Folks,

I am converting existing code to use paramaterised generic collections.
I need to add 2 different object  types to a common list. Both object are interfaces that extend  a
common interface.

e..:

Assuming MyType, MyTypeA, MyTypeB, where MyTypeA and MyTypeB are interfaces that extend interface
MyType.

List<? extends MyType> list = getMyTypeAList();
List.addAll(getMyTypeBList());

The compiler barfs at the addAll() as follows:

"The method addAll(Collection<? extends capture#1-of ? extends Bean>) in the type List<capture#1-of
? extends Bean> is not applicable for the arguments (List<MyTypeB>)"
   
I dont understand why as interface MyTypeB extends interface MyType.

I have also tried it with:

List<MyType> = getMyTypeAList();
List.addAll(getMyTypeBList());

This time the compiler complains "Type mismatch: cannot convert from List<MyTypeA> to List<Bean>"

What am doing to wrong? How to do this?

TIA - Adam