java basic tutorial column introduces the method of implementing user lottery:

JAVA implements user lottery

Requirement analysis

1) Implement three basic functions: login, registration, and lottery.
2) Login: The user enters the account and password to log in. After entering the account, it will match the registered user. If the entered user does not exist, exit. There are three opportunities to enter the password. After successful login, the main interface will display the account of the logged in user. information.
3) Registration: The user first enters the account name. The system checks whether the name exists. If it exists, the user is asked to change the name. Otherwise, enter the password. The password requires a 6-digit string. After successful registration, the system randomly assigns a A four-digit ID number that is unique from existing users.
4) Lottery: Prerequisite for function implementation: The user must be logged in. When this prerequisite is met, the system randomly selects 5 different users from existing users and marks them as lucky users, and determines whether the logged-in user has been selected.
5) Data storage: Use the file system, import the java.io.* package,
6) Data structure: Login user information is stored in ArrayList, lucky user number and id are stored in HasMap where id is Key and name is Value.

Results achieved

1) Login:
2) Registration:
3) Lottery:

Notes

	運行代碼之前務必在user.txt中創(chuàng)建五個以上的用戶。

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?"此用戶不存在!\n":"");
                    System.out.print((k==-2)?"===<<警告>>用戶：["+user.userName+"]已處于登錄狀態(tài)，無需重復登錄！\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("********************主菜單********************");
????????System.out.println("**********************************************");
????????System.out.println("******??????????<1>?登???錄?????????????******");
????????System.out.println("******??????????<2>?注???冊?????????????******");
????????System.out.println("******??????????<3>?抽???獎?????????????******");
????????System.out.println("******??????????<4>?退???出?????????????******");
????????System.out.println("**********************************************");
????????System.out.println("==============================================");
????????System.out.println(logined???"-[已登錄]-??（1）用戶名:"+user.userName+"???（2）用戶賬號:"+user.userId:"-[未登錄]-???（1）用戶名:NaN???（2）用戶賬號:NaN");
????????System.out.println("==============================================");
????????System.out.print("###===>請輸入您的選擇：");
????????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<String>?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("======>請輸入您的用戶名：");
????????String?uName="";
????????getUserMessage.setUser(uName=scanner.nextLine());
????????ArrayList<String>?userMess=getUserMessage.getUserMess(0);
????????if(userMess.size()<1)       return -1;//返回-1表示用戶不存在
        if (uName.equals(userName))     return -2;//返回-2表示用戶重復登錄
        System.out.print("======>請輸入您的登錄密碼：");
????????while(!scanner.next().equals(userMess.get(2))&&inputTimes>0)
????????????System.out.print("===>密碼輸入錯誤！"+((--inputTimes)>0?"您還剩"+inputTimes+"次機會！":"三次機會已經(jīng)用完了！輸入任意退出"));
????????System.out.println(inputTimes>0?"==>登錄成功！您本次輸入密碼"+(4-inputTimes)+"次！":"==>登錄失??！");
????????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("===>請輸入新的用戶名：");
????????String?name;
????????while(new?operatorFile(name=scanner.nextLine()).getUserMess(0).size()?>?0)
????????????System.out.print("已存在此用戶,注冊失??！\n===>請重新輸入新的用戶名：");
????????System.out.print("======>請設置您的(六位數(shù)字)登錄密碼：");
????????String?regex?=?"[0-9]{6}",?pwd;
????????while?(!(pwd?=?scanner.nextLine()).matches(regex))
????????????System.out.print("==>密碼格式不正確，請重新設置您的(六位數(shù)字)登錄密碼：");
????????System.out.println("已為用戶：?"+(u.userName=name)+"?生成唯一ID:?"+(u.userPwd=pwd));
????????(new?operatorFile()).writeUserMess(u);
????????System.out.println("=======>注冊成功！");
????}
????public?static?HashMap<String,String>?lucklyUsers=new?HashMap<>();
????public?void?getLuckly()?{
????????if?(!Dos.logined)???{
????????????System.out.println("===>警告：沒有用戶登錄，無法抽獎！");
????????????return?;
????????}
????????while(lucklyUsers.size()<5)
????????{
????????????String?id="";
????????????ArrayList<String>?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("====>恭喜以下用戶獲得幸運稱號：");
????????while(iterator.hasNext()){
????????????Map.Entry?entry=(Map.Entry)?iterator.next();
????????????System.out.println("幸運用戶["+(no++)+"]??用戶名："+entry.getValue()+"???用戶編號："+entry.getKey());
????????????LUCKLY?=?entry.getKey().equals(this.userId)???true?:?LUCKLY;
????????}
????????System.out.println(LUCKLY?"=========>恭喜您在本次抽獎中獲得幸運稱號！":"=========>很遺憾，今日您未獲獎?！-_-！");
????}
????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<String>?getUserMess(int?index){
????????ArrayList<String>?temp=new?ArrayList<String>();
????????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<String>():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){?}
????}}

? ? ? ? ? ? ? ? ?

2) Login: The user enters the account and password to log in. After entering the account, it will match the registered user. If the entered user does not exist, exit. There are three opportunities to enter the password. After successful login, the main interface will display the account of the logged in user. information.
3) Registration: The user first enters the account name. The system checks whether the name exists. If it exists, the user is asked to change the name. Otherwise, enter the password. The password requires a 6-digit string. After successful registration, the system randomly assigns a A four-digit ID number that is unique from existing users.
4) Lottery: Prerequisite for function implementation: The user must be logged in. When this prerequisite is met, the system randomly selects 5 different users from existing users and marks them as lucky users, and determines whether the logged-in user has been selected.
5) Data storage: Use the file system, import the java.io.* package,
6) Data structure: Login user information is stored in ArrayList, lucky user number and id are stored in HasMap where id is Key and name is Value.

2) Registration:
3) Lottery:

	運行代碼之前務必在user.txt中創(chuàng)建五個以上的用戶。

rrree

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