title: how to compile extended class in java?
body: <p>i want to compile <code>child.java</code> class an get <code>child.class</code>, child class extends parent class.
  i want child.class include all necessary code from parent class, in fact i can use it independently.</p>
  
  <p>is it possible?</p>
  
  <p>second Question: suppose we have a .jar library containing a.class , b.class , c.class ... i have make an updated version of a.class, how can i replace the new one with the original a.class in jar?  is it possible ?</p>
  
  <p>sorry for bad English.</p>