需求：模拟ATM机的存取钱功能

用户类

/**

* 用户类

* @author hp

*

*/

public class Person {

String name=”zs”;//姓名

int pwd=123456;//密码

}

import java.util.Scanner;

ATM类

/**

* ATM类

*

* @author hp

*

*/

public class ATM {

double lastMoney = 1000;// 账户余额

/** * 插卡开始 */public void start() {    boolean flag = login();    if (flag) {        Scanner sc = new Scanner(System.in);        int num = 0;        do {            System.out.println("1.查询\t" + "2.存款\t" + "3.取款\t" + "0.退出");            System.out.print("请选择你需要办理的业务：");            num = sc.nextInt();            switch (num) {            case 0:                exit();                break;            case 1:                showMoney();                break;            case 2:                addMoney();                break;            case 3:                takeMoney();                break;            default:                System.out.println("您输入数字有误！");                break;            }        } while (num != 0);    }}/** * 登录 */public boolean login() {    Person p = new Person();    boolean flag = false;    Scanner sc = new Scanner(System.in);    for (int i = 0; (i < 3) && (!flag); i++) {        System.out.println("请输入用户名:");        String nowName = sc.next();        if (p.name.equals(nowName)) {            for (int j = 0; j < 3; j++) {                System.out.println("请输入密码:");                int nowPWD = sc.nextInt();                if (nowPWD == p.pwd) {                    System.out.println("登录成功");                    flag = true;                    break;                } else {                    System.out.println("密码错误，您还有" + (2 - i) + "次机会！");                    i++;                }            }        } else {            System.out.println("用户名错误，您还有" + (2 - i) + "次机会！");        }    }    return flag;}/** * 查询方法 */public void showMoney() {    System.out.println("****\n当前余额为：" + lastMoney + "****\n");}/** * 存钱方法 */public void addMoney() {    Scanner sc = new Scanner(System.in);    System.out.print("请输入存款金额：");    double money = sc.nextDouble();    if (money % 100 == 0) {        lastMoney += money;        System.out.println("存款成功");    } else {        System.out.println("存款失败");    }    System.out.println("\n****当前余额为：" + lastMoney + "****");}/** * 取钱方法 */public void takeMoney() {    Scanner sc = new Scanner(System.in);    System.out.print("请输入取款金额：");    double money = sc.nextDouble();    if (money > lastMoney || money % 100 != 0) {        System.out.println("取款失败");    } else {        lastMoney -= money;        System.out.println("取款成功");    }    System.out.println("\n****当前余额为：" + lastMoney + "****\n");}/** * 退出方法 */public void exit() {    System.out.println("取卡，谢谢使用！");}

}

ATM测试类

/**

* ATM测试类

*

* @author hp

*

*/

public class ATMTest {

public static void main(String[] args) {

ATM atm = new ATM();

atm.start();

}

}

运行图