Available for download at http://drjava.org .
DrJava is a lightweight programming environment for Java designed to
foster test-driven software development. It includes an intelligent
program editor, an interactions pane for evaluating program text, a
source level debugger, and a unit testing tool.
In addition to bug fixes, this stable release supports Java 7 in addition
to Java 5 and 6. It is nearly identical to the previous beta release.