title: set value in 2d arraylist Java
body: <p>i have 2d ArrayList:</p>
  
  <pre><code>ArrayList&lt;List&lt;Integer&gt;&gt; group;
  group.add(Arrays.asList(i1, i2, i3));
  group.add(Arrays.asList(i4, i5, i6));
  group.add(Arrays.asList(i7, i8, i9));
  </code></pre>
  
  <p>how to set value on for example i5?</p>
  
  <p>i should use:</p>
  
  <pre><code>group.set(index, value); 
  </code></pre>
  
  <p>but how get correct index i5?</p>