Java Console Application for User Login, Registration, and Lottery System

Requirement Analysis

1) Implement three basic functions: login, registration, and lottery. 2) Login: Users input account and password; the system matches registered users, allows three password attempts, and displays logged‑in user info upon success. 3) Registration: Users choose a unique account name, set a six‑digit numeric password, and the system assigns a unique four‑digit ID. 4) Lottery: Requires a logged‑in user; the system randomly selects five distinct users as lucky winners and checks if the current user is among them. 5) Data storage: Uses the file system with java.io.*. 6) Data structures: Logged‑in user information stored in an ArrayList ; lucky user IDs and names stored in a HashMap<String, String> of length 5.

Implementation Results

Login interface screenshot:

Registration interface screenshot:

Lottery interface screenshot:

Note

Before running the code, be sure to create a user.txt file containing at least five users.

Full Source Code

import java.util.Scanner;
import java.util.ArrayList;
import java.io.*;
import java.util.StringTokenizer;
public class Dos {
static boolean logined=false;
public static void main(String[] args) {
User user=new User();
int k=0;
while( (k=Main(user))>=1&&k<5){
switch (k){
case 1:
System.out.print((k=user.login(user))==-1?"此用户不存在!\n":"");
System.out.print((k==-2)?"===<<警告>>用户：["+user.userName+"]已处于登录状态，无需重复登录！\n":"");
break;
case 2:
user.regist();
break;
case 3:
user.getLuckly();
break;
default:System.exit(0);
}
}
}
static int Main(User user){
System.out.println("**********************************************");
System.out.println("********************主菜单********************");
System.out.println("**********************************************");
System.out.println("******          <1> 登   录             ******");
System.out.println("******          <2> 注   册             ******");
System.out.println("******          <3> 抽   奖             ******");
System.out.println("******          <4> 退   出             ******");
System.out.println("**********************************************");
System.out.println("==============================================");
System.out.println(logined ? "-[已登录]-  （1）用户名:"+user.userName+"   （2）用户账号:"+user.userId:"-[未登录]-   （1）用户名:NaN   （2）用户账号:NaN");
System.out.println("==============================================");
System.out.print("###===>请输入您的选择：");
return (new Scanner(System.in)).nextInt();
}
}
public class User{
String userName,userId,userPwd;
public User(){}
public User(String userName, String userId, String userPwd){
this.userName = userName;
this.userId = userId;
this.userPwd = userPwd;
}
public String getUserName(){ return userName; }
public void setUserName(String userName){
if(!userName.equals("")) {
ArrayList
temp;
this.userId=(temp=(new operatorFile(this.userName = userName)).getUserMess(0)).get(1);
this.userPwd=temp.get(2);
}
}
public String getUserId(){ return userId; }
public String setUserId(){
String userId="";
while((new operatorFile(userId=String.valueOf ((int) (Math.random()*9000+1000)))).getUserMess(1)).size()>0){ }
return (this.userId = userId);
}
public String getUserPwd(){ return userPwd; }
public int login(User u){
int inputTimes=3;
Scanner scanner=new Scanner(System.in);
operatorFile getUserMessage=new operatorFile();
System.out.print("======>请输入您的用户名：");
String uName="";
getUserMessage.setUser(uName=scanner.nextLine());
ArrayList
userMess=getUserMessage.getUserMess(0);
if(userMess.size()<1)       return -1;//返回-1表示用户不存在
if (uName.equals(userName))     return -2;//返回-2表示用户重复登录
System.out.print("======>请输入您的登录密码：");
while(!scanner.next().equals(userMess.get(2))&&inputTimes>0)
System.out.print("===>密码输入错误！"+((--inputTimes)>0?"您还剩"+inputTimes+"次机会！":"三次机会已经用完了！输入任意退出"));
System.out.println(inputTimes>0?"==>登录成功！您本次输入密码"+(4-inputTimes)+"次！":"==>登录失败！");
setUserName(inputTimes>0?uName:"");
Dos.logined=inputTimes>0?true:false;
return 0;
}
public void regist(){
User u=new User();
Scanner scanner=new Scanner(System.in);
System.out.print("===>请输入新的用户名：");
String name;
while(new operatorFile(name=scanner.nextLine()).getUserMess(0).size() > 0)
System.out.print("已存在此用户,注册失败！\n===>请重新输入新的用户名：");
System.out.print("======>请设置您的(六位数字)登录密码：");
String regex = "[0-9]{6}", pwd;
while (!(pwd = scanner.nextLine()).matches(regex))
System.out.print("==>密码格式不正确，请重新设置您的(六位数字)登录密码：");
System.out.println("已为用户："+(u.userName=name)+" 生成唯一ID: "+(u.userPwd=pwd));
(new operatorFile()).writeUserMess(u);
System.out.println("======= >注册成功！");
}
public static HashMap
lucklyUsers=new HashMap<>();
public void getLuckly(){
if (!Dos.logined)   {
System.out.println("===>警告：没有用户登录，无法抽奖！");
return ;
}
while(lucklyUsers.size()<5)
{
String id="";
ArrayList
u;
while((u=(new operatorFile(id=String.valueOf ((int) (Math.random()*9000+1000)))).getUserMess(1)).size()<1){ }
lucklyUsers.put(u.get(1),u.get(0));
}
Iterator iterator=lucklyUsers.entrySet().iterator();
int no=1;
boolean LUCKLY=false;
System.out.println("====>恭喜以下用户获得幸运称号：");
while(iterator.hasNext()){
Map.Entry entry=(Map.Entry) iterator.next();
System.out.println("幸运用户["+(no++)+"]  用户名："+entry.getValue()+"   用户编号："+entry.getKey());
LUCKLY = entry.getKey().equals(this.userId) ? true : LUCKLY;
}
System.out.println(LUCKLY?"=========>恭喜您在本次抽奖中获得幸运称号！":"=========>很遗憾，今日您未获奖 ！-_-！");
}
public String toString(){
return this.userName+" "+this.userId+" "+this.userPwd;
}
}
public class operatorFile {
String user;
public void setUser(String user) { this.user = user; }
public operatorFile(String user) { this.user = user; }
public operatorFile() { }
public ArrayList
getUserMess(int index){
ArrayList
temp=new ArrayList
();
File file=new File("user.txt");
String line="";
try{
BufferedReader br=new BufferedReader(new FileReader(file));
while ((line = br.readLine())!=null && line!="\n"){
temp.clear();
StringTokenizer sk=new StringTokenizer(line);
while (sk.hasMoreTokens()) {
temp.add(sk.nextToken());
}
if (temp.get(index).equals(this.user))  break;
}
}
catch(IOException e){}
return (line==null)?new ArrayList
():temp;
}
public void writeUserMess(User u){
try{
BufferedWriter bw=new BufferedWriter(new FileWriter(new File("user.txt"),true));
bw.write(u.toString()+"\n");
bw.close();
}
catch (IOException e){ }
}
}

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