Comment ce code dans java serait changé pour en faire une file d'attente circulaire en utilisant la liste chaînée?

Question

En utilisant uniquement le pointeur externe arrière

public void enqueue(Object element) 
// Adds element to the rear of this queue. 
{ 
    LLObjectNode newNode = new LLObjectNode(element); 
    if (rear == null) 
     front = newNode; 
    else 
     rear.setLink(newNode); 
    rear = newNode; 
} 

public Object dequeue() 
// Throws QueueUnderflowException if this queue is empty; 
// otherwise, removes front element from this queue and returns it. 
{ 
    if (isEmpty()) 
     throw new QueueUnderflowException("Dequeue attempted on empty queue."); 
    else 
    { 
     Object element; 
     element = front.getInfo(); 
     front = front.getLink(); 
     if (front == null) 
     rear = null; 

     return element; 
    } 
} 

public boolean isEmpty() 
// Returns true if this queue is empty; otherwise, returns false. 
{ 
    if (front == null) 
     return true; 
    else 
     return false; 
} 

Answer 1

public void enqueue(Object element) 
... 
     rear.setLink(newNode); 
    rear = newNode; 
    rear.setLink(front); // make circular 
} 
... 
public Object dequeue() 
... 
    Object element; 
    element = front.getInfo(); 
    if (front.getLink() == front) { 
    // break circle for last element 
    front = null; 
    rear = null; 
    } else { 
    front = front.getLink(); 
    rear.setLink(front); // make circular 
    } 
...