Personally I feel I know java from J2EE/2004-5 days After that I have been doing more non tech work then tech work. As a example I missed out on annotations, an

Personally I feel I know java from J2EE/2004-5 days After that I have been doing more non tech work then tech work. As a example I missed out on annotations, and everything after that. While I do know what annotations and generics etc do. I feel my knowledge has gaps because I learned it in bits and pieces (read I learnt about it in passing when I need to). As a result I feel the need to 'brush up' - basically looking to feel confident such that I have a good grip on Java as it is today. If you have any specific tips on how I can brush up, I am all ears.