title: How do I loop thorough a 2D ArrayList in Java and fill it?
body: <p>I am trying to use 2D arrayLists in Java. 
  I have the definition: </p>
  
  <pre><code>ArrayList&lt;ArrayList&lt;Integer&gt;&gt; myList = new ArrayList&lt;ArrayList&lt;Integer&gt;&gt;();
  </code></pre>
  
  <p>How can I loop through it and enter in numbers starting from 1? 
  I know that I can access a specific index by using:</p>
  
  <pre><code>myList.get(i).get(j)
  </code></pre>
  
  <p>Which will get the value. But how do I add to the Matrix?</p>
  
  <p>Thanks</p>