MathQuiz using a thread in java

Question

I want the user to solve a simple quiz. The user has 30 seconds to give an answer. While he is thinking about that I want to display a countdown from 30 seconds.

If there was no answer the quiz should terminate and display TIMEOUT. So I started with a simple Countdown class:

public class Countdown implements Runnable{

    public Countdown(){}

    public void run(){
        try{
            //so let's start counting
            for(int i = 30; i > 0; i--){
                Thread.sleep(1000);
                System.out.println(i);
            }
        }catch(InterruptedException e){
            System.out.println("Countdown interrupted");
        }

        System.out.println("TIMEOUT");
    }
}

Both when user gives the right or wrong answer the quiz shoud terminate.

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

public class MathQuiz{
    public static void main(String args[]){
        //so this is our simple quiz
        System.out.println("19*24-1=?");

        Thread thread = new Thread(new Countdown());
        thread.start();

        try{
            Scanner sc = new Scanner(System.in);
            String text = sc.nextLine();

            if(!(thread.getState()).equals("TERMINATED")){
                if(text.equals("455")){
                    System.out.println("Right!");
                }else{
                    System.out.println("Wrong!");
                }

                thread.interrupt();

            }else{
                sc.close();
            }
        }catch(Exception e){
            System.out.println(e.toString());
        }   
    }
}

When the user gives the right or wrong answer the quiz terminates but gives me a timeout message too. So this is the first problem.

Another problem is that when I wait for the timeout the scanner is still open and waiting for input.

I think there might be something wrong with fetching the thread state.

Any ideas?

Answer 1

do this

public class Countdown implements Runnable{

    public Countdown(){}

    public void run(){
        try{
            //so let's start counting
            for(int i = 30; i > 0; i--){
                Thread.sleep(1000);
                System.out.println(i);
            }
              System.out.println("TIMEOUT");
        }catch(InterruptedException e){
            System.out.println("Countdown interrupted");
        }


    }
}

use another thread to get input form user and interrupt it after 30 sec

see this for example

Answer 2

Add a return statement after System.out in the catch(InterruptedException e) block.