用Properties类创建对象读取文档*txt格式书写ATM简单版本，看大神们有什么改进的，欢迎交流

先创建了一个ATM.txt格式的的文档，将卡的账号、密码、内存金额放在此文档

password=123
money=5000
userName=123

然后用类Properties创建一个对象，将银行卡的属性放进对象中，书写一个简单的ATM机实现简单的登录、存款、取款、查看、修改密码、退出程序等功能具体代码示例如下：package unit331;

import java.io.FileReader;
import java.io.FileWriter;
import java.util.Properties;

import javax.swing.JOptionPane;

public class ATM {
    public static void main(String[] args) {
        JOptionPane.showMessageDialog(null, "***欢迎光临***");
        boolean item = login();
        if (item == false) {
            JOptionPane.showMessageDialog(null, "你已经输入三次，超次，将退出程序");
            System.exit(0);
        }
        while (true) {
            String number = JOptionPane.showInputDialog(null, "1、存款 \n2、取款\n3、查询\n4、改密\n5、退出");
            switch (number) {
            case "1":
                add();
                break;
            case "2":
                setout();
                break;
            case "3":
                find();
                break;
            case "4":
                change();
                break;
            case "5":
                System.exit(0);
            default:
                JOptionPane.showMessageDialog(null, "请再选项里面选择");
            }
        }

    }// 主方法

    // 修改密码
    public static int change() {
        Properties pro = new Properties();
        try {
            pro.load(new FileReader("src/unit331/ATM.txt"));
        } catch (Exception e) {
            JOptionPane.showMessageDialog(null, "查无此文件");
        }
        String password = pro.getProperty("password");
        String code = JOptionPane.showInputDialog(null, "请输入原密码");
        if (password.equals(code) == false) {
            JOptionPane.showMessageDialog(null, "密码不正确");
            return 0;
        }
        int newpassword=Integer.parseInt(JOptionPane.showInputDialog(null, "请输入新密码")) ;
        int newpassword1=Integer.parseInt(JOptionPane.showInputDialog(null, "请确认新密码")) ;
        if (newpassword!=newpassword1) {
            JOptionPane.showConfirmDialog(null, "两次密码不一致");
            return 0;
        }
        pro.setProperty("password", newpassword+"");
        try {
            pro.store(new FileWriter("src/unit331/ATM.txt"), null);
        } catch (Exception e) {
            JOptionPane.showMessageDialog(null, "查无此文件");
        }
        return 0;
    }

    // 查询页面
    public static void find() {
        Properties p = new Properties();
        try {
            p.load(new FileReader("src/unit331/ATM.txt"));
        } catch (Exception e) {
            JOptionPane.showMessageDialog(null, "查无此文件");
        }
        int money = Integer.parseInt(p.getProperty("money"));
        JOptionPane.showMessageDialog(null, "账号余额为:" + money);
    }

    // 取款页面
    public static int setout() {
        int money = Integer.parseInt(JOptionPane.showInputDialog(null, "请输入取款金额"));
        Properties pro = new Properties();
        try {
            pro.load(new FileReader("src/unit331/ATM.txt"));
        } catch (Exception e) {
            JOptionPane.showMessageDialog(null, "查无此文件");
        }
        int AtmMoney = Integer.parseInt(pro.getProperty("money"));
        if (money != AtmMoney) {
            JOptionPane.showMessageDialog(null, "账户余额不足");
            return 0;
        }
        int AllMoney = AtmMoney - money;
        pro.setProperty("money", AllMoney + "");
        try {
            pro.store(new FileWriter("src/unit331/ATM.txt"), null);
        } catch (Exception e) {
            JOptionPane.showMessageDialog(null, "查无此文件");
        }
        JOptionPane.showMessageDialog(null, "请从取款口取出现金");
        return 0;
    }

    // 存款页面
    public static void add() {
        int money = Integer.parseInt(JOptionPane.showInputDialog(null, "请输入存款金额"));
        Properties pro = new Properties();
        try {
            pro.load(new FileReader("src/unit331/ATM.txt"));
        } catch (Exception e) {
            System.out.println("查无此文件");
        }
        String atmmoney = pro.getProperty("money");
        int Atmmoney = Integer.parseInt(atmmoney);
        int allmoney = Atmmoney + money;
        pro.setProperty("money", allmoney + "");
        try {
            pro.store(new FileWriter("src/unit331/ATM.txt"), null);
        } catch (Exception e) {
            JOptionPane.showMessageDialog(null, "查无此文件");
        }
    }

    // 登录页面
    public static boolean login() {
        Properties pro = new Properties();
        try {
            pro.load(new FileReader("src/unit331/ATM.txt"));
        } catch (Exception e) {
            System.out.println("查无此文件");
        }
        String userName = pro.getProperty("userName");
        String password = pro.getProperty("password");
        for (int i = 0; i < 3; i++) {

            String name = JOptionPane.showInputDialog(null, "请输入用户名");
            String pwd = JOptionPane.showInputDialog(null, "请输入密码");
            if (userName.equals(name) && password.equals(pwd)) {
                return true;
            } else {
                JOptionPane.showMessageDialog(null, "用户名和密码错误，请重新输入");
            }
        }
        return false;
    }

}欢迎广大朋友指正，共同交流

原文地址：https://www.cnblogs.com/xiyuanxiaorenwu/p/8684855.html