A source code analysis tool. With it, you can edit your source code, display relationships between classes and functions and members, and display call trees. [Open Source]
Integrated Development Environment for Java, written in Java itself. It provides syntax highlight, automatic code completition, edit-compile-execute cycle. It require JDK 1.4. [Open source]
Programmer's text editor; includes support for dynamic download and installation of new plugins from a central plug in server. Java, XML and JSP source are well supported.
Gwydion Project's hypercode programming environment for Java supports complex hypertext interlinking, multiple groupings of code, and searching of code and documentation fragments. [Open Source, Public Domain]