类的抽象与封装

import java.util.Scanner;
public class Circle1 {
 private double radius;//用于存放圆的半径；
 
 public Circle1 ()// 将半径设为0 
 {
  radius = 0;
 }
 
 public Circle1(double r){// 创建Circle对象时将半径初始化为r.
  radius = r;
 }
 
 public Double getArea1()//获得圆的面积
 {
  return radius*radius*Math.PI;
 }
 
 public Double getPerimeter1() //获得圆的周长 
 {
  return 2*Math.PI*radius;
 }
 
 public  void disp1() //将圆的半径，周长，面积 输出到屏幕
 {
  System.out.printf("圆的半径为：%.2f,周长:%.2f，面积:%.2f", radius,getPerimeter1(),getArea1());
 }
public class Cylinder extends Circle1 {

 private double hight;

 

  public Cylinder (double r, double  h ){

   super(r);

   this.hight = h;

  }

  public double getVolume(){

   return Math.PI * this.getRadius() * this.getRadius() * hight;

   

  }  

  public void showVolume( ){

   System.out.println("圆柱体的体积：" + this.getVolume());

  }

}
 public static void main(String[] args) {
  Scanner s = new Scanner(System.in);
 System.out.print("输入半径：");
 double r = s.nextDouble();
 Circle1 c = new Circle1(r);
 c.disp1();

}

}