I sort of started pro-emacs when Java came out. There was JDE (which is still around) but it annoyed the hell out of me so I implemented a bunch of little things to help.
I got out of Java in the early 2000s but working in an Enterprise it's hard to avoid. I just refuse to use any of these IDE things. I'd rather not use Java than use one of those.
So here's my, probably growing, collection of things that I use to wrangle Java, some of them rescued from 20 years ago when Java started.
key binding
--- -------
C-c # nj-open-shell
C-c . nj-open-project
C-c 4 Prefix Command
C-c f nj-open-file-in-project
nj-open-project opens a project view with the java files listed.
nj-open-shell opens a shell in the top level of your project.
key binding
--- -------
RET nj-list-open
q nj-list-quit
nj-list-open opens a Java file from the list.
Something with a pom.xml file.
Emacs uses it's find-program. This may not be available, on Windows
for example.