NetBeans is Sun's official Java IDE.

"NetBeans IDE includes comprehensive support for developing IDE
plug-in modules and rich client applications based on the NetBeans
platform. It also includes the intuitive GUI builder Matisse,
redesigned CVS support, support for Sun Application Server 8.2,
Weblogic9 and JBoss 4, and many editor enhancements including new
refactorings. NetBeans IDE is a robust, open source Java IDE
that has everything software developers need to develop cross-platform
desktop, web and mobile applications straight out of the box. ..."

NetBeans is modular, and many add-ons can be downloaded from
netbeans.org.  NetBeans is also used as the platform for many of
Sun's commercial development environments.