//矩形

public class Rectangle extends Shape {
 int a=1;
 int b=2;
 @Override
 public void zhouzhang() {
  // TODO Auto-generated method stub
  int zz=(a+b)*2;
  System.out.println("矩形周长为："+zz);
 }

 @Override
 public void mianji() {
  // TODO Auto-generated method stub
  int mj=a*b;
  System.out.println("矩形面积为："+mj);
 }

}

测试类

public class Shapexam {

 public static void main(String[] args) {
  // TODO Auto-generated method stub
  Rectangle re=new Rectangle();
  re.a=2;
  re.b=5;
  re.zhouzhang();
  re.mianji();
  Shape s1=new Rectangle();
  s1.zhouzhang();
  s1.mianji();
  Shape s2=new Circle();
  s2.zhouzhang();
  s2.mianji();
 }

}

运行结果

矩形周长为：14
矩形面积为：10
矩形周长为：6
矩形面积为：2