Hi all,

I encounter a strange behavior with generics that I do not understand.

I have the following interfaces:

public interface Int1<E> {   
}

and

public interface Int2<E> extends Int1<Integer> {
}

and I have somewhere the following lines:

void foo(Int2 o) {
 Int1<Integer> p = o;
}

The java compiler gives the following warning:

Type safety: The expression of type Int2 needs unchecked conversion to
conform to Int1<Integer>

I do not understand why this warning exists. Moreover it prevents the
compiler to understand that an Int2<E> is also an Int1<Integer>, so it
prevents a lot of type checking.

Is there any solution ?

Thanks.

    Benjamin Lerman