Demo

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Demo {

    public static void main(String[] args) {
        int chon;
        menu();
        Scanner s = new Scanner(System.in);
        do {
            System.out.println("Nhap menu: ");
            chon = s.nextInt();
            switch (chon) {
                case 1:
                    System.out.println("Thoat");
                    break;
                case 2:
                    CreateAccount();
                    break;
                case 3:
                    Display();
                    break;
                case 4:
                    Login();
                    break;
                default:
                    System.out.println("Chon sai");
                    break;
            }
        } while (chon != 1);
    }

    public static void menu() {
        System.out.println("1. Thoat");
        System.out.println("2. Đăng ký tài khoản");
        System.out.println("3. Xem thông tin tài khoản");
        System.out.println("4. Dang nhap vao tai khoan");
    }

    public static void CreateAccount() {
        String user, password;
        System.out.println("Dang ky tai khoan");
        System.out.print("Nhap user Account: ");
        Scanner s = new Scanner(System.in);
        user = s.nextLine();

        System.out.print("Nhap pass Account: ");
        Scanner s1 = new Scanner(System.in);
        password = s1.nextLine();
        try {
            FileOutputStream fos = new FileOutputStream("login.txt");
            fos.write(user.getBytes());
            fos.write(password.getBytes());
            fos.close();
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Demo.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(Demo.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public static void Login() {
        String user1, password1;
        System.out.println("Nhap thong tin dang nhap");
        System.out.print("Nhap User: ");
        Scanner s = new Scanner(System.in);
        user1 = s.nextLine();

        System.out.print("Nhap Password: ");
        Scanner s2 = new Scanner(System.in);
        password1 = s2.nextLine();
        try {
            BufferedReader br = new BufferedReader(new FileReader("login.txt"));
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Demo.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public static void Display() {
        String u = null, p = null;
        try {
            BufferedReader br = new BufferedReader(new FileReader("login.txt"));
            u = br.readLine();
            p = br.readLine();
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Demo.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(Demo.class.getName()).log(Level.SEVERE, null, ex);
        }
        System.out.println("Thong tin dang nhap");
        System.out.println("User: " + u);
        System.out.println("Password: " + p);
    }
}