Understand for Java is a reverse engineering, documentatin, code
exploration and metrics tool for Java source code. It offers code
navigation using a detailed cross reference, a syntax colorizing
"smart" editor, and a variety of graphical reverse engineering
views. Understand for Java is an interactive development environment
(IDE) designed to help maintain and understand large amounts of
Java code.

You need a limited time period license to run the product in
evaluation mode or a purchased permanent license. Both can be
obtained in the www site.

WWW: http://www.scitools.com/