Eclipse is good. But as a die hard Emacs fan, Emacs is the IDE for me.
Install this eclipse plugin so that at the click of a button in the
toolbar, the current active file in Eclipse will open in Emacs. It
will also try to position the cursor at the same place it was in the
Eclipse window. You can configure the plug-in to execute any lisp code
after doing this.

The original plugin used gnuserve but has been ported to emacsclient
for simplifying the installation.

Original blog post: http://anirudhsasikumar.net/blog/2009.05.01.html

* Installation

1. Copy com.anirudh.emacseclipse_1.3.0.jar into the eclipse/plugins folder.

2. Copy eclipse-goto-offset.el to your hard disk and load it on
startup by editing your .emacs file:

(load "~/elisp/eclipse-goto-offset.el")

The plugin will work without the second step, but character
positioning may not be accurate without it.

3. If emacsclientw is not in your PATH variable, go to the plugin
settings page in Eclipse and fill in the full absolute path to
emacsclientw which should be in the bin folder of your Emacs
installation.

4. Enable server mode in Emacs by either running the command server-start
in an existing Emacs process or run Emacs using the command-line option '--daemon'
For further information please see: http://www.gnu.org/software/emacs/manual/html_node/emacs/Emacs-Server.html

Tested on Eclipse 3.5, 3.8; Emacs 24.3.

* Contributors

Rick Watson contributed a fix for finding the correct buffer offset.