How to output basic arithmetic operations correctly?

[monkey0525]

I'm creating a program that adds and subtracts fractions together. That being said however, my program does not seem to be responding correctly. Every time I run the client code, it outputs
4/4, when I want it to add 1/2 and 1/2 (instead of 1), and 6/36, when I subtract 2/6 and 1/6 (instead of 1/6). My constructor code and client code is as follows:

 // Constructor //
public class RationalNumber
{
	int num;
	int den;
	
	private int gcd(int x, int y)
	{
		while(y != 0)
		{
			int temp = x % y;
			x = y;
			y = temp;
		} 		
		return x;
	}
	public void reduce()
	{
		int d;
		while (true)
		{
			d = this.gcd(this.num,this.den);
			if (d == 1)
			{
				return;
			}
			this.num /= d;
			this.den /= d;
		}
	}			
	public RationalNumber add(RationalNumber r1)
	{
		int commonDen = den * r1.getDenominator();
		int num1 = num * r1.getDenominator();
		int num2 = r1.getNumerator() * den;
		int sum = num1 + num2;
		
		return new RationalNumber (sum, commonDen);
	}
	public RationalNumber sub(RationalNumber r1)
	{
		int commonDen = den * r1.getDenominator();
		int num1 = num * r1.getDenominator();
		int num2 = r1.getNumerator() * den;
		int dif = num1 - num2;
		
		return new RationalNumber (dif, commonDen);
	}
}

 // Client Code //
public class RationalTest
{
   public static void main (String[] args)
   {
		RationalNumber r1 = new RationalNumber(2,6);
		RationalNumber r2 = new RationalNumber(1,6);
		RationalNumber r3 = new RationalNumber(1,2);
		RationalNumber r4 = new RationalNumber(1,2);
		
		System.out.println(r1.add(r2));
		
		System.out.println(r3.sub(r4));
	}
}

Hopefully this code segment is sufficient enough in exchange for your help. Thank you for your time.

[horace1]

the methods getDenominator( ) and getNumerator() appear to be missing from class RationalNumber

[monkey0525]

Ah, no. It does exist. I just excluded it from my code to make it as small as possible. I apologize that it exceeds 20 lines.

[Rabbit]

You never call your reduce function.