hashCode = 17; hashCode = 37 * hashCode + numerator; hashCode = 37 * hashCode + denominator;
hashCode = 37 * (37 * 17 + getNumerator()) + getDenominator();
    public int hashCode() {        if (hashCode == 0) {            hashCode = 17;            hashCode = 37 * hashCode + numerator;            hashCode = 37 * hashCode + denominator;        }        return hashCode;    }