Configure your build

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The Android build system compiles app resources and source code and packages them into APKs or Android App Bundles that you can test, deploy, sign, and distribute.

Android Studio uses Gradle, an advanced build toolkit, to automate and manage the build process while letting you define flexible, custom build configurations. Each build configuration can define its own set of code and resources while reusing the parts common to all versions of your app. The Android Gradle plugin works with the build toolkit to provide processes and configurable settings that are specific to building and testing Android apps.

Gradle and the Android Gradle plugin run independent of Android Studio. This means that you can build your Android apps from within Android Studio, the command line on your machine, or on machines where Android Studio is not installed, such as continuous integration servers.

If you aren't using Android Studio, you can learn how to build and run your app from the command line. The output of the build is the same whether you are building a project from the command line, on a remote machine, or using Android Studio.

Note: Because Gradle and the Android Gradle plugin run independently from Android Studio, you need to update the build tools separately. Read the release notes to learn how to update Gradle and the Android Gradle plugin.

The flexibility of the Android build system lets you create custom build configurations without modifying your app's core source files. This page helps you understand how the Android build system works and how it can help you customize and automate multiple build configurations. If you want to learn more about deploying your app, see Build and run your app. To start creating custom build configurations right away using Android Studio, see Configure build variants.

The build process

The build process involves many tools and processes that convert your project into an Android Application Package (APK) or Android App Bundle (AAB).

The Android Gradle plugin does much of the build process for you, but it can be useful to understand certain aspects of the build process so you can adjust the build to meet your requirements.

Different projects may have different build goals. For example, the build for a third-party library produces AAR or JAR libraries. However, an app is the most common type of project, and the build for an app project produces a debug or release APK or AAB of your app that you can deploy, test, or release to external users.

This page focuses on app development, but many of the build steps and concepts are common to most build types.

Android build glossary

Gradle and the Android Gradle plugin help you configure the following aspects of your build:

Build types

Build types define certain properties that Gradle uses when building and packaging your app. Build types are typically configured for different stages of your development lifecycle.

For example, the debug build type enables debug options and signs the app with the debug key, while the release build type may shrink, obfuscate, and sign your app with a release key for distribution.

You must define at least one build type to build your app. Android Studio creates the debug and release build types by default. To start customizing packaging settings for your app, learn how to configure build types.

Product flavors
Product flavors represent different versions of your app that you can release to users, such as free and paid versions. You can customize product flavors to use different code and resources while sharing and reusing the parts that are common to all versions of your app. Product flavors are optional, and you must create them manually. To start creating different versions of your app, learn how to configure product flavors.
Build variants
A build variant is a cross-product of build type and product flavor and is the configuration Gradle uses to build your app. Using build variants, you can build the debug version of your product flavors during development and signed release versions of your product flavors for distribution. Although you don't configure build variants directly, you configure the build types and product flavors that form them. Creating additional build types or product flavors also creates additional build variants. To learn how to create and manage build variants, read the Configure build variants overview.
Manifest entries
You can specify values for some properties of the manifest file in the build variant configuration. These build values override the existing values in the manifest file. This is useful if you want to generate multiple variants of your app with a different application name, minimum SDK version, or target SDK version. When multiple manifests are present, the manifest merger tool merges manifest settings.
Dependencies
The build system manages project dependencies from your local file system and from remote repositories. This means you don't have to manually search, download, and copy binary packages of your dependencies into your project directory. To find out more, see Add build dependencies.
Signing
The build system lets you specify signing settings in the build configuration, and it can automatically sign your app during the build process. 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 don't have a release key, you can generate one as described in Sign your app. Signed release builds are required for distributing apps through most app stores.
Code and resource shrinking
The build system lets you specify a different ProGuard rules file for each build variant. When building your app, the build system applies the appropriate set of rules to shrink your code and resources using its built-in shrinking tools, such as R8. Shrinking your code and resources can help reduce your APK or AAB size.
Multiple APK support
The build system lets you automatically build different APKs that each contain only the code and resources needed for a specific screen density or Application Binary Interface (ABI). For more information see Build multiple APKs. However, releasing a single AAB is the recommended approach, as it offers splitting by language in addition to screen density and ABI, while avoiding the need to upload multiple artifacts to Google Play. All new apps submitted after August 2021 are required to use AABs.

Build configuration files

Creating custom build configurations requires you to make changes to one or more build configuration files or build.gradle files. These plain-text files use Domain Specific Language (DSL) to describe and manipulate the build logic using either Groovy, which is a dynamic language for the Java Virtual Machine (JVM), or Kotlin script, which is a flavor of the Kotlin language.

You don't need to know Groovy or Kotlin script to start configuring your build, because the Android Gradle plugin introduces most of the DSL elements you need. To learn more about the Android Gradle plugin DSL, read the DSL reference documentation for Groovy. Kotlin script also relies on the underlying Gradle Kotlin DSL.

When starting a new project, Android Studio automatically creates some of these files for you, as shown in figure 1, and populates them based on sensible defaults.

Figure 1. The default project structure for an Android app module.

There are a few Gradle build configuration files that are part of the standard project structure for an Android app. Before you can start configuring your build, it's important to understand the scope and purpose of each of these files and the basic DSL elements they define.

The Gradle settings file

The settings.gradle file (for Groovy) or settings.gradle.kts file (for Kotlin script) is located in the root project directory. This settings file defines project-level repository settings and informs Gradle which modules it should include when building your app. Multi-module projects need to specify each module that should go into the final build.

For most projects, the file looks like the following by default:

Groovy

pluginManagement {

    /**
     * The pluginManagement {repositories {...}} block configures the
     * repositories Gradle uses to search or download the Gradle plugins and
     * their transitive dependencies. Gradle pre-configures support for remote
     * repositories such as JCenter, Maven Central, and Ivy. You can also use
     * local repositories or define your own remote repositories. The code below
     * defines the Gradle Plugin Portal, Google's Maven repository,
     * and the Maven Central Repository as the repositories Gradle should use to look for its
     * dependencies.
     */

    repositories {
        gradlePluginPortal()
        google()
        mavenCentral()
    }
}
dependencyResolutionManagement {

    /**
     * The dependencyResolutionManagement {repositories {...}}
     * block is where you configure the repositories and dependencies used by
     * all modules in your project, such as libraries that you are using to
     * create your application. However, you should configure module-specific
     * dependencies in each module-level build.gradle file. For new projects,
     * Android Studio includes Google's Maven repository and the Maven Central
     * Repository by default, but it does not configure any dependencies (unless
     * you select a template that requires some).
     */

    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
    }
}
rootProject.name = "My Application"
include ‘:app’

Kotlin

pluginManagement {

    /**
     * The pluginManagement {repositories {...}} block configures the
     * repositories Gradle uses to search or download the Gradle plugins and
     * their transitive dependencies. Gradle pre-configures support for remote
     * repositories such as JCenter, Maven Central, and Ivy. You can also use
     * local repositories or define your own remote repositories. The code below
     * defines the Gradle Plugin Portal, Google's Maven repository,
     * and the Maven Central Repository as the repositories Gradle should use to look for its
     * dependencies.
     */

    repositories {
        gradlePluginPortal()
        google()
        mavenCentral()
    }
}
dependencyResolutionManagement {

    /**
     * The dependencyResolutionManagement {repositories {...}}
     * block is where you configure the repositories and dependencies used by
     * all modules in your project, such as libraries that you are using to
     * create your application. However, you should configure module-specific
     * dependencies in each module-level build.gradle file. For new projects,
     * Android Studio includes Google's Maven repository and the Maven Central
     * Repository by default, but it does not configure any dependencies (unless
     * you select a template that requires some).
     */

    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
    }
}
rootProject.name = "My Application"
include(":app")

The top-level build file

The top-level build.gradle file (for Groovy) or build.gradle.kts file (for Kotlin script) is located in the root project directory. It defines dependencies that apply to all modules in your project. By default, the top-level build file uses the plugins block to define the Gradle dependencies that are common to all modules in the project. In addition, the top-level build file contains code to clean your build directory.

The following code sample describes the default settings and DSL elements in the top-level build.gradle file after creating a new project:

Groovy

plugins {

    /**
     * Use `apply false` in the top-level build.gradle file to add a Gradle
     * plugin as a build dependency but not apply it to the current (root)
     * project. Don't use `apply false` in sub-projects. For more information,
     * see Applying external plugins with same version to subprojects.
     */

    id 'com.android.application' version '7.3.1' apply false
    id 'com.android.library' version '7.3.1' apply false
    id 'org.jetbrains.kotlin.android' version '1.7.20' apply false
}

Kotlin

plugins {

    /**
     * Use `apply false` in the top-level build.gradle file to add a Gradle
     * plugin as a build dependency but not apply it to the current (root)
     * project. Don't use `apply false` in sub-projects. For more information,
     * see Applying external plugins with same version to subprojects.
     */

    id("com.android.application") version "7.3.1" apply false
    id("com.android.library") version "7.3.1" apply false
    id("org.jetbrains.kotlin.android") version "1.7.20" apply false
}

Configure project-wide properties

For Android projects that include multiple modules, it might be useful to define certain properties at the project level and share them across all the modules. You can do this by adding extra properties to the ext block in the top-level build.gradle file (for Groovy) or build.gradle.kts file (for Kotlin script):

Groovy

// This block encapsulates custom properties and makes them available to all
// modules in the project. The following are only a few examples of the types
// of properties you can define.
ext {
    sdkVersion = 33
    // You can also create properties to specify versions for dependencies.
    // Having consistent versions between modules can avoid conflicts with behavior.
    appcompatVersion = "1.5.1"
    ...
}
...

Kotlin

// This block encapsulates custom properties and makes them available to all
// modules in the project. The following are only a few examples of the types
// of properties you can define.
ext {
    extra["sdkVersion"] = 33
    // You can also create properties to specify versions for dependencies.
    // Having consistent versions between modules can avoid conflicts with behavior.
    extra["appcompatVersion"] = "1.5.1"
    ...
}
...

To access these properties from a module in the same project, use the following syntax in the module's build.gradle file.

Groovy

android {
    // Use the following syntax to access properties you defined at the project level:
    // rootProject.ext.property_name
    compileSdk rootProject.ext.sdkVersion
    ...
}
...
dependencies {
    implementation "androidx.appcompat:appcompat:${rootProject.ext.appcompatVersion}"
    ...
}

Kotlin

android {
    // Use the following syntax to access properties you defined at the project level:
    // rootProject.extra["property_name"]
    compileSdk = rootProject.extra["sdkVersion"]

    // Alternatively, you can access properties using a type safe delegate:
    val sdkVersion: Int by rootProject.extra
    ...
    compileSdk = sdkVersion
}
...
dependencies {
    implementation("androidx.appcompat:appcompat:${rootProject.ext.appcompatVersion}")
    ...
}

Note: Although Gradle lets you define project-wide properties at the module level, avoid doing so, because it causes the modules that share those properties to be coupled. Module coupling makes it more difficult to later export a module as a standalone project and prevents Gradle from using parallel project execution to speed up multi-module builds.

The module-level build file

The module-level build.gradle file (for Groovy) or build.gradle.kts (for Kotlin script) is located in each project/module/ directory. It lets you configure build settings for the specific module it is located in. Configuring these build settings lets you provide custom packaging options, such as additional build types and product flavors, and override settings in the main/ app manifest or top-level build.gradle or build.gradle.kts file.

This sample Android app module build.gradle file outlines some of the basic DSL elements and settings:

Groovy

/**
 * The first line in the build configuration applies the Android Gradle plugin
 * to this build and makes the android block available to specify
 * Android-specific build options.
 */

plugins {
    id 'com.android.application'
}

/**
 * The android block is where you configure all your Android-specific
 * build options.
 */

android {

    /**
     * The app's namespace. Used primarily to access app resources.
     */

    namespace 'com.example.myapp'

    /**
     * compileSdk specifies the Android API level Gradle should use to
     * compile your app. This means your app can use the API features included in
     * this API level and lower.
     */

    compileSdk 33

    /**
     * The defaultConfig block encapsulates default settings and entries for all
     * build variants and can override some attributes in main/AndroidManifest.xml
     * dynamically from the build system. You can configure product flavors to override
     * these values for different versions of your app.
     */

    defaultConfig {

        // Uniquely identifies the package for publishing.
        applicationId 'com.example.myapp'

        // Defines the minimum API level required to run the app.
        minSdk 21

        // Specifies the API level used to test the app.
        targetSdk 33

        // Defines the version number of your app.
        versionCode 1

        // Defines a user-friendly version name for your app.
        versionName "1.0"
    }

    /**
     * The buildTypes block is where you can configure multiple build types.
     * By default, the build system defines two build types: debug and release. The
     * debug build type is not explicitly shown in the default build configuration,
     * but it includes debugging tools and is signed with the debug key. The release
     * build type applies ProGuard settings and is not signed by default.
     */

    buildTypes {

        /**
         * By default, Android Studio configures the release build type to enable code
         * shrinking, using minifyEnabled, and specifies the default ProGuard rules file.
         */

        release {
              minifyEnabled true // Enables code shrinking for the release build type.
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    /**
     * The productFlavors block is where you can configure multiple product flavors.
     * This lets you create different versions of your app that can
     * override the defaultConfig block with their own settings. Product flavors
     * are optional, and the build system does not create them by default.
     *
     * This example creates a free and paid product flavor. Each product flavor
     * then specifies its own application ID, so that they can exist on the Google
     * Play Store, or an Android device, simultaneously.
     *
     * If you declare product flavors, you must also declare flavor dimensions
     * and assign each flavor to a flavor dimension.
     */

    flavorDimensions "tier"
    productFlavors {
        free {
            dimension "tier"
            applicationId 'com.example.myapp.free'
        }

        paid {
            dimension "tier"
            applicationId 'com.example.myapp.paid'
        }
    }
}

/**
 * The dependencies block in the module-level build configuration file
 * specifies dependencies required to build only the module itself.
 * To learn more, go to Add build dependencies.
 */

dependencies {
    implementation project(":lib")
    implementation 'androidx.appcompat:appcompat:1.5.1'
    implementation fileTree(dir: 'libs', include: ['*.jar'])
}

Kotlin

/**
 * The first section in the build configuration applies the Android Gradle plugin
 * to this build and makes the android block available to specify
 * Android-specific build options.
 */

plugins {
    id("com.android.application")
}

/**
 * The android block is where you configure all your Android-specific
 * build options.
 */

android {

    /**
     * The app's namespace. Used primarily to access app resources.
     */

    namespace = "com.example.myapp"

    /**
     * compileSdk specifies the Android API level Gradle should use to
     * compile your app. This means your app can use the API features included in
     * this API level and lower.
     */

    compileSdk = 33

    /**
     * The defaultConfig block encapsulates default settings and entries for all
     * build variants and can override some attributes in main/AndroidManifest.xml
     * dynamically from the build system. You can configure product flavors to override
     * these values for different versions of your app.
     */

    defaultConfig {

        // Uniquely identifies the package for publishing.
        applicationId = "com.example.myapp"

        // Defines the minimum API level required to run the app.
        minSdk = 21

        // Specifies the API level used to test the app.
        targetSdk = 33

        // Defines the version number of your app.
        versionCode = 1

        // Defines a user-friendly version name for your app.
        versionName = "1.0"
    }

    /**
     * The buildTypes block is where you can configure multiple build types.
     * By default, the build system defines two build types: debug and release. The
     * debug build type is not explicitly shown in the default build configuration,
     * but it includes debugging tools and is signed with the debug key. The release
     * build type applies ProGuard settings and is not signed by default.
     */

    buildTypes {

        /**
         * By default, Android Studio configures the release build type to enable code
         * shrinking, using minifyEnabled, and specifies the default ProGuard rules file.
         */

        getByName("release") {
            isMinifyEnabled = true // Enables code shrinking for the release build type.
            proguardFiles(
                getDefaultProguardFile("proguard-android.txt"),
                "proguard-rules.pro"
            )
        }
    }

    /**
     * The productFlavors block is where you can configure multiple product flavors.
     * This lets you create different versions of your app that can
     * override the defaultConfig block with their own settings. Product flavors
     * are optional, and the build system does not create them by default.
     *
     * This example creates a free and paid product flavor. Each product flavor
     * then specifies its own application ID, so that they can exist on the Google
     * Play Store, or an Android device, simultaneously.
     *
     * If you declare product flavors, you must also declare flavor dimensions
     * and assign each flavor to a flavor dimension.
     */

    flavorDimensions += "tier"
    productFlavors {
        create("free") {
            dimension = "tier"
            applicationId = "com.example.myapp.free"
        }

        create("paid") {
            dimension = "tier"
            applicationId = "com.example.myapp.paid"
        }
    }
}

/**
 * The dependencies block in the module-level build configuration file
 * specifies dependencies required to build only the module itself.
 * To learn more, go to Add build dependencies.
 */

dependencies {
    implementation(project(":lib"))
    implementation("androidx.appcompat:appcompat:1.5.1")
    implementation(fileTree(mapOf("dir" to "libs", "include" to listOf("*.jar"))))
}

Gradle properties files

Gradle also includes two properties files, located in your root project directory, that you can use to specify settings for the Gradle build toolkit itself:

gradle.properties
This is where you can configure project-wide Gradle settings, such as the Gradle daemon's maximum heap size. For more information, see Build Environment.
local.properties
Configures local environment properties for the build system, including the following:
  • ndk.dir - Path to the NDK. This property has been deprecated. Any downloaded versions of the NDK are installed in the ndk directory within the Android SDK directory.
  • sdk.dir - Path to the SDK.
  • cmake.dir - Path to CMake.
  • ndk.symlinkdir - In Android Studio 3.5 and higher, creates a symlink to the NDK that can be shorter than the installed NDK path.

Remap the NDK to a shorter path (Windows only)

In Windows, tools in the installed NDK folder, such as ld.exe, end up with long paths. The tools don't support long paths well.

To create a shorter path, in local.properties, set the property ndk.symlinkdir to request that the Android Gradle plugin create a symlink to the NDK. The path of that symlink can be shorter than the existing NDK folder. For example, ndk.symlinkdir = C:\ will result in the following symlink: C:\ndk\19.0.5232133

Sync project with Gradle files

When you make changes to the build configuration files in your project, Android Studio requires that you sync your project files so that it can import your build configuration changes and run some checks to make sure your configuration doesn't create build errors.

To sync your project files, click Sync Now in the notification bar that appears when you make a change, as shown in figure 2, or click Sync Project from the menu bar. If Android Studio finds any errors with your configuration—for example, your source code uses API features that are only available in an API level higher than your compileSdkVersion—the Messages window describes the issue.

Figure 2. Sync the project with build configuration files in Android Studio.

Source sets

Android Studio logically groups source code and resources for each module into source sets. When you create a new module, Android Studio creates a main/ source set within the module. A module’s main/ source set includes the code and resources used by all its build variants.

Additional source set directories are optional, and Android Studio doesn't automatically create them for you when you configure new build variants. However, creating source sets, similar to main/, helps organize files and resources that Gradle should only use when building certain versions of your app:

src/main/
This source set includes code and resources common to all build variants.
src/buildType/
Create this source set to include code and resources only for a specific build type.
src/productFlavor/
Create this source set to include code and resources only for a specific product flavor.

Note: If you configure your build to combine multiple product flavors, you can create source set directories for each combination of product flavors between the flavor dimensions: src/productFlavor1ProductFlavor2/.

src/productFlavorBuildType/
Create this source set to include code and resources only for a specific build variant.

For example, to generate the "fullDebug" version of your app, the build system merges code, settings, and resources from following source sets:

  • src/fullDebug/ (the build variant source set)
  • src/debug/ (the build type source set)
  • src/full/ (the product flavor source set)
  • src/main/ (the main source set)

Note: When you create a new file or directory in Android Studio, use the File > New menu options to create it for a specific source set. The source sets you can choose from are based on your build configurations, and Android Studio automatically creates the required directories if they don't already exist.

If different source sets contain different versions of the same file, Gradle uses the following priority order when deciding which file to use. Source sets on the left override the files and settings of source sets to the right:

build variant > build type > product flavor > main source set > library dependencies

This allows Gradle to use files that are specific to the build variant you are trying to build while reusing activities, application logic, and resources that are common to other versions of your app.

When merging multiple manifests, Gradle uses the same priority order so each build variant can define different components or permissions in the final manifest. To learn more about creating custom source sets, read Create source sets.

Other build systems

Building Android apps with Bazel is possible but not officially supported. Android Studio does not officially support Bazel projects.

To better understand the current limitations of building with Bazel, see the known issues.