A simple Quadratic equation solver capable of real number output both in the form of fractions and decimals

KvadratickaSranda.java

/**
 * KvadratickaSranda
 */
public class KvadratickaSranda
{
    public static void main(String[] args)
    {
        Fraction a = new Fraction();
        Fraction b = new Fraction();
        Fraction c = new Fraction();
        try
        {
            a.parseFraction(args[0]);
            b.parseFraction(args[1]);
            c.parseFraction(args[2]);
        }
        catch (Exception e)
        {
            System.out.println("Expected parameters: a b c");
            System.exit(1);
        }
        
        Fraction discriminant = new Fraction(b).multiply(b)
                                .subtract(new Fraction(4,1).multiply(a).multiply(c));

        Fraction temp_1 = new Fraction(b).multiply(-1);//move
        Fraction temp_2 = new Fraction(a).multiply(2);

        double sqrt_result = Math.sqrt(discriminant.toDouble());
        if (sqrt_result % 1 == 0)
        {
            Fraction x1 = new Fraction(temp_1).add((long)sqrt_result).divide(temp_2);
            Fraction x2 = new Fraction(temp_1).subtract((long)sqrt_result).divide(temp_2);
            System.out.printf("x1: %s approx: %f\n", x1.displayFraction(), x1.toDouble());
            System.out.printf("x2: %s approx: %f\n", x2.displayFraction(), x2.toDouble());
        }
        else
        {
            double approx1 = (temp_1.toDouble() + sqrt_result) / temp_2.toDouble();
            double approx2 = (temp_1.toDouble() - sqrt_result) / temp_2.toDouble();
            System.out.printf("x: (%s +- sqrt(%s))/%s\n", temp_1.displayFraction(), discriminant.displayFraction(), temp_2.displayFraction());//could look a lot better with GUI or rendered in LaTeX
            System.out.printf("x1: %f\n", approx1);
            System.out.printf("x2: %f\n", approx2);
        }
    }
}

class Fraction
{
    public long numerator;//myb hide
    public long denominator;

    Fraction(Fraction frac)
    {
        this.numerator = frac.numerator;
        this.denominator = frac.denominator;
    }

    Fraction(long a, long b)
    {
        this.numerator = a;
        this.denominator = b;
    }

    Fraction()
    {
        
    }

    Fraction parseFraction(String s)//this could be very easily changed to parse fractions in the a/b format instead of double
    {
        try
        {
            final int nums_after_decimal = (s.split("\\."))[1].length();
            this.denominator = (long) Math.pow(10,nums_after_decimal);
        }
        catch(Exception e)
        {
            this.denominator = 1;
        }

        this.numerator = (long) (Double.parseDouble(s) * this.denominator);

        simplify();
        return this;
    }

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

    private void simplify()
    {
        final long i_gcd = gcd(this.numerator, this.denominator);
        this.numerator /= i_gcd;
        this.denominator /= i_gcd;

        if (this.denominator < 0)
        {
            this.numerator *= -1;
            this.denominator *= -1;
        }
    }

    String displayFraction()
    {
        if (this.denominator == 1)
        {
            return String.valueOf(this.numerator);
        }
        return String.join("/", String.valueOf(this.numerator), String.valueOf(this.denominator));
    }

    //

    static long gcd(long a, long b)
    {
        if (b == 0)
        {
            return a;
        }
        return gcd(b, a % b);
    }

    static long lcm(long a, long b)
    {
        return ((a / gcd(a,b)) *b);
    }

    //Math operations

    Fraction add(Fraction frac)
    {
        final long lcm = lcm(frac.denominator, this.denominator);
        this.numerator = this.numerator * (lcm / this.denominator) + frac.numerator * (lcm / frac.denominator);
        this.denominator = lcm;

        this.simplify();
        return this;
    }

    Fraction add(long a)
    {
        this.numerator += a * this.denominator;

        this.simplify();
        return this;
    }

    Fraction subtract(Fraction frac)
    {
        final long lcm = lcm(frac.denominator, this.denominator);
        this.numerator = this.numerator * (lcm / this.denominator) - frac.numerator * (lcm / frac.denominator);
        this.denominator = lcm;

        this.simplify();
        return this;
    }

    Fraction subtract(long a)
    {
        this.numerator -= a * this.denominator;

        this.simplify();
        return this;
    }

    Fraction multiply(long a)
    {
        this.numerator *= a;

        this.simplify();
        return this;
    }

    Fraction multiply(Fraction frac)
    {
        this.numerator *= frac.numerator;
        this.denominator *= frac.denominator;

        this.simplify();
        return this;
    }

    Fraction divide(long a)
    {
        return multiply(new Fraction(1,a));
    }

    Fraction divide(Fraction frac)
    {
        return multiply(new Fraction(frac.denominator, frac.numerator));
    }
}