Android source set layout

The new Android source set layout was introduced in Kotlin 1.8.0 and became the default in 1.9.0. Follow this guide to understand the key differences between the deprecated and the new layouts, as well as how to migrate your projects.

Check the compatibility

The new layout requires Android Gradle plugin 7.0 or later and is supported in Android Studio 2022.3 and later. Check your version of the Android Gradle plugin and upgrade if necessary.

Rename Kotlin source sets

If applicable, rename the source sets in your project, following this pattern:

Previous source set layout	New source set layout
`targetName` + `AndroidSourceSet.name`	`targetName` + `AndroidVariantType`

{AndroidSourceSet.name} maps to {KotlinSourceSet.name} as follows:

	Previous source set layout	New source set layout
main	androidMain	androidMain
test	androidTest	androidUnitTest
androidTest	androidAndroidTest	androidInstrumentedTest

Move source files

If applicable, move your source files to the new directories, following this pattern:

Previous source set layout	New source set layout
The layout had additional `/kotlin` SourceDirectories	`src/{KotlinSourceSet.name}/kotlin`

{AndroidSourceSet.name} maps to {SourceDirectories included} as follows:

	Previous source set layout	New source set layout
main	src/androidMain/kotlin src/main/kotlin src/main/java	src/androidMain/kotlin src/main/kotlin src/main/java
test	src/androidTest/kotlin src/test/kotlin src/test/java	src/androidUnitTest/kotlin src/test/kotlin src/test/java
androidTest	src/androidAndroidTest/kotlin src/androidTest/java	src/androidInstrumentedTest/kotlin src/androidTest/java, src/androidTest/kotlin

Previous source set layout

New source set layout

main

src/androidMain/kotlin

src/main/kotlin

src/main/java

src/androidMain/kotlin

src/main/kotlin

src/main/java

test

src/androidTest/kotlin

src/test/kotlin

src/test/java

src/androidUnitTest/kotlin

src/test/kotlin

src/test/java

androidTest

src/androidAndroidTest/kotlin

src/androidTest/java

src/androidInstrumentedTest/kotlin

src/androidTest/java, src/androidTest/kotlin

Move the AndroidManifest.xml file

If you have the AndroidManifest.xml file in your project, move it to the new directory, following this pattern:

Previous source set layout	New source set layout
src/{AndroidSourceSet.name}/AndroidManifest.xml	src/{KotlinSourceSet.name}/AndroidManifest.xml

{AndroidSourceSet.name} maps to {AndroidManifest.xml location} as follows:

	Previous source set layout	New source set layout
main	src/main/AndroidManifest.xml	src/androidMain/AndroidManifest.xml
debug	src/debug/AndroidManifest.xml	src/androidDebug/AndroidManifest.xml

Check the relationship between Android and common tests

The new Android source set layout changes the relationship between Android-instrumented tests (renamed to androidInstrumentedTest in the new layout) and common tests.

Previously, the dependsOn relationship between androidAndroidTest and commonTest was the default. It meant the following:

The code in commonTest was available in androidAndroidTest.
expect declarations in commonTest had to have corresponding actual implementations in androidAndroidTest.
Tests declared in commonTest were also running as Android instrumented tests.

In the new Android source set layout, the dependsOn relationship is not added by default. If you prefer the previous behavior, manually declare the following relationship in your build.gradle.kts file:

kotlin {
// ...
    sourceSets {
        val commonTest by getting
        val androidInstrumentedTest by getting {
            dependsOn(commonTest)
        }
    }
}

Adjust the implementation of Android flavors

Previously, the Kotlin Gradle plugin eagerly created source sets that corresponded to Android source sets containing debug and release build types or custom flavors like demo and full. It made the source sets accessible by using expressions like val androidDebug by getting { ... }.

The new Android source set layout makes use of Android's onVariants to create source sets. It makes such expressions invalid, leading to errors like org.gradle.api.UnknownDomainObjectException: KotlinSourceSet with name 'androidDebug' not found.

To work around that, use the new invokeWhenCreated() API in your build.gradle.kts file:

kotlin {
// ...
    @OptIn(ExperimentalKotlinGradlePluginApi::class)
    sourceSets.invokeWhenCreated("androidFreeDebug") {
// ...
    }
}

Last modified: 25 September 2024