Normally you would compile java using this:
javac Hello.java java Hello
Under certain conditions you can compile from Vim by just typing :make by placing this in .vimrc
autocmd Filetype java set makeprg=java\ %
Recently it hasn't been working though.
I've figured out that the path is the problem. How do I include it in my vimrc? I'm not sure exactly what the semantics behind that would be.