Inheritance and
part-of
relationship
On the object level it is
possible now to use a circle just as we would use a point, because a circle is-a point. For
example, a circle object and
set its center point coordinates can be defined as follows:
Circle
acircle
acircle.setX(1) /* Inherited from Point */
acircle.setY(2)
acircle.setRadius(3) /* Added by Circle */