I have to make a rational class in java, i need to add gcd and a way to test it

Question

public class Main   
{
    public static void main(String[] args) 
 {
       Rational a = new Rational(1,2);
       Rational b = new Rational(1,4);
             System.out.println(a + " + " + b + " = " + a.add(b));
             System.out.println(a + " - " + b + " = " + a.sub(b));
             System.out.println(a + " * " + b + " = " + a.mul(b)); 
             System.out.println(a + " / " + b + " = " + a.div(b));
}
}


 class Rational
 {

private int numerator, denominator;
public Rational (int numer, int denom)
{
   if (denom == 0)
      denom = 1;
   if (denom < 0)
   {
      numer = numer * -1;
      denom = denom * -1;
   }

   numerator = numer;
   denominator = denom;   
}


public Rational add (Rational b)
{
   
   int commonDenominator = denominator * b.getDenominator();
   int numerator1 = numerator * b.getDenominator();
   int numerator2 = b.getNumerator() * denominator;
   int sum = numerator1 + numerator2;

   return new Rational (sum, commonDenominator);
}

public Rational sub(Rational b) {
           int commonDenominator = denominator * b.getDenominator();
           int numerator1 = numerator * b.getDenominator();
           int numerator2 = b.getNumerator() * denominator;
           int difference = numerator1 - numerator2;

       return new Rational (difference, commonDenominator);
}   
  public Rational mul(Rational b) {
    int numer = numerator * b.getNumerator();
       int denom = denominator * b.getDenominator();

       return new Rational (numer, denom);
    
}
public Rational div(Rational b) {
     return mul (b.reciprocal());
}
public int getNumerator ()
{
   return numerator;
}

public int getDenominator ()
{
   return denominator;
}

public Rational reciprocal ()
{
   return new Rational (denominator, numerator);
}
public String toString ()
{
   String result;

   if (numerator == 0)
      result = "0";
   else
      if (denominator == 1)
         result = numerator + "";
      else
         result = numerator + "/" + denominator;
 
   return result;
 }
}

I have all of these done: constructor add sub mul div toString i just need the gcd and a testing method, I'm not sure how to implement the GCD into my code, if anyone could help, that would be great.

I'm supposed to make the code for GCD using Euclid's algorithm — David De La Cruz, Feb 07 '17 at 01:28
Possible duplicate of [How does the Euclidean Algorithm work?](http://stackoverflow.com/questions/6005582/how-does-the-euclidean-algorithm-work) — CL., Feb 07 '17 at 08:10

David Choweller · Accepted Answer · 2017-02-07T02:32:23.127

Here's the pseudocode for it, taken from Wikipedia, as well as the recursive version. You should be able to implement either of them in Java. I would have posted this as a comment, since it's not really an answer, but the formatting would have been terrible.

function gcd(a, b)
    while b ≠ 0
       t := b; 
       b := a mod b; 
       a := t; 
    return a;

function gcd_r(a,b) {
    if (b = 0) {
        return a;
    }
    return gcd_r( b, a mod b );
}

I have to make a rational class in java, i need to add gcd and a way to test it

1 Answers1