Quick ArrayList Question

Hey guys, Let's say I have three classes: Polygon, Rectangle, and Oval. Both Oval and Rectangle extend Polygon. So now I'm creating a new ArrayList that I want to hold Polygons and anything that is-a polygon (Rectangle, Oval, etc.).

How can I make an ArrayList take Polygon objects, and any object that is a subclass of Polygon?

Just simply doing this:

private ArrayList<Polygon> shapes = new ArrayList<Polygon>(); shapes.add(new Rectangle());

Does not work.

What error do you get? The following compiles and runs.

static class A {} static class B extends A{} public static void main(String[] args) { List<A> list = new ArrayList<A>(); list.add(new A()); list.add(new B()); }

Pointless thread, I guess it works now heh.