[NP] Дропки

import java.math.BigInteger;
import java.util.Scanner;

class ZeroDenominatorException extends Exception {
    @Override
    public String getMessage() {
        return "Denominator cannot be zero";
    }
}

class GenericFraction<T extends Number, U extends Number> {
    T numerator;
    U denominator;

    public GenericFraction(T numerator, U denominator) throws ZeroDenominatorException {
        if (denominator.doubleValue() == 0) {
            throw new ZeroDenominatorException();
        }
        this.numerator = numerator;
        this.denominator = denominator;
    }

    public GenericFraction<Double, Double> add(GenericFraction<? extends Number, ? extends Number> that)
            throws ZeroDenominatorException {
        double resultNumerator = this.numerator.doubleValue() * that.denominator.doubleValue() +
                that.numerator.doubleValue() * this.denominator.doubleValue();
        double resultDenominator = this.denominator.doubleValue() * that.denominator.doubleValue();
        return new GenericFraction<Double, Double>(resultNumerator, resultDenominator);
    }

    public GenericFraction<Double, Double> normalize() throws ZeroDenominatorException {
        int gcd = gcd((int) numerator.doubleValue(), (int) denominator.doubleValue());

        int AnotherWayToGetGCD = BigInteger.valueOf(this.numerator.longValue())
                .gcd(BigInteger.valueOf(this.denominator.longValue()))
                .intValue();

        double resultNumerator = this.numerator.doubleValue() / gcd;
        double resultDenominator = this.denominator.doubleValue() / gcd;
        return new GenericFraction<Double, Double>(resultNumerator, resultDenominator);
    }

    public int gcd(int a, int b) {
        if (b == 0) {
            return a;
        }
        return gcd(b, a % b);
    }

    public double toDouble() {
        return numerator.doubleValue() / denominator.doubleValue();
    }

    @Override
    public String toString() {
        GenericFraction<Double,Double> gf = null;
        try {
            gf = this.normalize();
        } catch (ZeroDenominatorException e) {
            e.printStackTrace();
        }
        return String.format("%.2f / %.2f", gf.numerator.doubleValue(), gf.denominator.doubleValue());
    }
}

public class GenericFractionTest {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double n1 = scanner.nextDouble();
        double d1 = scanner.nextDouble();
        float n2 = scanner.nextFloat();
        float d2 = scanner.nextFloat();
        int n3 = scanner.nextInt();
        int d3 = scanner.nextInt();
        try {
            GenericFraction<Double, Double> gfDouble = new GenericFraction<Double, Double>(n1, d1);
            GenericFraction<Float, Float> gfFloat = new GenericFraction<Float, Float>(n2, d2);
            GenericFraction<Integer, Integer> gfInt = new GenericFraction<Integer, Integer>(n3, d3);
            System.out.printf("%.2f\n", gfDouble.toDouble());
            System.out.println(gfDouble.add(gfFloat));
            System.out.println(gfInt.add(gfFloat));
            System.out.println(gfDouble.add(gfInt));
            gfInt = new GenericFraction<Integer, Integer>(n3, 0);
        } catch (ZeroDenominatorException e) {
            System.out.println(e.getMessage());
        }

        scanner.close();
    }

}