java 队列

队列：数据项遵循先进先出，就像是排队上车一样，排在最前面的最先上车，排在最后面的最后一个上车

java代码：

package com.gjy.queue;


public class Queue {
	private  int maxSize;
	private long [] a;
	private int front;//队头
	private int rear;//队尾
	private int nItems;//计数器

	public Queue(int x){
		this.maxSize = x ;
		this.a = new long[maxSize];
		this.front = 0;
		this.rear = -1;
		this.nItems = 0;
	}

	public void insert(long j){
		if(rear == maxSize-1){
			rear = -1;
		}
		a[++rear] = j;
		nItems++;
	}

	public long remove(){
		long temp = a[front++];
		if(front == maxSize){
			front = 0;
		}
		nItems--;
		return temp;
	}

	public long peekFront(){
		return a[front];
	}

	public boolean isEmpty(){
		return (nItems == 0);
	}

	public boolean isFull(){
		return (front == maxSize);
	}

	public int size(){
		return nItems;
	}

	public static void main(String[] args) {
		Queue queue = new Queue(5);

		queue.insert(30);
		queue.insert(40);
		queue.insert(50);
		queue.insert(60);
		queue.insert(70);

		long a = queue.peekFront();
		System.out.println(a);
		while(!queue.isEmpty()){
			long n= queue.remove();
			System.out.println(n);
		}

	}
}