Marker Interfaces

Question

Could somebody pls explain the contract of marker interfaces in java?

For Ex: If Clonable is a Marker Interface with no fields/methods, then where is t

Answer 1

Clonable does not contain clone() method, which is protected in java.lang.Object.

More info available here

Citation From Josh Bloch's Effective Java:

"The Cloneable interface was intended as a mixin interface for objects to advertise that they permit cloning. Unfortunately it fails to serve this purpose ... This is a highly atypical use of interfaces and not one to be emulated ... In order for implementing the interface to have any effect on a class, it and all of its superclasses must obey a fairly complex, unenforceable and largely undocumented protocol"