java.util.Scanner类，这是一个用于扫描输入文本的新的实用程序。其中nextInt()获取String型，而next()获取int、double型。

这是一个仿ATM的小程序。

实现条件 1.登陆界面，2.三次登陆机会，登陆成功进入登陆菜单，3，进入菜单进行选择，实现 1,查询，2，存款，3，取款，4，修改密码，5退出，再位选择退出时可一直重复操作。

import java.util.Scanner;
public class TestATM{public static void main(String[] args) {String user = "admin";String password ="123456";double  money = 10000;Scanner sc = new Scanner(System.in);welcome();boolean b = login(user,password);/*login successful come to the menu*/while(b==true){/System.out.println("login successful !");System.out.println("Now You In The Menu And Select Any Operation.");System.out.println("***1.Check the Balance***"+"\n"+ "***2.Withdrawing Money***"+"\n"+ "***3.Deposit Money***"+"\n"+ "***4.Change Password***"+"\n"+ "***5.exit***");while(true){int opt = sc.nextInt();switch (opt){case 1:checkMoney(money);retreate();break;case 2:money = withdrawMoney(money);System.out.println("operate successfully,you remaining sum is "+money);retreate();break;case 3:money = depositMoney(money);System.out.println("operate successfully,you remaining sum is "+money);retreate();break;case 4:password = changePassword(password);retreate();break;case 5:retreate();System.exit(0);default:break;}}}}public static  void welcome(){System.out.println("***********************************************");System.out.println("--------------------------Welcoming------------");System.out.println("--------------------------Version 1 ------------");System.out.println("-----------------------------------------------");}/*Three times to verify login*/public static boolean login(String us,String pw){System.out.println("***Only Thirds Tiems Please Carefully***");int k = 2;for(int i = 1; i<4;i++){	Scanner  sc = new Scanner(System.in);System.out.println("please input your username:");String user_name = sc.next();System.out.println("please input your password:");String user_pw = sc.next();if (us.equals(user_name)&&pw.equals(user_pw))return true;else{ if(k!=0){System.out.println("***Please Again Input Your Name And Password"+" "+"Only"+" "+k-- +" "+"Times***");}elseSystem.out.println("You Have No Time,Please Contact Our Staff Now.");continue;}}return false;}/*check money*/public static void checkMoney(double money){System.out.println("Your Balance is"+" "+money+" RMB ");}public static double withdrawMoney(double money1){Scanner sc =new Scanner(System.in);System.out.println("please input you want to withdraw money ");double wm  = sc.nextInt();money1 = money1 - wm;return money1;}public static double depositMoney(double money2){Scanner sc =new Scanner(System.in);System.out.println("please input you want to set money ");double sm = sc.nextInt();money2 = money2 + sm;return money2;}public static String changePassword(String old_password){System.out.println("please input your old ps");Scanner sc = new Scanner(System.in);String pd = sc.next();if(pd.equals(old_password)){	System.out.println("please input your new pw ");String pw1 = sc.next();System.out.println("please again input your new pw");String pw2 = sc.next();if (pw1.equals(pw2)) {System.out.println("chage password is successful.");return pw1;}else{System.out.println("The two passwords differ.");return pd;}}else{System.out.println("input old password is failed try again.");return old_password;}}public static void retreate(){System.out.println("Continue  OR Not Operation"+"(y/n)");Scanner sc = new Scanner(System.in);String cn = sc.next();if (cn.equals("y")) {return ;}else if (cn.equals("n")) {System.out.println("Exit  successful!1");System.exit(0);}else {while (true) {System.out.println("input is failed again?(y/n))");String temp = sc.next();if (temp.equals("y")) {return;} else if (temp.equals("n")) {System.out.println("Exit  successful!2");System.exit(0);}}}}
}