From the last couple of articles, I am writing about coding exercises for beginners e.g. yesterday you learned how to write a program from matrix multiplication in Java (see here) and a couple of days back, you have learned the recursive binary search algorithm. To continue that tradition today I am going to show you how to write a program for calculating the sum and difference of two complex numbers in Java. If you remember the complex number from you maths classes, it has two-part real and imaginary and to add a complex number we add their real and imaginary part separately, similar to subtract complex number we minus their real and imaginary part separately.

For example, if the first complex number is A + iB and the second complex number is X + iY then the addition of these two complex numbers will be equal to (A +X ) + i(B + Y).

Similarly, subtraction of these two complex numbers would be equal to (A - X) + i(B -Y). So, the formula is quite simple but the key is to implement that in a program using object-oriented techniques.

In order to solve the problem in an object-oriented way, I have created a ComplexNumber class to encapsulate both real and imaginary parts. This class has the getter to retrieve both real and imaginary parts but I have not provided any setter method because I made this class Immutable.

Similarly, subtraction of these two complex numbers would be equal to (A - X) + i(B -Y). So, the formula is quite simple but the key is to implement that in a program using object-oriented techniques.

In order to solve the problem in an object-oriented way, I have created a ComplexNumber class to encapsulate both real and imaginary parts. This class has the getter to retrieve both real and imaginary parts but I have not provided any setter method because I made this class Immutable.

This means, you cannot change the value of a complex number once created, any modification will result in the creation of a new ComplexNumber, much like String because String class is also immutable in Java.

This class also has methods to calculate the sum and difference of two complex numbers. The sum() method accepts a complex number and returns the sum of this complex number with the given complex number. Since ComplexNumber is an Immutable class, it returns a new instance of ComplexNumber and doesn't modify the existing instance.

Similarly, the difference() method also accepts a ComplexNumber and calculates the difference between this instance and given a complex number. It also returns a new ComplexNumber instance, whose real and imaginary parts are equal to the difference of real parts of two complex numbers.

If you are interested in learning more about immutability and its benefit, I suggest you join a good Java online course to learn fundamental Java concepts, a perfect companion in your Java journey.

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Here is our complete Java program to calculate the sum and difference of two complex numbers in Java. It's a simple program because addition is nothing but adding the real and imaginary parts of both complex numbers and subtraction is also subtracting both the real and imaginary parts of the complex number.

This class also has methods to calculate the sum and difference of two complex numbers. The sum() method accepts a complex number and returns the sum of this complex number with the given complex number. Since ComplexNumber is an Immutable class, it returns a new instance of ComplexNumber and doesn't modify the existing instance.

Similarly, the difference() method also accepts a ComplexNumber and calculates the difference between this instance and given a complex number. It also returns a new ComplexNumber instance, whose real and imaginary parts are equal to the difference of real parts of two complex numbers.

If you are interested in learning more about immutability and its benefit, I suggest you join a good Java online course to learn fundamental Java concepts, a perfect companion in your Java journey.

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__Java Program to calculate sum and difference of two Complex Numbers__

Here is our complete Java program to calculate the sum and difference of two complex numbers in Java. It's a simple program because addition is nothing but adding the real and imaginary parts of both complex numbers and subtraction is also subtracting both the real and imaginary parts of the complex number. Here is a nice diagram to explain the addition of complex numbers, may this will remind you of the maths lesson from school days:

That's all about

__Java program of addition and subtraction of two Complex Numbers__

__Java program of addition and subtraction of two Complex Numbers__

import java.util.Scanner; /* * Java Program to add and subtract two complex numbers * This program will calculate sum and difference of two * given a complex number in Java. */ public class Main { public static void main(String[] args) { // first complex number ComplexNumber c1 = new ComplexNumber(2, 4); ComplexNumber c2 = new ComplexNumber(3, 5); ComplexNumber sum = c1.sum(c2); ComplexNumber difference = c1.difference(c2); System.out.println("first complex number: " + c1); System.out.println("second complex number: " + c2); System.out.println("sum of two complex numbers: " + sum); System.out.println("difference of two complex numbers: " + difference); } } /* * A class to represent a complex number. A complex number has two parts, real * and imaginary. Make this class Immutable as it's a value class. */ class ComplexNumber { private final double real; private final double imaginary; public ComplexNumber(double real, double imaginary) { this.real = real; this.imaginary = imaginary; } public ComplexNumber sum(ComplexNumber other) { double r = this.real + other.real; double i = this.imaginary + other.imaginary; return new ComplexNumber(r, i); } public ComplexNumber difference(ComplexNumber other) { double r = this.real - other.real; double i = this.imaginary - other.imaginary; return new ComplexNumber(r, i); } public double getReal() { return real; } public double getImaginary() { return imaginary; } @Override public String toString() { return real + " + " + imaginary + "i"; } } Output first complex number: 2.0 + 4.0i second complex number: 3.0 + 5.0i sum of two complex numbers: 5.0 + 9.0i difference of two complex numbers: -1.0 + -1.0i

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**how to calculate the sum and difference of two complex numbers in Java**. In this program, we have followed object-oriented programming concepts to represent a complex number and methods for the addition and subtraction of complex numbers. You can also create some JUnit test to test the add() and subtract() or sum() and difference() methods.
Other

**coding exercises**for programmers- How to implement binary search using recursion in Java? (solution)
- How to do matrix multiplication in Java? (example)
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**P. S. -**It's a good exercise to start with. If you are interested in more programming and coding challenges then you can also solve problems given in Exercises for Programmers: 57 Challenges to Develop Your Coding Skills book.
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