1page.title=<uses-sdk>
2page.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,
51by means of an API Level integer. The API Level expressed by an application will be compared to the
52API 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>
56the version number of the SDK (software development kit) or Android platform.
57The API Level is always a single integer. You cannot derive the API Level from
58its associated Android version number (for example, it is not the same as the
59major 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
88value equals that given to {@code minSdkVersion}.
89
90  <p>This attribute informs the system that you have tested against the target version and the
91system should not enable any compatibility behaviors to maintain your app's forward-compatibility
92with the target version. The application is still able to run on older versions (down to {@code
93minSdkVersion}).</p>
94
95  <p>As Android evolves with each new version, some behaviors and even appearances might change.
96However, if the API level of the platform is higher than the version declared by your app's {@code
97targetSdkVersion}, the system may enable compatibility behaviors to ensure that your app
98continues to work the way you expect. You can disable such compatibility
99behaviors by specifying {@code targetSdkVersion} to match the API
100level of the platform on which it's running. For example, setting this value to "11" or higher
101allows the system to apply a new default theme (Holo) to your app when running on Android 3.0 or
102higher and also disables <a href="{@docRoot}guide/practices/screen-compat-mode.html">screen
103compatibility mode</a> when running on larger screens (because support for API level 11 implicitly
104supports larger screens).</p>
105
106  <p>There are many compatibility behaviors that the system may enable based on the value you set
107for this attribute. Several of these behaviors are described by the corresponding platform versions
108in the {@link android.os.Build.VERSION_CODES} reference.</p>
109
110  <p>To maintain your application along with each Android release, you should increase
111the value of this attribute to match the latest API level, then thoroughly test your application on
112the 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
161longer check or enforce the <code>maxSdkVersion</code> attribute during
162installation or re-validation. Google Play will continue to use the attribute
163as a filter, however, when presenting users with applications available for
164download. </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
188revision offered by a version of the Android platform.</p>
189
190<p>The Android platform provides a framework API that applications can use to
191interact 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
199enforcements included in the system</li>
200</ul>
201
202<p>Each successive version of the Android platform can include updates to the
203Android application framework API that it delivers. </p>
204
205<p>Updates to the framework API are designed so that the new API remains
206compatible with earlier versions of the API. That is, most changes in the API
207are additive and introduce new or replacement functionality. As parts of the API
208are upgraded, the older replaced parts are deprecated but are not removed, so
209that existing applications can still use them. In a very small number of cases,
210parts of the API may be modified or removed, although typically such changes are
211only needed to ensure API robustness and application or system security. All
212other API parts from earlier revisions are carried forward without
213modification.</p>
214
215<p>The framework API that an Android platform delivers is specified using an
216integer identifier called "API Level". Each Android platform version supports
217exactly 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
219API 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
222Android platform. For information about the relative numbers of devices that
223are running each version, see the <a href="{@docRoot}about/dashboards/index.html">Platform
224Versions 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>Android 6.0</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}preview/api-overview.html">API Changes</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
238Highlights</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
254Highlights</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
260Highlights</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
266Highlights</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
272Highlights</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
278Highlights</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
289Highlights</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
305Highlights</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
322Highlights</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
358experience for users and application developers:
359
360<ul>
361<li>It lets the Android platform describe the maximum framework API revision
362that it supports</li>
363<li>It lets applications describe the framework API revision that they
364require</li>
365<li>It lets the system negotiate the installation of applications on the user's
366device, 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
370the 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
374Levels under which they are able to run, as well as the preferred API Level that
375they 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
379on which the application is able to run. The default value is "1".</li>
380<li><code>android:targetSdkVersion</code> &mdash; Specifies the API Level
381on which the application is designed to run. In some cases, this allows the
382application to use manifest elements or behaviors defined in the target
383API Level, rather than being restricted to using only those defined
384for the minimum API Level.</li>
385<li><code>android:maxSdkVersion</code> &mdash; Specifies the maximum API Level
386on which the application is able to run. <strong>Important:</strong> Please read the <a
387href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><code>&lt;uses-sdk&gt;</code></a>
388documentation before using this attribute.  </li>
389</ul>
390
391<p>For example, to specify the minimum system API Level that an application
392requires 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>
394attribute. The value of <code>android:minSdkVersion</code> would be the integer
395corresponding to the API Level of the earliest version of the Android platform
396under which the application can run. </p>
397
398<p>When the user attempts to install an application, or when revalidating an
399appplication after a system update, the Android system first checks the
400<code>&lt;uses-sdk&gt;</code> attributes in the application's manifest and
401compares the values against its own internal API Level. The system allows the
402installation 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
406must be less than or equal to the system's API Level integer. If not declared,
407the system assumes that the application requires API Level 1. </li>
408<li>If a <code>android:maxSdkVersion</code> attribute is declared, its value
409must be equal to or greater than the system's API Level integer.
410If not declared, the system assumes that the application
411has no maximum API Level. Please read the <a
412href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><code>&lt;uses-sdk&gt;</code></a>
413documentation 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>
417element 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
426using APIs that were <em>introduced</em> in the API Level specified. If the
427application were to be somehow installed on a platform with a lower API Level,
428then it would crash at run-time when it tried to access APIs that don't exist.
429The system prevents such an outcome by not allowing the application to be
430installed if the lowest API Level it requires is higher than that of the
431platform version on the target device.</p>
432
433<p>For example, the {@link android.appwidget} package was introduced with API
434Level 3. If an application uses that API, it must declare a
435<code>android:minSdkVersion</code> attribute with a value of "3". The
436application will then be installable on platforms such as Android 1.5 (API Level
4373) and Android 1.6 (API Level 4), but not on the Android 1.1 (API Level 2) and
438Android 1.0 platforms (API Level 1).</p>
439
440<p>For more information about how to specify an application's API Level
441requirements, see the <a
442href="{@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
449consider 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
454the Android platform.</p>
455
456<p>Because almost all changes to the framework API are additive, an Android
457application developed using any given version of the API (as specified by its
458API Level) is forward-compatible with later versions of the Android platform and
459higher API levels. The application should be able to run on all later versions
460of the Android platform, except in isolated cases where the application uses a
461part of the API that is later removed for some reason. </p>
462
463<p>Forward compatibility is important because many Android-powered devices
464receive over-the-air (OTA) system updates. The user may install your
465application and use it successfully, then later receive an OTA update to a new
466version of the Android platform. Once the update is installed, your application
467will run in a new run-time version of the environment, but one that has the API
468and 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
471system itself, may affect your application when it is run in the new
472environment. For that reason it's important for you, as the application
473developer, to understand how the application will look and behave in each system
474environment. To help you test your application on various versions of the Android
475platform, the Android SDK includes multiple platforms that you can download.
476Each platform includes a compatible system image that you can run in an AVD, to
477test 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
482the 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
486as those that give applications access to new platform capabilities or replace
487existing API parts. The new APIs are accessible to applications when running on
488the new platform and, as mentioned above, also when running on later versions of
489the platform, as specified by API Level. Conversely, because earlier versions of
490the platform do not include the new APIs, applications that use the new APIs are
491unable to run on those platforms.</p>
492
493<p>Although it's unlikely that an Android-powered device would be downgraded to
494a previous version of the platform, it's important to realize that there are
495likely to be many devices in the field that run earlier versions of the
496platform. Even among devices that receive OTA updates, some might lag and
497might 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
502the platform version against which you will compile the application. In
503general, you should compile your application against the lowest possible
504version of the platform that your application can support.
505
506<p>You can determine the lowest possible platform version by compiling the
507application against successively lower build targets. After you determine the
508lowest version, you should create an AVD using the corresponding platform
509version (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
511set 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
516the latest platform version, you should set the
517<code>android:minSdkVersion</code> attribute to the API Level of the latest
518platform version. This ensures that users will only be able to install your
519application if their devices are running a compatible version of the Android
520platform. In turn, this ensures that your application can function properly on
521their devices. </p>
522
523<p>If your application uses APIs introduced in the latest platform version but
524does <em>not</em> declare a <code>android:minSdkVersion</code> attribute, then
525it 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
527case, the application will crash at runtime when it tries to use APIs that don't
528exist 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
533platform specified in the application's <code>android:minSdkVersion</code>
534attribute. To do so, create an AVD that uses the platform version required by
535your application. Additionally, to ensure forward-compatibility, you should run
536and test the application on all platforms that use a higher API Level than that
537used by your application. </p>
538
539<p>The Android SDK includes multiple platform versions that you can use,
540including the latest version, and provides an updater tool that you can use to
541download other platform versions as necessary. </p>
542
543<p>To access the updater, use the <code>android</code> command-line tool,
544located in the &lt;sdk&gt;/tools directory. You can launch the SDK updater by
545executing <code>android sdk</code>. You can
546also simply double-click the android.bat (Windows) or android (OS X/Linux) file.
547In ADT, you can also access the updater by selecting
548<strong>Window</strong>&nbsp;>&nbsp;<strong>Android SDK
549Manager</strong>.</p>
550
551<p>To run your application against different platform versions in the emulator,
552create an AVD for each platform version that you want to test. For more
553information about AVDs, see <a
554href="{@docRoot}tools/devices/index.html">Creating and Managing Virtual Devices</a>. If
555you are using a physical device for testing, ensure that you know the API Level
556of the Android platform it runs. See the table at the top of this document for
557a list of platform versions and their API Levels. </p>
558
559
560<h2 id="filtering">Filtering the Reference Documentation by API Level</h2>
561
562<p>Reference documentation pages on the Android Developers site offer a "Filter
563by API Level" control in the top-right area of each page. You can use the
564control to show documentation only for parts of the API that are actually
565accessible to your application, based on the API Level that it specifies in
566the <code>android:minSdkVersion</code> attribute of its manifest file. </p>
567
568<p>To use filtering, select the checkbox to enable filtering, just below the
569page search box. Then set the "Filter by API Level" control to the same API
570Level as specified by your application. Notice that APIs introduced in a later
571API Level are then grayed out and their content is masked, since they would not
572be accessible to your application. </p>
573
574<p>Filtering by API Level in the documentation does not provide a view
575of what is new or introduced in each API Level &mdash; it simply provides a way
576to view the entire API associated with a given API Level, while excluding API
577elements introduced in later API Levels.</p>
578
579<p>If you decide that you don't want to filter the API documentation, just
580disable the feature using the checkbox. By default, API Level filtering is
581disabled, so that you can view the full framework API, regardless of API Level.
582</p>
583
584<p>Also note that the reference documentation for individual API elements
585specifies the API Level at which each element was introduced. The API Level
586for packages and classes is specified as "Since &lt;api level&gt;" at the
587top-right corner of the content area on each documentation page. The API Level
588for class members is specified in their detailed description headers,
589at the right margin. </p>
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