Java Class File Editor

Quite an interesting tool to work on Java class files.

"This is a tool to open Java class file binaries, view their internal structure, modify portions of it if required and save the class file back. It also generates readable reports similar to the javap utility. Easy to use Java Swing GUI. The user interface tries to display as much detail as possible and tries to present a structure as close as the actual Java class file structure. At the same time ease of use and class file consistency while doing modifications is also stressed. For example, when a method is deleted, the associated constant pool entry will also be deleted if it is no longer referenced. In built verifier checks changes before saving the file. This tool has been used by people learning Java class file internals. This tool has also been used to do quick modifications in class files when the source code is not available. "

Java Class File Editor - http://classeditor.sourceforge.net/