SE books you must read: Effective Java

Although this book is kind of old, is still valid. All its concepts and best practices are still being used and its author is an authority in the development world > Joshua Bloch.

This was the first book I read when I got into professional development, and believe when I say that is one of the mandatory books to read if you want to write something functional in Java.

Effective Java at Amazon

PS: I would like to share the ebook version of it, but I'm not sure about the licensing/copying policies.