【每日日报】第十一天

1 今天写了  以点类Point及平面类Plane为基础设计圆类Circle

 题目要求：

 

 程序源代码：

package Plane;

public class Point {
 double x;
    double y;
    Point()//无参构造
    {
      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.print("("+x+","+y+")");
    }
   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 Plane;

public class Plane extends Point {
 Plane(){}
 Plane(double xv,double yv){super(xv,yv);}
 Plane(Plane p){super(p);}
   double length(){return 0;}
   double area(){return 0;}
}

 

package Plane;

public class Circle extends Plane{
 static double PI=3.14159;
 double radius;
 Circle()
 {
     System.out.println("Circle Constructor run");
    }
 Circle(double xx,double yy,double rr)
   {
     super(xx,yy);
  radius=rr;
     System.out.println("Circle Constructor run");
   }
   Circle(Circle cir)
   {
  super(cir);
  radius=cir.radius;
        System.out.println("Circle CopyConstructor run");
   }
 void setR(double r){radius=r;}
    double getR() {return radius;}
 double length() {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.print("Circle(Point(X="+x+",Y="+y+"),Radius="+getR()+")");}
}

 

package Plane;

import java.util.Scanner;

public class Ma extends Circle{
 void show(Circle p){p.show();}
 void length(Circle p){System.out.println("Length="+p.length());}
 void area(Circle p){System.out.println("Area="+p.area());}
 public static void main(String[] arge){
  Ma m=new Ma();
  double x,y,r;
     Circle c1=new Circle();
     Circle c2=new Circle(c1);
     m.show(c1);
     System.out.println();
     m.area(c1);
     m.length(c1);
     Scanner input = new Scanner(System.in);
     x=input.nextDouble();
     y=input.nextDouble();
     r=input.nextDouble();
     c2.setX(x);
     c2.setY(y);
     c2.setR(r);
     m.show(c2);
     System.out.println();
     m.area(c2);
     m.length(c2);
     input.close();
 }

}

 运行截图：

2 今天了解到：

C++                    Java
虚函数     --------   普通函数
纯虚函数   --------   抽象函数
抽象类     --------   抽象类虚基类     --------   接口

结论：java类中普通成员函数就是虚函数。
原文链接：https://blog.csdn.net/wuqiuping695/article/details/49069779

3 明天继续写题