code: public int getTrackNumberNumeric() {
          String number = getTrackNumber();
  
          if(number == null) return -1;
          try {
              return Integer.parseInt(number);
          } catch(NumberFormatException e) {
              return -1;
          }
      }
docs: Returns the track number, as converted into
  an integer, or -1 if not available / not numeric