Question

Ok I’m very new to Java and I’m trying to complete a homework assignment, but my object isn’t working in my class. (Forgive me if I’m using wrong terminology, noobie here)

So I’m making a basic stopwatch program that records 2 laps. I have gotten to the point of creating the 1st lap and it works great. Then when I call the timer.reset() object to reset the stopwatch it displays the same time as the first lap. Why isn’t my timer.reset() not working?

public class StopWatch
{

    /**
     * This method  
     *
     * @param args
     */
    public static void main(String[] args)
    {
        // TODO Auto-generated method stub

        Scanner input = new Scanner(System.in);
        System.out.println("Start stopwatch [press s]: ");
        System.out.println("Stop  stopwatch [press q]: ");

        Timer timer = new Timer();
        input.next();
        timer.start();

        input.next();
        timer.stop();

        int elapsedTime = timer.getElapsedTime();

        System.out.print("Elapsed time: ");
        System.out.print(elapsedTime);
        System.out.println(" milliseconds");

        timer.reset();

        input.next();
        timer.start();

        input.next();
        timer.stop();

        System.out.print("Elapsed time: ");
        System.out.print(elapsedTime);
        System.out.println(" milliseconds");

    }

}

Here’s the timer.java class im using in my program.

public class Timer {
  private long start;
  private long stop;
  private int elapsedTime;
  public Timer() {
  }
  public void start() {
    if (this.start == 0 && this.stop == 0)
      this.start = System.currentTimeMillis();
  }
  public void stop() {
    if (this.start > 0 && this.stop == 0) {
      this.stop = System.currentTimeMillis();
      this.elapsedTime = (int) (stop - start);
    }
  }
  public int getElapsedTime() {
    return this.elapsedTime;
  }
  public void reset() {
    this.start = 0;
    this.stop = 0;
    this.elapsedTime = 0;
  }
}

Answer 1

You missed to read the elapsed time again:

public static void main(String[] args)
{
    Scanner input = new Scanner(System.in);
    System.out.println("Start stopwatch [press s]: ");
    System.out.println("Stop  stopwatch [press q]: ");

    Timer timer = new Timer();
    input.next();
    timer.start();

    input.next();
    timer.stop();

    System.out.println("Elapsed time: "+ timer.getElapsedTime()+" milliseconds");

    timer.reset();

    input.next();
    timer.start();

    input.next();
    timer.stop();

    System.out.println("Elapsed time: "+ timer.getElapsedTime()+" milliseconds");
}