul>
    405 <li>If a <code>android:minSdkVersion</code> attribute is declared, its value
    406 must be less than or equal to the system's API Level integer. If not declared,
    407 the system assumes that the application requires API Level 1. </li>
    408 <li>If a <code>android:maxSdkVersion</code> attribute is declared, its value
    409 must be equal to or greater than the system's API Level integer.
    410 If not declared, the system assumes that the application
    411 has no maximum API Level. Please read the <a
    412 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><code>&lt;uses-sdk&gt;</code></a>
    413 documentation for more information about how the system handles this attribute.</li>
    414 </ul>
    415 
    416 <p>When declared in an application's manifest, a <code>&lt;uses-sdk&gt;</code>
    417 element might look like this: </p>
    418 
    419 <pre>&lt;manifest&gt;
    420   &lt;uses-sdk android:minSdkVersion="5" /&gt;
    421   ...
    422 &lt;/manifest&gt;</pre>
    423 
    424 <p>The principal reason that an application would declare an API Level in
    425 <code>android:minSdkVersion</code> is to tell the Android system that it is
    426 using APIs that were <em>introduced</em> in the API Level specified. If the
    427 application were to be somehow installed on a platform with a lower API Level,
    428 then it would crash at run-time when it tried to access APIs that don't exist.
    429 The system prevents such an outcome by not allowing the application to be
    430 installed if the lowest API Level it requires is higher than that of the
    431 platform version on the target device.</p>
    432 
    433 <p>For example, the {@link android.appwidget} package was introduced with API
    434 Level 3. If an application uses that API, it must declare a
    435 <code>android:minSdkVersion</code> attribute with a value of "3". The
    436 application will then be installable on platforms such as Android 1.5 (API Level
    437 3) and Android 1.6 (API Level 4), but not on the Android 1.1 (API Level 2) and
    438 Android 1.0 platforms (API Level 1).</p>
    439 
    440 <p>For more information about how to specify an application's API Level
    441 requirements, see the <a
    442 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><code>&lt;uses-sdk&gt;</code></a>
    443  section of the manifest file documentation.</p>
    444 
    445 
    446 <h2 id="considerations">Development Considerations</h2>
    447 
    448 <p>The sections below provide information related to API level that you should
    449 consider when developing your application.</p>
    450 
    451 <h3 id="fc">Application forward compatibility</h3>
    452 
    453 <p>Android applications are generally forward-compatible with new versions of
    454 the Android platform.</p>
    455 
    456 <p>Because almost all changes to the framework API are additive, an Android
    457 application developed using any given version of the API (as specified by its
    458 API Level) is forward-compatible with later versions of the Android platform and
    459 higher API levels. The application should be able to run on all later versions
    460 of the Android platform, except in isolated cases where the application uses a
    461 part of the API that is later removed for some reason. </p>
    462 
    463 <p>Forward compatibility is important because many Android-powered devices
    464 receive over-the-air (OTA) system updates. The user may install your
    465 application and use it successfully, then later receive an OTA update to a new
    466 version of the Android platform. Once the update is installed, your application
    467 will run in a new run-time version of the environment, but one that has the API
    468 and system capabilities that your application depends on. </p>
    469 
    470 <p>In some cases, changes <em>below</em> the API, such those in the underlying
    471 system itself, may affect your application when it is run in the new
    472 environment. For that reason it's important for you, as the application
    473 developer, to understand how the application will look and behave in each system
    474 environment. To help you test your application on various versions of the Android
    475 platform, the Android SDK includes multiple platforms that you can download.
    476 Each platform includes a compatible system image that you can run in an AVD, to
    477 test your application. </p>
    478 
    479 <h3 id="bc">Application backward compatibility</h3>
    480 
    481 <p>Android applications are not necessarily backward compatible with versions of
    482 the Android platform older than the version against which they were compiled.
    483 </p>
    484 
    485 <p>Each new version of the Android platform can include new framework APIs, such
    486 as those that give applications access to new platform capabilities or replace
    487 existing API parts. The new APIs are accessible to applications when running on
    488 the new platform and, as mentioned above, also when running on later versions of
    489 the platform, as specified by API Level. Conversely, because earlier versions of
    490 the platform do not include the new APIs, applications that use the new APIs are
    491 unable to run on those platforms.</p>
    492 
    493 <p>Although it's unlikely that an Android-powered device would be downgraded to
    494 a previous version of the platform, it's important to realize that there are
    495 likely to be many devices in the field that run earlier versions of the
    496 platform. Even among devices that receive OTA updates, some might lag and
    497 might not receive an update for a significant amount of time. </p>
    498 
    499 <h3 id="platform">Selecting a platform version and API Level</h3>
    500 
    501 <p>When you are developing your application, you will need to choose
    502 the platform version against which you will compile the application. In
    503 general, you should compile your application against the lowest possible
    504 version of the platform that your application can support.
    505 
    506 <p>You can determine the lowest possible platform version by compiling the
    507 application against successively lower build targets. After you determine the
    508 lowest version, you should create an AVD using the corresponding platform
    509 version (and API Level) and fully test your application. Make sure to declare a
    510 <code>android:minSdkVersion</code> attribute in the application's manifest and
    511 set its value to the API Level of the platform version. </p>
    512 
    513 <h3 id="apilevel">Declaring a minimum API Level</h3>
    514 
    515 <p>If you build an application that uses APIs or system features introduced in
    516 the latest platform version, you should set the
    517 <code>android:minSdkVersion</code> attribute to the API Level of the latest
    518 platform version. This ensures that users will only be able to install your
    519 application if their devices are running a compatible version of the Android
    520 platform. In turn, this ensures that your application can function properly on
    521 their devices. </p>
    522 
    523 <p>If your application uses APIs introduced in the latest platform version but
    524 does <em>not</em> declare a <code>android:minSdkVersion</code> attribute, then
    525 it will run properly on devices running the latest version of the platform, but
    526 <em>not</em> on devices running earlier versions of the platform. In the latter
    527 case, the application will crash at runtime when it tries to use APIs that don't
    528 exist on the earlier versions.</p>
    529 
    530 <h3 id="testing">Testing against higher API Levels</h3>
    531 
    532 <p>After compiling your application, you should make sure to test it on the
    533 platform specified in the application's <code>android:minSdkVersion</code>
    534 attribute. To do so, create an AVD that uses the platform version required by
    535 your application. Additionally, to ensure forward-compatibility, you should run
    536 and test the application on all platforms that use a higher API Level than that
    537 used by your application. </p>
    538 
    539 <p>The Android SDK includes multiple platform versions that you can use,
    540 including the latest version, and provides an updater tool that you can use to
    541 download other platform versions as necessary. </p>
    542 
    543 <p>To access the updater, use the <code>android</code> command-line tool,
    544 located in the &lt;sdk&gt;/tools directory. You can launch the SDK updater by
    545 executing <code>android sdk</code>. You can
    546 also simply double-click the android.bat (Windows) or android (OS X/Linux) file.</p>
    547 
    548 <p>To run your application against different platform versions in the emulator,
    549 create an AVD for each platform version that you want to test. For more
    550 information about AVDs, see <a
    551 href="{@docRoot}tools/devices/index.html">Creating and Managing Virtual Devices</a>. If
    552 you are using a physical device for testing, ensure that you know the API Level
    553 of the Android platform it runs. See the table at the top of this document for
    554 a list of platform versions and their API Levels. </p>
    555 
    556 
    557 <h2 id="filtering">Filtering the Reference Documentation by API Level</h2>
    558 
    559 <p>Reference documentation pages on the Android Developers site offer a "Filter
    560 by API Level" control in the top-right area of each page. You can use the
    561 control to show documentation only for parts of the API that are actually
    562 accessible to your application, based on the API Level that it specifies in
    563 the <code>android:minSdkVersion</code> attribute of its manifest file. </p>
    564 
    565 <p>To use filtering, select the checkbox to enable filtering, just below the
    566 page search box. Then set the "Filter by API Level" control to the same API
    567 Level as specified by your application. Notice that APIs introduced in a later
    568 API Level are then grayed out and their content is masked, since they would not
    569 be accessible to your application. </p>
    570 
    571 <p>Filtering by API Level in the documentation does not provide a view
    572 of what is new or introduced in each API Level &mdash; it simply provides a way
    573 to view the entire API associated with a given API Level, while excluding API
    574 elements introduced in later API Levels.</p>
    575 
    576 <p>If you decide that you don't want to filter the API documentation, just
    577 disable the feature using the checkbox. By default, API Level filtering is
    578 disabled, so that you can view the full framework API, regardless of API Level.
    579 </p>
    580 
    581 <p>Also note that the reference documentation for individual API elements
    582 specifies the API Level at which each element was introduced. The API Level
    583 for packages and classes is specified as "Since &lt;api level&gt;" at the
    584 top-right corner of the content area on each documentation page. The API Level
    585 for class members is specified in their detailed description headers,
    586 at the right margin. </p>
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