Java Reference
In-Depth Information
The output is shown here:
Notice how
NumericFns
is now declared by this line:
Because the type
T
is now bounded by
Number
, the Java compiler knows that all objects
of type
T
can call
doubleValue( )
because it is a method declared by
Number
. This is, by
itself, a major advantage. However, as an added bonus, the bounding of
T
also prevents
nonnumeric
NumericFns
objects from being created. For example, if you remove the com-
ments from the lines at the end of the program, and then try re-compiling, you will receive
compile-time errors because
String
is not a subclass of
Number
.
