When the simple code below is run, the following error is reported. /Users/enebo/jruby/releases/jruby-0_9_8/src/builtin/javasupport.rb:486:in `__jcreate!': wrong # of arguments for constructor (NameError) — require 'java' Observable = java.util.Observable Observer = java.util.Observer class Weather < Observable def initialize(temp) @temp = temp end def temperature @temp end def temperature=(temp) @temp = temp setChanged notifyObservers end end class Meteorologist < Observer def initialize(weather) weather.addObserver(self) end def update(observable, arg) puts "The current temperature is #{observable.temperature}." end end weather = Weather.new(70) meteorologist = Meteorologist.new(weather) weather.temperature = 100