咖啡自动售货机系统设计的Java代码

以下是一个简单的咖啡自动售货机系统的Java代码示例：

import java.util.Scanner;

public class CoffeeVendingMachine {
    private int coffeeCount = 10;
    private int sugarCount = 10;
    private int milkCount = 10;
    private int moneyEarned = 0;
    private int coffeePrice = 5;

    public void start() {
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("Welcome to the Coffee Vending Machine");
            System.out.println("1. Buy coffee");
            System.out.println("2. Check coffee count");
            System.out.println("3. Check sugar count");
            System.out.println("4. Check milk count");
            System.out.println("5. Check money earned");
            System.out.println("6. Exit");

            int choice = scanner.nextInt();

            switch (choice) {
                case 1:
                    buyCoffee();
                    break;
                case 2:
                    checkCoffeeCount();
                    break;
                case 3:
                    checkSugarCount();
                    break;
                case 4:
                    checkMilkCount();
                    break;
                case 5:
                    checkMoneyEarned();
                    break;
                case 6:
                    return;
                default:
                    System.out.println("Invalid choice. Please try again.");
            }
        }
    }

    private void buyCoffee() {
        if (coffeeCount == 0) {
            System.out.println("Sorry, no coffee available.");
            return;
        }

        if (sugarCount == 0) {
            System.out.println("Sorry, no sugar available.");
            return;
        }

        if (milkCount == 0) {
            System.out.println("Sorry, no milk available.");
            return;
        }

        System.out.println("Please insert " + coffeePrice + " dollars.");
        Scanner scanner = new Scanner(System.in);
        int money = scanner.nextInt();

        if (money < coffeePrice) {
            System.out.println("Not enough money inserted.");
            return;
        }

        coffeeCount--;
        sugarCount--;
        milkCount--;
        moneyEarned += coffeePrice;

        System.out.println("Enjoy your coffee!");
    }

    private void checkCoffeeCount() {
        System.out.println("Coffee count: " + coffeeCount);
    }

    private void checkSugarCount() {
        System.out.println("Sugar count: " + sugarCount);
    }

    private void checkMilkCount() {
        System.out.println("Milk count: " + milkCount);
    }

    private void checkMoneyEarned() {
        System.out.println("Money earned: " + moneyEarned);
    }
}

这个代码示例中，我们定义了一个`CoffeeVendingMachine`类，其中包含了自动售货机的各种属性和方法。在`start`方法中，我们使用一个循环来不断接收用户输入的选择，并根据选择调用相应的方法。在`buyCoffee`方法中，我们首先判断是否有足够的咖啡、糖和牛奶，如果有，则要求用户插入硬币，如果硬币不足，则返回错误信息；如果硬币充足，则减少咖啡、糖和牛奶的数量，并增加售货机的收入。在其他方法中，我们只是简单地返回相应的属性值。