《数据结构》严蔚敏版（java解）——第三章 栈和队列04 链式队列操作

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package csdn.wj.linear;

import csdn.wj.assistant.Node;
import csdn.wj.assistant.Queue;
import csdn.wj.assistant.Queue.QueueEmptyException;

public class Queue02 implements Queue {
	private Node front;
	private Node rear;
	private int size;
	public Queue02() {
		front = new Node(size);
		rear = front;
		size = 0;
	}
	//返回队列的大小
	public int getSize() {
		return size;
	}
	//判断队列是否为空
	public boolean isEmpty() {
		return size==0;
	}
	//数据元素 e入队
	public void enqueue(Object e) {
		Node p = new Node((int)e);
		rear.next = p;
		rear = p;
		size++;
	}
	//队首元素出队
	public Object dequeue() throws QueueEmptyException {
		if (size<1)
			throw new QueueEmptyException("错误：队列为空");
			Node p = front.next;
			front.next = p.next;
			size--;
			if (size<1) rear = front;   //如果队列为空,rear指向头结点
			return p.data;
	}
	//取队首元素
	public Object peek() throws QueueEmptyException {
		if (size<1)
			throw new QueueEmptyException("错误：队列为空");
			return front.next.data;
	}
}