Java Reference
In-Depth Information
consistent interface. Thus, by combining inheritance with overridden methods, a superclass
can define the general form of the methods that will be used by all of its subclasses.
Applying Method Overriding to TwoDShape
To better understand the power of method overriding, we will apply it to the
TwoDShape
class. In the preceding examples, each class derived from
TwoDShape
defines a method
called
area( )
. This suggests that it might be better to make
area( )
part of the
TwoDShape
class, allowing each subclass to override it, defining how the area is calculated for the type
of shape that the class encapsulates. The following program does this. For convenience, it
also adds a name field to
TwoDShape
. (This makes it easier to write demonstration pro-
grams.)
