rJava is an r-process code developed by the Quark Nova Project at the University of Calgary (http://www.quarknova.ca).
From the rJava website (http://www.quarknova.ca/rJava/):
We present r-Java 2.0, an r-process nucleosynthesis code equipped with a simple-to-use graphical user interface (GUI) that solves a full reaction network of over 8000 nuclei. Built to be an instrument for the nuclear physics and astrophysics community, r-Java 2.0 allows users to test the effects of varying nuclear reaction rates as well as study the r-process in a host of different astrophysical environments. On top of solving an r-process reaction network over a large range of input parameters r-Java 2.0 computes; nuclear statistical equilibrium (NSE) distributions, fission mass fragmentation and allows for the investigation of individual nuclear reactions.