Java實戰（二）定義複數類Complex，實現加減乘除、toString()函數、equals()函數

定義複數類Complex，實現以下功能：

(1)構造函數
(2)加減乘除函數
(3)toString()函數
(4)equals()函數
(5)編寫測試類，實現鍵盤讀取數據創建複數對象，並測試Complex類定義的函數

實現代碼：

package CurriculumDesign;

import java.util.Scanner;

/*
1.定義複數類Complex，實現以下功能：
  (1)構造函數
  (2)加減乘除函數
  (3)toString()函數
  (4)equals()函數
  (5)編寫測試類，實現鍵盤讀取數據創建複數對象，並測試Complex類定義的函數
*/

public class Test1 {
    public static void main(String[] args)
    {
        //初始化數組
        double[] array = Complex.init();

        //初始化複數對象
        Complex complex1 = new Complex(array[0],array[1]);
        Complex complex2 = new Complex(array[2],array[3]);

        //加減乘除運算並輸出
        System.out.println("加："+complex1.add(complex2).toString());
        System.out.println("減："+complex1.subtract(complex2).toString());
        System.out.println("乘："+complex1.multiply(complex2).toString());
        System.out.println("除："+complex1.divide(complex2).toString());

        //判斷是否相等並輸出
        System.out.println("是否相等：" + complex1.equals(new Complex(1.0, 1.0)));
    }
}

class Complex {

    private double real = 0.0;
    private double image = 0.0;

    //無參構造
    public Complex() {
    }

    //有參構造函數
    Complex(double real, double image) {
        this.real = real;
        this.image = image;
    }

    //加
    public Complex add(Complex complex)
    {
        return new Complex(this.real+complex.real,this.image+complex.image);
    }

    //減
    public Complex subtract(Complex complex)
    {
        return new Complex(this.real-complex.real,this.image-complex.image);
    }

    //乘
    //設z1=a+bi，z2=c+di(a、b、c、d∈R)是任意兩個複數，那麼它們的積(a+bi)(c+di)=(ac-bd)+(bc+ad)i
    public Complex multiply(Complex complex)
    {
        return new Complex(this.real*complex.real-this.image*complex.image,this.image*complex.real+this.real*complex.image);
    }

    //除
    //(a+bi)/(c+di)=(ac+bd)/(c^2+d^2) +((bc-ad)/(c^2+d^2))i
    public Complex divide(Complex complex)
    {
        double real = (this.real*complex.real+this.image*complex.image)/(complex.real*complex.real+complex.image*complex.image);
        double image = (this.image*complex.real-this.real*complex.image)/(complex.real*complex.real+complex.image*complex.image);
        return new Complex(real,image);
    }

    //重寫toString()
    public String toString()
    {
        //當虛部爲零時省略虛部，當虛部不爲零但實部爲零時省略實部
        if (this.image == 0) { return this.real+""; }
        else if (this.image > 0) {
            if (this.real == 0) return this.image + "i";
            else return this.real + "+" + this.image + "i";
        }
        else{
            if (this.real == 0) return this.image+"i";
            else return this.real+""+this.image+"i";
        }
    }

    //是否相等
    public boolean equals(Complex complex)
    {
        if ((this.real == complex.real) && (this.image == complex.image))
        {
            return true;
        }
        return false;
    }

    //從鍵盤輸入，並存放在數組中
    public static double[] init()
    {
        Scanner scanner = new Scanner(System.in);
        double[] array = new double[4];
        System.out.println("請分別輸入第一個複數的實部、虛部，第二個複數的實部、虛部：");
        for (int i = 0; i < 4; i++) array[i] = Double.parseDouble(scanner.next());
        scanner.close();
        return array;
    }
}

運行結果：