I need help with the following Java code

In a doubly linked chain (as displayed bwloe) the first and last nodes each contain one null reference, since the first node has no previous node and last node has no node after it. In a circular doubly linked chain, the first node references the last node, and the last node references the first. Only one external reference is necessary - a reference to the first node - since you can quickly get to the last node from the first node. Use a circular doubly linked chain to implement the ADT deque. Name your class CircularDoublyLinkedDeque.

Here is the interface the class needs to implement

/** An interface for the ADT deque. @author Frank M. Carrano @author Timothy M. Henry @version 4.0 */ public interface DequeInterface { /** Adds a new entry to the front/back of this deque. @param newEntry An object to be added. */ public void addToFront(T newEntry); public void addToBack(T newEntry); /** Removes and returns the front/back entry of this deque. @return The object at the front/back of the deque. @throws EmptyQueueException if the deque is empty before the operation. */ public T removeFront(); public T removeBack(); /** Retrieves the front/back entry of this deque. @return The object at the front/back of the deque. @throws EmptyQueueException if the deque is empty. */ public T getFront(); public T getBack(); /** Detects whether this deque is empty. @return True if the deque is empty, or false otherwise. */ public boolean isEmpty(); /* Removes all entries from this deque. */ public void clear(); } // end DequeInterface

A Doubly Linked Implementation of a Deque -O D D G D - Doubly linked chain Doubly linked chain firstNode lastNode To boro to coarch