I recently wanted an easier way to look up Java class documentation from Emacs and found this project: Javadoc-Help
Works great. You add localtions (local or remote) with generated Javadoc and then this code will open up the page in your browser.
Installation was easy. I added the one .el file to my .emacs.d/lisp directory and then added the following lines:
;; Javadoc Help
(autoload 'javadoc-lookup "javadoc-help" "Look up Java class in Javadoc." t)
(autoload 'javadoc-help "javadoc-help" "Open up the Javadoc-help menu." t)
(autoload 'javadoc-set-predefined-urls "javadoc-help" "Set pre-defined urls." t)
(global-set-key [f8] 'javadoc-lookup)
(global-set-key [(shift f8)] 'javadoc-help)
This way I can use F8 (which is currently the Starcraft II random dice icon!) to look up Javadoc classes or go to the interface to add more locations. Perfect!