Java generics, Unbound wildcards vs

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There are two separate issues here. A List<Object> can in fact take any object as you say. A List<Number> can take at least Number objects, or of course any subclasses, like Integer.

However a method like this:

public void print(List<Number> list);

will actually only take a List which is exactly List<Number>. It will not take any list which is declared List<Integer>.

So the difference is List<?> will take any List with whatever declaration, but List<Object> will only take something that was declared as List<Object>, nothing else.

The last quote simply states, that List<?> is a list for which you literally don’t know what type its items are. Because of that, you can not add anything to it other than null.

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