队列----循环数组实现队列

/**
 * 循环数组实现队列的演示代码
 */
package com.szy.structure.queues;

import java.util.Scanner;

public class CircularArrayQueues {
	private final int SIZE=5;  //数组大小
	private int FRONT; //前端
	private int REAR;  //末端
	private int[] queueArray=null;  //存储队列的数组

	public CircularArrayQueues(){
		FRONT=-1;
		REAR=-1;
		queueArray=new int[SIZE];
	}
	/**
	 * 向队列中插入元素
	 * @param info
	 */
	public void insert(int info){
		//如果栈已经满
		if ((FRONT==0&&REAR==SIZE-1)||(FRONT==REAR+1)) {
			System.out.println("队列已满");
			return;
		}
		//如果栈为空
		if (FRONT==-1) {
			FRONT=0;
			REAR=0;
		}
		else {
			//如果末端已经到达数组末尾
			if (REAR==SIZE-1) {
				REAR=0;
			}
			else {
				REAR++;
			}
		}
		queueArray[REAR]=info;
	}
	/**
	 * 从队列中删除元素
	 */
	public void remove(){
		if (FRONT==-1) {
			System.out.println("空队列！");
			return;
		}
		//如果栈中只有一个元素
		if (REAR==FRONT) {
			REAR=-1;
			FRONT=-1;
		}
		else {
			//如果前端位于数组末尾
			if (FRONT==SIZE-1) {
				FRONT=0;
			}
			else {
				FRONT++;
			}
		}
	}
	/**
	 * 输出栈中元素
	 */
	public void display(){
		if (FRONT==-1) {
			System.out.println("空队列！");
			return;
		}
		int front_position=FRONT;
		int rear_position=REAR;
		System.out.println("队列中元素：");
		if (front_position <= rear_position) {
			while (front_position <= rear_position) {
				System.out.print(queueArray[front_position]+" ");
				front_position++;
			}
		}
		else {
			System.err.println(rear_position);
			while(front_position<SIZE){
				System.out.print(queueArray[front_position]+" ");
				front_position++;
			}
			front_position=0;
			while(front_position<=rear_position){
				System.out.print(queueArray[front_position]+" ");
				front_position++;
			}
		}
		System.out.println("\n");
	}
	
	public static void main(String[] args) throws Exception {
		CircularArrayQueues queues=new CircularArrayQueues();
		int choice=0;
		while(true)
		{
			System.out.println("\n---MENU---");
			System.out.println("1.Insert");
			System.out.println("2.Delete");
			System.out.println("3.Display");
			System.out.println("4.Exit");
			System.out.println("----------");
			System.out.println("请选择：");
			Scanner scanner=new Scanner(System.in);
			choice=scanner.nextInt();
			switch (choice) {
			case 1:
			{
				System.out.println("请输入数字：");
				int input=scanner.nextInt();
				queues.insert(input);
			}
				break;
			case 2:
			{
				queues.remove();
			}
			break;
			case 3:
			{
				queues.display();
			}
			break;
			case 4:
				return;
			default:
				System.err.println("无效的输入！");
				break;
			}
		}
	}
}