04. Marker Annotation.md

Marker Annotation

• special kind of annotation that contains no members.
• sole purpose is to mark an item.

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.Method;

@Retention(RetentionPolicy.RUNTIME)
@interface Mark{}

class Main{
    @Mark
    public static void m(){}

    public static void main(String[] args){
        try{
            Method m = Main.class.getMethod("m");
            if (m.isAnnotationPresent(Mark.class)){
                System.out.println("Marker annotation is present");
            }else{
                System.out.println("Marker annotation is not present");
            }
        }catch (Exception ex){
            System.out.println(ex.getMessage());
        }
    }
}