transient for serializing singleton

Question

Effective Java - To maintain the singleton guarantee, you have to declare all instance fields transient and provide a \'readResolve\' method. What do we achieve by declaring

Answer 1

What you gain by making the attribute transient is that you don't serialize the state. Serializing it is unnecessary, since it's discarded anyway by the readResolve() method.

If the state consists in an int, it doesn't matter much. But if the state is a complex graph of objects, it makes a significant performance difference. And of course, if the state is not serializable, you don't have any other choice.

That said, serializing a singleton is questionable.