1 page.title=Supporting Different Platform Versions 2 page.metaDescription=Training on how to declare support for minimum and target API levels. 3 page.tags=styles 4 helpoutsWidget=true 5 6 trainingnavtop=true 7 8 @jd:body 9 10 11 <div id="tb-wrapper"> 12 <div id="tb"> 13 14 <h2>This lesson teaches you to</h2> 15 <ol> 16 <li><a href="#sdk-versions">Specify Minimum and Target API Levels</a></li> 17 <li><a href="#version-codes">Check System Version at Runtime</a></li> 18 <li><a href="#style-themes">Use Platform Styles and Themes</a></li> 19 </ol> 20 21 <h2>You should also read</h2> 22 <ul> 23 <li><a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">Android API Levels</a></li> 24 <li><a 25 href="{@docRoot}tools/support-library/index.html">Android Support Library</a></li> 26 </ul> 27 </div> 28 </div> 29 30 <p>While the latest versions of Android often provide great APIs for your app, you should continue 31 to support older versions of Android until more devices get updated. This 32 lesson shows you how to take advantage of the latest APIs while continuing to support older 33 versions as well.</p> 34 35 <p>The dashboard for <a 36 href="http://developer.android.com/about/dashboards/index.html">Platform Versions</a> 37 is updated regularly to show the distribution of active 38 devices running each version of Android, based on the number of devices that visit the Google Play 39 Store. Generally, its a good practice to support about 90% of the active devices, while 40 targeting your app to the latest version.</p> 41 42 <p class="note"><strong>Tip:</strong> In order to provide the best features and 43 functionality across several Android versions, you should use the <a 44 href="{@docRoot}tools/support-library/index.html">Android Support Library</a> in your app, 45 which allows you to use several recent platform APIs on older versions.</p> 46 47 48 49 <h2 id="sdk-versions">Specify Minimum and Target API Levels</h2> 50 51 <p>The <a href="{@docRoot}guide/topics/manifest/manifest-intro.html">AndroidManifest.xml</a> file 52 describes details about your app and 53 identifies which versions of Android it supports. Specifically, the <code>minSdkVersion</code> 54 and <code>targetSdkVersion</code> attributes for the <a 55 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html">{@code <uses-sdk>}</a> element 56 identify the lowest API level with which your app is compatible and the highest API level against 57 which youve designed and tested your app.</p> 58 59 <p>For example:</p> 60 61 <pre> 62 <manifest xmlns:android="http://schemas.android.com/apk/res/android" ... > 63 <uses-sdk android:minSdkVersion="4" android:targetSdkVersion="15" /> 64 ... 65 </manifest> 66 </pre> 67 68 <p>As new versions of Android are released, some style and behaviors may change. 69 To allow your app to take advantage of these changes and ensure that your app fits the style of 70 each user's device, you should set the 71 <a 72 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code targetSdkVersion}</a> 73 value to match the latest Android version 74 available.</p> 75 76 77 78 <h2 id="version-codes">Check System Version at Runtime</h2> 79 80 <p>Android provides a unique code for each platform version in the {@link android.os.Build} 81 constants class. Use these codes within your app to build conditions that ensure the code that 82 depends on higher API levels is executed only when those APIs are available on the system.</p> 83 84 <pre> 85 private void setUpActionBar() { 86 // Make sure we're running on Honeycomb or higher to use ActionBar APIs 87 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { 88 ActionBar actionBar = getActionBar(); 89 actionBar.setDisplayHomeAsUpEnabled(true); 90 } 91 } 92 </pre> 93 94 95 96 <p class="note"><strong>Note:</strong> When parsing XML resources, Android ignores XML 97 attributes that arent supported by the current device. So you can safely use XML attributes that 98 are only supported by newer versions without worrying about older versions breaking when they 99 encounter that code. For example, if you set the 100 <code>targetSdkVersion="11"</code>, your app includes the {@link android.app.ActionBar} by default 101 on Android 3.0 and higher. To then add menu items to the action bar, you need to set 102 <code>android:showAsAction="ifRoom"</code> in your menu resource XML. It's safe to do this 103 in a cross-version XML file, because the older versions of Android simply ignore the 104 <code>showAsAction</code> attribute (that is, you <em>do not</em> need a separate 105 version in <code>res/menu-v11/</code>).</p> 106 107 108 109 <h2 id="style-themes">Use Platform Styles and Themes</h2> 110 111 <p>Android provides user experience themes that give apps the look and feel of the 112 underlying operating system. These themes can be applied to your app within the 113 manifest file. By using these built in styles and themes, your app will 114 naturally follow the latest look and feel of Android with each new release.</p> 115 116 <p>To make your activity look like a dialog box:</p> 117 118 <pre><activity android:theme="@android:style/Theme.Dialog"></pre> 119 120 <p>To make your activity have a transparent background:</p> 121 122 <pre><activity android:theme="@android:style/Theme.Translucent"></pre> 123 124 <p>To apply your own custom theme defined in <code>/res/values/styles.xml</code>:</p> 125 126 <pre><activity android:theme="@style/CustomTheme"></pre> 127 128 <p>To apply a theme to your entire app (all activities), add the <code>android:theme</code> 129 attribute 130 to the <a href="{@docRoot}guide/topics/manifest/application-element.html">{@code 131 <application>}</a> element:</p> 132 133 <pre><application android:theme="@style/CustomTheme"></pre> 134 135 <p>For more about creating and using themes, read the <a 136 href="{@docRoot}guide/topics/ui/themes.html">Styles and Themes</a> guide.</p> 137 138
