Advantages of Java over Ruby/JRuby

Question

I am learning Java. I have learned and used Ruby. The Ruby books always tell the advantages of Ruby over Java. But there must be some advantages, that's why lots of people (especially companies) use Java and not Ruby. Please tell the absolute(not philosophical!) advantages of Java over Ruby.

Answer 1

• Many more developers experienced with Java than with Ruby.
• Many existing libraries in Java (That helps JRuby too).
• Static typechecking (can be seen as advantage and as disadvantage).
• Existing codebase that has to be maintained.
• Good tool-support.
• More and deeper documentations and tutorials.
• More experiences with good practices and pitfalls.
• More commercial support. That's interesting for companies.

Many of these advantages are the result, that the Java-ecosystem is more matured, than that around Ruby. Many of these points are subjective, like static vs. dynamic typing.