Hi everyone,
Just released the first part of a two-part article that shows how to manipulate files and folders by using Drive Android API. It also covers the initial setup as well the whole sign in process.
Link for the article: http://androidahead.com/2018/07/04/driveapidemoapp-part-1/
You can also find a demo app (in Kotlin) that implements all the features covered in the article: ( https://github.com/JoaoMotondon/DriveApiDemoApp ).