A Java GUI Programmer's Primer - This book contains an introduction to the systematic development of Graphical User Interfaces (GUIs) using the Java environment.

http://www.scism.lsbu.ac.uk/jfl/jibook/jicontents.html

Advanced Programming for the Java 2 Platform - This book is for developers with more than a beginning level of understanding of writing programs in the Java programming language. The example application is written with the Java� 2 platform APIs and explained in terms of functional hows and whys, so if you need help installing the Java platform, setting up your environment, or getting your first application to work, you should first read a more introductory book.

http://java.sun.com/developer/onlineTraining/Programming/JDCBook/

Java Thin-Client Programming - This free java book is an IBM redbook. There may have been a link to it here before, but they seem to keep moving things around over there at IBM.

http://www.redbooks.ibm.com/redbooks/SG245118.html

IBM Redbook - Java Thin-Client Programming for a Network Computing Environment.

http://www.redbooks.ibm.com/redbooks/SG245115.html

Sams Teach Yourself Java 2 in 24 Hours - Sams Teach Yourself Java in 24 Hours is a step-by-step tutorial that teaches someone with no previous programming experience how to create simple Java programs and applets.

http://www.informit.com/library/library.aspx?b=STY_Java2_24hours

Thinking in Java - Bruce Eckel's free Java book can be downloaded for free.

http://www.mindview.net/Books/TIJ/

The JavaTM Virtual Machine Specification - In The JavaTM Virtual Machine Specification, Second Edition, Sun's designers of the Java virtual machine provide comprehensive coverage of the Java virtual machine class file format and instruction set.

http://java.sun.com/docs/books/jvms/second_edition/html/VMSpecTOC.doc.html

Securing Java on the Web - Free online Java book.

http://www.securingjava.com/toc.html

Java Look and Feel Design Guilelines - Free online Java book.

http://java.sun.com/products/jlf/ed1/dg/higtoc.nf.htm