Serialization of Enum Constants

Enum constants are serialized differently than ordinary serializable or externalizable objects. The serialized form of an enum constant consists solely of its name; field values of the constant are not present in the form.

To serialize an enum constant, ObjectOutputStream writes the value returned by the enum constant's name method.

To deserialize an enum constant, ObjectInputStream reads the constant name from the stream; the deserialized constant is then obtained by calling the java.lang.Enum.valueOf method, passing the constant's enum type along with the received constant name as arguments.

Important points:

enum constants are serialization cannot be customized with writeObject, readObject, readObjectNoData, writeReplace, and readResolve methods, enum types are ignored during serialization and deserialization by these methods.

All enum types have a fixed serialVersionUID of 0L.

http://docs.oracle.com/javase/6/docs/platform/serialization/spec/serial-arch.html