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docs: Add 101 class about supporting various devices
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‎docs/html/training/basics/supporting-devices/index.jd‎

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page.title=Supporting Different Devices
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trainingnavtop=true
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startpage=true
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next.title=Supporting Multiple Languages
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next.link=languages.html
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@jd:body
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<div id="tb-wrapper">
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<div id="tb">
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<h2>Dependencies and prerequisites</h2>
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<ul>
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<li>Android 1.6 or higher</li>
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</ul>
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<h2>You should also read</h2>
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<ul>
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<li><a href="{@docRoot}guide/topics/resources/index.html">Application Resources</a></li>
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<li><a href="{@docRoot}training/multiscreen/index.html">Designing for Multiple Screens</a></li>
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</ul>
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</div>
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</div>
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<p>Android devices come in many shapes and sizes all around the world. With a wide range of device
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types, you have an opportunity to reach a huge audience with your app. In order to be as successful
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as possible on Android, your app needs to adapt to various device configurations. Some of the
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important variations that you should consider include different languages, screen sizes, and
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versions of the Android platform.</p>
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<p>This class teaches you how to use basic platform features that leverage alternative
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resources and other features so your app can provide an optimized user experience on a
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variety of Android-compatible devices, using a single application package (APK).</p>
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<h2>Lessons</h2>
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<dl>
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<dt><b><a href="languages.html">Supporting Different Languages</a></b></dt>
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<dd>Learn how to support multiple languages with alternative string resources.</dd>
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<dt><b><a href="screens.html">Supporting Different Screens</a></b></dt>
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<dd>Learn how to optimize the user experience for different screen sizes and densities.</dd>
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<dt><b><a href="platforms.html">Supporting Different Platform Versions</a></b></dt>
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<dd>Learn how to use APIs available in new versions of Android while continuing to support
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older versions of Android.</dd>
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</dl>
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‎docs/html/training/basics/supporting-devices/languages.jd‎

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page.title=Supporting Different Languages
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parent.title=Supporting Different Devices
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parent.link=index.html
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trainingnavtop=true
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next.title=Supporting Different Screens
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next.link=screens.html
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@jd:body
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<div id="tb-wrapper">
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<div id="tb">
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<h2>This class teaches you to</h2>
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<ol>
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<li><a href="#CreateDirs">Create Locale Directories and String Files</a></li>
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<li><a href="#UseString">Use the String Resources</a></li>
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</ol>
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<h2>You should also read</h2>
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<ul>
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<li><a href="{@docRoot}guide/topics/resources/localization.html">Localization</a></li>
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</ul>
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</div>
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</div>
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<p>It’s always a good practice to extract UI strings from your app code and keep them
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in an external file. Android makes this easy with a resources directory in each Android
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project.</p>
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<p>If you created your project using the Android SDK
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Tools (read <a href="{@docRoot}training/basics/firstapp/creating-project.html">Creating an
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Android Project</a>), the tools create a <code>res/</code> directory in the top level of
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the project. Within this <code>res/</code> directory are subdirectories for various resource
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types. There are also a few default files such as <code>res/values/strings.xml</code>, which holds
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your string values.</p>
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<h2 id="CreateDirs">Create Locale Directories and String Files</h2>
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<p>To add support for more languages, create additional <code>values</code> directories inside
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<code>res/</code> that include a hyphen and the ISO country code at the end of the
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directory name. For example, <code>values-es/</code> is the directory containing simple
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resourcess for the Locales with the language code "es". Android loads the appropriate resources
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according to the locale settings of the device at run time.</p>
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<p>Once you’ve decided on the languages you will support, create the resource subdirectories and
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string resource files. For example:</p>
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<pre class="classic no-pretty-print">
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MyProject/
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res/
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values/
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strings.xml
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values-es/
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strings.xml
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values-fr/
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strings.xml
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</pre>
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<p>Add the string values for each locale into the appropriate file.</p>
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<p>At runtime, the Android system uses the appropriate set of string resources based on the
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locale currently set for the user's device.</p>
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<p>For example, the following are some different string resource files for different languages.</p>
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<p>English (default locale), <code>/values/strings.xml</code>:</p>
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<pre>
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&lt;?xml version="1.0" encoding="utf-8"?>
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&lt;resources>
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&lt;string name="title">My Application&lt;/string>
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&lt;string name="hello_world">Hello World!&lt;/string>
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&lt;/resources>
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</pre>
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<p>Spanish, <code>/values-es/strings.xml</code>:</p>
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<pre>
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&lt;?xml version="1.0" encoding="utf-8"?>
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&lt;resources>
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&lt;string name="title">Mi Aplicación&lt;/string>
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&lt;string name="hello_world">Hola Mundo!&lt;/string>
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&lt;/resources>
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</pre>
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<p>French, <code>/values-fr/strings.xml</code>:</p>
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<pre>
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&lt;?xml version="1.0" encoding="utf-8"?>
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&lt;resources>
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&lt;string name="title">Ma Application&lt;/string>
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&lt;string name="hello_world">Bonjour tout le Monde!&lt;/string>
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&lt;/resources>
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</pre>
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<h2 id="UseString">Use the String Resources</h2>
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<p>You can reference your string resources in your source code and other XML files using the
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resource name defined by the {@code &lt;string>} element's {@code name} attribute.</p>
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<p>In your source code, you can refer to a string resource with the syntax {@code
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R.string.&lt;string_name>}. There are a variety of methods that accept a string resource this
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way.</p>
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<p>For example:</p>
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<pre>
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// Get a string resource from your app's {@link android.content.res.Resources}
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String hello = {@link android.content.Context#getResources()}.getString(R.string.hello_world);
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// Or supply a string resource to a method that requires a string
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TextView textView = new TextView(this);
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textView.setText(R.string.hello_world);
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</pre>
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<p>In other XML files, you can refer to a string resource with the syntax {@code
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&#64;string/&lt;string_name>} whenever the XML attribute accepts a string value.</p>
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<p>For example:</p>
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<pre>
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&lt;TextView
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android:layout_width="wrap_content"
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android:layout_height="wrap_content"
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android:text="@string/hello_world" />
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</pre>
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‎docs/html/training/basics/supporting-devices/platforms.jd‎

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page.title=Supporting Different Platform Versions
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parent.title=Supporting Different Devices
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parent.link=index.html
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trainingnavtop=true
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previous.title=Supporting Different Screens
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previous.link=screens.html
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@jd:body
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<div id="tb-wrapper">
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<div id="tb">
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<h2>This lesson teaches you to</h2>
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<ol>
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<li><a href="#sdk-versions">Specify Minimum and Target API Levels</a></li>
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<li><a href="#version-codes">Check System Version at Runtime</a></li>
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<li><a href="#style-themes">Use Platform Styles and Themes</a></li>
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</ol>
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<h2>You should also read</h2>
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<ul>
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<li><a href="{@docRoot}guide/appendix/api-levels.html">Android API Levels</a></li>
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<li><a
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href="{@docRoot}sdk/compatibility-library.html">Android Support Library</a></li>
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</ul>
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</div>
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</div>
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<p>While the latest versions of Android often provide great APIs for your app, you should continue
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to support older versions of Android until more devices get updated. This
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lesson shows you how to take advantage of the latest APIs while continuing to support older
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versions as well.</p>
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<p>The dashboard for <a
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href="http://developer.android.com/resources/dashboard/platform-versions.html">Platform Versions</a>
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is updated regularly to show the distribution of active
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devices running each version of Android, based on the number of devices that visit the Google Play
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Store. Generally, it’s a good practice to support about 90% of the active devices, while
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targeting your app to the latest version.</p>
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<p class="note"><strong>Tip:</strong> In order to provide the best features and
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functionality across several Android versions, you should use the <a
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href="{@docRoot}sdk/compatibility-library.html">Android Support Library</a> in your app,
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which allows you to use several recent platform APIs on older versions.</p>
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<h2 id="sdk-versions">Specify Minimum and Target API Levels</h2>
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<p>The <a href="{@docRoot}guide/topics/manifest/manifest-intro.html">AndroidManifest.xml</a> file
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describes details about your app and
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identifies which versions of Android it supports. Specifically, the <code>minSdkVersion</code>
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and <code>targetSdkVersion</code> attributes for the <a
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href="{@docRoot}guide/topics/manifest/uses-sdk-element.html">{@code &lt;uses-sdk}</a> element
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identify the lowest API level with which your app is compatible and the highest API level against
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which you’ve designed and tested your app.</p>
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<p>For example:</p>
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<pre>
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&lt;manifest xmlns:android="http://schemas.android.com/apk/res/android" ... >
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&lt;uses-sdk android:minSdkVersion="4" android:targetSdkVersion="15" />
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...
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&lt;/manifest>
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</pre>
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<p>As new versions of Android are released, some style and behaviors may change.
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To allow your app to take advantage of these changes and ensure that your app fits the style of
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each user's device, you should set the
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<a
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href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code targetSdkVersion}</a>
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value to match the latest Android version
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available.</p>
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<h2 id="version-codes">Check System Version at Runtime</h2>
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<p>Android provides a unique code for each platform version in the {@link android.os.Build}
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constants class. Use these codes within your app to build conditions that ensure the code that
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depends on higher API levels is executed only when those APIs are available on the system.</p>
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<pre>
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private void setUpActionBar() {
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// Make sure we're running on Honeycomb or higher to use ActionBar APIs
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if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
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ActionBar actionBar = getActionBar();
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actionBar.setDisplayHomeAsUpEnabled(true);
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}
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}
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</pre>
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<p class="note"><strong>Note:</strong> When parsing XML resources, Android ignores XML
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attributes that aren’t supported by the current device. So you can safely use XML attributes that
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are only supported by newer versions without worrying about older versions breaking when they
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encounter that code. For example, if you set the
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<code>targetSdkVersion="11"</code>, your app includes the {@link android.app.ActionBar} by default
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on Android 3.0 and higher. To then add menu items to the action bar, you need to set
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<code>android:showAsAction="ifRoom"</code> in your menu resource XML. It's safe to do this
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in a cross-version XML file, because the older versions of Android simply ignore the
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<code>showAsAction</code> attribute (that is, you <em>do not</em> need a separate
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version in <code>res/menu-v11/</code>).</p>
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<h2 id="style-themes">Use Platform Styles and Themes</h2>
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<p>Android provides user experience themes that give apps the look and feel of the
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underlying operating system. These themes can be applied to your app within the
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manifest file. By using these built in styles and themes, your app will
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naturally follow the latest look and feel of Android with each new release.</p>
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<p>To make your activity look like a dialog box:</p>
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<pre>&lt;activity android:theme="@android:style/Theme.Dialog"></pre>
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<p>To make your activity have a transparent background:</p>
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<pre>&lt;activity android:theme="@android:style/Theme.Translucent"></pre>
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<p>To apply your own custom theme defined in <code>/res/values/styles.xml</code>:</p>
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<pre>&lt;activity android:theme="@style/CustomTheme"></pre>
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<p>To apply a theme to your entire app (all activities), add the <code>android:theme</code>
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attribute
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to the <a href="{@docRoot}guide/topics/manifest/application-element.html">{@code
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&lt;application>}</a> element:</p>
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<pre>&lt;application android:theme="@style/CustomTheme"></pre>
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<p>For more about creating and using themes, read the <a
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href="{@docRoot}guide/topics/ui/themes.html">Styles and Themes</a> guide.</p>
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