public void update(TrackDatabase trackDatabase) {
   Track[] tracks = trackDatabase.getTracks();
   for (int i = 0; i < tracks.length; i++) {
     Track track = getTrack(tracks[i]);
     if (track != null) {
       remove(track);
       add(tracks[i]);
     }
   }
 }
 public void add(TrackDatabase trackDatabase) {
   Track[] tracks = trackDatabase.getTracks();
   for (int i = 0; i < tracks.length; i++) add(tracks[i]);
 }