Thread: How to improve this method?

I don't really understand your question or what you mean by, "I can only use a while-loop." What you've described seems more appropriately done with an if() codition, something like:

if ( trackIsNotAlreadyPlaying )
{
    playANewTrack();
}

If you require a while() loop to do this same thing, please be specific or give us an example of how you might write it with any issues there are with your approach.

I dont necessarily need to use a while loop to do it. I assumed i did, because the section of the book the exercise is, is introducing the while loop...
The whole point of my problem is how to stop playing the track I originally selected by calling the method for the first time, before a second one will start playing by calling the method for a second time. The way the method is written for now it will play the tracks simultaneously...
There is this method inside MusicOrganiser class that calls a method of the MusicPlayer class in oreder to to stop playing the track that is currently playing.

 
 /**
     * Stop the player.
     */
    public void stopPlaying()
    {
        player.stop();
    }

Now How to make use of this method inside the startPlaying method, so that to stop the previous track that started playing when I first called the method, before the next one starts by calling the method again...

I am really puzzled and cant go on if I dont first solve this...

The method playTrack() should play the track passed to it, period. If checking for a track already playing and deciding what to do should occur before calling playTrack(). So back up the bus. Write down the requirements and logic flow for your application. A very small piece of that logic flow should be something like:

User selects track to play
If track already playing,
- stop track currently playing
Call playTrack() with user's selection

The if() statement can be resolved using a flag (a boolean) that is set to true when a track is playing and false when there are no tracks playing.

Greg Thank you very much for your time and help, I did it finally and I feel soooooo excited...
I see it now and it seems so simple after all... I mean I struggled to find the solution thinking the wrong way and it was so straightforward...
I am a very beginner in Object Oriented Programming but I am really hooked... Its absolutely amazing stuff...
I post the improved method bellow... (just to show my success to somebody)

public void playTrack(int index)
    {
        if(indexValid(index)) {
            Track track = tracks.get(index);
            if(TrackIsNotPlaying) {
                player.startPlaying(track.getFilename());
                track.incrementCount();
                TrackIsNotPlaying = false;
                System.out.println("Now playing: " + track.getArtist() + " - " + track.getTitle());
            }
            else {
                stopPlaying();
                player.startPlaying(track.getFilename());
                System.out.println("Now playing: " + track.getArtist() + " - " + track.getTitle());
            }
        }
 
    }

And I really appreciate the fact that you didnt just write the code and send it to me but you explained how to do it by my self...