Java: Which File reading Writing IO class to use and when?

As we all know with Java comes the very complicated list of IO classes plus there is another thing called NIO.

1. I was wondering if there is some tutorial/advice that could explain the situations and best IO to use for the problem( considering Web development in mind ).

2. I always get confused which one to use when, another query is How should I remember the implementation of all these classes. It get confusing all the time