public class MyTimer extends Thread
{
    private long startime;

    MyTimer(long start){
        startime = start;
    }
    @Override
    public void run()
    {
        try
        {
            do
            {
                long miliseconds;
                miliseconds = System.currentTimeMillis() - startime;
                System.out.println("Прошло времени: " + (miliseconds / (1000*60)) % 60 + " : " + (miliseconds / 1000) % 60 + " : " + miliseconds % 1000);
                sleep(1);
            }while(!this.isInterrupted());
        }
        catch(Exception e)
        {
            System.out.println(e.getMessage());
        }
    }
}