I had some (one year as a university student) C skills and when I wanted to learn Java 2, I bought the Core Java 2 duo. This two vol. set is the best I've seen (I have read other books after beginning with these). The first book is more of a tutorial, but this second part is clearly a reference that can be read in any order. It is a good cover to cover read too. If you want nothing but a reference, then go for the Java In A Nutshell, but if you want someone to quickly explain how to really use the stuff too, then buy the Core Java 2 duo.