title: What exactly does this mean Collection<? extends E> c
body: <p>Some times, well a lot of times I see this thing occurring in the documentation. It leaves me wondering what to type. Could someone explain to me the meaning of this in clear dumbed down text :D. How this:</p>
  
  <pre><code>ArrayList(Collection&lt;? extends E&gt; c)
  </code></pre>
  
  <p>end up to be used as this:</p>
  
  <pre><code>new ArrayList&lt;&gt;(Arrays.asList("a","b","c"));
  </code></pre>
  
  <p>so I don't need to ask this "question" anymore by googling it, but being able to figure it out by myself.</p>