title: List LinkedList ArrayList
body: <pre><code>List arrayList = new ArrayList();
  List linkedList = new LinkedList();
  
  arrayList = linkedList;
  </code></pre>
  
  <p><code>arrayList</code> is an instance of <code>ArrayList</code>. <code>linkedList</code> is a instance of <code>LinkedList</code>. So if assign <code>linkedList</code> to <code>arrayList</code>, it should hit error but why does not?</p>