Interface(marker)

[Rambabu Gonela]

Any object that implements the java.io.Serializable interface can be made as serialazable., that means JVM performs serialization internally...Similarly if i define a marker interface, how would JVM know what task to be performed on behalf of my marker interface. How should i intimate the JVM about the task that should be performed by it, if any object implements my marker interface?

[Ernest Friedman-Hill]

Here's how marker interfaces work: some code, somewhere, knows to do this:

if (theObject instanceof MyMarkerInterface)
    doSomething();

You can define a marker interface of your own, and write code of your own like the above, but of course you can't somehow get the JVM to automatically do anything. But that's all that the Serializable interface does -- some code checks for it using "instanceof" and takes that as permission to serialize the object.