public void addSortKey(int column,Comparator<String> comparator){
  sortKeys.add(column);
  sortComparators.add(comparator);
}

public void addSortKey ( int column , Comparator < String > comparator ) { sortKeys . add ( column ) ; sortComparators . add ( comparator ) ; }
adds a table sort key . the table will be sorted according to the provided string comparator .
