Java——购物车案例

package demo;

import java.util.Scanner;

public class ShopCarTest {
    public static void main(String[] args) {
        //1.定义商品类，用于后期创建商品对象
        //2.定义购物车对象，使用数组表示
        Goods[] shopCar = new Goods[100];
        //3.搭建操作架构
        while (true) {
            System.out.println("请选择如下命令操作");
            System.out.println("添加商品：addt查询商品：queryt修改数量：updatet结算金额：pay");
            Scanner sc = new Scanner(System.in);
            System.out.println("请输入命令：");
            String command = sc.next();
            switch (command){
                case"add":
                    addGoods(shopCar, sc);
                    break;
                case"query":
                    queryGoods(shopCar);
                    break;
                case"update":
                    updateGoods(shopCar, sc);
                    break;
                case"pay":
                    pay(shopCar);
                    break;
                default:
                    System.out.println("没有该功能");
            }
        }
    }

    public static void pay(Goods[] shopCar) {
        double money = 0.0;
        for (int i = 0; i < shopCar.length; i++) {
            Goods g = shopCar[i];
            if (g != null){
                money += (g.price * g.buyNumber);
            }else {
                break;
            }
        }
        System.out.println("您需要支付"+money);

    }

    public static void updateGoods(Goods[] shopCar, Scanner sc) {
        while (true) {
            System.out.println("请您输入id");
            int id = sc.nextInt();
            Goods g = getGoodsById(shopCar, id);
            if (g == null){
                System.out.println("对不起，没有该商品");
            }else {
                System.out.println(g.name+",请您输入最新购买数量：");
                int buyNumber = sc.nextInt();
                g.buyNumber = buyNumber;
                System.out.println("修改成功");
                queryGoods(shopCar);
                break;
            }
        }
    }

    public static Goods getGoodsById(Goods[] shopCar,int id){
        for (int i = 0; i < shopCar.length; i++) {
            Goods g = shopCar[i];
            if (g != null){
                if (g.id == id){
                    return g;
                }
            }else {
                return null;//找完了存在的商品，都没有找到
            }
        }
        return null;//找完了100个商品都没有找到
    }

    public static void queryGoods(Goods[] shopCar) {
        System.out.println("==========查询信息==========");
        System.out.println("编号tt名称tt价格tt数量");
        for (int i = 0; i < shopCar.length; i++) {
            Goods g = shopCar[i];
            if (g != null){
                System.out.println(g.id+"tt"+g.name+"tt"+g.price+"tt"+g.buyNumber);
            }else {
                break;
            }
        }
        System.out.println("===========================");
    }

    private static void addGoods(Goods[] shopCar, Scanner sc) {
        //1.录入信息
        System.out.println("输入编号:");
        int id = sc.nextInt();
        System.out.println("输入名称:");
        String name = sc.next();
        System.out.println("输入数量:");
        int buyNumber = sc.nextInt();
        System.out.println("输入价格:");
        double price = sc.nextDouble();
        //2.封装为一个对象
        Goods g = new Goods();
        g.id = id;
        g.name = name;
        g.buyNumber = buyNumber;
        g.price = price;
        //3.把这个商品对象添加到购物车
        for (int i = 0; i < shopCar.length; i++) {
            if (shopCar[i] == null){
                shopCar[i] = g;
                break;
            }
        }
        System.out.println("您的商品："+g.name+"已经添加成功");
    }

}

package demo;

public class Goods {
    int id;
    String name;
    double price;
    int buyNumber;
}