title: remove unused class from rt.jar in jre
body: <p>i tried to remove unused .class files from rt.jar and bundle it to my program but there are 2 problems:</p>
  
  <ol>
  <li><p>java is a JIT language and some required libs will load after some process like click and ... so if you delete files with ERROR-SUCCESS method you will fail.</p></li>
  <li><p>many of classess needed by java runtime for first prepration.</p></li>
  </ol>
  
  <p>so how i can find out which of class files are not required?</p>