tips?

I hope this is not off-topic here. In that case please remove it if you have to.

I have been working in Java for a while now though haven't had an opportunity to learn much. I've mainly done Core Java with manipulations with strings and JUnit etc.

I want to learn better but don't know where to start from. Can anybody here direct me to a good tutorial on Java that has sample problems as well helping me with self-study? I just want to be a better Java developer!

Thanks in advance!