Question

I decided to check out JRuby and JOGL to see if I could get some graphics sim stuff running. I’ve got the classpath set up and the OpenGL things included properly. Following some tutorials, they suggest using an AWT frame instead of a Swing one, as Swing won’t support graphics acceleration (which is really what I’m looking for).

I can’t figure out how to close the AWT frame from Ruby, however. I have a WindowAdapter that fires a Kernel.exit event when the close button on the frame is clicked. It looks like this:

class Controller < WindowAdapter
  def windowClosing(event)
    Kernel.exit
  end
end

The Frame adds this with add_window_listener(Controller.new). The event successfully fires when I click the close button, but it spits out the following error:

Exception in thread "AWT-EventQueue-0" org.jruby.exceptions.RaiseException: (SystemExit) exit

Calling Kernel.exit from the Frame’s initialize successfully exits the program. So I’m not sure why calling it from the listener fails. I know in java you can define an anonymous WindowAdapter inline, but I have no idea what the syntax for that would be in Ruby.

Answer 1

I did some extra searching and experimentation and found an answer. It appears to be a quirk of the Ruby implementation in the JVM. Calling exit or Kernel.exit from inside the WindowAdapter is useless.

Calling java.lang.System.exit(0), however, does work. I’m not sure why the distinction should make a difference. I would expect exit to alias to the Java system command, but it apparently doesn’t Hope this is helpful to anyone else who might run into the same problem.