Why Serializable doesnot have any method

[chets patel]

Hi
If Serializable interface does not have any method, then how it serve the purpose of serialization.
What happens internally.
I am confused.
Please let me know.

Thanks in advance.

[Jesper de Jong]

Serializable is a marker interface. You use it to indicate that a class should be serializable. Other code can check if an object is serializable using the instanceof operator, for example:

if (someObject instanceof Serializable) {
    System.out.println("The object is serializable");
}
else {
    System.out.println("The object is not serializable");
}

[Campbell Ritchie]

The JVM looks at any object it is trying to serialise, and checks it is marked as "Serializable".

[Gaurav Sagar]

Serializable is a markup interface just like many other as SingleThreadModel, EventListener, Cloneable, RandomAccess, etc. These interfaces are just used to tag the class having certain special characterstic which is recognized by the JVM at runtime, for eg.:-
Only the classes implementing the Serializable have the capability to save their state. Here the marker Serializable on the class suggests the JVM at runtime that its state could be saved.
This is the reason these are also known as TAG intefaces. Java gives the facility to create empty interfaces.

Regards,
Gaurav

[Rob Spoor]

Gaurav Sagar wrote:many other as SingleThreadModel, EventListener, Cloneable, RandomAccess, etc.

I think EventListener does not fit in that list. It's not just a marker interface, it's the root of the entire event listener interface hierarchy.

[Gaurav Sagar]

Rob Prime wrote:

Gaurav Sagar wrote:many other as SingleThreadModel, EventListener, Cloneable, RandomAccess, etc.

I think EventListener does not fit in that list. It's not just a marker interface, it's the root of the entire event listener interface hierarchy.

I said so since java.util.EventListener is just another empty interface, so it ought to be a marker interface.

[Rob Spoor]

Empty interface and marker interface are not necessarily synonyms. A marker interface is empty, but an empty interface can also have other purposes than just type checking, which is essentially what marker interfaces are for. Cloneable, Serializable, RandomAccess, SingleThreadModel - all just perfect examples.