java annotations - problem with calling a locator class from a Vaadin Project

Question

Hello,

I'm not sure how to explain this without writing several pages so I hope the actual code is more expressive.

I've made a jar containing multiple annotation declaration similar to the following:

@Target(ElementType.PACKAGE)
@Retention(RetentionPolicy.RUNTIME)
public @interface MarkedPackage {
}

then I have made a test jar containing several classes in several packages and marked just one package with the above annotation (with package-info.java) like below:

@myPackage.MarkedPackage
package package.test.jar;

this jar had in its build path the jar containing the annotations.

then I made a static class that has a method (LoadPlugins) that retrieves a list with all the jars of a directory. Then it searches through the jars for the 'package-info' class and checks if that classes package contains the MarkedPackage annotation. by calling this:

if (checkPackageAnnotation(thisClass.getPackage()))

where thisClass is the package-info class retrieved via a classloader. and:

public static boolean checkPackageAnnotation(AnnotatedElement elem) {
  System.out.println(elem.getAnnotations().length);
  if (elem == null || !elem.isAnnotationPresent(MarkedPackage.class))
   return false;
return true;
}

the elem.getAnnotatios().length is there for debug purposes.

And the problem appears when I call the method from the static class:

if I call it from a main function:

public class MyMain {
 public static void main(String[] args){
  PluginUtils.LoadPlugins();
 }
}

everything works perfectly it displays '1' from that System.out.println(elem.getAnnotations().length);

But if I call it from a button from my Vaadin project:

header.addComponent(new Button("CallThat",
 new Button.ClickListener() {
 public void buttonClick(ClickEvent event) {
 PluginUtils.LoadPlugins();
 }
}));

It displays '0' from that System.out.println(elem.getAnnotations().length);

Also I should mention that I created the main inside my Vaadin project so it would have the exact same build path and resources.

Is there a problem with web applications and that "@Retention(RetentionPolicy.RUNTIME)" ?

hope I was clear enough... Hope someone has a solution for me... If you need more information - let me know.

Thank you.

Answer 1

yes,

because there is only one package-info class in one package.