Java - Interview Questions and Answers on "Marker Interfaces"

Q1.  What are Marker Interfaces ? Name few Java marker interfaces ?

Ans. These are the interfaces which have no declared methods.

Serializable and cloneable are marker interfaces.

Q2.  Is runnable a Marker interface ?

Ans. No , it has run method declared.

Q3.  Difference between serializable and externalizable interface ?

Ans. Serializable is a marker interface whereas externalizable  is not.

Q4.  What is a cloneable interface and what all methods does it contain?

Ans. It is not having any method because it is a MARKER interface.

Q5.  What is the purpose of marker interfaces ?

Ans. They just tell the compiler that the objects of the classes implementing the interfaces with no defined methods need to be treated differently.