This section builds on the Build System Overview and Build and Running from Android Studio to show you how to use build variants based on product flavors and build types.
Android Studio projects contain a top-level build file and a build file for each module. The
build files are called build.gradle, and they are plain text files that use
Groovy 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
BuildSystemExample project looks like this:
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'])
}
apply plugin: 'com.android.application' applies the Android plugin for Gradle to this build.
This adds Android-specific build tasks to the top-level build tasks and makes the
android {...} element available to specify Android-specific build options.
android {...} configures all the Android-specific build options:
compileSdkVersion property specifies the compilation target.The buildToolsVersion property specifies what version of the build tools
to use. To install several versions of the build tools, use the SDK Manager.
Note: Always use a build tools version whose major revision number is higher or equal to that of your compilation target and target SDK.
The defaultConfig element configures core settings and
entries in the manifest file (AndroidManifest.xml) dynamically from the
build system. The values in defaultConfig override those in the manifest
file.
The configuration specified in the defaultConfig element applies
to all build variants, unless the configuration for a build variant overrides some
of these values.
buildTypes element controls how to build and package your app.
By default, the build system defines two build types: debug and
release. 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.The dependencies element is outside and after the android element.
This element declares the dependencies for this module. Dependencies are covered in the following
sections.
Note: When you make changes to the build files in your project, Android Studio requires a project sync to import the build configuration changes. Click Sync Now on the yellow notification bar that appears for Android Studio to import the changes.
Figure 1. Sync the project in Android Studio.
The app module in this example declares three
dependencies:
...
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'])
}
Each of these dependencies is described below. The build system adds all the
compile dependencies to the compilation classpath and includes them in the final
package.
The app module depends on the lib module, because
MainActivity launches LibActivity1 as described in
Open an Activity from a Library Module.
compile project(":lib") declares a dependency on the lib
module of BuildSystemExample. When you build the app module,
the build system assembles and includes the lib module.
The app and lib modules both use the ActionBarActivity
class from the Android Support Library, so these modules depend on it.
compile 'com.android.support:appcompat-v7:19.0.1' 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 Android Repository package of the Android SDK. If your
SDK installation does not have this package, download and install it using the SDK Manager.
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 <moduleName>/libs inside your project.
compile fileTree(dir: 'libs', include: ['*.jar']) tells the build system that any
JAR file inside app/libs is a dependency and should be included in the compilation
classpath and in the final package.
For more information about dependencies in Gradle, see Dependency Management Basics in the Gradle User Guide.
The build system can run
ProGuard to obfuscate your
classes during the build process. In BuildSystemExample, modify the build file for
the app module to run ProGuard for the release build:
...
android {
...
buildTypes {
release {
minifyEnabled true
proguardFiles getDefaultProguardFile('proguard-android.txt'), \
'proguard-rules.txt'
}
}
}
...
getDefaultProguardFile('proguard-android.txt') obtains the default ProGuard
settings from the Android SDK installation. Android Studio adds the module-specific rules file
proguard-rules.txt at the root of the module, where you can add custom ProGuard
rules.
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 Signing your Applications.
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.
The build system uses product flavors 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.
This example project consists of the two default build types (debug and release) and two product flavors for app type (demo and full). For more information on advanced uses of build variants, see Build System Overview .
To create different product versions of your app:
The rest of this section walks you through these steps in detail using a
BuildSystemExample project. You create two flavors of the
BuildSystemExample app, a demo flavor and a full flavor. Both flavors share
MainActivity, to which you add a new button to launch a new activity,
SecondActivity. 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.
To define two product flavors, edit the build file for the app module to add the following configuration:
...
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"
}
}
}
...
The product flavor definitions support the same properties as the defaultConfig
element. The base configuration for all flavors is specified in defaultConfig, and each
flavor overrides any default values. The build file above uses the applicationId
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.
Note: To distribute your app using
Multiple APK Support in
Google Play, assign the same package name to all variants and give each variant a different
versionCode. To distribute different variants of your app as separate apps in Google
Play, assign a different package name to each variant.
Now you create source folders and add a SecondActivity to each flavor. To create
the source directory structure for the demo flavor:
Similarly, create the following directories:
app/src/demo/javaapp/src/demo/resapp/src/demo/res/layoutapp/src/demo/res/valuesThe resulting directory structure looks like figure 1.
Figure 1. New source directories for the demo flavor.
To add SecondActivity to the demo flavor:
To add the layout for SecondActivity and a strings resource to the demo flavor:
OK.Replace the contents of the new copy of strings.xml with the
following:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="hello_world">Demo version only.</string>
</resources>
Now you add source folders and SecondActivity to the full flavor by making a copy
of the demo flavor:
Replace the contents of strings.xml under src/full/res/values with the following:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="hello_world">This is the full version!</string>
</resources>
Note: From this point on, you could develop
SecondActivity independently inside each
flavor. For example, you could add more features to this activity in the full flavor.
To work on files from a particular flavor, click on Build Variants on the left of the IDE window and select the flavor you want to modify in the Build Variants panel, as shown in figure 2. Android Studio may show errors in source files from flavors other than the one selected in the Build Variants panel, but this does not affect the outcome of the build.
Figure 2. The Build Variants panel.
Since the flavor-specific activity (SecondActivity) 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:
Edit activity_main.xml and add a new button to
MainActivity:
<LinearLayout ...>
...
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button2"
android:onClick="onButton2Clicked"/>
</LinearLayout>
onButton2Clicked method to
MainActivity.Add the following code to the onButton2Clicked method of
MainActivity:
public void onButton2Clicked(View view) {
Intent intent = new Intent(this, SecondActivity.class);
startActivity(intent);
}
Edit the app's manifest to include a reference to SecondActivity:
<manifest ...>
<application ...>
...
<activity
android:name="com.buildsystemexample.app.SecondActivity"
android:label="@string/title_activity_second" >
</activity>
</application>
</manifest>
Build types represent the build packaging versions generated for each app package. By default, the debug and release build types are provided.
...
android {
...
defaultConfig { ... }
signingConfigs { ... }
buildTypes { ... }
productFlavors {...}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
debug {
debuggable true
}
}
}
...
Note: Although only the release build type appears in the default build.gradle file, both the release and debug build types are applied to each build.
In this example, the product flavors and build types create the following build variants:
To build this example, invoke the assemble task from Android Studio or from the
command line.
Separate output folders are created for each build variant.