An application might have multiple configurations which slightly modify the code base, such as defining multiple endpoints for different servers. Achieving these small modifications might look something like this:

Making this modification is a small and simple task, but it is error-prone and slow, on top of it not being expandable if you needed to add additional changes to this configuration.

Product flavors allow you to group these configuration changes into their own code set and switch between them on the fly without code modification. Product flavors are achieved by defining them in the build.gradle file and creating the folder structure for each flavor.

As you can see, each flavor has its own code set. A blue icon for the java folder signifies that flavor is active and is being included in the main code base. When another flavor is selected, the previous flavor becomes deactivated. To take advantage of this, each class that is defined in a flavor is duplicated by the other flavors with their configuration changes added in. For example:

Since the package and class names are the same, including the Constants class in your networking class will always resolve.

You switch between product flavors using the Build Variants toolbar located at View > Tool Windows > Build Variants. Every application has two build types (debug and release), so the build variants list will show every combination of build type and product flavor.

Each flavor has its own task that can be invoked. To assemble the integration product flavor with the debug build type: gradle assembleIntegrationDebug. Invoking a task that does not define a product flavor will run that task for each product flavor. For instance, running gradle assembleDebug will run the assemble task with the debug build type for integration, staging, and release.

Common/Unflavored Code

The majority of your code is likely not part of a flavor. This code continues to reside in src/main/java and is part of EVERY flavor.

Therefore, code can only go either in src/main/java or in one of the flavors’ folders but not both.

Putting code in both places will result in “duplicate class” errors from the compiler.

Gradle can be slow at times, but there are ways to speed this process up. Android integration with Gradle is still in its infancy, so hopefully with future update, it’ll continue to get faster.

How to Speed up Gradle

1. In Finder, navigate to ~/.gradle
2. Open gradle.properties. If it does not exist, create it.
3. Add the following lines:
   gradle.properties

   org.gradle.daemon=true org.gradle.parallel=true

4. Save and close the file.
5. Restart Android Studio if necessary.

Additional Reading

Gradle Plugin User Guide – Build Variants