title: How do I implement nested ArrayList?
body: <p>I want to implement a data structure which looks something like this.</p>
  
  <pre><code>{{RowID, N1, N2, N3},
   {RowID, N4, N5, N6},
   {RowID, N7, N8, N9}}
  </code></pre>
  
  <p>And goes on. It basically is a table in Java with 3 columns and RowID.
  What data structure should I use and how do I implement it as in code?</p>