Caching in the Android Build Process

Photo by Mylon Ollila on Unsplash

Table of Contents

• What is Gradle?
• The build directory and incremental builds
• Gradle build cache
• Android Studio system cache
• Android Gradle Plugin build cache
• Additional resources

So what is Gradle?

Android Studio includes a powerful code editor and developer tools but rather than reinventing the wheel and managing a project’s build process as well, it delegates to an existing build automation tool: Gradle. At a high level, Grade’s build process includes compiling your source code into Dalvik bytecode (.dex files) and compiled resources, then combining the compiled files into an APK, and finally signing the APK. Each step is configurable, and all the Gradle-related files you see in an Android project — build.gradle, gradle.properties, etc — are used to customize and configure the project’s build.

Gradle is flexible enough to build almost any type of software, and can be used for specific project types by adding a layer of conventions and prebuilt functionality through plugins. Android Studio uses the Android Gradle plugin, which adds features specific to the app build process. For example, you probably have a buildTypes block in your project’s build.gradle file, which doesn’t exist in the base Gradle API but is used by the Android Gradle plugin to support building different versions (debug, release, etc) of your app from a single project.

You can see which version of Gradle you’re using by looking at the dependencies block in your root-level build.gradle:

dependencies {
    classpath ‘com.android.tools.build:gradle:<GRADLE_VERSION>’
}

Since Gradle and the Android plugin run independently of Android Studio, you can build and run your app from the command line as well, by using various ./gradlew <TASK> command-line commands. In Gradle, a task represents one piece of work you may do on a project, for example running tests (./gradlew test) or generating Javadoc (./gradlew javadoc). They can have dependencies on other tasks. You can see all the tasks available for your project by opening the Gradle panel located on Android Studio’s top right: