【每日日报】第八天

1 今天写了

 题目要求：

 

 

 程序源代码：

package Point;

public class Point {
   double x;
     double y;
     Point()//有参构造
     {
      x=0;
      y=0;
         System.out.println("Point Constructor run");
     }
     Point(double xv,double yv)//有参构造
     {
      x=xv;
      y=yv;
         System.out.println("Point Constructor run");
     }
     Point(Point p)            //拷贝构造
     {
      x=p.x;
      y=p.y;
         System.out.println("Point CopyConstructor run");
     }
     void show()            //显示Point信息
     {
      System.out.println("("+x+","+y+")");
     }
     double area(){return 0;}           //面积=0
     void setX(double xv){x=xv;}        //设置X坐标
     void setY(double yv){y=yv;}        //设置Y坐标
     double getX() {return x;}           //获取X坐标
     double getY() {return y;}           //获取Y坐标
}

package Point;

import java.util.Scanner;

public class Circle extends Point{
 public static void main(String[] args){
  Scanner input = new Scanner(System.in);
     double r = input.nextDouble();
     Circle c1=new Circle(1,2,4);
     Circle c2=new Circle();
     Circle c3=new Circle(c1);
     c1.show();
     System.out.println();
     System.out.println("Area="+c1.area());
     System.out.println("Circumference="+c1.circumference());
     c2.show();
     System.out.println();
     System.out.println("Area="+c2.area());
     System.out.println("Circumference="+c2.circumference());
     c3.setRadius(r);
     c3.show();
     System.out.println();
     System.out.println("Area="+c3.area());
     System.out.println("Circumference="+c3.circumference());
     input.close();
 }
 static double PI=3.14159;
 double radius;
 Circle()
    {
     x=0;
     y=0;
        radius=0;
        System.out.println("Circle Constructor run");
    }
 Circle(double xx)
    {
     x=xx;
     y=0;
        radius=0;
        System.out.println("Circle Constructor run");
    }
    Circle(double xx,double yy,double rr)
     {
         x=xx;
         y=yy;
         radius=rr;
         System.out.println("Circle Constructor run");
     }
  Circle(Circle cir)
     {
      x=cir.x;
      y=cir.y;
         radius=cir.radius;
         System.out.println("Circle CopyConstructor run");
     }
  void setRadius(double r){radius=r;}
  double getRadius() {return radius;}
     double circumference() {return 2*PI*radius;}        //用于计算圆的周长
     double area() {return PI*radius*radius;}            //用于计算圆的面积
     void show() {System.out.println("("+x+","+y+"),"+"Radius="+getRadius());}
}

 运行截图：

2 类的继承用extend  public class Circle extends Point

3 明天继续做题