ComplexNumber.java Source code

Introduction

Here is the source code for ComplexNumber.java

Source

/*
 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit http://www.davidflanagan.com/javaexamples3.
 */

/**
 * This class represents complex numbers, and defines methods for performing
 * arithmetic on complex numbers.
 */
public class ComplexNumber {
    // These are the instance variables. Each ComplexNumber object holds
    // two double values, known as x and y. They are private, so they are
    // not accessible from outside this class. Instead, they are available
    // through the real() and imaginary() methods below.
    private double x, y;

    /** This is the constructor. It initializes the x and y variables */
    public ComplexNumber(double real, double imaginary) {
        this.x = real;
        this.y = imaginary;
    }

    /**
     * An accessor method. Returns the real part of the complex number. Note that
     * there is no setReal() method to set the real part. This means that the
     * ComplexNumber class is "immutable".
     */
    public double real() {
        return x;
    }

    /** An accessor method. Returns the imaginary part of the complex number */
    public double imaginary() {
        return y;
    }

    /** Compute the magnitude of a complex number */
    public double magnitude() {
        return Math.sqrt(x * x + y * y);
    }

    /**
     * This method converts a ComplexNumber to a string. This is a method of
     * Object that we override so that complex numbers can be meaningfully
     * converted to strings, and so they can conveniently be printed out with
     * System.out.println() and related methods
     */
    public String toString() {
        return "{" + x + "," + y + "}";
    }

    /**
     * This is a static class method. It takes two complex numbers, adds them, and
     * returns the result as a third number. Because it is static, there is no
     * "current instance" or "this" object. Use it like this: ComplexNumber c =
     * ComplexNumber.add(a, b);
     */
    public static ComplexNumber add(ComplexNumber a, ComplexNumber b) {
        return new ComplexNumber(a.x + b.x, a.y + b.y);
    }

    /**
     * This is a non-static instance method by the same name. It adds the
     * specified complex number to the current complex number. Use it like this:
     * ComplexNumber c = a.add(b);
     */
    public ComplexNumber add(ComplexNumber a) {
        return new ComplexNumber(this.x + a.x, this.y + a.y);
    }

    /** A static class method to multiply complex numbers */
    public static ComplexNumber multiply(ComplexNumber a, ComplexNumber b) {
        return new ComplexNumber(a.x * b.x - a.y * b.y, a.x * b.y + a.y * b.x);
    }

    /** An instance method to multiply complex numbers */
    public ComplexNumber multiply(ComplexNumber a) {
        return new ComplexNumber(x * a.x - y * a.y, x * a.y + y * a.x);
    }
}