Java数据结构与算法之队列

package com.lee.queue;

public class ArrayQueueDemo {
    public static void main(String[] args) {
        ArrayQueue queue = new ArrayQueue(3);
        queue.addQueue(1);
        queue.addQueue(2);
        queue.addQueue(3);
        queue.showQueue();
        System.out.println(queue.getQueue());
        queue.showQueue();
        System.out.println(queue.headQueue());
        System.out.println(queue.getQueue());
        System.out.println(queue.getQueue());
        System.out.println(queue.headQueue());
    }
}

class ArrayQueue{
    private int maxSize;    //队列最大存储容量
    private int front;      //指向队列头的前一个位置
    private int rear;       //指向队列尾的位置
    private int[] arr;      //存放队列的数组

    public ArrayQueue(int maxSize){
        this.maxSize = maxSize;
        arr = new int[maxSize];
        front = -1;
        rear = -1;
    }

    //判断队列是否满
    public boolean isFull(){
        return rear == maxSize - 1;
    }

    //判断队列是否为空
    public boolean isEmpty(){
        return rear == front;
    }

    //入队
    public void addQueue(int n){
        if(isFull()){
            System.out.println("队列满，不能入队");
            return;
        }
        rear++;             //尾部标志后移
        arr[rear] = n;      //添加数据
    }

    //出队
    public int getQueue(){
        if(isEmpty()){
            throw new RuntimeException("队列空，不能出队");
        }
        front++;            //头部标志后移
        return arr[front];  //返回数据
    }

    //显示队列数据
    public void showQueue(){
        if(isEmpty()){
            System.out.println("队列空，没有数据");
        }
        for(int i = 0; i < arr.length; i++){
            System.out.println("arr["+ i +"]=" + arr[i]);
        }
    }

    //显示队列头数据
    public int headQueue(){
        if(isEmpty()){
            throw new RuntimeException("队列空，没有数据");
        }
        return arr[front + 1];
    }
}