Java代码 使用字符用户界面。当输入给定的卡号和密码（初始卡号为123456，密码是666666）时，系统能登录ATM柜员机系统，用户可以按照以下规则进行： 1、如果三次不能正确输入密码，则退出程序。 2、查询余额：初始余额为10000元 3、ATM取款：每次取款金额为100的倍数，总额不超过5000元，支取金额不允许透支。 4、ATM存款：不能出现负存款。 5、修改密码：新密码长度不小于6位，不允许出现6位完全相同的情况，只有旧密码正确，新密码符合要求才可以成功修改密码。 6、卡号、密码、余额可以写入文件中。

以下是Java代码实现：

import java.io.*;
import java.util.Scanner;

public class ATM {
    private static final String CARD_FILE = "card.txt";  // 卡信息文件名
    private static final int MAX_TRIES = 3;  // 最大尝试次数
    private static final int MAX_WITHDRAWAL = 5000;  // 最大取款额
    private static final int MULTIPLE = 100;  // 取款金额倍数
    private static final int INITIAL_BALANCE = 10000;  // 初始余额
    private static final int MIN_PASSWORD_LENGTH = 6;  // 密码最小长度
    private static final int MAX_SAME_DIGITS = 6;  // 最大相同数字个数

    private String cardNum;  // 卡号
    private String password;  // 密码
    private int balance;  // 余额

    public ATM(String cardNum, String password, int balance) {
        this.cardNum = cardNum;
        this.password = password;
        this.balance = balance;
    }

    // 读取卡信息文件
    public static ATM readCardFile() throws IOException {
        try (Scanner scanner = new Scanner(new File(CARD_FILE))) {
            String cardNum = scanner.nextLine();
            String password = scanner.nextLine();
            int balance = scanner.nextInt();
            return new ATM(cardNum, password, balance);
        } catch (FileNotFoundException e) {
            throw new IOException("Card file not found");
        }
    }

    // 写入卡信息文件
    public void writeCardFile() throws IOException {
        try (PrintWriter writer = new PrintWriter(new FileWriter(CARD_FILE))) {
            writer.println(cardNum);
            writer.println(password);
            writer.println(balance);
        }
    }

    // 登录
    public boolean login() {
        Scanner scanner = new Scanner(System.in);
        for (int i = 0; i < MAX_TRIES; i++) {
            System.out.print("Card number: ");
            String cardNum = scanner.nextLine();
            System.out.print("Password: ");
            String password = scanner.nextLine();
            if (cardNum.equals(this.cardNum) && password.equals(this.password)) {
                return true;
            }
            System.out.println("Invalid card number or password");
        }
        return false;
    }

    // 查询余额
    public void queryBalance() {
        System.out.println("Balance: " + balance);
    }

    // 取款
    public void withdraw() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Amount to withdraw: ");
        int amount = scanner.nextInt();
        if (amount % MULTIPLE != 0 || amount > balance || amount > MAX_WITHDRAWAL) {
            System.out.println("Invalid amount");
            return;
        }
        balance -= amount;
        System.out.println("New balance: " + balance);
    }

    // 存款
    public void deposit() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Amount to deposit: ");
        int amount = scanner.nextInt();
        if (amount < 0) {
            System.out.println("Invalid amount");
            return;
        }
        balance += amount;
        System.out.println("New balance: " + balance);
    }

    // 修改密码
    public void changePassword() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Old password: ");
        String oldPassword = scanner.nextLine();
        if (!oldPassword.equals(password)) {
            System.out.println("Invalid password");
            return;
        }
        System.out.print("New password: ");
        String newPassword = scanner.nextLine();
        if (newPassword.length() < MIN_PASSWORD_LENGTH || countSameDigits(newPassword) > MAX_SAME_DIGITS) {
            System.out.println("Invalid password");
            return;
        }
        password = newPassword;
        System.out.println("Password changed");
    }

    // 计算相同数字个数
    private int countSameDigits(String s) {
        int count = 0;
        for (int i = 0; i < s.length() - 1; i++) {
            if (s.charAt(i) == s.charAt(i + 1)) {
                count++;
            }
        }
        return count;
    }

    public static void main(String[] args) {
        try {
            ATM atm = readCardFile();
            if (!atm.login()) {
                return;
            }
            while (true) {
                System.out.println();
                System.out.println("1. Query balance");
                System.out.println("2. Withdraw");
                System.out.println("3. Deposit");
                System.out.println("4. Change password");
                System.out.println("5. Exit");
                Scanner scanner = new Scanner(System.in);
                System.out.print("Choice: ");
                int choice = scanner.nextInt();
                switch (choice) {
                    case 1:
                        atm.queryBalance();
                        break;
                    case 2:
                        atm.withdraw();
                        break;
                    case 3:
                        atm.deposit();
                        break;
                    case 4:
                        atm.changePassword();
                        break;
                    case 5:
                        atm.writeCardFile();
                        return;
                    default:
                        System.out.println("Invalid choice");
                        break;
                }
            }
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }
    }
}

注意事项：

1. 卡信息写在文件中，格式为卡号、密码、余额，每行一个。
2. 修改密码时，新密码必须符合要求才能成功修改。