title: Concatenating multiple ArrayLists
body: <p>Is there a method to concatenate multiple <code>ArrayLists</code>?</p>
  
  <p>ex:</p>
  
  <pre><code>ArrayList&lt;Integer&gt; a
  ArrayList&lt;Integer&gt; b
  ArrayList&lt;Integer&gt; c
  
  ArrayList&lt;Integer&gt; d = a + b + c
  </code></pre>
  
  <p>where d is a single <code>ArrayList&lt;Integer&gt;</code> that contains all of the values of a,b,c in their preserved orders</p>