Java has a ScriptEngine system that allows you to run/evaluate statements in a different language.
I know for a fact that JavaScript is supported, but I couldn't find any other languages to work with it.
Is, for example, Ruby implemented?
..I know for a fact that JavaScript is supported,..
ECMAscript, technically.
.. but I couldn't find any other languages to work with it. Is, for example, Ruby implemented?
No. The ECMAscript engine is the only one included by default, the last time I heard.
Update
The comments of Pointy below, suggest that the Nashorn engine has been deprecated and will be removed 'soon'.