Serializing interfaces

Question

I'm trying to run code similar to this:

using System;
using System.Collections.Generic;
using System.IO;
using System.Xml.Serialization;

namespace ConsoleApplication1
{
    [Serializable]
    [XmlInclude(typeof(List<Class2>))]
    public class Class1
    {
        private IList<Class2> myArray;

        public IList<Class2> MyArray
        {
            get { return myArray; }
            set { myArray = value; }
        }

    }

    public class Class2
    {
        private int myVar;

        public int MyProperty
        {
            get { return myVar; }
            set { myVar = value; }
        }

    }

    class Program
    {
        static void Main(string[] args)
        {
            XmlSerializer ser = new XmlSerializer(typeof(Class1), new Type[] { typeof(List<Class2>) });
            FileStream stream = File.OpenWrite("Data.xml");
            ser.Serialize(stream, new List<Class1>());
            stream.Close();
        }
    }
}

Can somebody explain to me what am I doing wrong?

I get a:

Cannot serialize member .. MyArray ... because it is an interface.

Shouldn't the XmlInclude resolve this?

Answer 1

No. You can't serialize an interface. Ever. It just told you that.

An interface is nothing more than a description of a set of behaviors. It says nothing about the contents of an instance. In particular, although an instance of a class implementing an interface must implement all of its members, it will certainly have properties of its own which need to be serialized.

How would it be deserialized?

What class would be used to deserialize the interface on the other side?