Error include_class "com.example.CallMe"

Running the example code from the JRuby Wiki. I’m not your programmer
savant, so I’m probably missing some of the basics. When running “JRuby
call_java.rb” I get the following error.

(eval):1:in include_class’: cannot load Java class com.example.CallMe
(NameError)

Any one have thoughts on remedy?