Why does java linkedlist implementation use the interface deque?

Question

I was looking at the java implementation of LinkedList, and found this:

public class LinkedList<E> 
       extends AbstractSequentialList<E> implements List<E>,
               Deque<E>, Cloneable, java.io.Serializable

Why should a LinkedList support the Deque interface? I understand the desire to add elements to the end of the linked list, but those methods should have been incuded in the List interface.

Answer 1

The LinkedList implementation happens to to satisfy the Deque contract, so why not make it implement the interface?