Understanding Java Annotations

This code snippet give us better understanding on Java Annotations usage and their benifits.

import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;


//test class 
public class AnontationsExamplesKKC {
 public static void main(String args[]) throws Exception {
  Class<AnnotatedClass> classObject = AnnotatedClass.class;
  readAnnotation(classObject);
  Method method1 = classObject.getMethod("annotatedMethod1",
    new Class[] {});
  readAnnotation(method1);
  Method method2 = classObject.getMethod("annotatedMethod2",
    new Class[] {});
  readAnnotation(method2);
 }
//this method to read the annotations of the Annotated class.
 static void readAnnotation(AnnotatedElement element) {
  try {
   System.out.println("nFinding annotations on "
     + element.getClass().getName());
   Annotation[] classAnnotations = element.getAnnotations();
   for (Annotation annotation : classAnnotations) {
    if (annotation instanceof Author) {
     Author author = (Author) annotation;
     System.out.println("Author name:" + author.name());
    } else if (annotation instanceof Version) {
     Version version = (Version) annotation;
     System.out.println("Version number:" + version.number());
    }
   }
  } catch (Exception exception) {
   exception.printStackTrace();
  }
 }
}

@Target(value = { ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@interface Author {
 String name() default "unknown";
}

@Target(value = { ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@interface Version {
 double number();
}

@Author(name = "Sam")
@Version(number = 1.0)
class AnnotatedClass {
 @Author(name = "Author1")
 @Version(number = 2.0f)
 public void annotatedMethod1() {
 }

 @Author(name = "Author2")
 @Version(number = 4.0)
 public void annotatedMethod2() {
 }
}