Casting List to Array of Unknown SubClass

Question

How do I cast a java.util.List to an array of a unknown subclass of a known parent class?
Parent[] parents = someMethod();
// someMethod returns ChildA[] or ChildB[] both extends Parent and are unknown to this method
List list = new Vector();
for (int i=0;i<parents.length;i++) {
  if (parents.someBoolean)
    list.add(parents[ i ]);
return (Parent[])list.toArray(?????);
// return (Parent[])list.toArray(new Parent[]{});
// Not of the child type, will cause ClassCastException
// return (Parent[])list.toArray(parents);
// Correct type, but uses size of parents which is potentially too big.Any way to do this without reflection?

Answer 1

But is is that at any given time, the array contains all elements of
either ChildA or ChildB? If not, I'm not sure how can you cast the
entire array. If so, why not check for one of the elements in the list
for its type using instanceof operator and then cast the entire array
appropriately.
I'm actually getting confused as to what exactly you are looking for.I should have been more clear on that point. Yes all elements will be of the same type, i.e., all of type ChildA or all of type ChildB.
The problem comes in the fact that even though one has an Object[] array where all Objects are of type ChildA, a ClassCastException will still be thrown when casting to ChildA[]
I have no idea what you're looking to do, but, regardless of what
parent class you cast some instance as, the current implementation
of each method is still going to execute. In other words, the
toString method of some instance always returns the same String,
whether you have it casted as a Parent or Child because it just
returns the implemetnation of the current classTrue, except of course for methods that only exist on the child objects.
A friend has given me a solution that I suspect will work:
import java.lang.reflect.*;
return (Parent[])list.toArray(Array.newInstance(parents[0].getClass(),0));