What is wrong?-posted again and better to understand

Question

Okay. I saw a few answers. So here is again the program I have to do and the whole code I made:
-Create a class called Rational for performing arithmetic with fractions. Write a driver program to test your class.
Use integer variables to represent the private instance variables of the class�the numerator and the denominator. Provide a constructor method that enables an object of this class to be initialized when it is declared. The constructor should store the fraction in reduced form (i.e., the fraction
2/4
would be stored in the object as 1 in the numerator and 2 in the denominator). Provide a no- argument constructor with default values in case no initializers are provided. Provide public methods for each of the following:
-Addition of two Rational numbers. The result of the addition should be stored in reduced form.
Subtraction of two Rational numbers. The result of the subtraction should be stored in reduced form.
-Multiplication of two Rational numbers. The result of the multiplication should be stored in reduced form.
-Division of two Rational numbers. The result of the division should be stored in reduced form.
-Printing Rational numbers in the form a/b, where a is the numerator and b is the denominator.
-Printing Rational numbers in floating-point format. (Consider providing formatting capabilities that enable the user of the class to specify the number of digits of precision to the right of the decimal point.)
MY CODE:
// Definition of class Rational
public class Rational extends Object {
// variables
private int numerator;
private int denominator;
// Rational constructor with no arguments:
// numerator initialized to 0 and denominator initialized to 1
public Rational()
this( 0/1, 0/1 );
// Rational constructor: numerator initialized to n
// and denominator initialized to 1
public Rational( int n )
this( n/1, n/1 );
// Rational constructor: numerator initialized to n
// and denominator initialized to d
public Rational( int n, int d )
numerator = n;
denominator = d;
// Add two Rational numbers
public Rational sum( Rational right )
return new Rational( ( numerator * right.denominator + denominator * right.numerator ) / denominator * right.denominator );
// Subtract two Rational numbers
public Rational subtract( Rational right )
return new Rational( ( numerator * right.denominator - denominator * right.numerator ) / denominator * right.denominator );
// Multiply two Rational numbers
public Rational multiply( Rational right )
return new Rational( ( numerator * right.numerator ) / denominator * right.denominator );
// Divide two Rational numbers
public Rational divide( Rational right )
return new Rational( ( numerator * right.denominator ) / denominator * right.numerator );
// Reduce the fraction
private void reduce()
int gcd = 0;
int smaller = Math.min( numerator, denominator );
for ( int x = 2; x <= smaller; x++ )
if ( numerator % x == 0 && denominator % x == 0 )
gcd = x;
if ( gcd != 0 )
numerator /= gcd;
denominator /= gcd;
} // end method reduce
// Return String representation of a Rational number
public String toString()
return numerator + "/" + denominator;
// Return floating-point String representation of a Rational number
public String toFloatString()
return Double.toString(
( double ) numerator / denominator );
} // end public class Rational
This is the test program I wrote:
// Java core packages
import java.awt.*;
import java.awt.event.*;
// Java extension packages
import javax.swing.*;
public class RationalTest extends JApplet implements ActionListener
private Rational a, b;
// GUI components
private JLabel nlabel1, nlabel2, dlabel1, dlabel2;
private JTextField numer1Field, numer2Field, denom1Field, denom2Field;
private JButton additButton, subtractButton, multiplyButton, divideButton;
// set up applet's GUI
public void init()
// obtain content pane and set its layout to FlowLayout
Container container = getContentPane();
container.setLayout( new FlowLayout() );
// create nlabel1, numer1Field and attach them to content pane
nlabel1 = new JLabel( "Enter numerator 1:" );
numer1Field = new JTextField( 5 );
container.add( nlabel1 );
container.add( numer1Field );
// create dlabel1, denomField1 and attach them to content pane
dlabel1 = new JLabel( "Enter denominator 1:" );
denom1Field = new JTextField( 5 );
container.add( dlabel1 );
container.add( denom1Field );
// create nlabel2, numer2Field and attach them to content pane
nlabel2 = new JLabel( "Enter numerator 2:" );
numer2Field = new JTextField( 5 );
container.add( nlabel2 );
container.add( numer2Field );
// create dlabel2, denomField2 and attach them to content pane
dlabel2 = new JLabel( "Enter denominator 2:" );
denom2Field = new JTextField( 5 );
container.add( dlabel2 );
container.add( denom2Field );
// set up additButton and attach it to content pane
additButton = new JButton( "Add" );
additButton.addActionListener( this );
container.add( additButton );
// set up subtractButton and attach it to content pane
subtractButton = new JButton( "Subtract" );
subtractButton.addActionListener( this );
container.add( subtractButton );
// set up multiplyButton and attach it to content pane
multiplyButton = new JButton( "Multiply" );
multiplyButton.addActionListener( this );
container.add( multiplyButton );
// set up divideButton and attach it to content pane
divideButton = new JButton( "Divide" );
divideButton.addActionListener( this );
container.add( divideButton );
} // end method init
// handle button events
public void actionPerformed( ActionEvent actionEvent )
Rational r;
a = new Rational( Integer.parseInt( numer1Field.getText() ),
Integer.parseInt( denom1Field.getText() ) );
b = new Rational( Integer.parseInt( numer2Field.getText() ),
Integer.parseInt( denom2Field.getText() ) );
// process additButton event
if ( actionEvent.getSource() == additButton )
r = a.sum( b );
showStatus( "a + b = " + r + " = " + r.toFloatString() );
// process subtractButton event
else if ( actionEvent.getSource() == subtractButton )
r = a.subtract( b );
showStatus( "a - b = " + r + " = " + r.toFloatString() );
// process multiplyButton event
else if ( actionEvent.getSource() == multiplyButton )
r = a.multiply( b );
showStatus( "a * b = " + r + " = " + r.toFloatString() );
// process divideButton event
else if ( actionEvent.getSource() == divideButton )
r = a.divide( b );
showStatus( "a / b = " + r + " = " + r.toFloatString() );
} // end method actionPerformed
} // end public class RationalTest
The html for the applet is:
<html>
<applet code = "RationalTest.class" width = "400" height = "100">
</applet>
</html>
I decided post all this, so you guys have a better idea of what is this about.
The program compiles without errors, but the calculations (add, subtract, multiply and divide) don't work well.
If I follow one of the advices someone gave me here [enclose between parenthesis what follows to the symbol "/" in the calculation for the denominator. It would be, for example for the addition:
return new Rational( ( numerator * right.denominator + denominator * right.numerator ) / ( denominator * right.denominator ) ); ],
I always get the output, a+b = 0/0 = NAN
Do you guys think the problem is in the calculations? is it maybe in the reduce method? Well, my instructor told me that the reduce method works okay. And I still don't know/see what is wrong with the calculations.
Again, the instructor is telling me that

Answer 1

The problem is that the sum, subtract, multiply, and divide methods all use integer arithmetic, so anything less than 1 gets rounded to zero. Try replacing the division symbol '/' by a comma in each method.
Also, your two-argument constructor doesn't reduce the fraction before storing it, as the assignment stated it should. Also, your one-argument constructor doesn't do what the comments state; it initializes both numerator and denominator to n. If n==0, then you get 0/0 as you have discovered.