I like Java Threads published by O'Reilly. Checkout Javaranch bunkhouse for great book reviews. I also like the Core Java volume II ( Advanced Java conepts ) which has a chapter on Threads. Remember, both of these books discuss threads in detail which may be more than what is required for your SCJP exam. Another fool-proof way of mastering the thread concepts is by writing programs!..write a lot of code, experiment different concpets. I bet that'll help you more than reading a book Also checkout Threads and Synchronization forum.
Good luck, Ajith
Open Group Certified Distinguished IT Architect. Open Group Certified Master IT Architect. Sun Certified Architect (SCEA).