Question

I have made a counter application where it uses threads to interrupt the count when the user enters “stop” into the console. I have double checked my code and I can’t see the problem. I am new to threads so can anyone please take a look at this.

import java.util.Scanner;

public class CounterInterruptApp 
{

    public static void main(String[] args) 
    {
      new CounterInterruptApp().start();
    }

    public void start()
    {
        Thread counter = new Counter(); //Instantiate the counter thread.
        counter.start(); //Start the counter thread.

        Scanner scanner = new Scanner(System.in);
        String s = "";
        while(!s.equals("stop")); //Wait for the user to enter stop.
        s=scanner.next();
        counter.interrupt(); //Interrupt the counter thread.
    }

}



public class Counter extends Thread //Extend Thread for the use of the Thread Interface.
{
    public void run()//Run method.  This is part of the Thread interface.
    {
        int count = 0;
        while(!isInterrupted())
        {
            System.out.println(this.getName() + "Count: " + count);
            count++;
            try //Try/Catch statement.
            {
              Thread.sleep(1000); //Make the Thread sleep for one second.
            } catch(InterruptedException e) {
              break;
            }
        }
        System.out.println("Counter Interrupted."); //Display the message Counter Interrupted.
    }

}

Answer 1

Your while loop checking for the ‘stop’ string is bad-formed.
It should be like this:

while(!s.equals("stop"))
{   //Wait for the user to enter stop.
    s=scanner.nextLine();
}
counter.interrupt();  //Interrupt the counter thread.