We appreciate your enthusiasm and the fact that you're asking lots of questions! I'd like to make a recommendation though. It seems like many of your questions might fall into the category of: "I haven't done any of my own research, could you guys recite a paragraph out of a book for me?"
There are lots of good Java resources available, and many of them are free! It would be much better for all of us if you do a little research, then posted questions here when you get confused. For instance you could say something like:
"The Java language spec says blah, blah, blah about topic xyz" I thought it was more like blah2, blah2, blah2 - what's wrong with my understanding?"
If you ask questions like this, it'll help your understanding and learning, and it will also help the question answerers
The last idea is that you ought to put a more descriptive title on your post than "answer this".
The general idea at the ranch is that we're all volunteers, so you want to make it as easy as possible for us volunteers to help you!!
We look forward to lots more questions from you, welcome to the ranch!