Java IDEs / Editors

Eclipse
Already the dominant IDE for Java, free. Lots of plug-ins here and here. The plugins give Eclipse capabilities in anything from highlighting HTML to using UML to generate Java code. In most cases, installing a plugin involves:
- Downloading a ZIP or TAR archive
- Expanding the archive to a temporary directory
- The archive will have one or two folders in it: features and plugins
- Copy the files inside the features folder into the features folder inside your Eclipse installation folder. Copy the files inside the plugins folder to the plugins folder inside your Eclipse installation folder.
- My budding repository of Eclipse issuesmay help.
NetBeans
Another great, somewhat bulky IDE, free. [All Platforms]
JEdit
For quick changes, having a text editor is handy.
JEdit is a pretty nifty editor in Java. It is not light, but it is extremely powerful thanks to its plug-ins, which can be installed by the editor using its plugin manager.
Nothing wrong with emacs, vi or pico either.
JEdit can also do a great job editing XML for you - just make sure you have all the XML plug-ins installed.
PSPad
A very powerful, small, lightweight text and code editor.

Enavigo