@Override
    public int compareTo(Object o) {
        if (o instanceof Score) {
            long otherScore = ((Score) o).getScore();
            if (otherScore > _score)
                return -1;
            else if (otherScore < _score)
                return 1;
            else {
                return -_date.compareTo(((Score) o).getDate());
            }
        } else
            throw new IllegalArgumentException("Expected Score");
    }