I needed to do some reflection today so I fired up interactive JRuby (jirb) to inspect a jar.  Surprisingly, I couldn’t remember exactly how to use Java classes in JRuby.  So I did some searching on the internet and found this to be a common question with many answers.  So I figure I will document it here in case I forget how in the future.

Add it’s folder to the load path, require it, then use it!

$: << '/path/to/my/jars/'
require 'myjar'

# so we don't have to reference it absolutely every time (optional)
include Java::com.goodercode

my_object = SomeClass.new