Reading an ElementType.LOCAL_VARIABLE

Question

I have been trying read a ElementType.LOCAL_VARIABLE annotation using reflect package.
Here is my annotation:
@Target(value={ElementType.TYPE,ElementType.LOCAL_VARIABLE})
@Retention(value=RetentionPolicy.RUNTIME)
public @interface TestAnnotation{
     String theName();
Here is my program to try read the annotation:
public class TestTheAnnotation{
     public static void main(String[] args){
          @TestAnnotation(theName="My_LastName,My_FirstName")
          Integer id=new Integer(1);
          System.out.println(">> "+id.getClass().getAnnotations().length);
          System.out.println(">> "+id.getClass().getDeclaredAnnotations().length);
The methods getAnnotations, and getDeclaredAnnotations only return the annotations declared for the object, but I want the annotation declared for the local variable.
Is there any way to do this?
Thanks.

Answer 1

getAnnotations() and getDeclaredAnnotations() are methods that you can invoke on an object of the type java.lang.Class (it's where they are defined).
In your code, id.getClass() is exactly such an object and it is the same as Integer.class, because id refers to an Integer object.
Now, it seems that the Integer class has no annotations at all or no annotations with RetentionPolicy.RUNTIME.
You annotated a local variable.
According to http://download.oracle.com/javase/6/docs/api/index.html, there are a few classes that extend the AnnotatedElement interface (java.lang.Class among them),
but none that corresponds to the local variable element. So, your annotation is inaccessible at run-time.
On the other hand, check out this:
@TestAnnotation(theName="My_LastName,My_FirstName")
public class TestTheAnnotation
     public static void main(String[]args) throws Exception
          Class cl = TestTheAnnotation.class;
          System.out.println(">> "+cl.getAnnotations().length);
          System.out.println(">> "+cl.getDeclaredAnnotations().length);
@Target(value={ElementType.TYPE,ElementType.LOCAL_VARIABLE})
@Retention(value=RetentionPolicy.RUNTIME)
@interface TestAnnotation
     String theName();
}Edit: Found this: "Local variable annotations are not retained in class files (or at runtime) regardless of the retention policy set on the annotation type. See JLS 9.6.1.2."
Less words than me, but authoritative (from http://www.eclipse.org/aspectj/doc/released/adk15notebook/annotations.html).
Edited by: baftos on May 14, 2011 12:23 PM