[求助]关于用Java实现ATM机的挠头难题，大家会么？

package com.kay.bank;

import java.util.Scanner;

public class Bank {

    Scanner input = new Scanner(System.in);
    Data data = new Data();
    User crUser; //当前登陆的用户
    
    public void start()
    {
        System.out.println("--------------------");
        System.out.println("1.开户");
        System.out.println("2.插卡");
        System.out.println("3.系统管理");
        System.out.println("4.退出");
        System.out.println("--------------------");
        System.out.println("请选择菜单：");
        int num = input.nextInt();
        switch(num)
        {
        case 1:
            //开户操作
            openAccount();
            break;
        case 2:
            //插卡操作
            insertCard();
            break;
        case 3:
            //x系统管理操作
            systemManager();
            break;
        default:
            //退出
        }
    }
    /**
     * 开户
     */
    public void openAccount()
    {
        User user = new User();
        System.out.println("****************");
        System.out.println("请输入用户名：");
        user.name = input.next();
        //验证系统中用户名是否存在
        User checkUser = data.checkUserByName(user.name);
        if(checkUser == null)
        {
            //系统中用户名不存在
        
            System.out.println("请输入密码：");
            String pwd = input.next();
            System.out.println("请确认密码：");
            String repwd = input.next();
            
            if(pwd.equals(repwd))
            {
                user.pwd = pwd;
                System.out.println("请输入存款金额：");
                double money = input.nextDouble();
                if(money <= 0)
                {
                    System.out.println("输入的金额不合法，请重新输入！");
                    openAccount();
                }
                else
                {
                    user.money = money;
                    //向数据库中存放新创建的User
                    data.saveUser(user);
                    
                    System.out.println("创建新用户成功！");
                    start();
                }
            }
            else
            {
                System.out.println("密码不一致，请重新输入！");
                openAccount();
            }
        }
        else
        {
            System.out.println("用户名已存在");
            start();
        }
    }
    /**
     * 插卡操作
     */
    public void insertCard()
    {
        System.out.println("请输入用户名：");
        String name = input.next();
        System.out.println("请输入密码：");
        String pwd = input.next();
        
        
            User user = data.checkUser(name, pwd);
            if(user != null)
            {
                if(user.isEnable == true)
                {
                    System.out.println("登陆成功");
                    crUser = user;
                    showCustomMenu();
                }
                else
                {
                    System.out.println("您的账户被冻结，请打110");
                    start();
                }
            }
            else
            {
                System.out.println("用户名或密码错误");
                insertCard();
            }
        
        
    }
    /**
     * 显示插卡登陆成功后二级菜单
     */
    public void showCustomMenu()
    {
        System.out.println("---------------");
        System.out.println("1.查询余额");
        System.out.println("2.取款");
        System.out.println("3.存款");
        System.out.println("4.转账");
        System.out.println("5.修改密码");
        System.out.println("6.退出");
        System.out.println("---------------");
        System.out.println("请选择：");
        int num = input.nextInt();
        switch(num)
        {
        case 1:
            //查询余额
            getMoney();
            break;
        case 2:
            //取款
            minusMoney();
            break;
        case 3:
            //存款
            addMoney();
            break;
        case 4:
            //转账
            transitionMoney();
            break;
        case 5:
            //修改密码
            updatePwd();
            break;
        case 6:
            exitCustomMenu();
            //退出
        }    
    }
    /**
     * 获得当前用户的余额
     */
    public void getMoney()
    {
        System.out.println("您的余额为：" + crUser.money);
        showCustomMenu();
    }
    /**
     * 取款
     */
    public void minusMoney()
    {
        System.out.println("请输入取款额：");
        double money = input.nextDouble();
        if(money >= 0 && money < crUser.money)
        {
            //可以取款
            crUser.money = crUser.money - money;
            showCustomMenu();
        }
        else
        {
            System.out.println("金额有误！请重新输入！");
            minusMoney();
        }
    }
    
    public void exitCustomMenu()
    {
        start();
    }
    /**
     * 存款
     */
    public void addMoney()
    {
        System.out.println("请输入存款额：");
        double money = input.nextDouble();
        if(money >= 0)
        {
            crUser.money = crUser.money + money;
            showCustomMenu();
        }
        else
        {
            System.out.println("金额不合法！");
            addMoney();
        }
    }
    /**
     * 修改密码
     */
    public void updatePwd()
    {
        System.out.println("请输入原始密码：");
        String oldPwd = input.next();
        if(oldPwd.equals(crUser.pwd))
        {
            System.out.println("请输入新密码：");
            crUser.pwd = input.next();
            showCustomMenu();
        }
        else
        {
            System.out.println("原始错误，请重新输入！");
            updatePwd();
        }
    }
    /**
     * 转账
     */
    public void transitionMoney()
    {
        System.out.println("请输入要转入的账号名称：");
        String name = input.next();
        User intoUser = data.checkUserByName(name);
        
        if(intoUser != null)
        {
            //转入的账号存在
            System.out.println("请输入转入的金额：");
            double money = input.nextDouble();
            if(money >= 0 && money < crUser.money)
            {
                //金额合法并且余额满足转账条件 可以进行转账
                crUser.money = crUser.money - money;
                intoUser.money = intoUser.money + money;
                showCustomMenu();
            }
            else
            {
                System.out.println("金额不合法，请重新输入！");
                transitionMoney();
            }
        }
        else
        {
            System.out.println("转入的账号不存在，请重新输入！");
            transitionMoney();
        }
    }
    /**
     * 系统管理
     */
    public void systemManager()
    {
        System.out.println("请输入管理员密码：");
        String pwd = input.next();
        if(pwd.equals("admin"))
        {
            //管理员登陆成功
            showManagerMenu();
        }
        else
        {
            System.out.println("密码错误！");
            start();
        }
    }
    /**
     * 显示管理员登陆后的菜单
     */
    public void showManagerMenu()
    {
        System.out.println("******************");
        System.out.println("1.显示所有用户");
        System.out.println("2.冻结账号");
        System.out.println("3.恢复账号");
        System.out.println("4.退出");
        System.out.println("******************");
        System.out.println("请选择菜单项：");
        int num = input.nextInt();
        switch(num)
        {
        case 1:
            //显示所有用户
            showAllUser();
            break;
        case 2:
            //冻结账号
            freezeAccount();
            break;
        case 3:
            //恢复账户
            renewAccount();
            break;
        case 4:
            start();
            //退出
        }
    }
    /**
     * 显示所有用户
     */
    public void showAllUser()
    {
        System.out.println("系统中所有用户：");
        System.out.println("--------------------------------");
        System.out.println("用户名\t是否可用");
        for (int i = 0; i < data.userArray.length; i++) {
            User user = data.userArray[i];
            if(user != null)
            {
                System.out.println(user.name + "\t" + user.isEnable);
            }
        }
        System.out.println("--------------------------------");
        showManagerMenu();
    }
    /**
     * 冻结账户
     */
    public void freezeAccount()
    {
        System.out.println("系统中所有可被冻结用户：");
        System.out.println("--------------------------------");
        System.out.println("用户名\t是否可用");
        for (int i = 0; i < data.userArray.length; i++) {
            User user = data.userArray[i];
            if(user != null && user.isEnable == true)
            {
                System.out.println(user.name + "\t" + user.isEnable);
            }
        }
        System.out.println("--------------------------------");
        System.out.println("请输入要被冻结的账户：");
        String name = input.next();
        User user = data.checkUserByName(name);
        if(user != null)
        {
            //要冻结的账户存在
            user.isEnable = false;
            System.out.println("冻结成功！");
            
        }
        else
        {
            System.out.println("用户不存在！");
        }
        showManagerMenu();
    }
    /**
     * 恢复账户
     */
    public void renewAccount()
    {
        System.out.println("系统中所有可被恢复用户：");
        System.out.println("--------------------------------");
        System.out.println("用户名\t是否可用");
        for (int i = 0; i < data.userArray.length; i++) {
            User user = data.userArray[i];
            if(user != null && user.isEnable == false)
            {
                System.out.println(user.name + "\t" + user.isEnable);
            }
        }
        System.out.println("--------------------------------");
        System.out.println("请输入要被恢复的账户：");
        String name = input.next();
        User user = data.checkUserByName(name);
        if(user != null)
        {
            //要恢复的账户存在
            user.isEnable = true;
            System.out.println("恢复成功！");
            
        }
        else
        {
            System.out.println("用户不存在！");
        }
        showManagerMenu();
    }
    
    
    
    
    
    
    
    
    
}





package com.kay.bank;

public class Data {

    User[] userArray = new User[100];
    
    /**
     * 存储新的用户
     * @param user 新用户对象
     */
    public void saveUser(User user)
    {
        for (int i = 0; i < userArray.length; i++) {
            if(userArray[i] == null)
            {
                userArray[i] = user;
                break;
            }
            
        }
    }
    /**
     * 根据用户名和密码验证用户是否在数组中存在
     * @param name 用户名
     * @param pwd 密码
     */
    public User checkUser(String name,String pwd)
    {
        for (int i = 0; i < userArray.length; i++) {
            User user = userArray[i];
            if(user != null
                    && user.name.equals(name)
                    && user.pwd.equals(pwd))
            {
                //代表用户存在
                return user;
            }
        }
        return null;
    }
    /**
     * 根据用户名验证用户是否存在
     * @param name
     * @return
     */
    public User checkUserByName(String name)
    {
        for (int i = 0; i < userArray.length; i++) {
            User user = userArray[i];
            if(user != null
                    && user.name.equals(name))
            {
                //代表用户存在
                return user;
            }
        }
        return null;
    }
}



package com.kay.bank;

public class Test {

    public static void main(String[] args) {
        Bank atm = new Bank();
        atm.start();
    }
}



package com.kay.bank;

public class User {

    String name;
    String pwd;
    double money;
    boolean isEnable = true;
}