These are resources suggested by my Java friends online.
- W3Schools Java tutorial A nice high-level tutorial of basic Java features.
- SAMS Teach Yourself Java There's multiple editions for different Java versions, so later editions may use features the robobrain doesn't support.
- Modern Java Recommended by someone who used this to teach his kids.
- Head First Java Highly recommended online but I have not read it myself.
- Thinking in Java (free PDF) Old, from 2006, but very in-depth and probably ok for robobrain work.
@headius Shoudn't SAMS Teach Yourself Java be under Books?