Marker Annotations : Annotations Types « Language « Java Tutorial

1. Java Tutorial
2. Language
3. Annotations Types

1. Marker Annotations are used to mark a declaration.
2. A marker annotation is a special kind of annotation.
3. A marker annotation contains no members.
4. 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) {
    }
  }
}

All annotations for myMeth:
@MyAnnotation()