Singleton class

[amarkirt saroay]

Can a singleton class be serializable?

[Campbell Ritchie]

Yes, but it will no longer be a true singleton.

Singleton ---> same object ---> same object ---> same object ---> serialise ---> deserialise ---> different object

[Campbell Ritchie]

Probably not easy enough a question for beginners. Moving.

[Rob Spoor]

Campbell Ritchie wrote:Yes, but it will no longer be a true singleton.

Singleton ---> same object ---> same object ---> same object ---> serialise ---> deserialise ---> different object

That's what the readResolve and writeReplace are for, especially the former:

private Object readResolve()
{
    return getInstance();
}

But Joshua Bloch has given a very good alternative in his "Effective Java" book: use an enum with only one element:

public enum Singleton
{
    INSTANCE;

    // fields, constructors, methods go here
}

[Campbell Ritchie]

Thank you Rob. I had quite forgotten about readResolve.