You should first clone the repo.
Now you can use the gradlew script, which is in the root of the project (think of an elaborated makefile). There is a Linux version (simply named gradlew) and a Windows version (named gradlew.bat), you call it by giving 'targets', which are the things you want to execute.
For example, ./gradlew clean build will remove compilation-generated files, then compile & test everything. Gradle is smart, and will not recompile everything everytime -- as long as you don't clean, it will not rerun tests that were not modified, etc. It also understands tasks dependencies : if you ask it to test the project, it knows it's necessary to compile beforehand.
You can run ./gradlew tasks to get a list of the targets you can use. The main ones are:
- clean - Remove compilation-generated files
- test - Unit tests
- build - Compile & unit test
- javadoc - Generates the documentation of the project, found in build/docs/javadoc/index.html
- publish - Publish a new version to MavenCentral, you need additional setup for it to work
- check - Static code analysis