java - 私の合理的なコードの主な方法

Question

それで、有理数の足し算、引き算などを含む有理テストのコードを完成させました。実際にコードを出力するメインクラスを作ろうとして立ち往生しています。

Rational クラスのコードは次のとおりです。

package rational;

public class Rational {

    private static int gcd(int u, int v) {
        if (u == 0) {
            return v;
        } else if (v == 0) {
            return u;
        } else if (u == 1 || v == 1) {
            return 1;
        }
        int temp;
        while (v != 0) {
            temp = u % v;
            u = v;
            v = temp;
        }
        return u;
    }

    private static Rational reduce(Rational num) {
        int gcd = gcd(num.getNumerator(), num.getDenominator());
        return new Rational(num.getNumerator() / gcd, num.getDenominator() / gcd);
    }

    private static Rational neg(Rational num) {
        return new Rational(-(num.getNumerator()), num.getDenominator());
    }

    public static Rational add(Rational a, Rational b) {
        return reduce(new Rational(a.getNumerator() * b.getDenominator() + a.getDenominator() * b.getNumerator(), a.getDenominator() * b.getDenominator()));
    }

    public static Rational subtract(Rational a, Rational b) {
        return add(a, neg(b));
    }

    public static Rational multiply(Rational a, Rational b) {
        return reduce(new Rational(a.getNumerator() * b.getNumerator(), a.getDenominator() * b.getDenominator()));
    }

    public static Rational divide(Rational a, Rational b) {
        return multiply(a, new Rational(b.getDenominator(), b.getNumerator()));
    }

    public static String getString(Rational num) {
        return String.format("%d/%d", num.getNumerator(), num.getDenominator());
    }

    public static String getFloatString(Rational num) {
        return getFloatString(num, 6);
    }

    public static String getFloatString(Rational num, int fixedTo) {
        return String.format("%." + fixedTo + "f", num.getNumerator() / ((float) num.getDenominator()));
    }

    private final int numerator;
    private final int denominator;

    public Rational() {
        this(0, 1); // Note that division by zero is not allowed
    }

    public Rational(int numerator, int denominator) {
        if (denominator == 0) {
            throw new ArithmeticException("Division by zero");
        }
        this.numerator = numerator;
        this.denominator = denominator;
    }

    public int getNumerator() {
        return numerator;
    }

    public int getDenominator() {
        return denominator;
    }

}