title: How to get the unique ID of an object which overrides hashCode()?
body: <p>When a class in Java doesn't override <strong>hashCode()</strong>, 
  printing an instance of this class gives a nice unique number.</p>
  
  <p>The Javadoc of Object says about <strong>hashCode()</strong>:</p>
  
  <blockquote>
    <p><em>As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects.</em></p>
  </blockquote>
  
  <p>But when the class overrides <strong>hashCode()</strong>, how can I get
  its unique number?</p>