【每日日报】第五天

1 今天做了圆类的习题

 题目要求：

 程序源代码：

package Circle;

import java.io.IOException;
import java.util.Scanner;

public class Circle {
 
 public static void main(String[] args)throws IOException{
  Circle c1 = new Circle();
  Scanner input = new Scanner(System.in);
        double r = input.nextDouble();
     c1.setRadius(r);
     System.out.println(c1.circumference());
     System.out.println(c1.area());
     Circle c2 = new Circle(c1);
     System.out.println(fCircle_L(c2));
     System.out.println(fCircle_S(c2));
 }
 
 
 static double PI = 3.1415;
 static double radius;
 Scanner input = new Scanner(System.in);
 
 public Circle(){
  radius=0;
  System.out.println("Constructor run");
 }
 public Circle(double r){
  radius = r;
        System.out.println("Constructor run");
        }
    public Circle(Circle cir){
     radius = cir.radius;
     System.out.println("CopyConstructor run");
     }
    void setRadius(double r){radius = r;}
    double getDadius(){return radius;}
    double circumference(){return 2*PI*radius;}
    double area(){return PI*radius*radius;}
    static double fCircle_L(Circle r){return 2*PI*r.radius;}
    static double fCircle_S(Circle r){return PI*r.radius*r.radius;}
}

 运行截图：

2 今天学习到，在java语言中没有友元函数也没有析构函数

3 明天接着写习题