Cross-platform: Linux, Mac OS X, Solaris, Windows
Free and open source software community...
The Eclipse IDE for Java Developers contains what you need to build Java applications. Considered by many to be the best Java development tool available, the Eclipse IDE for Java Developers provides superior Java editing with validation, incremental compilation, cross-referencing, code assist; an XML Editor; Mylyn; and much more.
Just working out which version you want to download takes about 3 hours . Pros: Seriously customisable. Cons: Seriously customisable.
The mother of all development platforms, pretty much has it all, sweet satisfaction when you realize it does most of what you want and and even more of what you didnt know you wanted. Pros: Versatile, comprehensive, customisable. Cons: Takes a while to get the hang of it.