.NET: Is Public Declaration a Requirement for a Class to be Serializable?

Question

Is public declaration a requirement for a class to be serializable? I've been going through some code where all classes marked as [Serializable] were also declared public. I could not find formal documentation stating this.

Answer 1

No, there is no such requirement for Serializable. It's not surprising that you see Serializable on public classes, since data that's going to be persisted to a stream is very likely to be shared with others, and therefore motivates the choice of a public class.

Answer 2

I don't know .net very well. but what about private nested classes?

If the (public) outer class is serialisable then you'll probably want to serialise any inner classes as well.

Answer 3

Not always true, perhaps you have a object that has an internal class that represents the state of another object and is Serializable, that is quite valid too

Answer 4

Depends on the serialization. AFAIK, binary serialization (ie--[Serializable]) doesn't require public member access, it just does some voodoo to take an in-memory snapshot of the class.

XmlSerialization (and JsonSerialization, etc) do generally require the class be public, with a defualt parameterless constructor and automatically serialize all public properties or fields.