[RyanCahoon]

You can compile the Squawk VM to run on desktop platforms. Instructions are given at http://java.net/projects/squawk/pages/BuildingSquawk with the small caveat that the SVN repository has moved to https://svn.java.net/svn/squawk~svn/trunk/. Note that this isn't a complete answer because a lot of the WPILib/FRC Framework functionality require native library calls, but it should get you very close if all you need is the NetworkTables.

Alternately, there's an effort going on at http://sourceforge.net/projects/frcsimulator/ with some alpha code to develop a "cRIO simulator" for the Java platform.