In my experience most of the best Java learning resources are books - I got the most out of Joshua Bloch's Effective Java Second Edition which assumes some familiarity with the language. Bruce Eckel's Thinking in Java is an excellent introductory approach, particularly if you're new to OO, but you could probably give it a miss.
I don't know if it would apply to your development situation, but also consider investigating other JVM languages like Clojure and Scala - these two languages probably represent the future of the platform.
In my experience most of the best Java learning resources are books - I got the most out of Joshua Bloch's Effective Java Second Edition which assumes some familiarity with the language. Bruce Eckel's Thinking in Java is an excellent introductory approach, particularly if you're new to OO, but you could probably give it a miss.
I don't know if it would apply to your development situation, but also consider investigating other JVM languages like Clojure and Scala - these two languages probably represent the future of the platform.