A couple other good ones that haven't been mentioned yet are Eclipse
(www.eclipse.org) which is free and Idea (www.intellij.com) which is not free
but
doesn't cost as much money as other IDE's. Personally I think these two IDE's
(along with Websphere which is built on top of Eclipse) are the best on the
market.
Of the two I like Idea better but Eclipse is almost as good.