title: Why ArrayList<Integer> Contains is not working?
body: <p>I have:</p>
  
  <pre><code>ArrayList&lt;Integer&gt; onlyOne = new ArrayList&lt;Integer&gt;();
  onlyOne.add(Integer.valueOf(3));
  
  ArrayList&lt;Integer&gt; two = new ArrayList&lt;Integer&gt;();
  two.add(Integer.valueOf(3));
  two.add(Integer.valueOf(4));
  
  boolean check = two.contains(onlyOne);
  </code></pre>
  
  <p>But this <strong>always</strong> returns false, why?</p>