I have an List<Animal> but in that list I have subclasses of Animal such as Mammal.
(Yes that is right; it is a school assignment, so don't be specific, just give me some pointers.)
I should persist it with [Serializable] interface and that is no problem, except when I shall read it back again, I have no idea what subclass the data came from when it's time for reviving the information.
So the question is, how do I store that information?
You don't need to take care of that yourself, since the framework serializes the type as well it knows which instance to create before the content is actually deserialized. Just create a sample and you'll see what happens... ;-)
The is and as keywords will be your friends for this.
It is good to know that the is keyword tries to perform a cast and returns true or false depending on whether or not the cast was successful.
If you want the actual object, and aren't just interested in its type, you are better of using the as keyword and then checking it for null. This will save you the step of having to cast it again once you've determined the type.