rating.add(track);
rating.add(track, weight);
  public void add(ServerDatabase db) {    Track[] tracks = db.getTracks();    for (int i = 0; i < tracks.length; i++) {      Track track = tracks[i];      Rating rating = (Rating) hash.get(track.getKey());      if (rating == null)        hash.put(track.getKey(), new Rating(track));      else        rating.add(track);    }  }