一个复数是一个形式为a+bi的数，这里的a和b都是实数，i是-1的平方根。数字a和b分别称为复数的实部和虚部。 可以使用下面的公式完成复数的加、减、乘、除：(a+bi)+(c+di)=(a+c)+(b+d)i;(a+bi)-(c+di)=(a-c)+(b-d)i;(a+bi)*(c+di)=(ac-bd)+(ad+bc)i;(a+bi)/(c+di)=(ac+bd)/(c^2+d^2)+ (bc-ad)/(c^2+d^2)i;还可以使用下面的公式得到复数的绝对值： |a+bi|=sqrt(a^2+b^2);设计一个名为Complex的复数类来表示复数以及完成复数运算的add、substract、multiply、divide和 calAbs（绝对值）方法，并且覆盖toString方法以返回一个表示复数的字符串。方法toString返回字符串 a+bi。如果b是0，那么它只返回a。实现三个构造器：Complex(a, b)、Complex(a)和Complex()。Complex()创建数字0的Complex 对象，而Complex(a)创建一个b为0的Complex对象。 还提供getA()和getB()方法以返回复数的实部和虚部。编写一个测试程序，提示用户输入两个复数，然后显示它们做加、减、乘、除之后的结果。
import java.util.Scanner;

 class Complex {private double realPart;private double imaginPart;Complex(double r, double i) {this.realPart = r;this.imaginPart = i;}Complex(double real){this.realPart=real;this.imaginPart=0;}Complex() {this.realPart = 0;this.imaginPart = 0;}//3个构造方法//public double getB() {return this.imaginPart;}//返回imagine的值//public double getA() {return this.realPart;}//返回real的值//public  Complex complexAdd(Complex a) {//传进来的complex a和b类似于c中的指针Complex c = new Complex();//定义一个c的complex类给c初始化c.realPart = this.realPart + a.realPart;c.imaginPart = this.imaginPart + a.imaginPart;return c;//返回c这个子类的值//}public Complex complexSubtract(Complex a) {Complex c = new Complex();c.realPart = this.realPart - a.realPart;c.imaginPart = this.imaginPart - a.imaginPart;return c;}//减法//public  Complex mutiply(Complex a) {Complex c = new Complex();c.realPart = this.realPart * a.realPart - this.imaginPart * a.imaginPart;c.imaginPart = this.realPart * a.imaginPart + this.imaginPart * a.realPart;return c;}public  Complex divide(Complex a) {Complex c = new Complex();c.realPart = (a.realPart * this.realPart + a.imaginPart * this.imaginPart) / (a.realPart * a.realPart + a.imaginPart * a.imaginPart);c.imaginPart = (a.realPart * this.imaginPart - this.realPart * a.imaginPart) / (a.realPart * a.realPart + a.imaginPart * a.imaginPart);return c;}public double calAbs() {double temp = Math.sqrt(this.realPart * this.realPart +this.imaginPart * this.imaginPart);return temp;}//求模//public String toString() {if (this.realPart >= 0 && this.realPart < 0.01) {if (this.imaginPart >= 0 && this.imaginPart < 0.01)return "0.00";elsereturn String.format("%.2fi", this.imaginPart);}else {if (this.imaginPart >= 0 && this.imaginPart < 0.01)return String.format("%.2f", this.realPart);elseif (this.imaginPart > 0)return String.format("%.2f+%.2fi", this.realPart, this.imaginPart);elsereturn String.format("%.2f%.2fi", this.realPart, this.imaginPart);}}
}class Main{public static void main(String[] args) {Scanner in = new Scanner(System.in);double real1=in.nextDouble();double image1=in.nextDouble();double real2=in.nextDouble();double image2=in.nextDouble();Complex a=new Complex(real1,image1);Complex b=new Complex(real2,image2);System.out.printf("Real:%.2f imaginary:%.2f Fabs:%.2fn",a.getA(),a.getB(),a.calAbs());System.out.printf("Real:%.2f imaginary:%.2f Fabs:%.2fn",b.getA(),b.getB(),b.calAbs());System.out.println(a.complexAdd(b));System.out.println(a.complexSubtract(b));System.out.println(a.mutiply(b));System.out.println(a.divide(b));}
}