1. 获取标准屏幕的输入时，需导入java.util.Scanner包。
2. 主类的名称与.java的文件名需一致。
3. 文件中主类设置为public，其他类前面无需加访问级别。
4. 继承时，使用extends关键字，访问父类的成员时，使用super。
import java.util.Scanner;
class Circle
{
private double radius;
public
Circle()
{
radius = 0.0;
}
public Circle( double
radius0 )
{
radius = radius0;
}
public double
getRadius()
{
return radius;
}
public double
getArea()
{
return
3.14*radius*radius;
}
public double
getLength()
{
return 2*3.14*radius;
}
public
void Display()
{
System.out.println( "Radius is: " + radius
);
System.out.println( "Length is: " + getLength()
);
System.out.println( "Area is: " + getArea()
);
}
}
class Cylinder extends Circle
{
private double
height;
public Cylinder( double height0, double radius0
)
{
super( radius0 );
height =
height0;
}
public double getHeight()
{
return
height;
}
public double getRadius()
{
return
super.getRadius();
}
public double
getArea()
{
double area0 =
super.getLength()*height;
double area1 =
super.getArea()*2;
return area0 + area1;
}
public
double getVolume()
{
return
super.getArea()*height;
}
public void
Display()
{
System.out.println( "Radius is: " +
super.getRadius() );
System.out.println( "Height is: " + height
);
System.out.println( "Area is: " + getArea()
);
System.out.println( "Volume is: " + getVolume()
);
}
}
public class TestCylinder
{
public static void main(String[] args)
{
Scanner sc =
new Scanner( System.in );
System.out.println( "Please input
radius:" );
double radius =
sc.nextDouble();
System.out.println( "Please input height:"
);
double height = sc.nextDouble();
Circle circle =
new Circle( radius );
Cylinder cylinder = new Cylinder( height,
radius
);
circle.Display();
cylinder.Display();
}
}