public Comparator<?> getComparator(int columnIndex){
            if (columnIndex == 0){
                return new Comparator<String>() {
                    @Override
                    public int compare(String s1, String s2) {
                        Date d1 = sqlStringToDate(s1);
                        Date d2 = sqlStringToDate(s2);
                        return new Double(d1.getTime() - d2.getTime()).intValue();
                    }
                };
            }
            if ((columnIndex == 1) || (columnIndex == 2)){
                return new Comparator<String>() {
                    @Override
                    public int compare(String s1, String s2) {
                        return cutNumber(s1) - cutNumber(s2);
                    }

                    Integer cutNumber(String s){
                        if (s.contains("<")) s = s.substring(s.indexOf('<') + 1, s.indexOf('>'));
                        return Integer.valueOf(s);
                    }
                };

            }
            if (columnIndex == 3){
                return new Comparator<String>() {
                    @Override
                    public int compare(String s1, String s2) {
                        return Integer.valueOf(s1) - Integer.valueOf(s2);
                    }
                };
            }
            return super.getComparator(columnIndex);
        }