After I got the Java port of the GNU Chess engine working last month, I mentioned converting XBoard to Java to provide a GUI for the engine. These days I’m investigating using Jin as a GUI. Jin is a Java client app for Internet chess servers. The architecture is pluggable with plug-ins for FICS and ICC. My plan is to make a plug-in for local engines, perhaps pretending to be other players on the network to play against.
Before doing any of that though, I realized I could run XBoard on my Mac within X11 and let it talk to chessbox_gnu4j via the command line like it talks to other engines. Putting the jar file in the same directory as XBoard, the command to launch XBoard and have it use the Java engine is:
./xboard -fcp "java -cp chessbox_gnu4j.jar org.chessbox.gnu4j.Main"
Playing this way uncovered a couple of bugs, which I have fixed. Taking back a move and starting a new game didn’t work. I’ve updated the download at chessbox.org to version 1.02.