public void add(Track track) { sum += track.getRating(); weight += track.getWeight(); track.setRating(sum / weight);
public void add(Track track, float weight) { this.sum += track.getRating() * weight; this.weight += weight; this.track.setRating(sum / this.weight);
    public void add(Track track) {      sum += track.getRating();      weight += track.getWeight();      track.setRating(sum / weight);    }