I’ve always wanted Emacs to be able to open Java class files. This week I picked up the development of JReversePro and wrote a little Emacs interface to it.

I started by looking around for an open-source, command-line Java decompiler. Almost all had no activity since 2004-2008. JReversePro was last touched in January, 2010 so seemed like a good candidate to pick up and continue.

I updated the run scripts, made changes to the spacing, started work on JSR-14 (Adding Generics to the Java Programming Language) and wrote an Emacs script for automatically decompiling .class files.

If you want to try it out, build JReversePro:

git clone https://github.com/pufuwozu/jreversepro.git
cd jreversepro
mvn package

In Emacs, use M-x load-file to load the jrevpro.el file under the scripts directory. Use M-x set-variable jrevpro-script to change the location to the jrevpro script under the same directory. You should now be able to open a .class file and have it automatically decompiled to Java.