Java - loading annotated classes

Question

I know there are incredible set of tools for loading plugin classes in java, but today an idea came to my mind.

What if I have a bunch of annotated and un-annotated

Answer 1

It can be done with techniques that check the filesystem because it is more a classloader issue than a reflection one. Check this: Can you find all classes in a package using reflection?.

If you can check all the class files that exists in a directory, you can easily get the corresponding class using this method

Class klass = Class.forName(className)

To know if a class is annotated or not is a reflection issue. Getting the annotations used in a class is done this way:

Annotation[] annotations = klass.getAnnotations();

Be sure to define your custom annotation with a retention policy type visible at run time.

@Retention(RetentionPolicy.RUNTIME) 

This article is a good resource for more info on that: http://tutorials.jenkov.com/java-reflection/annotations.html.