/*② 设计一个表示二维平面上的圆的类Circle,它继承类Point,
还包含有表示圆半径的protected类型的成员变量r、获取和设置r值的public方法、计算圆面积的public方法。*/
public class Point
{
private float x,y;
public void setPoint(int x,int y)
{
this.x=x;
this.y=y;
}
public float getX(){return x;}
public float getY(){return y;}
}
public class Circle extends Point
{
public static final float PI=3.14159;
public float r;
public Circle(int x,int y,int radius)
{
setPoint(x,y);
r=radius;
}
public float getR()
{
return r;
}
public float Area()
{
return PI*r*r;
}
public static void main(String args[])
{
float m;
Circle c=new Circle(5,6,7);
c.getR();
m=c.Area();
System.out.println("圆的面积事:"+m);
}
}请问怎么改?
还包含有表示圆半径的protected类型的成员变量r、获取和设置r值的public方法、计算圆面积的public方法。*/
public class Point
{
private float x,y;
public void setPoint(int x,int y)
{
this.x=x;
this.y=y;
}
public float getX(){return x;}
public float getY(){return y;}
}
public class Circle extends Point
{
public static final float PI=3.14159;
public float r;
public Circle(int x,int y,int radius)
{
setPoint(x,y);
r=radius;
}
public float getR()
{
return r;
}
public float Area()
{
return PI*r*r;
}
public static void main(String args[])
{
float m;
Circle c=new Circle(5,6,7);
c.getR();
m=c.Area();
System.out.println("圆的面积事:"+m);
}
}请问怎么改?
{
private float x,y;
public void setPoint(int x,int y) // 类型不符,警告一下
{
this.x=x;
this.y=y;
}
public float getX(){return x;}
public float getY(){return y;}
}
public class Circle extends Point
{
private static final float PI=3.14159; //public static final float PI=3.14159;
private float r; //public float r;
Circle(int x,int y,int radius) //public Circle(int x,int y,int radius)
{
setPoint(x,y);
r=radius;
}
public float getR()
{
return r;
}
public float Area()
{
return PI*r*r;
}public static void main(String args[])
{
float m;
Circle c=new Circle(5,6,7);
//c.getR(); 这句话有用?不知道楼主想表达什么- -!
m=c.Area();
System.out.println("圆的面积事:"+m);
}
}那个π 最好用 Math 类的 Math.π 系统提供的 比你那好多了
以上代码是目测,最后以楼主测试为准
pi值由于定义为float类型,需要在后面加个f。即public static final float PI=3.14159f;
import java.lang.*;
import java.io.*;
class Point
{
private float x,y;
public void setPoint(float x, float y)
{
this.x=x;
this.y=y;
}
public float getX(){return x;}
public float getY(){return y;}
}class Circle extends Point
{
public static final float PI=3.14159f;
public float r;
public Circle(float x, float y, float radius)
{
setPoint(x, y);
r = radius;
}
public float getR() {return r;}
public float getArea() {return PI * r * r;}
}public class Area
{
public static void main(String [] args)
{
float m;
Circle c = new Circle(5, 6, 7);
c.getR();
m=c.getArea();
System.out.println("圆的面积:" + m);
}
}