title: How to calculate the intersection of two sets?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/2851938/efficiently-finding-the-intersection-of-a-variable-number-of-sets-of-strings">Efficiently finding the intersection of a variable number of sets of strings</a>  </p>
  </blockquote>
  
  
  
  <p>Say, have two Hashset, how to calculate the intersection of them?</p>
  
  <pre><code>Set&lt;String&gt; s1 = new HashSet&lt;String&gt;();
  
  Set&lt;String&gt; s2 = new HashSet&lt;String&gt;();
  
  S1 INT S2 ?
  </code></pre>