用java实现atm机功能

实现ATM机功能需要以下步骤：

1. 创建一个用户类，包含用户名、密码、余额等信息。

2. 创建一个ATM类，包含以下功能：

a. 登录功能：输入用户名和密码，验证用户信息是否正确。

b. 查询余额功能：查询当前用户的余额。

c. 存款功能：输入存款金额，将金额加入当前用户的余额中。

d. 取款功能：输入取款金额，将金额从当前用户的余额中减去。

e. 转账功能：输入转账金额和对方账户名，将金额从当前用户的余额中减去，加入对方账户的余额中。

f. 修改密码功能：输入原密码和新密码，修改当前用户的密码。

g. 退出功能：退出ATM机操作。

下面是一个简单的Java代码实现：

import java.util.Scanner;

public class ATM {
    private static User[] users = new User[10]; // 最多支持10个用户
    private static int userCount = 0; // 用户数
    private static User currentUser = null; // 当前用户

    public static void main(String[] args) {
        initUsers(); // 初始化用户数据
        
        System.out.println("欢迎使用ATM机！");
        login(); // 登录
        System.out.println("登录成功，当前余额：" + currentUser.getBalance());
        
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请选择操作：");
            System.out.println("1. 查询余额");
            System.out.println("2. 存款");
            System.out.println("3. 取款");
            System.out.println("4. 转账");
            System.out.println("5. 修改密码");
            System.out.println("6. 退出");
            int choice = scanner.nextInt();

            if (choice == 1) {
                queryBalance();
            } else if (choice == 2) {
                deposit();
            } else if (choice == 3) {
                withdraw();
            } else if (choice == 4) {
                transfer();
            } else if (choice == 5) {
                changePassword();
            } else if (choice == 6) {
                System.out.println("退出成功，欢迎下次使用！");
                break;
            } else {
                System.out.println("请选择正确的操作！");
            }
        }
    }

    // 初始化用户数据
    private static void initUsers() {
        users[0] = new User("张三", "123456", 1000);
        users[1] = new User("李四", "123456", 2000);
        userCount = 2;
    }

    // 登录
    private static void login() {
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请输入用户名：");
            String username = scanner.nextLine();
            System.out.println("请输入密码：");
            String password = scanner.nextLine();

            for (int i = 0; i < userCount; i++) {
                if (users[i].getUsername().equals(username) && users[i].getPassword().equals(password)) {
                    currentUser = users[i];
                    return;
                }
            }

            System.out.println("用户名或密码错误，请重新输入！");
        }
    }

    // 查询余额
    private static void queryBalance() {
        System.out.println("当前余额：" + currentUser.getBalance());
    }

    // 存款
    private static void deposit() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入存款金额：");
        double amount = scanner.nextDouble();
        if (amount < 0) {
            System.out.println("存款金额不能为负数！");
            return;
        }
        currentUser.setBalance(currentUser.getBalance() + amount);
        System.out.println("存款成功，当前余额：" + currentUser.getBalance());
    }

    // 取款
    private static void withdraw() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入取款金额：");
        double amount = scanner.nextDouble();
        if (amount < 0) {
            System.out.println("取款金额不能为负数！");
            return;
        }
        if (amount > currentUser.getBalance()) {
            System.out.println("余额不足！");
            return;
        }
        currentUser.setBalance(currentUser.getBalance() - amount);
        System.out.println("取款成功，当前余额：" + currentUser.getBalance());
    }

    // 转账
    private static void transfer() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入转账金额：");
        double amount = scanner.nextDouble();
        if (amount < 0) {
            System.out.println("转账金额不能为负数！");
            return;
        }
        if (amount > currentUser.getBalance()) {
            System.out.println("余额不足！");
            return;
        }
        System.out.println("请输入对方账户名：");
        String username = scanner.nextLine();
        User otherUser = null;
        for (int i = 0; i < userCount; i++) {
            if (users[i].getUsername().equals(username)) {
                otherUser = users[i];
                break;
            }
        }
        if (otherUser == null) {
            System.out.println("对方账户不存在！");
            return;
        }
        currentUser.setBalance(currentUser.getBalance() - amount);
        otherUser.setBalance(otherUser.getBalance() + amount);
        System.out.println("转账成功，当前余额：" + currentUser.getBalance());
    }

    // 修改密码
    private static void changePassword() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入原密码：");
        String oldPassword = scanner.nextLine();
        if (!currentUser.getPassword().equals(oldPassword)) {
            System.out.println("原密码错误！");
            return;
        }
        System.out.println("请输入新密码：");
        String newPassword = scanner.nextLine();
        currentUser.setPassword(newPassword);
        System.out.println("修改密码成功！");
    }
}

class User {
    private String username; // 用户名
    private String password; // 密码
    private double balance; // 余额

    public User(String username, String password, double balance) {
        this.username = username;
        this.password = password;
        this.balance = balance;
    }

    public String getUsername() {
        return username;
    }

    public String getPassword() {
        return password;
    }

    public double getBalance() {
        return balance;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }
}