Question

I have something like this going on in my Java program:

void f(Object o) {
    g(o);
}

<T extends MySuperClass & MyInterface> void g(T x) {
    ...;
}

How can I cast o so that this works? There seems to be no way to specify both a base class and an interface in variable declarations without using generics. I don’t think generics will work here, because o is being created dynamically using reflection, so its actual class is not known at compile time.

(Yeah, I know this is a weird thing to want to do. But I actually do need functionality from both the superclass and the interface. I guess I could do all of the type checking at runtime with instanceof, but that just seems so Java 1.4…)

Answer 1

It seems to be there is no way to invoke a “raw” generic method. But you can create an object of raw type (the following conversion is, obviously, unsafe):

void f(Object o) {
    Caster<?> c = new Caster(); 
    g(c.cast(o)); 
}

class Caster<T extends MySuperClass & MyInterface> {
    public T cast(Object o) {
        return (T) o;
    }
}