title: How can I add a class file into a jar file inside another jar
body: <p>I have a jar file which contain another jar inside:</p>
  
  <pre><code>abc.jar --&gt; a.class, b.jar, c.txt
  </code></pre>
  
  <p>which <code>a.jar --&gt; x.class, y.class</code></p>
  
  <p>I want to add new class file <code>z.class</code> into <code>a.jar</code> &amp; return <code>abc.jar</code> with updated <code>a.jar</code></p>
  
  <p>1 way is that extract &amp; pack again.</p>
  
  <p>Can I do it on-fly without extracting? </p>