android_frameworks_base/docs/html/tools/building/configuring-gradle.jd

page.title=Configuring Gradle Builds

@jd:body

<div id="qv-wrapper">
<div id="qv">
<h2>In this document</h2>
<ol>
  <li><a href="#buildFileBasics">Build Configuration Basics</a>
    <ol>
      <li><a href="#buildFileBasics">Declare dependencies</a></li>
      <li><a href="#buildFileBasics">Run ProGuard</a></li>
      <li><a href="#configureSigning">Configure signing settings</a></li>
    </ol>
  </li>


  <li><a href="#workBuildVariants">Work with build variants</a></li>
</ol>


<h2>See also</h2>
<ul>
<li><a href="{@docRoot}tools/building/plugin-for-gradle.html">
Android Plugin for Gradle</a></li>
</ul>
</div>
</div>


<p>This section builds on the
<a href="{@docRoot}sdk/installing/studio-build.html">Build System Overview</a> and
<a href="{@docRoot}tools/building/building-studio.html">Build and Running from Android Studio</a>
to show you how to use build variants based on product flavors and build types.</p>


<h2 id="buildFileBasics">Build Configuration Basics</h2>

<p>Android Studio projects contain a top-level build file and a build file for each module. The
build files are called <code>build.gradle</code>, and they are plain text files that use
<a href="http://groovy.codehaus.org">Groovy</a> syntax to configure the build with the elements
provided by the Android plugin for Gradle. In most cases, you only need to edit the build files
at the module level. For example, the build file for the app module in the
<code>BuildSystemExample</code> project looks like this:</p>

<pre>
apply plugin: 'com.android.application'

android {
    compileSdkVersion 19
    buildToolsVersion "19.0.0"

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 19
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), \
            'proguard-rules.txt'
        }
    }
}

dependencies {
    compile project(":lib")
    compile 'com.android.support:appcompat-v7:19.0.1'
    compile fileTree(dir: 'libs', include: ['*.jar'])
}
</pre>

<p><code>apply plugin: 'com.android.application'</code> applies the Android plugin for Gradle to this build.
This adds Android-specific build tasks to the top-level build tasks and makes the
<code>android {...}</code> element available to specify Android-specific build options.</p>

<p><code>android {...}</code> configures all the Android-specific build options:</p>

<ul>
    <li>The <code>compileSdkVersion</code> property specifies the compilation target.</li>
    <li><p>The <code>buildToolsVersion</code> property specifies what version of the build tools
        to use. To install several versions of the build tools, use the SDK Manager.</p>
        <p class="note"><strong>Note:</strong> Always use a build tools version whose major
        revision number is higher or equal to that of your compilation target and target SDK.</p>
    </li>
    <li><p>The <code>defaultConfig</code> element configures core settings and
        entries in the manifest file (<code>AndroidManifest.xml</code>) dynamically from the
        build system. The values in <code>defaultConfig</code> override those in the manifest
        file.</p>
        <p>The configuration specified in the <code>defaultConfig</code> element applies
        to all build variants, unless the configuration for a build variant overrides some
        of these values.</p>
    </li>
    <li>The <code>buildTypes</code> element controls how to build and package your app.
        By default, the build system defines two build types: <em>debug</em> and
        <em>release</em>. The debug build type includes debugging symbols and is signed with
        the debug key. The release build type is not signed by default.
        In this example the build file configures the release version to use
        ProGuard.</li>
</ul>

<p>The <code>dependencies</code> element is outside and after the <code>android</code> element.
This element declares the dependencies for this module. Dependencies are covered in the following
sections.</p>

<p class="note"><strong>Note:</strong> When you make changes to the build files in your project,
Android Studio requires a project sync to import the build configuration changes. Click
<strong>Sync Now</strong> on the yellow notification bar that appears for Android Studio
to import the changes.</p>

<img src="{@docRoot}images/tools/as-gradlesync.png" alt="" />
<p class="img-caption"><strong>Figure 1.</strong> Sync the project in Android Studio.</p>

<h3 id="declareDeps">Declare dependencies</h3>

<p>The <code>app</code> module in this example declares three
dependencies:</p>

<pre>
...
dependencies {
    // Module dependency
    compile project(":lib")

    // Remote binary dependency
    compile 'com.android.support:appcompat-v7:19.0.1'

    // Local binary dependency
    compile fileTree(dir: 'libs', include: ['*.jar'])
}
</pre>

<p>Each of these dependencies is described below. The build system adds all the
<code>compile</code> dependencies to the compilation classpath and includes them in the final
package.</p>

<h4>Module dependencies</h4>

<p>The <code>app</code> module depends on the <code>lib</code> module, because
<code>MainActivity</code> launches <code>LibActivity1</code> as described in
<a href="#openActFromLib">Open an Activity from a Library Module</a>.</p>

<p><code>compile project(":lib")</code> declares a dependency on the <code>lib</code>
module of <code>BuildSystemExample</code>. When you build the <code>app</code> module,
the build system assembles and includes the <code>lib</code> module.</p>

<h4>Remote binary dependencies</h4>

<p>The <code>app</code> and <code>lib</code> modules both use the <code>ActionBarActivity</code>
class from the Android Support Library, so these modules depend on it.</p>

<p><code>compile 'com.android.support:appcompat-v7:19.0.1'</code> declares a dependency on
version 19.0.1 of the Android Support Library by specifying its Maven coordinates. The Android Support
Library is available in the <em>Android Repository</em> package of the Android SDK. If your
SDK installation does not have this package, download and install it using the SDK Manager.</p>

Android Studio configures projects to use the Maven Central Repository by default. (This
configuration is included in the top-level build file for the project.)</p>

<h4>Local binary dependencies</h4>

<p>Some modules do not use any binary dependencies from the
local file system. If you have modules that require local binary dependencies, copy the JAR
files for these dependencies into <code>&lt;moduleName>/libs</code> inside your project.</p>

<p><code>compile fileTree(dir: 'libs', include: ['*.jar'])</code> tells the build system that any
JAR file inside <code>app/libs</code> is a dependency and should be included in the compilation
classpath and in the final package.</p>

<p>For more information about dependencies in Gradle, see
<a href="http://www.gradle.org/docs/current/userguide/artifact_dependencies_tutorial.html">Dependency
Management Basics</a> in the Gradle User Guide.</p>

<h3 id="runProguard">Run ProGuard</h3>

<p>The build system can run
<a href="http://developer.android.com/tools/help/proguard.html">ProGuard</a> to obfuscate your
classes during the build process. In <code>BuildSystemExample</code>, modify the build file for
the app module to run ProGuard for the release build:</p>

<pre>
...
android {
    ...
    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), \
                          'proguard-rules.txt'
        }
    }
}
...
</pre>

<p><code>getDefaultProguardFile('proguard-android.txt')</code> obtains the default ProGuard
settings from the Android SDK installation. Android Studio adds the module-specific rules file
<code>proguard-rules.txt</code> at the root of the module, where you can add custom ProGuard
rules.</p>

<h3 id="configureSigning">Configure signing settings</h3>

<p>The debug and the release versions of the app differ on whether the application can be
debugged on secure devices and on how the APK is signed. The build system signs the debug
version with a default key and certificate using known credentials to avoid a password prompt at
build time. The build system does not sign the release version unless you explicitly define a
signing configuration for this build. If you do not have a release key, you can generate one as
described in <a href="{@docRoot}tools/publishing/app-signing.html">Signing your Applications</a>.</p>


<h2 id="workBuildVariants">Work with build variants</h2>

<p>This section describes how the build system can help you create different versions of the same
application from a single project. This is useful when you have a demo version and a paid version
of your app, or if you want to distribute multiple APKs for different device configurations on
Google Play.</p>

<p>The build system uses <em>product flavors</em> to create different product versions of your app.
Each product version of your app can have different features or device requirements. The build
system also uses build types to apply different build and packaging settings to each product version.
Each product flavor and build type combination forms a build variant. The build system generates a
different APK for each build variant of your app. </p>

<h3>Build variants</h3>

<p>This example project consists of the two default build types (<em>debug</em> and <em>release</em>)
and two product flavors for app type (demo and full). For more information on advanced uses of
build variants, see
<a href="{@docRoot}sdk/installing/studio-build.html"> Build System Overview</a> .</p>


<h4>Product flavors </h4>

<p>To create different product versions of your app:</p>

<ol>
    <li>Define product flavors in the build file.</li>
    <li>Create additional source directories for each flavor.</li>
    <li>Add the flavor-specific sources to your project.</li>
</ol>

<p>The rest of this section walks you through these steps in detail using a
<code>BuildSystemExample</code> project. You create two flavors of the
<code>BuildSystemExample</code> app, a demo flavor and a full flavor. Both flavors share
<code>MainActivity</code>, to which you add a new button to launch a new activity,
<code>SecondActivity</code>. This new activity is different for each flavor, so you simulate a
situation where the new activity would have more features in the full flavor than in the demo
flavor. At the end of the exercise, you end up with two different APKs, one for each flavor.</p>

<h3>Define product flavors in the build file</h3>

<p>To define two product flavors, edit the build file for the app module to add the following
configuration:</p>

<pre>
...
android {
    ...
    defaultConfig { ... }
    signingConfigs { ... }
    buildTypes { ... }
    productFlavors {
        demo {
            applicationId "com.buildsystemexample.app.demo"
            versionName "1.0-demo"
        }
        full {
            applicationId "com.buildsystemexample.app.full"
            versionName "1.0-full"
        }
    }
}
...
</pre>

<p>The product flavor definitions support the same properties as the <code>defaultConfig</code>
element. The base configuration for all flavors is specified in <code>defaultConfig</code>, and each
flavor overrides any default values. The build file above uses the <code>applicationId</code>
property to assign a different package name to each flavor: since each flavor definition creates a
different app, they each need a distinct package name.</p>

<p class="note"><strong>Note:</strong> To distribute your app using
<a href="{@docRoot}google/play/publishing/multiple-apks.html">Multiple APK Support</a> in
Google Play, assign the same package name to all variants and give each variant a different
<code>versionCode</code>. To distribute different variants of your app as separate apps in Google
Play, assign a different package name to each variant.</p>

<h4>Add additional source directories for each flavor</h4>

<p>Now you create source folders and add a <code>SecondActivity</code> to each flavor. To create
the source directory structure for the demo flavor:</p>

<ol>
    <li>On the <em>Project</em> panel, expand <strong>BuildSystemExample</strong>, and then expand
        the <strong>app</strong> directory.</li>
    <li>Right-click the <strong>src</strong> directory under <em>app</em> and select
        <strong>New</strong> > <strong>Directory</strong>.</li>
    <li>Enter "demo" as the name of the new directory and click <strong>OK</strong>.</li>
    <li><p>Similarly, create the following directories:</p>
        <ul>
            <li><code>app/src/demo/java</code></li>
            <li><code>app/src/demo/res</code></li>
            <li><code>app/src/demo/res/layout</code></li>
            <li><code>app/src/demo/res/values</code></li>
        </ul>
    </li>
</ol>

<p>The resulting directory structure looks like figure 1.</p>

<img src="{@docRoot}images/tools/as-demoflavordirs.png" alt="" />
<p class="img-caption"><strong>Figure 1.</strong> New source directories for the demo flavor.</p>

<h4>Add a new activity to each flavor</h4>

<p>To add <code>SecondActivity</code> to the <code>demo</code> flavor:</p>

<ol>
    <li>On the <em>Project</em> panel, right click on the <strong>app</strong> module and select
        <strong>New</strong> > <strong>Activity</strong>.</li>
    <li>Select <strong>Blank Activity</strong> and click <strong>Next</strong>.</li>
    <li>Enter "SecondActivity" as the activity name.</li>
    <li>Enter "com.buildsystemexample.app" as the package name and click
        <strong>Finish</strong>.</li>
    <li>Right click on the <strong>java</strong> directory under <em>app/src/demo</em> and select
        <strong>New</strong> > <strong>Package</strong>.</li>
    <li>Enter "com.buildsystemexample.app" as the package name and click <strong>OK</strong>.</li>
    <li>Drag <strong>SecondActivity</strong> and drop it under the new package in
        <em>app/src/demo/java</em>.</li>
    <li>Accept the default values and click <strong>Refactor</strong>.</li>
</ol>

<p>To add the layout for <code>SecondActivity</code> and a strings resource to the demo flavor:</p>

<ol>
    <li>Drag <strong>activity_second.xml</strong> from <em>app/src/main/res/layout</em> and drop it
        inside <em>app/src/demo/res/layout</em>.</li>
    <li>Accept the default values on the window that appears and click <code>OK</code>.</li>
    <li>Copy <strong>strings.xml</strong> from <em>app/src/main/res</em> into
        <em>app/src/demo/res</em>.</li>
    <li><p>Replace the contents of the new copy of <code>strings.xml</code> with the
        following:</p>
        <p><pre>
&lt;?xml version="1.0" encoding="utf-8"?>
&lt;resources>
    &lt;string name="hello_world">Demo version only.&lt;/string>
&lt;/resources>
</pre></p>
    </li>
</ol>

<p>Now you add source folders and <code>SecondActivity</code> to the full flavor by making a copy
of the <code>demo</code> flavor:</p>

<ol>
    <li>On the <em>Project</em> panel, right click on the <strong>demo</strong> directory under
        <em>app/src</em> and select <strong>Copy</strong>.</li>
    <li>Right-click on the <strong>src/</strong> directory under <em>app/</em> and select
        <strong>Paste</strong>.</li>
    <li>On the window that appears, enter "full" as the new name and click <strong>OK</strong>.</li>
    <li><p>Replace the contents of <strong>strings.xml</strong> under <em>src/full/res/values</em>
        with the following:</p>
        <p><pre>
&lt;?xml version="1.0" encoding="utf-8"?>
&lt;resources>
    &lt;string name="hello_world">This is the full version!&lt;/string>
&lt;/resources>
</pre></p>
    </li>
</ol>

<p class="note"><strong>Note:</strong> From this point on, you could develop
<code>SecondActivity</code> independently inside each
flavor. For example, you could add more features to this activity in the <code>full</code> flavor.</p>

<p>To work on files from a particular flavor, click on <strong>Build Variants</strong> on the left
of the IDE window and select the flavor you want to modify in the <em>Build Variants</em> panel,
as shown in figure 2. Android Studio may show errors in source files from flavors other than the
one selected in the <em>Build Variants</em> panel, but this does not affect the outcome of the
build.</p>

<img src="{@docRoot}images/tools/as-buildvariants.png" alt="" />
<p class="img-caption"><strong>Figure 2.</strong> The Build Variants panel.</p>

<h4>Launch a flavor-specific activity from the main activity</h4>

<p>Since the flavor-specific activity (<code>SecondActivity</code>) has the same package name and
activity name in both flavors, you can launch it from the main activity, which is common to all
flavors. To modify the main activity:</p>

<ol>
    <li><p>Edit <code>activity_main.xml</code> and add a new button to
        <code>MainActivity</code>:</p>
        <p><pre>
&lt;LinearLayout ...>
    ...
    &lt;Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/button2"
        android:onClick="onButton2Clicked"/>
&lt;/LinearLayout>
</pre></p>
    </li>
    <li>Click on the areas marked in red in the layout file and press <strong>Alt</strong>+
        <strong>Enter</strong>. Follow the suggestions from Android Studio to add a new string
        resource with value “Open Second Activity” and an <code>onButton2Clicked</code> method to
        <code>MainActivity</code>.</li>
    <li><p>Add the following code to the <code>onButton2Clicked</code> method of
        <code>MainActivity</code>:</p>
        <p><pre>
public void onButton2Clicked(View view) {
    Intent intent = new Intent(this, SecondActivity.class);
    startActivity(intent);
}
</pre></p>
    </li>
    <li><p>Edit the app's manifest to include a reference to <code>SecondActivity</code>:</p>
        <p><pre>
&lt;manifest ...>
    &lt;application ...>
        ...
        &lt;activity
            android:name="com.buildsystemexample.app.SecondActivity"
            android:label="@string/title_activity_second" >
        &lt;/activity>
    &lt;/application>
&lt;/manifest>
</pre></p>
    </li>
</ol>


<h4>Build types </h4>
<p>Build types represent the build packaging versions generated for each app package. By default,
the debug and release build types are provided.
</p>

<pre>
...
android {
    ...
    defaultConfig { ... }
    signingConfigs { ... }
    buildTypes { ... }
    productFlavors {...}
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
         debug {
            debuggable true
        }
    }
}
...
</pre>

<p class="note"><strong>Note:</strong> Although only the <em>release</em> build type appears in
the default <strong>build.gradle</strong> file, both the release and debug build types are
applied to each build. </p>

<p>In this example, the product flavors and build types create the following build variants:
<ul>
<li>demoDebug</li>
<li>demoRelease</li>
<li>fullDebug</li>
<li>fullRelease</li>
</ul>

<p>To build this example, invoke the <code>assemble</code> task from Android Studio or from the
command line.</p>

<p>Separate output folders are created for each build variant. </p>