This is a crappy port of DmxPy to Java.
Instantiate:
DmxJava dmx = new DmxJava();
Set a DMX address's value:
dmx.setChannel(dmx_address, value);
Receive DMX packet to be sent
byte[] dmx_packet = dmx.render(); You can now send the packet to the ENTTEC using whatever serial libary you are using.