Implements the Fraction2 Class which illustrates the use of accessor, mutator and helper methods.

Use set (mutator) methods instead.

use the new simplify helper method.

mutator methods

A new simplify method.

Every Java Class descends fron Class Object, therefore every Java Class has a toString() method, whether you can see it or not.

See Inheritance in Topic 5.

/**
* A Class for implementing the data type fraction
* Modified with accessor, mutator and helper methods
*
* @author Mr J
* @version 20040217
*/
public class Fraction2
{
   private int numerator;    // top part
   private int denominator;  // bottom part

  /**
   * Constructor for objects of class Fraction
   */
   public Fraction2()
   {
     // initialise instance variables
     setNumerator(0);
     setDenominator(1);
   }
   /**
   * Construct a fraction given two ints (numerator first)
   *
   * @param n the numerator
   * @param d the denominator
   */
   public Fraction2(int n, int d)
   {
     setNumerator(n);
     setDenominator(d);
   }

  /**
   * A method to add two fractions
   *
   * @param a a Fraction
   * @param b another Fraction
   * @return the sum of fractions a and b
   */
   public static Fraction2 add(Fraction2 a, Fraction2 b)
   {
     // find the common denominator, multiply the numerators
     int cd = (a.denominator * b.denominator);
     a.numerator = a.numerator * b.denominator;
     b.numerator = b.numerator * a.denominator;
     // now add them
     int nm = a.numerator + b.numerator;

     // return a new (simplified) fraction instance
     Fraction2 newOne = new Fraction2(nm, cd);
     newOne.simplify();
     return newOne;
   }
   /**
   * sets the numerator field
   *
   * @param n top part of fraction
   */
   public void setNumerator(int n)
   {
     this.numerator = n;
   }
   /**
   * sets the denominator field
   *
   * @param d bottom part of fraction
   */
   public void setDenominator(int d)
   {
     this.denominator = d;
   }
   /**
   * reduces fraction to lowest common denominator
   */
   private void simplify()
   {
     int start = numerator;
     boolean done = false;
     while ( (!done) && (start > 1) )
     {
       // check that the numerator can be divided exactly by start
       if (numerator%start == 0)
       {
         // see if the denominator can be divided exactly by the same number
         if (denominator%start == 0)
         {
           // got a result
           numerator = numerator / start;
           denominator = denominator / start;
           done = true;
         }
       }
       start = start - 1;
     }
   }
   /**
   * Override toString() method of Class Object
   *
   * @return a String representation of the Fraction
   */
   public String toString()
   {
     return("" + numerator + "/" + denominator);
   }
}

Related: [ Java Home | classes page ]

Modified from Fraction

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