title: Use of extends keyword in generics
body: <p>I am trying this - </p>
  
  <pre><code>List&lt;? extends Integer&gt; l = new ArrayList&lt;Integer&gt;();
  l.add(10);
  </code></pre>
  
  <p>and compiler says - </p>
  
  <pre><code>The method add(int, capture#1-of ? extends Integer) in the type List&lt;capture#1-of ? extends Integer&gt; is not applicable for the arguments (int)
  </code></pre>
  
  <hr>
  
  <p>Why i am not able to add an integer to a List of Integer, Why compiler is not complaining at first line itself if i will not be able to add integers?</p>