Head First Java, 2nd Edition [ILLUSTRATED] (Paperback)
by Kathy Sierra, Bert Bates

A wonderful job of explaining not only the how-to, but also the "why" of Java fundamentals, in very down-to-earth language.

Head First Design Patterns (Head First) [ILLUSTRATED] (Paperback)
by Elisabeth Freeman, Eric Freeman, Bert Bates, Kathy Sierra

Written in a typically Head First refreshing style, this is one of the easiest to read and absorb among the major reference sources for design patterns.