I tried several things bu couldn\'t get the root folder id in Java Api v3.
What I tried:
String id = service.files().get(\"fileId=root\").setFields(\
Try the following combination to see if that works.
String id = service.files().get("root").setFields("id").execute().getId();
To execute the above combination, you have to give your application full access to use Drive. OAuth 2.0 scope that needs to be given: https://www.googleapis.com/auth/drive or https://www.googleapis.com/auth/drive.readonly