Free Java Source Code
There appear to be hundreds of short code examples targeted at specific tasks, such as GZipping a file, various aspects of working with xml, Swing, Beans, the Java EE API and various frameworks.
Free java projects with source code. Examples include calculators, simple notepad applications and a Login System in Java using MS Access Database.
Planet Source Code Java Archive
Introduction to Programming Using Java, Sixth Edition - Source Code
This page contains links to the source code for examples appearing in the free, on-line textbook Introduction to Programming Using Java, Sixth Edition. You should be able to compile the files and use them.
Java source code index with a number of categories.
Sample Java Programs from a Java book
Free download of the program examples in a book entitled "Murach's Beginning Java 2"