SCJP Exam for J2SE 5 by Paul Sanghera (it's designed for people taking the cert but it's pretty good) Effective Java (teaches you the common pitfalls) Concurre

SCJP Exam for J2SE 5 by Paul Sanghera (it's designed for people taking the cert but it's pretty good) Effective Java (teaches you the common pitfalls) Concurrency in practice (if you're doing multithreaded stuff)