What are Marker Annotations?

Marker Annotations are used to mark a declaration.

A marker annotation is a special kind of annotation.

A marker annotation contains no members.

Using isAnnotationPresent( ) to determine if the marker is present.

import java.lang.annotation.Annotation;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.reflect.Method;

 

 

@Retention(RetentionPolicy.RUNTIME)

@interface MyAnnotation {

}

 

@MyAnnotation

public class MainClass {

  // Annotate a method.

  @MyAnnotation()

  public static void myMethod() {

  }

 

  public static void main(String[] arg) {

    try {

      MainClass ob = new MainClass();

 

      Method m = ob.getClass( ).getMethod("myMethod");

      Annotation[] annos = m.getAnnotations();

 

      System.out.println("All annotations for myMeth:");

      for(Annotation a : annos)

      System.out.println(a);

 

    } catch (Exception exc) {

    }

  }

}

 

out put:

All annotations for myMeth:

@MyAnnotation()