面向对象java简单购物车案例

源代码：
public class 购物车案例 {
    public static void main(String[] args) {
        Goods[] shopcar = new Goods[100];
        while (true) {
            System.out.println("请您选择如下命令进行操作:");
            System.out.println("添加商品到购物车: add");
            System.out.println("查询商品到购物车: find");
            System.out.println("修改商品购买数量: update");
            System.out.println("结算商品购买金额: pay");
            Scanner sc = new Scanner(System.in);
            System.out.println("请您输入命令:");
            String command = sc.next();
            switch (command) {
                case "add":
                    add(shopcar);
                    break;
                case "find":
                    find(shopcar);
                    break;
                case "update":
                    update(shopcar);
                    break;
                case "pay":
                    pay(shopcar);
                    break;
                default:
                    System.out.println("您输入的命令有误!!");
            }
        }

    }

    private static void pay(Goods[] shopcar) {
        find(shopcar);
        double money = 0;
        for (int i = 0; i < shopcar.length; i++) {
            Goods g = shopcar[i];
            if (g != null) {
                money += (g.price * g.many);
            } else {
                break;
            }
        }
        System.out.println("一共消费" + money + "元");
    }

    private static void update(Goods[] shopcar) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入要修改商品信息的id");
        int id = sc.nextInt();
        Goods g = chaxun(shopcar, id);
        if (g == null) {
            System.out.println("对不起，没有查询到该id的商品");
        } else {
            System.out.println("请您输入" + g.name + "商品的最新购买数量");
            int many = sc.nextInt();
            g.many = many;
            System.out.println("修改完成");
            find(shopcar);
        }
    }

    private static Goods chaxun(Goods[] shopcar, int id) {
        for (int i = 0; i < shopcar.length; i++) {
            if (shopcar[i] != null) {
                if (shopcar[i].id == id) {
                    return shopcar[i];
                }
            } else {
                break;//找完了前面存在的商品 没找到一样id的
            }
        }
        return null;//找完了所有100个商品 没有找到一样id的
    }

    private static void find(Goods[] shopcar) {
        System.out.println("------------查询购物车信息如下-------------");
        System.out.println("编号tt名称tt价格tt数量");
        for (int i = 0; i < shopcar.length; i++) {
            if (shopcar[i] != null) {
                System.out.println(shopcar[i].id + "tt" + shopcar[i].name + "tt" + shopcar[i].price + "tt" + shopcar[i].many);
            } else {
                break;
            }
        }
    }

    private static void add(Goods[] shopcar) {
        Scanner sc = new Scanner(System.in);//录入用户购买商品的信息
        System.out.println("请您输入购买商品的编号");
        int id = sc.nextInt();
        System.out.println("请您输入购买商品的名称");
        String name = sc.next();
        System.out.println("请您输入购买商品的数量");
        int many = sc.nextInt();
        System.out.println("请您输入购买商品的价格");
        double price = sc.nextDouble();

        Goods g = new Goods();//将该信息封装成一个商品对象
        g.id = id;
        g.name = name;
        g.many = many;
        g.price = price;

        //把这个商品对象存入购物车数组
        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 + "已经存入购物车中");
    }
}

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 运行结果（程序测试）