队列的基本概念

1. 队列的概念和基本特征

队列的特点是节点的排队次序和出队次序按入队时间先后确定, 即先入队者先出队, 后入队者后出队, 即我们常说的FIFO (first in first out)先进先出。

2. 实现队列

基于链表的实现:

public class LinkQueue {
    private Node front;
    private Node rear;
    private int size;
    public LinkQueue() {
        this.front = new Node(0);
        this.rear = new Node(0);
    }
    /**
     * 入队
     */
    public void push(int value) {
        Node newNode = new Node(value);
        Node temp = front;
        while (temp.next != null) {
            temp = temp.next;
        }
        temp.next = newNode;
        rear = newNode;
        size++;
    }

    /**
     * 出队
     */
    public int pull() {
        if (front.next == null) {
            System.out.println("队列已空");
        }
        Node firstNode = front.next;
        front.next = firstNode.next;
        size--;
        return firstNode.data;
    }
    
    /**
     * 遍历队列
     */
    public void traverse() {
        Node temp = front.next;
        while (temp != null) {
            System.out.print(temp.data + "\t");
            temp = temp.next;
        }
    }

    static class Node {
        public int data;
        public Node next;
        public Node(int data) {
            this.data = data;
        }
    }
//测试main方法
    public static void main(String[] args) {
        LinkQueue linkQueue = new LinkQueue();
        linkQueue.push(1);
        linkQueue.push(2);
        linkQueue.push(3);
        System.out.println("第一个出队的元素为:" + linkQueue.pull());
        System.out.println("队列中的元素为:");
        linkQueue.traverse();
    }
}