gistfile1

~/projects/jruby ➔ cat my_java_thing.rb 
require 'java'

java_package 'foo.bar'

class SomeJavaThing
  java_signature 'void main(String[] args)'
  def self.main(args)
    puts args.to_a
  end
end

~/projects/jruby ➔ jrubyc --javac my_java_thing.rb 
Generating Java class SomeJavaThing to /Users/headius/projects/jruby/foo/bar/SomeJavaThing.java
javac  -d /Users/headius/projects/jruby -cp /Users/headius/projects/jruby/lib/jruby.jar:. /Users/headius/projects/jruby/foo/bar/SomeJavaThing.java

~/projects/jruby ➔ java -cp .:lib/jruby.jar foo.bar.SomeJavaThing hello world
hello
world