Type Safe enum with Serializable issue

Question

The following code is copied from www.javapractices.com
public final class SimpleSuit {
  public static final SimpleSuit CLUBS = new SimpleSuit ("Clubs");
  public static final SimpleSuit DIAMONDS = new SimpleSuit ("Diamonds");
  public static final SimpleSuit HEARTS = new SimpleSuit ("Hearts");
  public static final SimpleSuit SPADES = new SimpleSuit ("Spades");
  public String toString() {
    return fName;
  private final String fName;
  private SimpleSuit(String aName) {
    fName = aName;
}It is known to be typesafe and able to perform object equality.
Eg:
SimpleSuit s = SimpleSuit.SPADES;
if (s == SimpleSuit.SPASES)
..Thus, it is simple and fast enough by object equality comparison.
But if I implement SimpleSuit with java.io.Serializable and send it over the network, of course that would become a totally new objects, therefore I can't usr object equality anymore. Any solution to make it work over Serialization?
Thanks,
Jax

Answer 1

A serializable class may provide a 'readResolve' method. This is used to "designate a replacement when an instance of it is read".
A common approach with enums is to provide a unique identifier (e.g, a string name, or integer id). The enum class can then provide a readResolve method which determines the correct replacement instance based on this id.
An example of this is also available on the javapractices site you mentioned:
http://www.javapractices.com/Topic1.cjp