The null when passed as argument will try to fit the appropriate child
class method in case it will find the null argument for Animal, this is
what if i Uncomment the child(Dig D) Method they will fight for
allocation/best fit
>javac Animal.java
Animal.java:13: error: reference to child is ambiguous, both method
child(Dog) i
n Animal and method child(Cat) in Animal match
an.child(null);
^
1 error
On Fri, Feb 17, 2012 at 10:41 PM, ABHISHEK TRIPATHI
<[email protected]>wrote:
> Hi All,
> I was keep exploring the solution for this problem and later I found that
> is due to charecteristic of Overloading-Widening/Boxing.
>
> Here is rule:
> "In every case, when Exact match is not found, the JVM uses the method
> with the SMALLEST argument which is Wider then the Parameter.
> So when we pass Null as parameter, JVM will look for the method which has
> next higher level of Argument and it find that CAT is Child of Animal and
> smaller then Animal so it calls method Add from Cat class.
>
> Thanks,
> Abhishek
> On Thu, Feb 16, 2012 at 11:33 PM, Asher Fawad <[email protected]>wrote:
>
>> To tell you the truth, your code is very complex. There is no clarity
>> in there. If you want to learn something, learn it simply.
>>
>> You should define Animal as a separate class with proper method
>> overloading (same method with different arguments). Put main method into a
>> class of its own.
>>
>> I also don't see the purpose of sending arguments like "Cat c" or "Dog d"
>> when you aren't even using it.
>>
>> What do you expect an.child(null) to print??? Of course, it might only
>> print "Animal" (I think it shouldn't print anything).
>>
>> Your method declaration--> void child(Animal a){System.out.println("
>> Animal");}
>> should be rewritten as [ void child(){System.out.println("Animal");}
>>
>> and your function call an.child(null) should be [an.child()]
>>
>> Advice:
>>
>> Rewrite your program with more clarity and simplicity and then tell if
>> you face same problem.
>>
>> --- On *Wed, 2/15/12, ABHISHEK TRIPATHI <[email protected]>* wrote:
>>
>>
>> From: ABHISHEK TRIPATHI <[email protected]>
>> Subject: [jpassion_java] Overloaded method
>> To: "JPassion.com: Java Programming" <[email protected]>
>> Date: Wednesday, February 15, 2012, 11:04 PM
>>
>> Hi,
>> Can you plz tell why output is coming as Cat not Animal?
>> Also if I un-comment all lines, I get compile time error.
>>
>> thanks
>> Abhi
>>
>> ***********************************
>> package Overload;
>> public class Animal {
>>
>> // void child(Dog d) {System.out.println(" Dog");}
>> void child(Cat c){System.out.println(" Cat");}
>> void child(Animal a){System.out.println(" Animal");}
>> // void child(Mouse m){System.out.println(" Mouse");}
>> // private void child(Cat x){}
>>
>> public static void main(String[] args) {
>> Animal an=new Animal();
>> an.child(null);
>> }
>> }
>> ************
>> class Dog extends Animal{}
>> class Cat extends Animal{}
>> class Mouse extends Dog{}
>>
>>
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>>
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--
Vishnu Narayan Dubey
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