@Override public int compare(String lKey,String rKey){
  int lCat=categoryOf(lKey);
  int catDiff=lCat - categoryOf(rKey);
  if (catDiff != 0 || lCat != 0) {
    return catDiff;
  }
  return lKey.compareTo(rKey);
}

@ Override public int compare ( String lKey , String rKey ) { int lCat = categoryOf ( lKey ) ; int catDiff = lCat - categoryOf ( rKey ) ; if ( catDiff != 0 || lCat != 0 ) { return catDiff ; } return lKey . compareTo ( rKey ) ; }
returns a negative integer , zero , or a positive integer as the left key is less than , equal to , or greater than the right key .
