overriding

Is there any way to override a non-virtual method? or something that gives similar results (other than creating a new method to call the desired method)? I would like to override a method from Microsoft.Xna.Framework.Graphics.GraphicsDevice with unit testing in mind. Andrew Hare No, you cannot override a non-virtual method. The closest thing you can do is hide the method by creating a new method with the same name but this is not advisable as it breaks good design principles. But even hiding a method won't give you execution time polymorphic dispatch of method calls like a true virtual method

Is it possible to override onBackPressed() for only one activity ? On back button click I want to call a dialog on a specific Activity, but in all other activities i want it to work as it worked before (going to previous activities). EDITED Thank you everyone for your answers, I already had everything like you told me, but my problem was that when i was clicking back button on another Activity, I was going to my previous Activity (The one where i had back button Overridden) and i thought that it wasn't working, i thought it was overriding onBackPressed() in whole Application, now i got it. Yes

Is there way to override return types in C#? If so how, and if not why and what is a recommended way of doing it? My case is that I have an interface with an abstract base class and descendants of that. I would like to do this (ok not really, but as an example!) : public interface Animal { Poo Excrement { get; } } public class AnimalBase { public virtual Poo Excrement { get { return new Poo(); } } } public class Dog { // No override, just return normal poo like normal animal } public class Cat { public override RadioactivePoo Excrement { get { return new RadioActivePoo(); } } } RadioactivePoo