public abstract class Telphone {     // 抽象类

public abstract void zhouchang();  //抽象方法

public abstract void mianji();

}

public class Circle extends Telphone {

int a;

final float Pi=3.14f;

public Circle(int a){        //构造方法 来产生对象的属性

this.a=a;     //两个a一样 为了防止看不懂 就加this

}

@Override

public void zhouchang() {

int z=4*a;

System.out.println("周长"+z);

}

@Override

public void mianji(double a) {

Stringm=String.format("%.2f",Pi*a*a); // 格式化输出

System.out.println("面积"+m);

}

}

public class Rectangle extends Telphone {

int a;

int b;

public Rectangle(int a,int b){

this.a=a;

this.b=b;

}

@Override

public void zhouchang() {

int z=2*(a+b);

System.out.println("周长"+z);

}

@Override

public void mianji() {

int m=a*b;

System.out.println("面积"+m);

}

}

public class Initiaal {

public static void main(String[] args) {

Telphone t1=new Circle(2);

t1.mianji();

t1.zhouchang();

Telphone t2=new Rectangle(3,4);

t2.zhouchang();

t2.mianji();

}

}

面积12.56

周长8

周长14

面积12