Ruby has the heart, and Java has the reach. With JRuby, you can bring the best of Ruby into the world of Java. Written in 100% Java, JRuby has Ruby’s expressiveness and wide array of open-source libraries—it’s an even better Ruby. With Using JRuby, the entire JRuby core team helps experienced Java developers and Rubyists exploit the interoperability of their respective languages. With JRuby, you’ll be surprised at what’s now possible.