java超市收银系统进阶

package demo;

import java.util.Scanner;

public class demo01 {

	public static void main(String[] args) {
		ShopSys s = new ShopSys();
		System.out.print("接待员姓名为：");
		Scanner scanner = new Scanner(System.in);
		String str = scanner.next();
		
		int choose = 0;
		double sum = 0;
		do {
			System.out.println("*******欢迎使用拼夕夕购物结算系统，接待员：" + str + "*******");
			System.out.println("1.输入商品信息");
			System.out.println("2.查询待付金额");
			System.out.println("3.结算");
			System.out.println("4.退出系统");
			System.out.println("请输入你的选择：");
			choose = scanner.nextInt();
			switch (choose) {
			case 1:
				sum = s.SaveShop();
				break;
			case 2:
				s.CheckShop(sum);
				break;
			case 3:
				s.PayShop(sum);
				break;
			case 4:
				System.out.println("退出成功！");
				break;
			default:
				System.out.println("输入有误，请重新输入！");
				break;
			}
		} while (choose != 4);
			}
       		 }


            class ShopSys {

         
            	public double SaveShop() {
            		System.out.println("请输入需要计算的商品数量：");
            		Scanner scanner = new Scanner(System.in);
            		int n = scanner.nextInt();
            		double sum = 0;
            		double[] arr = new double[n];
            		for (int i = 0; i < n; i++) {
            			System.out.println("请输入第" + (i + 1) + "件商品的金额：");
            			arr[i] = scanner.nextDouble();
            			sum = sum + arr[i];
            		}
            		return sum;
            	}
            	
            	
        
            			public void CheckShop(double sum) {
            			System.out.println("您购买的商品待付金额为" + sum);
            		}
            	
            	
            	
      	
           	
		   public void PayShop(double sum) {
			System.out.println("请输入支付金额：");
			Scanner scanner = new Scanner(System.in);
			double pay = scanner.nextDouble();
		if (pay < sum) {
			System.out.println("您输入的金额小于购买商品的金额，请重新支付！");
			// 输入的金额小于购买商品的总金额时，一直重复输入，直到输入的金额大于商品的总金额
			pay = scanner.nextDouble();
		}
		if (pay > sum) {
			System.out.println("您支付了" + pay + "元，找您" + (pay - sum) + "元！");
		}
	}


}