The java class “Class” basically has a private member named “annotations” which is a map of annotation classes to annotation objects Here’s how that utility method could look like :Ĭ("annotations") We are conveniently ignoring JDK6 because hardly anyone uses it. So in JDK7 its a different approach and in JDK8 its a different version. I learnt that the approach to alter annotation values at runtime differs across JDK versions. So lets go about building the logic that would basically help us alter the value of the “name” attribute in the Greet annotation at runtime. In the above example, we have an example class named “Demo” which has our custom annotation “Greet” and we are now using reflection to get the value that was set viz., “Dragon Warrior”. ("Hello there [" + greet.name() + (name = "Dragon Warrior") An example usage of this would be something like below : I was now looking to alter the value of “name” at runtime based on some condition. Lets first imagine that I have an annotation such as the one below that I would like to (RetentionPolicy.RUNTIME) But since we don’t currently have all that luxury when it comes to playing around with the annotation that I was trying to alter at runtime, I had to resort to using “Reflections”… and once again I stand amazed at the amount of thought process that was put into building it. What I didn’t realise was how difficult this would turn out to be and not to mention, the flakiness of the solution. afterall, TestNG lets me use AnnotationTransformers to change annotations. I had worked a lot with TestNG and so thought that this must be a piece of cake. So it all boiled down to “Altering annotations at runtime”. Parameters: annotationTypes - the list of Class objects corresponding to theĪnnotation types clazz - the Class object corresponding to the class on which to checkįor the annotations, or null Returns: the first Class in the inheritance hierarchy of the specifiedĬlazz which declares an annotation of at least one of the specifiedĪnnotationTypes, or null if not found Since: 3.2.2 See Also: Class.Sometime back last week, I was tasked with adding some reporters via annotations into a cucumber based test. Which class in an inheritance hierarchy actually declares one of severalĬandidate annotations, so we need to handle thisĮxplicitly. The standard Class API does not provide a mechanism for determining Will be checked the inheritance hierarchy for interfaces will not be traversed. If the supplied clazz is an interface, only the interface itself If the supplied clazz is null, null will be None of the specified annotation types could be found. findAnnotationDeclaringClassForTypes public static Class findAnnotationDeclaringClassForTypes( List> annotationTypes,įind the first Class in the inheritance hierarchy of the specifiedĬlazz (including the specified clazz itself) which declaresĪt least one of the specified annotationTypes, or null if.
IsAnnotationDeclaredLocally(Class, Class) If not found See Also: Class.isAnnotationPresent(Class),įindAnnotationDeclaringClassForTypes(List, Class),
Which declares an annotation for the specified annotationType, or null Parameters: annotationType - the annotation type to look for, both locally and as a meta-annotation clazz - the class on which to check for the annotation (may be null) Returns: the first Class in the inheritance hierarchy of the specified clazz In an inheritance hierarchy actually declares an Annotation, so we need to handle The standard Class API does not provide a mechanism for determining which class The inheritance hierarchy for interfaces will not be traversed. If the supplied clazz is an interface, only the interface itself will be checked Specified annotationType, or null if not found. (including the specified clazz itself) which declares an annotation for the findAnnotationDeclaringClass public static Class findAnnotationDeclaringClass( Class annotationType,įind the first Class in the inheritance hierarchy of the specified clazz.Parameters: clazz - the class to look for annotations on annotationType - the annotation type to look for Returns: the annotation found, or null if none found Recursing up through the entire superclass With the interfaces that the superclass declares. Of the given class, checking the superclass itself if no annotation found there, proceeds Else proceeds with introspection of the superclass
Else searches all interfaces that the given class declares, returning the annotationįrom the first matching candidate, if any. The algorithm operates as follows: Searches for an annotation on the given class and returns Inherited as well as annotations on interfaces. This method explicitly handles class-level annotations which are not declared as Traversing its interfaces and superclasses if no annotation can be found on the given class itself. Find a single Annotation of annotationType from the supplied Class,
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