package com.logein;/*** @author alina* @date 2021年09月15日 10:49 下午* User类，封装用户信息的类*/
public class User {//保存用户名private String username;//保存用户密码private String passwoer;public User() { }public User(String username,String passwoer ){this.username = username;this.passwoer = passwoer;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPasswoer() {return passwoer;}public void setPasswoer(String passwoer) {this.passwoer = passwoer;}
}

package com.logein;import java.util.Scanner;/*** @author alina* @date 2021年09月15日 10:58 下午* 用户操作的类*/
public class UserInterface {public static void main(String[] args) {Scanner  sc = new Scanner(System.in);UserOperator u = new UserOperator();while (true){//提示用户选择功能System.out.println("Please select the current function：A:register   B：Sign in");String s = sc.nextLine();if (s.equalsIgnoreCase("a")){//选择的是注册功能System.out.println("please input username: ");String username = sc.nextLine();System.out.println("please input password: ");String password = sc.nextLine();u.regegit(username,password);System.out.println("register success!");}else if (s.equalsIgnoreCase("b")){//选择的是登录功能System.out.println("please input username: ");String username = sc.nextLine();System.out.println("please input password: ");String password = sc.nextLine();//判断用户名和密码是不是在集合里面boolean b = u.login(username,password);if (b==false){System.out.println("sign in  default!");}else{System.out.println("sign in  success!");}}else {System.out.println("Please enter the correct option ！");break;}}}
}

package com.logein;import java.util.ArrayList;
import java.util.Iterator;/*** @author alina* @date 2021年09月15日 11:11 下午* 操作集合的类* 存储集合，迭代集合*/
public class UserOperator {//成员位置，定义集合，存储User类的对象private ArrayList<User> list = new ArrayList<User>();//定义注册功能，接收用户名和密码，存储到集合//功能不检验用户名是否存在，只要注册就成功public void regegit(String username,String password){list.add(new User(username,password));}//定义登录功能，接收用户名和密码，查询是否在集合中//没查到返回falsepublic boolean login(String username,String password) {Iterator<User> it = list.iterator();while (it.hasNext()){User U = it.next();if(U.getUsername().equals(username) && U.getPasswoer().equals(password)){return true;}}return false;}}