Rational

import java.util.Scanner;

/**
 * Class description of the class Rational
 * The class Rational allows the user to do basic operations between two fractions
 *
 * @author Ryan Norng
 * @version version 1.0
 * @since 2020-01-26*/

public class Rational
{

	private int numerator;
	private int denominator;

	/**
	 * Default constructor. Creates a Rational object with a numerator and denominator of 1*/
	public Rational()
	{
		numerator = 1;
		denominator = 1;
	}

	/**
	 * Constructor. Creates a Rational object with specified numerator and denominator
	 * @param num An integer specifying the numerator
	 * @param den An integer specifying the denominator*/
	public Rational(int num, int den)
	{
		numerator = num;
		denominator = den;
	}

	/** Gets the Rational object's numerator
	 * @return Returns the integer representing the numerator*/
	public int getNumerator()
	{
		return numerator;
	}

	/** Gets the Rational object's denominator
	 * @return Returns the integer representing the denominator*/
	public int getDenominator()
	{
		return denominator;
	}

	/** Sets the Rational object's numerator
	 * @param value An integer representing the value to set the numerator to */
	public void setNumerator(int value)
	{
		numerator = value;
	}

	/** Sets the Rational object's denominator
	 * @param value An integer representing the value to set the denominator to*/
	public void setDenominator(int value)
	{
		denominator = value;
	}

	/** Allows us to print the Rational object as a String
	 * @return A String of the Rational object in the format of numerator/denominator*/
	public String toString()
	{
		String numstring = String.valueOf(numerator);
		String denstring = String.valueOf(denominator);

		return numstring + "/" + denstring;
	}

	/** Asks the user for inputs to set values of a Rational object. */
	public void inputRational()
	{
		Scanner ui = new Scanner(System.in);
		int userNum = 1;
		int userDen = 1;
		boolean numflag = false;
		boolean denflag = false;
		//input validation for non-zero integers (numerator)
		do // only allows int as an input
		{
			System.out.println("Please enter the numerator.");
			while (!ui.hasNextInt())
			{
				System.out.println("Invalid input. Please enter an integer.");
				ui.next();
			}

		userNum = ui.nextInt();
		numflag = true;

		}
		while (numflag == false || userNum == 0);
		//input validation for non-zero integers (denominator)
		do // only allows int as an input
		{
			System.out.println("Please enter the denominator.");
			while (!ui.hasNextInt())
			{
				System.out.println("Invalid input. Please enter an integer.");
				ui.next();
			}

		userDen = ui.nextInt();
		denflag = true;

		}
		while (denflag == false || userDen == 0);

	//	ui.close();

		int gcd = 1;
		gcd = gcd(userNum,userDen);

		numerator = userNum / gcd;
		denominator = userDen / gcd;

	}

	/** Finds gcd of two integers. Used to simply fractions of Rational objects
	 * @return An integer representing the gcd of two integers*/
	private int gcd(int m, int n)
	{
		int r;
		while(n!=0)
		{
			r = m % n;
			m = n;
			n = r;
		}

		return m;
	}

	/** Adds two Rational objects
	 * @param r1 A Rational object
	 * @param r2 A Rational object*/
	public void add(Rational r1, Rational r2)
	{
		int gcd, tnum, tden;
		tnum = (r1.numerator * r2.denominator) + (r1.denominator * r2.numerator);
		tden = r1.denominator * r2.denominator;
		gcd = gcd(tnum,tden);

		numerator = tnum / gcd;
		denominator = tden / gcd;
	}
	/** Subtracts a Rational object from another Rational object, and returns a Rational object
	 * @param r A Rational object (the value being subtracted)
	 * @return The Rational resulting from the subtraction*/
	public Rational sub(Rational r)
	{
		Rational tRational = new Rational();
		int gcd, tnum, tden;
		tnum = (numerator * r.denominator) - (denominator * r.numerator);
		tden = denominator * r.denominator;
		gcd = gcd(tnum,tden);

		tRational.numerator = tnum / gcd;
		tRational.denominator = tden / gcd;

		return tRational;

	}

	/** Multiplies two Rational objects
	 * @param r1 A Rational object
	 * @param r2 A Rational object*/
	public void mul(Rational r1, Rational r2)
	{
		int gcd, tnum, tden;
		tnum = r1.numerator * r2.numerator;
		tden = r1.denominator * r2.denominator;
		gcd = gcd(tnum,tden);

		numerator = tnum / gcd;
		denominator = tden / gcd;
	}

	/** Divides a Rational object from another Rational object, and returns a Rational object
	 * @param r A Rational object (the value used for division)
	 * @return The Rational resulting from the division*/
	public Rational div(Rational r)
	{
		Rational tRational = new Rational();
		int gcd, tnum, tden;
		tnum = numerator * r.denominator;
		tden = denominator * r.numerator;
		gcd = gcd(tnum,tden);

		tRational.numerator = tnum / gcd;
		tRational.denominator = tden / gcd;

		return tRational;
	}

	/** Performs division between two Rational objects, and returns a decimal value as a double
	 * @param r1 A Rational object
	 * @param r2 a Rational object
	 * @return A double representing the resulting value of the division between two Rational objects*/
	public static double divToDouble(Rational r1, Rational r2)
	{
		double tnum, tden;
		double realValue;
		tnum = r1.numerator * r2.denominator;
		tden = r1.denominator * r2.numerator;
		realValue = tnum / tden;

		return realValue;

	}
}

public class CECS277Lab1 {

	public static void main(String[] args)
	{
		Rational r1 = new Rational();
		Rational r2 = new Rational();
		Rational r3 = new Rational();

		r1.inputRational();
		r2.inputRational();

		r3.add(r1, r2);

		System.out.println(r1 + " + " + r2 +" = " + r3);

		r3 = r1.sub(r2);

		System.out.println(r1 + " - " + r2 +" = " + r3);

		r3.mul(r1, r2);;

		System.out.println(r1 + " * " + r2 +" = " + r3);

		r3 = r1.div(r2);

		System.out.println(r1 + " / " + r2 +" = " + r3);

		double d3 = Rational.divToDouble(r1, r2);

		System.out.println(r1 + " + " + r2 +" = " + d3);

		r1.setNumerator(2);
		System.out.println("The numerator of Rational r1 has been set to 2");
		r2.setDenominator(5);
		System.out.println("The denominator of Rational r2 has been set to 5");

		System.out.println("Numerator: " + r1.getNumerator());
		System.out.println("Denominator: " + r2.getDenominator());

		//System.out.println(r3);
		//System.out.print(d1);

	}

}