类的封装与抽象
//Programme Name TestCylinder.java
class Circle
{
private double radius;
Circle()
{
radius=0.0;
}
Circle(double r)
{
radius=r;
}
double getPerimeter()
{
return 2*Math.PI*radius;
}
double getArea()
{
return Math.PI*radius*radius;
}
void disp()
{
System.out.println("圆半径 ="+radius);
System.out.println("圆周长 ="+getPerimeter());
System.out.println("圆面积 ="+getArea());
}
}
class Cylinder extends Circle
{
private double hight;
Cylinder(double r,double h)
{
super(r);
hight=h;
}
public double getVol()
{
return getArea()*hight;
}
public void dispVol()
{
System.out.println("圆柱体积 ="+getVol());
}
}
public class TestCylinder
{
public static void main(String[] args)
{
Circle Ci=new Circle(10.0);
Ci.disp();
Cylinder Cyl=new Cylinder(5.0,10.0);
Cyl.disp();
Cyl.dispV ol();
}
}