question about the generic methods : ExamLab final test

[Prasad Kharkar]

I am unable to interpret the meaning of the following code

   
class A<E>{
}

class GenClass <E extends A>{
     public <T extends E> A<? super T>getNow(A< ? super T> a){
          return new A();
     }
     
}
 

I am not able to understand what the statement

    
public <T extends E> A<? super T>getNow(A< ? super T> a)

means
what I know is this
1. This is generic method
2. that can be passed any instantiation which can be <T extends E>
3. Its return type is A

but I am not able to understand what <? super T> means after A

please help me

[Ankit Garg]

There is a generic type declared in the GenClass which is E. E can be any class which extends A (or A itself). In the method declaration you declare another type T which extends E (E in itself is A or its subclass). The parameter the method gets is A<? super T>. This means that the method will receive an instance of A which has a type of T or a super class of T. To make this simpler to understand, lets replace A with a class from the Java API

class GenClass <E extends List>{
     public <T extends E> List<? super T> getNow(List<? super T> list){
          return new ArrayList();
     }
}

The method parameter and return type are now easier to understand (I hope)...

[Prasad Kharkar]

of course they are easier now
after this nice explanation
thanks a lot