主题：程序代码——利用继承实现的几个几何类

点类：
public class Point
{
        protected int x;
        protected int y;
        
        public Point()
        {              
        }
        
        public Point(int x,int y)
        {
                this.x=x;
                this.y=y;
        }
        
        public void setX(int i)
        {
                x=i;
        }
        public int getX()
        {
                return x;
        }
        public void setY(int i)
        {
                y=i;
        }
        public int getY()
        {
                return y;
        }      
        
        public String toString()
        {
                return "("+x+","+y+")";
        }
}

圆类：
public class Circle extends Point
{
        protected int r;
        
        public Circle()
        {
        }
        
        public Circle(int x,int y,int r)
        {
                setPoint(x,y);
                setR(r);
        }
        
        public void setR(int rr)
        {
                r=rr;
        }
                
        public int getR()
        {
                return r;
        }
        
        public void setPoint(int i,int j)
        {
                x=i;
                y=j;
        }
        
        public String getPoint()
        {
                return super.toString();
        }
        
        public String toString()
        {
                return super.toString()+";Radius="+r;
        }
        
        public double getArea()
        {
                return Math.PI*r*r;
        }
}

圆柱类：
public class Cylinder extends Circle
{
        protected int height;
        
        public Cylinder()
        {
        }
        
        public Cylinder(int x,int y,int r,int h)
        {
                setCircle(x,y,r);
                setHeight(h);
        }
        
        public void setCircle(int x,int y,int r)
        {
                setPoint(x,y);
                setR(r);
        }
        
        public String getCircle()
        {
                return super.toString();
        }
        
        public void setHeight(int h)
        {
                height=h;
        }
        
        public int getHeight()
        {
                return height;
        }
        
        public String toString()
        {
                return super.toString()+";Height="+r;
        }
        
        public double getVolume()
        {
                return getArea()*height;
        }
}

应用程序：
public class exec
{
        public static void main(String [] args)
        {
                Cylinder cylinder=new Cylinder();
                cylinder.setCircle(1,2,3);
                cylinder.setHeight(2);
                System.out.println(cylinder.getCircle());
                System.out.println(cylinder.getHeight());
                System.out.println(cylinder.getVolume());
                System.out.println(cylinder.toString());
                
                
        }
}