Overriding Fragments

[harmeet saini]

Hi
Following is a problem form CertPal


Given the following classes what can be inserted in the code fragment shown ?

   
class Marmaduke { public int hello(){return 0;}}
public class Cert extends Marmaduke 
{
    public static void main(String [] args)
    {}
// Insert code here
}
 

public Integer hello(){ return 0;} //1

Why line 1 is not a correct answer, i think Boxing is allowed in this case.

Thanks in advance

[Seetharaman Venkatasamy]

int return type is not same as Integer return type. there is no concept of boxing/unboxing in method signature. the boxing/unboxing happens when ever you work with operator, and return a value

[M. White]

public Integer hello(){ return 0;} //1

So, what is really wrong with the code? in still runs fine. I still dont get it. Hoping for a more detailed explanation. thanks.

[Abimaran Kugathasan]

Java method overriding rules :

* We can not override final methods.
* Methods declared as private cannot be overridden as they are not visible outside the class.
* Access modifier must be same or less restrictive. For example if super class contains protected you can have public or protected.
* The return type must be same, or it may be co variant return (sub class)
* Must have the same argument list
* We can throw any unchecked exceptions
* We can throw fewer or narrowed checked exceptions

So, you can't return a boxing/unboxing values.