来个大佬帮一下吧。。

package com.chouxiang;

public abstract class Shape {

int r;

int a;

int b;

public abstract void zhouchang();

public abstract void mianji();

}

package com.chouxiang;

public class juxing extends Shape {

@Override

public void zhouchang() {

System.out.println((a+b)*2);

}

@Override

public void mianji() {

System.out.println(a*b);

}

}

package com.chouxiang;

public class yuanxing extends Shape {

@Override

public void zhouchang() {

// TODO Auto-generated method stub

System.out.println(6*r);

}

@Override

public void mianji() {

// TODO Auto-generated method stub

System.out.println(3*r*r);

}

}

package com.chouxiang;

public class test {

public static void main(String[] args) {

// TODO Auto-generated method stub

Shape c=new juxing();

Shape d=new yuanxing();

c.a=6;

c.b=4;

d.r=2;

System.out.println("矩形周长为"+c.zhouchang+"\n"+"矩形面积为"+c.mianji);

System.out.println("圆形周长为"+d.zhouchang+"\n"+"圆形面积为"+d.mianji);

}

}