INHERITANCE AND POLYMORPHISM - Java Programming: From Problem Analysis to Program Design - page 667

public BoxFigure( double l, double w, double h)
{

super (l, w);
if (h >= 0)
height = h;

else

height = 0;

}

public void setDimension( double l, double w, double h)
{

super .setDimension(l, w);

if (h >= 0)
height = h;

else

height = 0;

}

public double getHeight()
{

return height;

}

public double area()
{

return 2 * (getLength() * getWidth()
+ getLength() * height
+ getWidth() * height);

}

public double volume()
{ 1

0

return super .area() * height;

}

public String toString()
{

return ("Length = " + getLength()
+ "; Width = " + getWidth()
+ "; Height = " + height
+ "\n"
+ "Surface Area = " + area()
+ "; Volume = " + volume());

}

}

Note that the class BoxFigure is derived from the class RectangleFigure . The
definition of the class BoxFigure is similar to the definition of the class Box given
previously. The method toString of the class BoxFigure , in addition to returning
the length, width, and height, also returns the surface area and volume of the box.