Java

Java on wikipedia

Books

• The Java Programming Language, Fourth Edition, 
  Ken Arnold, James Gosling, David Holmes,
  Addison-Wesley, 2005, ISBN 0-321-34980-6(link is external)
• The Java Language Specification, Third Edition
  James Gosling, Bill Joy, Guy L. Steele Jr., Gilad Bracha, 
  Addison-Wesley, 2005, ISBN 0-321-24678-0(link is external)

• The Java tutorial
  The official Java tutorial by the original source.
  http://docs.oracle.com/javase/tutorial/index.html(link is external)

• Object Oriented Programming
  http://en.wikibooks.org/wiki/Object_Oriented_Programming(link is external)
• Java Programming
  http://en.wikibooks.org/wiki/Java_Programming(link is external)

• Data Structures and Algorithms with Object-Oriented Design Patterns in Java
  Preiss
  Wiley, 2000, 
  A Data Structure and Algorithms book which is a bit theoretical but I am sure you can make it.
  http://www.brpreiss.com/books/opus5/html/book.html(link is external)

Specification

Java Language and Virtual Machine Specifications(link is external)

Learning Java

• Java Video Tutorial(link is external) by y Derek Banas