How to create and use marker annotation in Java
Description
A marker annotation contains no members. It is used to mark a declaration.
To determine if a marker annotation is present, use the method isAnnotationPresent( ).
isAnnotationPresent( ) is a defined by the AnnotatedElement interface.
Example
Here is an example that uses a marker annotation.
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.Method;
/*from w w w .ja v a 2 s .com*/
@Retention(RetentionPolicy.RUNTIME)
@interface MyMarker {
}
public class Main {
@MyMarker
public static void myMethod() throws Exception{
Main ob = new Main();
Method m = ob.getClass().getMethod("myMethod");
if (m.isAnnotationPresent(MyMarker.class)){
System.out.println("MyMarker is present.");
}
}
public static void main(String args[]) throws Exception{
myMethod();
}
}
The code above generates the following result.
