title: Java Hash Collection
body: <p>There is a class called HashSet in Java</p>
  
  <p>For example, I'll add following int-shaped value to HashSet, </p>
  
  <p>[input]</p>
  
  <pre><code>1,2,3,4,5,6,1,2,3,1, 
  </code></pre>
  
  <p>[hash structure]</p>
  
  <pre><code>1,1,1
  2,2
  3,3
  4
  5
  6
  </code></pre>
  
  <p>Is there the collection to become such a structure?</p>