Purpose of marker interface in java?

Answer 1

Generally, they are used to give additional information about the behaviour of a class.It is just used to "mark" Java classes which support a certain capability . Examples: java.util.RandomAccess

java.io.Serializable

java.rmi.Remote

java.util.EventListner

javax.servlet.SingleThreadModel

java.lang.Clonable

javax.ejb.EnterpriseBean

Answer 2

Marker interface is used as a tag to inform a message to the java compiler so that it can add special behaviour to the class implementing it. Java marker interface has no members in it

Lets take the java.io.Serializable marker interface. It doesnot has any members defined it it. When a java class is to be serialized, you should intimate the java compiler in some way that there is a possibility of serializing this java class. In this scenario, marker interfaces are used. The java class which may be serialized has to implement the java.io.Serializable marker interface. In such way, we are intimating the java compiler.

Naresh Tuhania From IBM