Android sample app to learn about the gradle dependency configurations compileonly and runtimeonly (implementation and api are pretty common, so I didn't touch on them in this sample).

compileonly is used for dependencies that are required only at compile time, but not at runtime. runtimeonly is used for dependencies that are required only at runtime, but not at compile time.

In this sample, I take logging as an example. The highlevel API of a Logger is defined in the module compileonly (quite original name!), and two implementations of this logging class are defined in two other separate modules: runtimeonly and otherruntimeonly. The main module of the sample app uses an instance of this Logger.

The main module uses the Gradle dependency configuration compileonly with the compileonly module, as it only requires the Logger's API to compile. At runtime, one of the implementation modules provide the concrete implementation of the Logger, thus the main module uses one of these modules with the Gradle dependency configuration runtimeonly.