Custom Marker Interface Implementation in Java

Marker interface has no method. Java has built-in marker interface like Serializable, Cloneable & Event Listener etc that are understand by JVM.

We can create our own marker interface, but it has nothing to do with JVM, we can add some checks with instanceOf.

Create the empty interface


interface Marker{    }

Write a class and implements the interface 


class A implements Marker {
  //do some task
}

Main class to check the marker interface instanceof
 

class Main {
    public static void main(String[] args) {
        A ob = new A(){
        if (ob instanceof A) {
            // do some task
        }
    }
}


Reference: 

https://stackoverflow.com/questions/11008033/how-to-write-our-own-marker-interface-in-java/35278304 

https://en.wikipedia.org/wiki/Marker_interface_pattern