（1）编写一个复数类ComplexNumber，其中包括实例变量real、image，方法如下： 1)构造方法 ComplexNumber（double a,double b） 2) ComplexNumber add(ComplexNumber x) //当前复数对象与另一复数对象进行复数的加法运算，返回一新的复数对象 3) ComplexNumber sub(ComplexNumber x) //当前复数对象与另一复数对象进行复数的减法运算，返回一新的复数对象 4)double getReal () //获取复数对象的实部 5)double getImage () //获取复数对象的虚部 6)void show( ) //按照实部+虚部i(如10+8i)的形式显示复数对象的值 7)String toString()//返回复数对象对应的串(如4+7i) -(1) the preparation of a complex class ComplexNumber, including instance variables real, image, as follows: 1) construction method ComplexNumber (double a, double b) the 2) ComplexNumber add (ComplexNumber x)// plural object with another plural object plural addition operations, and return a new complex object 3) ComplexNumber sub (ComplexNumber x)// plural object with another plural object subtraction of complex numbers, and returns a new complex object 4) a double getReal ()// access to complex objects the imaginary part of the real part 5) double getImage ()// Get the plural object) void show ()// display in accordance with the+ imaginary of the real part of the Department of i (such 10+8i) in the form of the value of the complex object) String toString ()// return complex object corresponding to the string (such as 4+7i)