public Comparator<?> getComparator(int columnIndex){
            if (columnIndex > 1){
                return new Comparator<String>(){
                    @Override
                    public int compare(String s1, String s2) {
                        return Integer.valueOf(s1) - Integer.valueOf(s2);
                    }
                };
            }
            return super.getComparator(columnIndex);
        }