Hello.This is an authentication service.How to use it? Create a new class of your project, called Authenticator.Copy there this and save it.Then open your first class, where is your main program.Then just write "extends Authenticator" after your class name.Enjoy :).

import java.io.*;
import java.util.*;

public class Authenticator implements Runnable{
	public Thread thread;
	public Random random;
	public BufferedReader reader;
	public int number;
	public String read0;
	public int read;
	
	Authenticator(){
		thread = new Thread();
		thread.start();
		random = new Random();
		reader = new BufferedReader(new InputStreamReader(System.in));
		
		number = random.nextInt(999999999);
		
		try{
		System.out.println("Generated code is: " + number);
		System.out.print("Please, insert generated code: ");
		read0 = reader.readLine();
		read = Integer.parseInt(read0); 
		}
		catch(IOException v){
			System.out.println("Error " + v);
		}
		
		try{
		System.out.println('\n' + "Checking...");
		Thread.sleep(5000);
		System.out.println("Confirming...");
		Thread.sleep(3000);
		System.out.println("Done!");
		}
		catch(InterruptedException v){
			System.out.println("Error " + v);
		}
		
		if(read == number){
			System.out.println('\n' + "Authentication succesful!");
		}
		else{
			System.out.println('\n' + "Authentication has not been succesful.");
			System.exit(0);
		}		
	}
	@Override
	public void run() {
		// TODO Auto-generated method stub	
	}
	public static void main(String args[])throws IOException{
		new Authenticator();	
	}
}