Generics Confusion in Overriding a method

[Soniaa Agarwal]

I am facing a problem in generics inheritance. I wrote foll 2 classes couldn't figure out why getting the compiler error. I read Angelika site regarding overriding but couldn't understand the foll :-----------


//GENERIC SUPERCLASS
class superc<T>{

void set(T arg){}

}



//GENERIC SUBCLASS

class subc extends superc<Number>{

void set(Object rr){}
}


On compiling above code I get foll compiler error. :-

superc.java:10: name clash: set(java.lang.Object) in subc and set(T) in
superc<java.lang.Number> have the same erasure, yet neither overrides the other
class subc extends superc<Number>{
^
1 error

CAN ANYONE HELP ??

[Henry Wong]

CAN ANYONE HELP ??

First, I am assuming "foll" means "following"?

superc.java:10: name clash: set(java.lang.Object) in subc and set(T) in
superc<java.lang.Number> have the same erasure, yet neither overrides the other

The error message is pretty clear. You have two overloaded methods set(T) and set(Object). These methods are overloading -- not overriding. Yet, after type erasure (generics is compile only), the methods have the same signature.

It is not possible for two methods with the same signature, to be overloaded methods.

Henry

[Soniaa Agarwal]

Thanks Henry for the prompt reply but I am still not getting it. How come
methods set(T) and set(Object). are overloaded methods.


Why does the following work :



class superc<T>{

void set(T arg){}

}


class subc extends superc<Number>{

void set(Number aa){}

}

[Soniaa Agarwal]

Is Generics Inheritance on the SCJP 5.0 exam.

Where should I study it from besides Angelika Langer.

[suavedeep kaur]

Go for Kathy & bert bates SCJP book its really good ......telling you from my experience sonia

[Ninad Kulkarni]

Hi Soniaa,
If you get more knowledge on Generics then its an advantage for you.
You can refer Sun Java Tutorial.

[Soniaa Agarwal]

Thanks Henry .

Finally I think I understand that its overloading and not overriding.

[reji singh]

Soniaa Agarwal wrote:
Thanks Henry for the prompt reply but I am still not getting it. How come
methods set(T) and set(Object). are overloaded methods.


Why does the following work :



class superc<T>{

void set(T arg){}

}


class subc extends superc<Number>{

void set(Number aa){}

}

Hi Sonia,
Can you pleaseadd why did void set(Number aa){} work?