title: JRuby limitations when working with Java Classes
body: <p>As far as I understand JRuby, it is perfectly possible to use Java class inside JRuby code and vice versa, however, I still don't understand few things.</p>
  
  <ul>
  <li>can JRuby work with Java Annotations?</li>
  <li>is it possible to use reflection from JRuby on Java class?</li>
  <li>is it possible to use reflection from Java on JRuby class?</li>
  <li>do I have executable classes in JRuby?</li>
  <li>is it possible to redefine Java class inside of JRuby script? (the same way as I can redefine eg. Integer in C Ruby)</li>
  <li>are there any other limitations, that prevent using JRuby as part of any Java application?</li>
  </ul>