Contrary to what one might expect, the elements of an annotation are not attributes – they are actually methods that return the provided value or a default value.
You have to iterate through the annotations’ methods and invoke them to get the values. Use annotationType()
to get the annotation’s class, the object returned by getClass()
is just a proxy.
Here is an example which prints all elements and their values of the @Resource
annotation of a class:
@Resource(name = "foo", description = "bar")
public class Test {
public static void main(String[] args) throws Exception {
for (Annotation annotation : Test.class.getAnnotations()) {
Class<? extends Annotation> type = annotation.annotationType();
System.out.println("Values of " + type.getName());
for (Method method : type.getDeclaredMethods()) {
Object value = method.invoke(annotation, (Object[])null);
System.out.println(" " + method.getName() + ": " + value);
}
}
}
}
Output:
Values of javax.annotation.Resource
name: foo
type: class java.lang.Object
lookup:
description: bar
authenticationType: CONTAINER
mappedName:
shareable: true
Thanks to Aaron for pointing out the you need to cast the null
argument to avoid warnings.