Java Reference
In-Depth Information
PITFALL:
(continued)
In some cases of overloading, a single method invocation can be resolved in two differ-
ent ways, depending on how overloading and type conversion interact. Such ambigu-
ous method invocations are not allowed in Java and will produce an error message. For
example, you can overload a method named
doSomething
by giving two definitions
that have the following two method headings in a
SampleClass
:
public class
SampleClass
{
public void
doSomething(
double
n1,
int
n2)
.
.
.
public void
doSomething(
int
n1,
double
n2)
.
.
.
Such overloading is legal, but there is a problem. Suppose
aSampleObject
is an object
of type
SampleClass
. An invocation such as the following will produce an error mes-
sage, because Java cannot decide which overloaded definition of
doSomething
to use:
aSampleObject.doSomething(5, 10);
Java cannot decide whether it should convert the
int
value
5
to a
double
value and
use the first definition of
doSomething
, or convert the
int
value
10
to a
double
value
and use the second definition. In this situation, the Java compiler issues an error mes-
sage indicating that the method invocation is ambiguous.
The following two method invocations are allowed:
aSampleObject.doSomething(5.0, 10);
aSampleObject.doSomething(5, 10.0);
However, such situations, while legal, are confusing and should be avoided.
■
Display 4.12
Using an Overloaded Method Name
(part 1 of 2)
1
public
class
OverloadingDemo
2{
3
public
static
void
main(String[] args)
4
{
5
DateSixthTry date1 =
new
DateSixthTry(),
6
date2 =
new
DateSixthTry(),
7
date3 =
new
DateSixthTry();
(continued)
