Data Structures, Algorithms, & Applications in Java
Chapter 10, Exercise 13

public class LinkedQueueWithNodeOperations
             extends LinkedQueue
{
   // constructors
   /** create an empty queue */
   public LinkedQueueWithNodeOperations(int initialCapacity)
      {super(initialCapacity);}

   public LinkedQueueWithNodeOperations()
      {this(0);}

   // new methods
   /** insert theNode at the rear of the queue */
   public void putNode(ChainNode theNode)
   {
      // append p to the chain
      if (front == null)
         front = theNode;                 // empty queue
      else 
         rear.next = theNode;             // nonempty queue

      rear = theNode;
      rear.next = null;
   }

   /** remove a node from the front of the queue
     * @return removed node
     * @return null if the queue is empty */
   public ChainNode removeNode()
   {
      if (isEmpty())
         return null;
      ChainNode frontNode = front;
      front = front.next;
      return frontNode;
   }
}