NetBeans IDE 6.8
The only IDE you need! Runs on Windows, Linux, Mac OS X and Solaris. NetBeans IDE is open-source and free.
The NetBeans IDE is a free, open-source Integrated Development Environment for software developers. You get all the tools you need to create professional desktop, enterprise, web and mobile applications, in Java, C/C++ and even Ruby. The IDE runs on many platforms including Windows, Linux, Mac OS X and Solaris; it is easy to install and use straight out of the box.
Download: NetBeans IDE 6.8