如何将数据返回后节点？我试图创建一个Dequeue后部功能

Question

如您所见，这是我的Deque。我认为我没有正确使用我的后指针。由于目前，它仅返回列表的正面值。我只需要帮助尝试弄清楚如何返回后方的值即可。它正确地将其删除，但是 它返回错误的值。抱歉，我试图尽可能保持紧凑。但是我想确保它可以运行

public class LinkedDeque <T> implements DequeInterface<T>
{
    protected LLNode<T> front;     // reference to the front of this queue
    protected LLNode<T> rear;      // reference to the rear of this queue
    protected int numElements = 0; // number of elements in this queue


  @Override
    public T dequeueRear ()throws QueueUnderflowException
    {


        if (isEmpty())
            throw new QueueUnderflowException("Dequeue attempted on empty queue.");

        LLNode<T> lastNode = front;
        LLNode<T> previoustolast = null;

            while(lastNode.getLink()!= null)
            {
                previoustolast = lastNode;
                lastNode= lastNode.getLink();

            }
            previoustolast.setLink(null);

            return lastNode.getInfo();


    }
 @Override
    public boolean isEmpty()
    {
        return (front == null);

    }
 public String toString() {
        String result = "";
        LLNode<T> temp = front;
        while(temp!=null) {
            result += temp.getInfo()+" ";
            temp = temp.getLink();
        }
        return result;
    }

}
public class LLNode<T>
{
  protected LLNode<T> link;
  protected T info;

  public LLNode(T info)
  {
    this.info = info;
    link = null;
  }

  public void setInfo(T info){
    this.info = info;
  }
  public T getInfo(){
    return info;
  }
  public void setLink(LLNode<T> link) {
    this.link = link;
  }
  public LLNode<T> getLink(){
    return link;
  }
}

public class LinkedDequeTestDriver
{
    public static void main(String[] args)
    {

        LinkedDeque<Integer> myLinkedDeque = new LinkedDeque();

        myLinkedDeque.enqueueRear(10);
        myLinkedDeque.enqueueRear(20);
        myLinkedDeque.enqueueRear(30);
        myLinkedDeque.enqueueRear(40);
        myLinkedDeque.enqueueRear(50);
        System.out.println("Queue");
        System.out.println(myLinkedDeque);
        myLinkedDeque.dequeueRear();
        System.out.println(myLinkedDeque);
        myLinkedDeque.dequeueRear();
        System.out.println(myLinkedDeque);
        System.out.println(myLinkedDeque.dequeueRear());
    }

public interface DequeInterface<T>
{
  void enqueueFront(T element) throws QueueOverflowException;
  // Throws QueueOverflowException if this queue is full;
  // otherwise, adds element to the front of this queue.

  void enqueueRear(T element) throws QueueOverflowException;
  // Throws QueueOverflowException if this queue is full;
  // otherwise, adds element to the rear of this queue.

  T dequeueFront() throws QueueUnderflowException;
  // Throws QueueUnderflowException if this queue is empty;
  // otherwise, removes front element from this queue and returns it.

  T dequeueRear() throws QueueUnderflowException;
  // Throws QueueUnderflowException if this queue is empty;
  // otherwise, removes rear element from this queue and returns it.

  boolean isFull();
  // Returns true if this queue is full; otherwise, returns false.

  boolean isEmpty();
  // Returns true if this queue is empty; otherwise, returns false.
  
  int size();
  // Returns the number of elements in this queue.

  String toString();
}