Install

Use pathogen and clone this into your $VIM/bundle directory.

If not using pathogen, copy the contents of doc into $VIM/doc and do a :helptags $VIM/doc to generate the tag list.

Using

When editing a Java file:

:help ArrayList

I find it helpful to do:

set keywordprg=

in my .vimrc so that the "K" command will look up the javadoc of the class I'm on

While hovering over a class name you can type while in the command-line mode and it will paste the name.