title: Want non duplicate elements from list
body: <p>From following list I need only 'wow' and 'quit'.</p>
  
  <pre><code>List&lt;String&gt; list = new ArrayList();                
  list.add("test");       
  list.add("test");                   
  list.add("wow");    
  list.add("quit");
  list.add("tree");
  list.add("tree");
  </code></pre>