I use vim, but when I want the features of an IDE like Eclipse, I use Eclim ( http://eclim.org/ ) to access a headless instance of Eclipse fairly seamlessly right from vim. The biggest things are that when Eclipse has an issues it's even less graceful about it than when you're using the GUI, and that I sometimes futz around a bit when I pull in a new dependency to get it recognized properly. Maybe that's an issue with the GUI Eclipse too, but I haven't used Eclipse "normally" in a while.
People have also made plugins to support using Eclim with other popular editors as well.