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int can not be dereferenced error

Vee Shall

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Posts: 7

posted 14 years ago

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Hi;
working with fractions which i absolutely hate (

).........uggh but anywhoo. i'm getting a "int can not be derreferenced" error but i don't see why. All i'm doing is comparing to values to see if they are equal. I'm not using a pointer. What can i do to correct this?

here is my code.

//********************************************************************
//  RationalNumber.java      
//
//  Represents one rational number with a numerator and denominator.
//********************************************************************

public class RationalNumber
{
   private int numerator, denominator;

//-----------------------------------------------------------------
   //  Constructor: Sets up the rational number by ensuring a nonzero
   //  denominator and making only the numerator signed.
   //-----------------------------------------------------------------
   public RationalNumber (int numer, int denom)
   {
    
	   if (denom == 0)
         denom = 1;

// Make the numerator "store" the sign
      if (denom < 0)
      {
         numer = numer * -1;
         denom = denom * -1;
      }

numerator = numer;
      denominator = denom;

reduce();
   }

//-----------------------------------------------------------------
   //  Returns the numerator of this rational number.
   //-----------------------------------------------------------------
   public int getNumerator ()
   {
      return numerator;
   }

//-----------------------------------------------------------------
   //  Returns the denominator of this rational number.
   //-----------------------------------------------------------------
   public int getDenominator ()
   {
      return denominator;
   }

//-----------------------------------------------------------------
   //  Returns the reciprocal of this rational number.
   //-----------------------------------------------------------------
   public RationalNumber reciprocal ()
   {
      return new RationalNumber (denominator, numerator);
   }

//-----------------------------------------------------------------
   //  Adds this rational number to the one passed as a parameter.
   //  A common denominator is found by multiplying the individual
   //  denominators.
   //-----------------------------------------------------------------
   public RationalNumber add (RationalNumber op2)
   {
      int commonDenominator = denominator * op2.getDenominator();
      int numerator1 = numerator * op2.getDenominator();
      int numerator2 = op2.getNumerator() * denominator;
      int sum = numerator1 + numerator2;

return new RationalNumber (sum, commonDenominator);
   }

//-----------------------------------------------------------------
   //  Subtracts the rational number passed as a parameter from this
   //  rational number.
   //-----------------------------------------------------------------
   public RationalNumber subtract (RationalNumber op2)
   {
      int commonDenominator = denominator * op2.getDenominator();
      int numerator1 = numerator * op2.getDenominator();
      int numerator2 = op2.getNumerator() * denominator;
      int difference = numerator1 - numerator2;

return new RationalNumber (difference, commonDenominator);
   }

//-----------------------------------------------------------------
   //  Multiplies this rational number by the one passed as a
   //  parameter.
   //-----------------------------------------------------------------
   public RationalNumber multiply (RationalNumber op2)
   {
      int numer = numerator * op2.getNumerator();
      int denom = denominator * op2.getDenominator();

return new RationalNumber (numer, denom);
   }

//-----------------------------------------------------------------
   //  Divides this rational number by the one passed as a parameter
   //  by multiplying by the reciprocal of the second rational.
   //-----------------------------------------------------------------
   public RationalNumber divide (RationalNumber op2)
   {
      return multiply (op2.reciprocal());
   }

//-----------------------------------------------------------------
   //  Determines if this rational number is equal to the one passed
   //  as a parameter.  Assumes they are both reduced.
   //-----------------------------------------------------------------
   public boolean equals (RationalNumber op2)
   {
      return ( numerator == op2.getNumerator() &&
               denominator == op2.getDenominator() );
   }

//-----------------------------------------------------------------
   //  Returns this rational number as a string.
   //-----------------------------------------------------------------
   public String toString ()
   {
      String result;

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

//-----------------------------------------------------------------
   //  Reduces this rational number by dividing both the numerator
   //  and the denominator by their greatest common divisor.
   //-----------------------------------------------------------------
   private void reduce ()
   {
      if (numerator != 0)
      {
         int common = gcd (Math.abs(numerator), denominator);

numerator = numerator / common;
         denominator = denominator / common;
      }
   }

//-----------------------------------------------------------------
   //  Computes and returns the greatest common divisor of the two
   //  positive parameters. Uses Euclid's algorithm.
   //-----------------------------------------------------------------
   private int gcd (int num1, int num2)
   {
      while (num1 != num2)
         if (num1 > num2)
            num1 = num1 - num2;
         else
            num2 = num2 - num1;

return num1;
   }
}

//********************************************************************
//  RationalTester.java  
//
//  Driver to exercise the use of multiple Rational objects.
//********************************************************************

import java.util.Scanner;

public class RationalTester
{
   //-----------------------------------------------------------------
   //  Creates some rational number objects and performs various
   //  operations on them.
   //-----------------------------------------------------------------

public static void main (String[] args)
   {

Scanner scan = new Scanner (System.in);

System.out.print ("Enter a rational number: ");		
       int r1 = scan.nextInt();

System.out.println ("You entered: " + r1);
		
		System.out.print ("Enter a second rational number: ");		
       int r2 = scan.nextInt();

System.out.println ("You entered: " + r2);

RationalNumber r3, r4, r5, r6, r7;

System.out.println ("First rational number: " + r1);
      System.out.println ("Second rational number: " + r2);

if (r1.equals(r2))
         System.out.println ("r1 and r2 are equal.");
      else
         System.out.println ("r1 and r2 are NOT equal.");

r3 = r1.reciprocal();
      System.out.println ("The reciprocal of r1 is: " + r3);

r4 = r1.add(r2);
      r5 = r1.subtract(r2);
      r6 = r1.multiply(r2);
      r7 = r1.divide(r2);

System.out.println ("r1 + r2: " + r4);
      System.out.println ("r1 - r2: " + r5);
      System.out.println ("r1 * r2: " + r6);
      System.out.println ("r1 / r2: " + r7);
   }
}

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