Playing with JRuby

Over the last couple of days, many Ruby-ist Twitter followers will have noticed the flourishing overgrowth of tweets directed at and around the JRubyConf. Being a huge fan of both Java and Ruby, I was watching with boundless engrossment. Unfortunately I haven’t yet seen any of the slides/videos from the speakers but I’m hoping some come along soon.

I’ve taken this time to dive into JRuby a little more. And what’s the outcome? mind == blown. Whilst I never really take the time out to truly indulge myself in a language enough to build extensions or read through the generally boggling platform source code, I took a shine to JRuby. I’ve been shunned back into some Java code this week (Don’t worry, that’s a good thing) and I’ve enjoyed it (no, seriously). JRuby is the tip of the iceberg.

Here, let’s see a quick example of using the Standard Widget Toolkit to extend a JRuby script and implement a simple GUI example.

require 'java'
require '~/downloads/swt/swt'

module SWT
  import org.eclipse.swt.widgets.Display
  import org.eclipse.swt.widgets.Shell
end

class GUI
  include SWT

  def initialize(title)
    @display = Display.new
    @shell = Shell.new(@display)
    @shell.set_text(title)
    @shell.set_size(500, 300)
  end

  def run!
    @shell.open

    while not @shell.is_disposed
      if not @display.read_and_dispatch
        @display.sleep
      end
    end
  end

end

GUI.new("Howdy").run!

The second line is fetching the swt.jar file from the downloads directory and with JRubys magical java include, we have our hands on the import method, which is grabbing the Java classes and throwing them into a Ruby module. Right about now your brain is probably exploding, but it’s ok, you’ll get used to it.

Check out the calling Java from Ruby wiki article for some more awesome extras that will no doubt entertain you. I’m off to play with SWT and JRuby a little more! I’ll try and post something later this week with more information.