Java实现超市结账系统_控制台交互式项目完整逻辑

public Product(String id, String name, double price, int stock) {
    this.id = id;
    this.name = name;
    this.price = price;
    this.stock = stock;
}

// Getter 和 Setter 方法
public String getId() { return id; }
public String getName() { return name; }
public double getPrice() { return price; }
public int getStock() { return stock; }
public void setStock(int stock) { this.stock = stock; }

@Override
public String toString() {
    return "ID:" + id + " | 名称:" + name + " | 价格:" + price + "元 | 库存:" + stock;
}

<font color="#0066cc">② 购物车条目类（CartItem）</font><br>
<p>记录每种商品的购买数量和对应商品信息。</p>
```java
public class CartItem {
    private Product product;
    private int quantity;

    public CartItem(Product product, int quantity) {
        this.product = product;
        this.quantity = quantity;
    }

    public Product getProduct() { return product; }
    public int getQuantity() { return quantity; }
    public double getTotalPrice() { return product.getPrice() * quantity; }

    public void setQuantity(int quantity) { this.quantity = quantity; }
}

public SupermarketSystem() {
    products = new ArrayList<>();
    cart = new ArrayList<>();
    scanner = new Scanner(System.in);
    initProducts(); // 初始化一些测试商品
}

// 初始化默认商品
private void initProducts() {
    products.add(new Product("001", "矿泉水", 2.0, 50));
    products.add(new Product("002", "面包", 8.0, 30));
    products.add(new Product("003", "牛奶", 15.0, 20));
    products.add(new Product("004", "苹果", 6.5, 100));
}

// 显示菜单
private void showMenu() {
    System.out.println("\n=== 欢迎光临超市自助结账系统 ===");
    System.out.println("1. 浏览所有商品");
    System.out.println("2. 添加商品到购物车");
    System.out.println("3. 查看购物车");
    System.out.println("4. 结算并打印小票");
    System.out.println("5. 退出系统");
    System.out.print("请选择操作：");
}

// 执行主循环
public void run() {
    while (true) {
        showMenu();
        String choice = scanner.nextLine();

        switch (choice) {
            case "1" -> displayProducts();
            case "2" -> addToCart();
            case "3" -> viewCart();
            case "4" -> checkout();
            case "5" -> {
                System.out.println("感谢使用，再见！");
                return;
            }
            default -> System.out.println("无效选择，请重新输入。");
        }
    }
}

// 展示所有商品
private void displayProducts() {
    System.out.println("\n--- 商品列表 ---");
    for (Product p : products) {
        System.out.println(p);
    }
}

// 添加商品到购物车
private void addToCart() {
    System.out.print("请输入商品编号: ");
    String id = scanner.nextLine();
    Product p = findProductById(id);
    if (p == null) {
        System.out.println("未找到该商品！");
        return;
    }
    System.out.print("请输入购买数量: ");
    int qty;
    try {
        qty = Integer.parseInt(scanner.nextLine());
    } catch (NumberFormatException e) {
        System.out.println("数量格式错误！");
        return;
    }
    if (qty <= 0 || qty > p.getStock()) {
        System.out.println("库存不足或数量无效！");
        return;
    }

    // 减少库存
    p.setStock(p.getStock() - qty);

    // 添加到购物车（如果已有则合并）
    for (CartItem item : cart) {
        if (item.getProduct().getId().equals(id)) {
            item.setQuantity(item.getQuantity() + qty);
            System.out.println("已将 " + qty + " 件 " + p.getName() + " 加入购物车（合并）");
            return;
        }
    }
    cart.add(new CartItem(p, qty));
    System.out.println("已将 " + qty + " 件 " + p.getName() + " 加入购物车");
}

// 查看购物车内容
private void viewCart() {
    if (cart.isEmpty()) {
        System.out.println("购物车为空！");
        return;
    }
    System.out.println("\n--- 当前购物车 ---");
    for (CartItem item : cart) {
        System.out.printf("商品: %s | 数量: %d | 小计: %.2f元\n",
                item.getProduct().getName(),
                item.getQuantity(),
                item.getTotalPrice());
    }
}

// 结算并打印小票
private void checkout() {
    if (cart.isEmpty()) {
        System.out.println("购物车为空，无法结算！");
        return;
    }

    System.out.println("\n正在生成小票...");
    System.out.println("================== 超市收据 ==================");
    double total = 0.0;
    for (CartItem item : cart) {
        double itemTotal = item.getTotalPrice();
        System.out.printf("%s × %d = %.2f元\n",
                item.getProduct().getName(),
                item.getQuantity(),
                itemTotal);
        total += itemTotal;
    }
    System.out.println("============================================");
    System.out.printf("总计: %.2f元\n", total);

    // 可扩展：会员折扣
    boolean isMember = askIfMember();
    if (isMember) {
        double discount = 0.9; // 9折
        double discounted = total * discount;
        System.out.printf("会员9折后: %.2f元\n", discounted);
        total = discounted;
    }

    System.out.printf("实付: %.2f元\n", total);
    System.out.println("谢谢惠顾，欢迎下次光临！");

    // 清空购物车
    cart.clear();
}

// 询问是否为会员
private boolean askIfMember() {
    System.out.print("是否为会员？(y/n): ");
    String input = scanner.nextLine().trim().toLowerCase();
    return input.equals("y") || input.equals("yes");
}

// 根据ID查找商品
private Product findProductById(String id) {
    for (Product p : products) {
        if (p.getId().equals(id)) {
            return p;
        }
    }
    return null;
}

<H3>3. 启动类 Main</H3>
<p>程序入口，运行系统。</p>
```java
public class Main {
    public static void main(String[] args) {
        new SupermarketSystem().run();
    }
}

=== 欢迎光临超市自助结账系统 ===
1. 浏览所有商品
2. 添加商品到购物车
3. 查看购物车
4. 结算并打印小票
5. 退出系统
请选择操作：1