DrJava was included in this overview of Java IDEs :
Dr. Java- This is a lightweight IDE geared towards students in introductory level classes, including the Advanced Placement Computer Science course. Dr. Java has support for evaluating snippets of code without compiling them. In addition, Dr. Java supports the AP Computer Science GridWorld API, having features to aid developers in getting it setup as well as some basic GridWorld tutorials.
One commenter even listed DrJava as his favorite. I agree, but I’ve probably made DrJava organically grow around me.