"[...] I use emacs, which might be thought of as a thermonuclear word processor. It was created by Richard Stallman; enough said. It is written in Lisp, which is the only computer language that is beautiful. It is colossal, and yet it only edits straight ASCII text files, which is to say, no fonts, no boldface, no underlining. In other words, the engineer-hours that, in the case of Microsoft Word, were devoted to features like mail merge, and the ability to embed feature-length motion pictures in corporate memoranda, were, in the case of emacs, focused with maniacal intensity on the deceptively simple-seeming problem of editing text. If you are a professional writer—i.e., if someone else is getting paid to worry about how your words are formatted and printed— emacs outshines all other editing software in approximately the same way that the noonday sun does the stars. It is not just bigger and brighter; it simply makes everything else vanish."
— Neal Stephenson , In the Beginning Was the Command Line
I consider myself a VIM-guy but I use Emacs org-mode for organizing some of my self-study notes. Using Emacs is like going to a place where you suddenly can do almost everything from within your comfy little nerd cave. All the greybeards know this. But programming in Java in the editor hasn't been exactly the smooth ride IDEs like IntelliJ or NetBeans gives you, but, to be honest, I think there's a place for learning a language without the helping hand of an intelligent IDE. At least when starting out, when you're doing the groundwork. What if you only know how to program when inside an IDE, which completes everything for you, gives you templates, marks possible errors with squiggly lines, automtaically imports libraries etc?
So, I guess I believe in doing manual labor to really "internalize" the know-how.
But eclim in Emacs is intriguing, so, yeah, that'll probably happen in the near future, if for no other reason than customization is king. :)