title: Why LinkedList and arraylist extends AbstractList in java?
body: <p>Why <code>LinkedList</code> and <code>ArrayList</code> extends <code>AbstractList</code> in <em>Java</em>?</p>
  
  <p>Abstract classes are used when we want to specify a common behaviour in implementation classes.</p>
  
  <p>But all the methods which are in <code>AbstractList</code> are overridden by <code>ArrayList</code> and <code>LinkedList</code>.</p>
  
  <p>So what is the use of extending this class?</p>