Question: What about when you need to do something that the IDE doesn't have built in?
(I use Emacs. Many years ago (mid 90s) I used the IDE that came with Turbo C++, but haven't used Visual Studio or Eclipse, and am genuinely curious how they handle extensibility.)
They don't handle it well. I haven't used Visual Studio in a few years, but Eclipse has plugins that you can get off eclipse-plugins.org. unfortunately, they are not all free :-( Emacs is certainly superior for most everything.
Honestly, I don't see it. It's been a while since I used emacs for development, but the entire reason I moved from emacs to eclipse was because I had at least a 10x improvement in productivity working with large [java] code bases.
Has jdee come a long way since? I just checked and it doesn't look like it.
As far as java on emacs, I can't exactly comment. Java is my one main exception to emacs. Its not that I dislike it on emacs, I just have never tried it there. I learned on Eclipse it worked for what I needed (although Eclipse is horribly slow...).
(I use Emacs. Many years ago (mid 90s) I used the IDE that came with Turbo C++, but haven't used Visual Studio or Eclipse, and am genuinely curious how they handle extensibility.)