（系统）商店购物管理系统

    package day62;
    
    public class Custom {
    String ID;
    String passWd;
    
    public Custom(String iD, String passWd) {
        this.ID = iD;
        this.passWd = passWd;
    }
    
    public int check(int sum) {
        if ((this.ID).equals("TOM") && (this.passWd).equals("123456")) {
            System.out.println("登陆成功");
            sum = 1;
        } else {
            System.out.println("账号密码不匹配");
            sum = 0;
        }
        return sum;
    }
    }

    package day62;
    
    import java.nio.channels.ShutdownChannelGroupException;
    
    public class Thing {
    int num = 0;
    double price = 0.0;
    String name = "";
    
    public Thing() {
    }
    
    public Thing(int num, String name, double price) {
        super();
        this.num = num;
        this.price = price;
        this.name = name;
    }
    
    public void show() {
        System.out.println("*********************欢迎进入商品批发城*********************");
        System.out.println("\t编号\t商品\t价格");
        System.out.println("\t1\t电风扇\t124.23");
        System.out.println("\t2\t洗衣机\t4,500.0");
        System.out.println("\t3\t电视机\t8,800.9");
        System.out.println("\t4\t冰箱\t5,000.88");
        System.out.println("\t5\t空调机\t4,456.0");
        System.out.println("******************************************************");
    }
    
    public double change(int sum, int add) {
        Thing goods = null;
        switch (sum) {
        case 1:
            goods = new Thing(1, "电风扇", 124.23);
            break;
        case 2:
            goods = new Thing(2, "洗衣机", 4500.0);
            break;
        case 3:
            goods = new Thing(3, "电视机", 8800.9);
            break;
        case 4:
            goods = new Thing(4, "冰箱", 5000.88);
            break;
        case 5:
            goods = new Thing(5, "空调机", 4456.0);
            break;
        }
        double price = goods.price * add;
    
        return price;
    }
    
    }

    package day62;
    
    import java.util.Scanner;
    
    public class ThingTest {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int sum = 0;
        do {
            System.out.println("请输入您的账号");
            String id = scanner.next();
            System.out.println("请输入您的密码");
            String pw = scanner.next();
            Custom custom = new Custom(id, pw);
            sum = custom.check(sum);
        } while (sum == 0);
        Thing thing = new Thing();
        thing.show();
        System.out.println("请输入商品编号：");
        int num = scanner.nextInt();
        System.out.println("请输入商品的数量");
        int add = scanner.nextInt();
        System.out.println(thing.change(num, add));
    }
    }