Generics, factories and reflection

From:
"Martin" <spam@e-renner.net>
Newsgroups:
comp.lang.java.programmer
Date:
19 Sep 2006 04:41:59 -0700
Message-ID:
<1158666119.246280.237740@h48g2000cwc.googlegroups.com>
Hi.

I have a problem with a factory method. This method should create
instances of the collection framework. The simplest implementation
looks like this:

--------------------------------------------------------------
public static List<E> createList() {
    return new ArrayList<E>();
}
List<String> l1 = createList();
--------------------------------------------------------------

But in my special case, I want to (and have to) pass the implementing
class as an argument. So the factory could create instances of
ArrayList but also of LinkedList. The following method compiles without
warnings and errors:

--------------------------------------------------------------
public static List<E> createList(Class<? extends List<E>> listImpl) {
    try {
        List<E> l = listImpl.newInstance();
        return l;
    }
    catch (Exception dontBotherMe) {
        return null;
    }
}
--------------------------------------------------------------

But how can I call this method?

List<String> l2 = createList(ArrayList.class)

does not work, because "Class<ArrayList>" does not match
"Class<List<E>>".

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