I have learned that the best way to learn a language is by finding a good project to start on, and working out how you would create it. I've been programming for 4 years as a hobby, and it's only been in PHP, so I decided that I should learn a "real" programming language. I have tried C++ in the past, however I was never able to find a project that I could apply it to, and therefore I never really learned much.
Now, though, I'm checking out Java, and so far I really like it. My question for you is: What would be a good project or projects for a beginner to learn the main features of Java? I understand basic OOP practices and such. What I really want to learn is all the little libraries and functions inside of it. For example, in PHP you learn to use many array manipulations and other functions built-in to do work for you. I would like to learn what these are in Java.
As I said, I don't really want just documentation, I'd like a project that I can apply Java to.
My advice, take a project based course some university puts up. Something past COMP 101, but not too theory heavy.
This one's how my university breaks sophomores. Its fun, and requires you to think about design and (a little) about data structures. Good "salt of the earth" programming: consoles, file IO, parsing, collections, etc. No GUI, though there's another project for that and threading.