Question

Assignment 1, Fraction

Instructions

For this assignment, you will create a class to store fractions. The class will hold two integer values: a numerator and a denominator. For your class we will stick to positive fractions, meaning the numerator and the denominator must both be greater than 0.

In previous assignments, we had a requirement that your class be named Main. In this assignment, the class is required to be named Fraction.

To get started, download the template file Fraction.java (Links to an external site.). Your job will be to add the constructors and methods described in the following sections to the class Fraction that is declared in this template file.

Fraction should include two constructors:

• Fraction(): default constructor which creates a fraction 1/1
• Fraction(int n, int d): If n is positive, set numerator to n. Otherwise, set numerator to 1. If d is positive, set denominator to d. Otherwise, set denominator to 1.

Fraction should include the following methods:

• String toString(): Returns the fraction as a string in the format “numerator/denominator”. For example 1/2 or 5/3.
• String mixedNumber(): Returns any improper (top-heavy) fraction as a mixed number, for example, 2 3/5. If the numerator of the fraction part is 0, return only the integer part of the mixed number. If the fraction is proper, return only the fraction part.
• void add(int n, int d): If n and d are both positive, add the fraction n/d to this fraction. Otherwise, leave the fractions unchanged. In general the sum of the fractions a/b and c/d is(a*d + c*b)/(b*d).

To test your code, download the runner class student_fraction_runner.java (Links to an external site.) into the same folder that holds your Fraction.java. Execute the method student_fraction_runner.main and verify that the output matches the sample run listed below.

We will use a similar but different runner to grade the program. In order to pass all tests, you will need to change student_fraction_runner.java to test different values to make sure your program fits the requirements. Note: You will not be submitting student_fraction_runner.java. This file is provided to help you test your implementation of the class Fraction.

When you are done coding and testing, copy and paste your entire Fraction class into the Code Runner and press "Submit Answers" in order for your assignment to count as turned in. We will be returning to and improving the Fraction class in a later assignment (you may have already spotted some potential flaws in how the class is implemented) so be sure to save your work.

Sample Run

Fraction 1: 7/4
As a mixed number: 1 3/4

Fraction 2: 1/1
As a mixed number: 1

Fraction 3: 2/7
As a mixed number: 2/7
Add 2/5: 24/35

Fraction 4: 24/6
As a mixed number: 4
Attempt to add 1/-2: 24/6

Fraction 5: 5/2
As a mixed number: 2 1/2
Add 2/3: 19/6
As a mixed number: 3 1/6

Milestones

As you work on this assignment, you can use the milestones below to inform your development process:

Milestone 1: Write the two class constructors Fraction() and Fraction(int n, int d). Test these compile by adding dummy return statements to the String methods.

Milestone 2: Write the two accessor methods toString() and mixedNumber().

Milestone 3: Write the mutator method add(int n, int d). Compile and run the student_fraction_runner class and check the results are as expected, fixing any errors identified.

Answer 1

Short Summary:

• Implemented Fraction class
  • Private members: numerator and denominator
  • Default and parameterized constructors
  • Member functions: toString(), mixedNumber() and add(int n, int d).
• Implemented a sample test runner class to test all the functions

Source Code:

Fraction.java

/* Fraction Java Class */
public class Fraction
{
//private variables
private int numerator;
private int denominator;

//Default constructor
//Assigns 1 to both numerator and denominator
public Fraction()
{
numerator = 1;
denominator = 1;
}

//Parameterized constructor
Fraction(int n, int d)
{
/*numerator and the denominator must both be greater than 0*/

//If n is positive, set numerator to n.
//Otherwise, set numerator to 1
if (n > 0)
{
numerator = n;
}
else
{
numerator = 1;
}

//If d is positive, set denominator to d.
//Otherwise, set denominator to 1.
if (d > 0)
{
denominator = d;
}
else
{
denominator = 1;
}   
}

//Returns the fraction as a string
public String toString()
{
//in the format “numerator/denominator”. For example 1/2 or 5/3.
String temp = numerator + "/" + denominator;
return temp;
}

//void add(int n, int d):
//If n and d are both positive, add the fraction n/d to this fraction.
//Otherwise, leave the fractions unchanged.
//In general the sum of the fractions a/b and c/d is(a*d + c*b)/(b*d).
public void add(int n, int d)
{
// check input parameters are positive
if ((n > 0) && (d > 0))
{
numerator = (numerator * d) + (denominator * n);
denominator = denominator * d;
}
}

//String mixedNumber(): Returns any improper (top-heavy) fraction as a mixed number,
//for example, 2 3/5. If the numerator of the fraction part is 0,
//return only the integer part of the mixed number.
//If the fraction is proper, return only the fraction part.
public String mixedNumber()
{
//Get the quotient using operator '/'
int quotient = numerator / denominator;
//Get the remainder using operator '%'
int remainder = numerator % denominator;

//If remainder is zero, return the whole number
if (remainder == 0)
{
return String.valueOf(quotient);
}
else
{
//format the output - for example, 2 3/5.
if (quotient == 0)
{
return String.valueOf(remainder) + "/" + String.valueOf(denominator);
}
else
{
return String.valueOf(quotient) + " " + String.valueOf(remainder) +
"/" + String.valueOf(denominator);
}
}
}
}

Refer the following screenshot for code indentation:

Sample test class:

public class Main
{
//student_fraction_runner sample
   public static void main(String[] args)
   {
   //test parameterized constructor
   Fraction MyFraction1 = new Fraction(7, 4);
   System.out.println("Fraction 1: " + MyFraction1.toString());
   System.out.println("As a mixed number: " + MyFraction1.mixedNumber());
  
   System.out.println();
  
   //test default constructor
   Fraction MyFraction2 = new Fraction();
   System.out.println("Fraction 2: " + MyFraction2.toString());
   System.out.println("As a mixed number: " + MyFraction2.mixedNumber());
  
   System.out.println();
  
   //test add and mixed number
   Fraction MyFraction3 = new Fraction(2, 7);
   System.out.println("Fraction 3: " + MyFraction3.toString());
   System.out.println("As a mixed number: " + MyFraction3.mixedNumber());
   MyFraction3.add(2, 5);
   System.out.println("Add 2/5: " + MyFraction3.toString());
  
   System.out.println();
  
   //test adding negative integers
   //the numerator and denominator should remain unchanged
   Fraction MyFraction4 = new Fraction(24, 6);
   System.out.println("Fraction 4: " + MyFraction4.toString());
   System.out.println("As a mixed number: " + MyFraction4.mixedNumber());
   MyFraction4.add(1, -2);
   System.out.println("Add 1/-2: " + MyFraction4.toString());
  
   System.out.println();
  
   //test adding positive integers
   //the sum of the fractions a/b and c/d is(a*d + c*b)/(b*d)
   Fraction MyFraction5 = new Fraction(5, 2);
   System.out.println("Fraction 5: " + MyFraction5.toString());
   System.out.println("As a mixed number: " + MyFraction5.mixedNumber());
   MyFraction5.add(2, 3);
   System.out.println("Add 2/3: " + MyFraction5.toString());
   System.out.println("As a mixed number: " + MyFraction5.mixedNumber());
   }
}

Sample Output:

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Happy Studying!!