Gigal: Java Fraction Calculator Example

This example show you how to implement a simple calculator which can calculate fractions. Some best practices have been used. This example also will be helpful with University of Westminster / Informatics Institute of Technology - BEng(Hons) in Software Engineering 1st year modules.

Validated For :

Non numeric inputs
x/0 type fractions
0/0 and 0/y type fractions
x/1 and x/x type fractions
-x/-y and x/-y type fractions

IDE used : Eclipse (Kepler)

Download source from GitHub (Eclipse project)

https://github.com/GigalBlog/Java-Fraction-Calculator-Example

Join code review
http://codereview.stackexchange.com/questions/43084/java-fraction-calculator

Screenshots

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package com.gigal.fractionexercise.model;

/*
* This class models the fraction
*/

public class Fraction {

private int Numerator; // x
private int Denominator; // y

public int getNumerator() {
return Numerator;
}

public void setNumerator(int Numerator) {
this.Numerator = Numerator;
}

public int getDenominator() {
return Denominator;
}

public void setDenominator(int Denominator) {
this.Denominator = Denominator;
}

// This method is used to display fractions
// Some kind of processing also
public void display() {

// 0/y and x/1 types
if (Numerator == 0 || Denominator == 1) {
System.out.print(Numerator);
}

// -x/-y and x/-y types
else {
if ((Numerator < 0 && Denominator < 0) || (Numerator > 0 && Denominator < 0)) {
Numerator *= -1;
Denominator *= -1;
}

// x/x type
if (Numerator == Denominator) {
System.out.print(Numerator);
return;
}

System.out.print(this.Numerator + "/" + this.Denominator);
}

}

}

Addition.java

package com.gigal.fractionexercise.model;

/*
* This class models addition
*/

import com.gigal.fractionexercise.helper.Messages;

public class Addition {

private Fraction fraction1;
private Fraction fraction2;
private Fraction answer;

// Constructor
public Addition(Fraction fraction1, Fraction fraction2) {
this.fraction1 = fraction1;
this.fraction2 = fraction2;
this.answer = new Fraction();
Calculate();
}

// perform the calculation
public void Calculate() {
answer.setNumerator((fraction1.getNumerator() * fraction2.getDenominator())
+ (fraction2.getNumerator() * fraction1.getDenominator()));
answer.setDenominator(fraction1.getDenominator() * fraction2.getDenominator());
}

// display the answer
public void display() {
Messages.displayAnswer("Addition", "+", fraction1, fraction2, answer);
}

}

Subtraction.java

package com.gigal.fractionexercise.model;

/*
* This class models subtraction
*/

import com.gigal.fractionexercise.helper.Messages;

public class Subtraction {

private Fraction fraction1;
private Fraction fraction2;
private Fraction answer;

// Constructor
public Subtraction(Fraction fraction1, Fraction fraction2) {
this.fraction1 = fraction1;
this.fraction2 = fraction2;
this.answer = new Fraction();
Calculate();
}

// perform the calculation
public void Calculate() {
answer.setNumerator((fraction1.getNumerator() * fraction2.getDenominator()) - (fraction2.getNumerator() * fraction1.getDenominator()));
answer.setDenominator(fraction1.getDenominator() * fraction2.getDenominator());
}

// display the answer
public void display() {
Messages.displayAnswer("Subtraction", "-", fraction1, fraction2, answer);
}

}

Multiplication.java

package com.gigal.fractionexercise.model;

/*
* This class models multiplication
*/

import com.gigal.fractionexercise.helper.Messages;

public class Multiplication {

private Fraction fraction1;
private Fraction fraction2;
private Fraction answer;

// Constructor
public Multiplication(Fraction fraction1, Fraction fraction2) {
this.fraction1 = fraction1;
this.fraction2 = fraction2;
this.answer = new Fraction();
Calculate();
}

// perform the calculation
public void Calculate() {
answer.setNumerator(fraction1.getNumerator() * fraction2.getNumerator());
answer.setDenominator(fraction1.getDenominator() * fraction2.getDenominator());
}

// display the answer
public void display() {
Messages.displayAnswer("Multiplication", "*", fraction1, fraction2, answer);
}

}

Division.java

package com.gigal.fractionexercise.model;

/*
* This class models division
*/

import com.gigal.fractionexercise.helper.Messages;

public class Division {

private Fraction fraction1;
private Fraction fraction2;
private Fraction answer;

// Constructor
public Division(Fraction fraction1, Fraction fraction2) {
this.fraction1 = fraction1;
this.fraction2 = fraction2;
this.answer = new Fraction();
Calculate();
}

// perform the calculation
public void Calculate() {
answer.setNumerator(fraction1.getNumerator() * fraction2.getDenominator());
answer.setDenominator(fraction1.getDenominator() * fraction2.getNumerator());
}

public void display() {
// Check for the divide by zero error
if (fraction2.getNumerator() == 0) {
System.out.println("Division : Cannot divide by zero!");
return;
} else {
// display the answer
Messages.displayAnswer("Division", "/", fraction1, fraction2,
answer);
}
}

}

Messages.java

package com.gigal.fractionexercise.helper;

import com.gigal.fractionexercise.model.Fraction;

/*
* This class is used to give meaningful messages to user
* So whenever we want to change a message we don't want to check whole app but this class
*/

public class Messages {

// This message is use to display the program header
public static void displayHeader() {
System.out.println("_________________________________________________________");
System.out.println(" Fraction App - a Gigal Blog Production");
System.out.println("_________________________________________________________");
newLine();
}

// This message is use to display the program footer
public static void displayFooter() {
newLine();
System.out.println(" ----------- Thank you for using Fraction App -----------");
System.out.println("_________________________________________________________");
newLine();
}

// This message is use to tell user to input value for Numerator in a fraction
public static void insertNumerator() {
System.out.print("Numerator : ");
}

// This message is use to tell user to input a value for denominator
public static void inputDenominator() {
System.out.print("Denominator : ");
}

// This method is used to get line of space
public static void newLine() {
System.out.println("\n");
}

// This message is used when user input something miss match
public static void inputError(Exception e) {
newLine();
System.out.println("Input Error: " + e.toString());
System.out.println("Closing application ...");
System.out.println("Fraction app is closed.");
displayFooter();
}

// This message is used when user input 0 for Denominator in a fraction
public static void DenominatorCannotBeZero() {
System.out.println("Input Error: Denominator Cannot be zero");
newLine();
}

// This message is used to display answers
public static void displayAnswer(String operation, String operator,
Fraction fraction1, Fraction fraction2, Fraction answer) {
System.out.print(operation + " : ");
fraction1.display();
System.out.print(" " + operator + " ");
fraction2.display();
System.out.print(" = ");
answer.display();
newLine();
}

}

FractionsApp.java

package com.gigal.fractionexercise.app;

/*
* Fraction Exercise
* Author - Gigal
*/

import java.util.Scanner;

import com.gigal.fractionexercise.helper.Messages;
import com.gigal.fractionexercise.model.Division;
import com.gigal.fractionexercise.model.Fraction;
import com.gigal.fractionexercise.model.Multiplication;
import com.gigal.fractionexercise.model.Subtraction;
import com.gigal.fractionexercise.model.Addition;

public class FractionsApp {

private static Scanner keyboard = new Scanner(System.in);

public static void main(String args[]) {

Fraction fraction1 = new Fraction(); // first fraction
Fraction fraction2 = new Fraction(); // second fraction

// Display application header
Messages.displayHeader();

// get user inputs for fraction one and validate them
do {
System.out.println("Enter values for fration one");
Messages.insertNumerator();
try {
fraction1.setNumerator(keyboard.nextInt()); // get user input
} catch (Exception e) {
Messages.inputError(e); // display error
return;
}
Messages.inputDenominator();
try {
fraction1.setDenominator(keyboard.nextInt()); // get user input
} catch (Exception e) {
Messages.inputError(e);
return;
}
if (fraction1.getDenominator() == 0) { // check for x/0 error
Messages.DenominatorCannotBeZero();
}
} while (fraction1.getDenominator() == 0);

// Display fraction one
System.out.print("Fraction one : ");
fraction1.display();
Messages.newLine();

// get user inputs for fraction two and validate them
do {
System.out.println("Enter values for fration two");
Messages.insertNumerator();
try {
fraction2.setNumerator(keyboard.nextInt()); // get user input
} catch (Exception e) {
Messages.inputError(e);
return;
}
Messages.inputDenominator();
try {
fraction2.setDenominator(keyboard.nextInt()); // get user input
} catch (Exception e) {
Messages.inputError(e);
return;
}
if (fraction2.getDenominator() == 0) { // check for x/0 error
Messages.DenominatorCannotBeZero();
}
} while (fraction2.getDenominator() == 0);

// Display fraction two
System.out.print("Fraction two : ");
fraction2.display();
Messages.newLine();

// Addition
Addition addition = new Addition(fraction1, fraction2);
addition.display();

// Subtraction
Subtraction subtraction = new Subtraction(fraction1, fraction2);
subtraction.display();

// Multiplication
Multiplication multiplication = new Multiplication(fraction1, fraction2);
multiplication.display();

// Division
Division division = new Division(fraction1, fraction2);
division.display();

// Display application footer
Messages.displayFooter();
}

}

1 comment:

TessieJune 17, 2020 at 6:36 AM
Calculator is very useful for Trigonometry, Calculus, and advanced mathematics subjects. There are also other calculator that are best for specific purpose such as fraction calculator for solving fraction problems. Scientific calculator is also best for Chemistry, Physics, and engineering subjects.

Gigal

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Sunday, February 16, 2014

Java Fraction Calculator Example

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