How does the JLS specify that wildcards cannot be formally used within methods?

Question

I\'ve always been wondering about some weird aspect of Java generics and the use of wildcards. Let\'s say, I have the following API:

public interface X

        

Answer 1

I've just seen this peculiar implementation of Collections.swap():

public static void swap(List list, int i, int j) {
    final List l = list;
    l.set(i, l.set(j, l.get(i)));
}

The JDK guys resort to a raw type, in order to handle this, locally. To me, this is a strong statement indicating that this probably should be supported by the compiler, but for some reason (e.g. lack of time to formally specify this) just wasn't done