隊(duì)列的鏈?zhǔn)酱鎯?chǔ)實(shí)現(xiàn)

使用單向鏈表來(lái)實(shí)現(xiàn)隊(duì)列；

把鏈表的頭部作為隊(duì)首, 把鏈表的尾部作為隊(duì)尾。

package com.wkcto.chapter02.queue;
/**
 * 隊(duì)列的鏈?zhǔn)酱鎯?chǔ)
 * @author 蛙課網(wǎng)
 *
 */
public class MyLinkQueue {
	private Node  front;		//隊(duì)首
	private Node  rear;			//隊(duì)尾
	private int size;			//元素的個(gè)數(shù)
	
	//返回元素的個(gè)數(shù)
	public int getSize() {
		return size;
	}
	//判斷隊(duì)列是否為空
	public boolean isEmpty() {
		return size == 0;
	}
	//入隊(duì)
	public void enQueue(Object e) {
		//根據(jù)添加的元素生成一個(gè)結(jié)點(diǎn)
		Node newNode = new Node(e, null);
		//把結(jié)點(diǎn)連接到隊(duì)列中
		if ( rear == null ) {
			//這是添加的第一個(gè)元素,即是頭結(jié)點(diǎn)也是尾結(jié)點(diǎn)
			rear = newNode;
			front = newNode;
		}else {
			//把結(jié)點(diǎn)鏈拉到隊(duì)列的尾部
			rear.next = newNode;
			rear = newNode ;		//rear指針指向新添加的元素
		}
		size++;			//元素個(gè)數(shù)加1
	}
	//出隊(duì)
	public Object deQueue() {
		//判斷隊(duì)列是否為空
		if (size <= 0 ) {
			throw new QueueEmptyException("隊(duì)列為空");
		}
		Object old = front.element ;
		front = front.next ;	 		//調(diào)整隊(duì)首指針 
		//如果出隊(duì)后,隊(duì)列為空, 調(diào)整尾指針 
		if (front == null) {
			rear = null;
		}
		size--;
		return  old;
	}
	//返回隊(duì)首元素
	public Object peek() {
		if (size <= 0 ) {
			throw new QueueEmptyException("隊(duì)列為空");
		}
		return  front.element;
	}
	
	//通過(guò)內(nèi)部類表示單向鏈表的結(jié)點(diǎn)
	private class Node{
		Object element;
		Node next;
		public Node(Object element, Node next) {
			super();
			this.element = element;
			this.next = next;
		}
		
	}
}