capture of ? extends scorecard.data.StoreData Inconvertible types

Question

This one baffles me.
I have
    private static ReferenceQueue<StoreData> freedReferences = new ReferenceQueue<StoreData>();
// and
    private static class StoreReference extends SoftReference<StoreData> {
}So why can't I do:
StoreReference ref = (StoreReference)freedReferences.remove();I get:
C:\Scorecard\ScoreCard\src\scorecard\data\StoreDataFactory.java:386: inconvertible types
found : java.lang.ref.Reference<capture of ? extends scorecard.data.StoreData>
required: scorecard.data.StoreDataFactory.StoreReference
The use of generics with these ReferenceQueues seems to be completely fouled up.

Answer 1

I have
private static ReferenceQueue<StoreData>
freedReferences = new ReferenceQueue<StoreData>();
// and
private static class StoreReference extends SoftReference<StoreData> {Imagine you also have this:
    private static class FooReference extends SoftReference<StoreData>Now, you could easily create a variable like this:
    SoftReference<StoreData> foo = new FooData();And you certainly shouldn't be able to assign the contents of that variable to StoreReference, even with casting (although I admit the cast should get it past the compiler in this case, with an unchecked conversion warning ...)
Edit: I think the compiler treats this as a case similar to the following:
    Integer i = new Integer(10);
    Double d = (Double)i;Saying that, I do believe that it appears to be more like:
    Number i = new Integer(10);
    Double d = (Double)i;