volatile in thread

public class TestCalc {

        public static void main(String[] args)

        {

            class StoppableThread extends Thread

            {

                private volatile boolean stopped; // defaults to false

                @Override

                public void run()

                {

                while(!stopped)

                   System.out.println("running");

                }

                void stopThread()

                {

                    stopped = true;

                }

            }

                StoppableThread thd = new StoppableThread();

            thd.start();

            try

            {

                Thread.sleep(); // sleep for 1 second

            }

            catch (InterruptedException ie)

            {

            }

            thd.stopThread();

    }

}