java - 了解链表队列的入队方法

Question

我无法理解链表队列的入队方法的代码。我理解 dequeue()、isEmpty()、First() 和 size()。首先，这是 LinearNode 类来创建新的节点对象:

public class LinearNode<T> {
    private T element;
    private LinearNode<T> next;

    /**
     * Constructor: Creates an empty node.
     */
    public LinearNode() {
        next = null;
        element = null;
    }

    /**
     * Constructor: Creates a node storing the specified element.
     * @param elem  The specified element that is to be kept by this LinearNode.
     */
    public LinearNode(T elem) {
        next = null;
        element = elem;
    }

    /**
     *  Returns the node that follows this one.
     * @return  The node that follows this one.
     */
    public LinearNode<T> getNext() {
        return next;
    }

    /**
     *  Sets the node that follows this one.
     * @param node  The node which is to follow this one.
     */
    public void setNext(LinearNode<T> node) {
        next = node;
    }

    /**
     *  Returns the element stored in this node.
     * @return  The element that is kept within this node.
     */
    public T getElement() {
        return element;
    }

    /**
     *  Sets the element stored in this node.
     * @param elem  The element that is to be kept within this node.
     */
    public void setElement(T elem) {
        element = elem;
    }
}

这是入队方法

public void enqueue(T element) {
    LinearNode<T> tmp = new LinearNode<T>(element);
    if (isEmpty()) {
        // set-up front to point to the new node
        front = tmp;
    } else {
        // add the node after the old tail node
        rear.setNext(tmp);
    }
    // update rear to point to the new node
    rear = tmp;
    count++; // increment size
}

我感到困惑的代码部分是 rear.setNext(tmp);我的意思是不应该是 temp.setNext(rear);如何使用 .setNext(); 方法关于LinearNode<T> rear;当你没有创建名为“rear”的新对象时，我能看到的唯一新对象称为“temp” ??

编辑这里是包含 Enqueue 方法的 LinkQueue 类:

public class LinkedQueue<T> implements QueueADT<T> {
private LinearNode<T> front; // front node of the queue
private LinearNode<T> rear;  // rear node of the queue
private int count;           // the current size of the queue

/**
 * Constructor: Creates an empty Queue.
 */
public LinkedQueue() { 
    count = 0;
    /* the following assignments are not actually necessary as references
     *  are initialised automatically to null, 
     *  but they are included for clarity.
     */
    front = null;
    rear = null;
}

Answer 1

从代码中我可以理解，front和rear只是指针。它们用于指向队列的第一个和最后一个节点。所以当你说:

rear.setNext(tmp);

您正在队列的最后一个节点之后标记新节点。

考虑这个队列:1,2,3,4

在此队列中，前面=1后=4

enqueue(5)

这导致 tmp=5

rear.setNext(5) 结果

1,2,3,4,5

rear=tmp 结果after=5 将后指针重置为最后一个节点