What exception type to use when a property cannot be null?

Question

In my application I need to throw an exception if a property of a specific class is null or empty (in case it\'s a string). I\'m not sure what is the best exception to use

Answer 1

Well, it's not an argument, if you're referencing a property of a class. So, you shouldn't use ArgumentException or ArgumentNullException.

NullReferenceException would happen if you just leave things alone, so I assume that's not what you're looking for.

So, using ApplicationExeption or InvalidOperationException would probably be your best bet, making sure to give a meaningful string to describe the error.

Answer 2

If it can't be null or empty, have your setter not allow null or empty values, or throw an ArgumentException if that is the case.

Also, require that the property be set in the constructor.

This way you force a valid value, rather than coming back later and saying that that you can't determine account balance as the account isn't set.

But, I would agree with bduke's response.

Answer 3

There is a precedent for stretching the interpretation of ArgumentNullException to meaning "string argument is null or empty": System.Windows.Clipboard.SetText will throw an ArgumentNullException in this case.

So I wouldn't see anything wrong with using this rather than the more general ArgumentException in your property setter, provided you document it.