[mahmud]

Hortsman & Cornell's, two volume "Core Java 1.2". I only read the first.

Gosling's "The Java Programming Language".

And Josh Bloch's "Effective Java".

After that, Java Concurrency in Practice.

Langr's "Agile Java" is good for just that.

Bloch, Goetz, and Doug Lea have each written excellent books on java concurrency.

That's just about all the java books I would want to recommend. Many j-books are trash.

[rkalla]

+1

Effective Java is a must-read once you understand Java. It points out what is magic and what is not. What takes up processing time and what doesn't.

It pulls the sheet back on the abstractions and shows you how everything works and what you should be aware of.

Doug Lea is a brilliant developer in the concurrency space. With his Executor framework that went into (Java 5?) he suddenly made threaded programming as easy as possible to get right.

[RodgerTheGreat]

Don't forget Java Puzzlers, also by Bloch: http://www.javapuzzlers.com/ Not only is it a fun read, but it delves very deeply into case studies of the dark corners of the Java language.

[andymoe]

Awesome. Thanks so much for the recommendations everyone.