Adding Fractions in Java

Rationalise (Canonise) the Fractions before Addition

Normally before fractions are added, they are rationalised; i.e., they are put in a form where their denominators become the same. This same denominator is the LCM of the denominators of all the separate fractions.
After this is done, the new numerators can then be added together.

Steps for Addition of Fractions Java code

The following steps will guide us in writing our code.
Let's illustrate with ²/₅ + ⁷/₄

Step 1:

Find the LCM of the denominators.
⇒ LCM of 5 & 4 = 20

Step 2:

In a turn by turn fashion, divide the found LCM from Step 1 by each denominator, multiplying the quotient by the corresponding numerator.
⇒ ^{((2 x 4) + (7 x 5))}/₂₀
= ^{(8 + 35)}/₂₀

Step 3:

Go ahead and add the numerators.
⇒ ⁴³/₂₀

Create a new class file; Call them AddFraction.;
Type out the adjoining Java code for adding fractions.

Note: The code module for finding LCM is from the Primary Category.
Create a new Class File called LCM in your current project and copy the L.C.M. code into it.

You can comment out the DivideFraction Java object code in the main class from the previous lesson or simply continue from where it stopped.

So!

Feel free to try out your own set of numerators and denominators for fractional addition.

Java code for AddFraction class file

package algebra;

import java.util.ArrayList;
import java.util.List;

public class AddFraction {

    protected final List<Integer> numerators;
    protected final List<Integer> denominators;
    protected List<Integer> new_numerators;
    protected int lcm;
    protected int answer = 0;

    public AddFraction(List<Integer> num, List<Integer> denom) {
        numerators = num;
        denominators = denom;
        new_numerators = new ArrayList<>();
    }

    protected void canonizeFraction() {
        LCM l_c_m = new LCM(denominators);
        lcm = l_c_m.getLCM();

        for (int i = 0; i < denominators.size(); i++) {
            new_numerators.add(lcm / denominators.get(i) * numerators.get(i));
        }
    }

    public int[] doAdd() {
        canonizeFraction();

        for (int n : new_numerators) {
            answer += n;
        }
        return new int[]{answer, lcm};
    }
}

main class

package algebra;

import java.util.ArrayList;
import java.util.List;

public class Algebra {

    public static void main(String[] args) {

        int numerator;
        int denominator;
        List<Integer> numerators;
        List<Integer> denominators;
        int[] solution;

        System.out.println("Welcome to our demonstration sequels");
        System.out.println("Hope you enjoy (and follow) the lessons.");
        System.out.println("");

        /*
        * Adding fractions
         */
        numerators = new ArrayList<>();
        numerators.add(1);
        numerators.add(1);
        numerators.add(1);
        numerators.add(1);

        denominators = new ArrayList<>();
        denominators.add(4);
        denominators.add(4);
        denominators.add(4);
        denominators.add(4);

        System.out.println("Solving:");
        // Print as fraction
        for (int n : numerators) {
            System.out.printf("%13d", n);
        }
        System.out.println();
        System.out.printf("%12s", " ");
        for (int i = 0; i < numerators.size() - 1; i++) {
            System.out.print("―     +     ");
        }
        System.out.printf("%2s", "―");
        System.out.println();
        for (int d : denominators) {
            System.out.printf("%13d", d);
        }
        System.out.println();

        // use the AddFraction class
        AddFraction add_fract = new AddFraction(numerators, denominators);
        solution = add_fract.doAdd();
        numerator = solution[0];
        denominator = solution[1];

        System.out.println();

        System.out.printf("%25d%n", numerator);
        System.out.printf("%24s%n", "Answer =     ―");
        System.out.printf("%25d%n", denominator);

        System.out.println("\n\n");
    }

}

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