It's amazing how much is assumed in most after-market Java books! I can't estimate how often I've seen, "It is assumed you know about Threaded Programming, and therefore it is not covered here." Well, good news, It IS covered here. And is is covered well.
As a professional programmer for 20 years, I can attest to the fact that Thread programming is the most schizophrenic of disciplines. In addition, since most legacy thread concepts come from 'procedural' languages, the Java implementation tends to be hard to hold on to.
I found this book to be a wonderful 'primer' into Java's Thread capabilities. It doesn't attempt to relate to older languages. It starts from the begining, and presents its subject clearly. It's a good learning tool, and is organized well enough to be a reliable refference.
Even if you have experience with threading, this is worth it to orient your head to Java Threading.