title: Why to make a class immutable?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/3769607/why-do-we-need-immutable-class">Why do we need immutable class?</a>  </p>
  </blockquote>
  
  
  
  <p>Can anyone give me an example of a real world use of immutable class in java?
  What is the real purpose? For example why is String immutable</p>