(1) 复数类Complex 的属性有：

RealPart :    int型，代表复数的实数部分

ImaginPart :  int型，代表复数的虚数部分

package applet;

import java.applet.*;

import java.awt.*;

public class j_1 extends Applet{

Complex a,b,c,d,e,f;

public void init()

{

a=new Complex(2,2);

b=new Complex(3,4);

c=new Complex();

d=new Complex();

e=new Complex();

f=new Complex();

}

public void paint(Graphics g)

{

c=a.add(b);

d=a.sub(b);

e=a.mul(b);

f=a.div(b);

g.drawString("第一个复数："+a.ToString(), 10, 50);

g.drawString("第二个复数："+b.ToString(), 10, 70);

g.drawString("两复数之和："+c.ToString(), 10, 90);

g.drawString("两复数之差："+d.ToString(), 10, 110);

g.drawString("两复数相乘："+e.ToString(), 10, 130);

g.drawString("两复数相除："+f.ToString(), 10, 150);

}

}

class Complex{

public int realPart;

public int imaginPart;

Complex(int r,int i)

{realPart=r;imaginPart=i;}

Complex(){realPart=0;imaginPart=0;}

Complex add(Complex a)

{

Complex temp=new Complex();

temp.realPart=realPart+a.realPart;

temp.imaginPart=imaginPart+a.imaginPart;

return temp;

}

Complex sub(Complex a)

{

Complex temp=new Complex();

temp.realPart=realPart-a.realPart;

temp.imaginPart=imaginPart-a.imaginPart;

return temp;

}

Complex mul(Complex a)

{

int r,i,ra,ia;

r=this.realPart;

i=this.imaginPart;

ra=a.realPart;

ia=a.imaginPart;

Complex temp=new Complex();

temp.realPart=r*ra-i*ia;

temp.imaginPart=i*ra+r*ia;

return temp;

}

Complex div(Complex a)

{

double r,i,ra,ia;

r=this.realPart;

i=this.imaginPart;

ra=a.realPart;

ia=a.imaginPart;

Complex temp=new Complex();

temp.realPart=(r*ra+i*ia)/(ra*ra+ia*ia);//这个地方应该如何修改，还是说只能改成把类成员变量改成double型数据才可以

temp.imaginPart=(i*ra-r*ia)/(ra*ra+ia*ia);

return temp;

}

public String ToString()

{

if(imaginPart<0)

{

return (realPart+(imaginPart+"i"));

}

else return(realPart+"+"+imaginPart+"i");

}

}