jme_example.rb

require 'java'
require 'jme3_2012_08_02.jar'
java_import "com.jme3.app.SimpleApplication"

class Sample1 < SimpleApplication

  def simpleInitApp
    # This method is required for jME to work
    # defining as simple_init_app fails
  end

end

Sample1.new.start

swt_example.rb

require 'java'
require 'swt'

@style = Swt::Custom::StyleRange.new
# This works
@style.fontStyle = Swt::SWT::BOLD

# undefined method font_style= for StyleRange
#@style.font_style = Swt::SWT::BOLD

# Original method is
# style.fontStyle = SWT.BOLD;