Fwd: Annotation element values

[Mohan Radhakrishnan]

I forgot to copy the list. Apology.

Mohan

---------- Forwarded message ----------
From: Mohan Radhakrishnan <radhakrishnan.mohan at gmail.com>
Date: Sat, Jan 4, 2014 at 5:38 PM
Subject: Re: Annotation element values
To: Alex Buckley <alex.buckley at oracle.com>


I was mislead by a wrong jdk 8 version.

It compiles and runs using b120 but I will show the actual code. I was
reading
http://docs.oracle.com/javase/tutorial/java/annotations/repeating.html but
the documentation seemed to be sketchy. The code had to be written like
this. The IDE showed there are some rules like the requirement for both
annotations to have the same retention policy.

import java.lang.annotation.*;

public class RepeatableAnnotation {

    @Retention(RetentionPolicy.RUNTIME)
    @Target(ElementType.TYPE_USE)
    public @interface TypeUses {
        TypeUse[] value();
    }

    @Retention(RetentionPolicy.RUNTIME)
    @Target(ElementType.TYPE_USE)
    @Repeatable(TypeUses.class)
    protected @interface  TypeUse {
        int value();
    }

    @TypeUse(value = 0) @TypeUse(value = 1)class Test1< T extends
@TypeUse(value = 2) @TypeUse(value = 3) Integer> {

        /**
         * A type annotation is permitted in front of a constructor
declaration, where declaration annotations are already
         permitted.
         */
        @TypeUse(value = 0) <S> Test1(String s){

        }
    }

}

-----------Processor-------------

    private void processEnclosedElements(List<? extends Element>
enclosedElements,
                                         RoundEnvironment roundEnv) {

        for( Element e : enclosedElements ){

            if (e.getKind() == ElementKind.CLASS){

                System.out.println( "Annotation [" +
e.getAnnotationMirrors() + "] [" + e  + "]");

                for( AnnotationMirror typeMirror :
e.getAnnotationMirrors())  {

                    for(Map.Entry< ? extends ExecutableElement, ? extends
AnnotationValue> m : typeMirror.getElementValues().entrySet()){

                        System.out.println( "[" + m.getKey() +"][" +
m.getValue() + "]");

                    }

                }
                processClassTypeParameters(e);

            }
        }
    }

    private void processClassTypeParameters(Element e) {

        for (TypeParameterElement typeParameterElement : ((TypeElement)
e).getTypeParameters()) {

            for (TypeMirror typeMirror : typeParameterElement.getBounds()) {

                System.out.println( "Annotation [" +
Arrays.asList(typeMirror.getAnnotationsByType(RepeatableAnnotation.TypeUse.class))
+ "] [" + typeMirror  + "]");

            }
        }
    }

----------Result-------------

Annotation
[@com.test.RepeatableAnnotation.TypeUses({@com.test.RepeatableAnnotation.TypeUse(0),
@com.test.RepeatableAnnotation.TypeUse(1)})]
[com.test.RepeatableAnnotation.Test1]
[value()][{@com.test.RepeatableAnnotation.TypeUse(0),
@com.test.RepeatableAnnotation.TypeUse(1)}]
Annotation [[]] [java.lang.Integer]

I was trying to

1. get the value '0' or '1' in the method 'processEnclosedElements'
2. get the Annotation applied on the bounds. Now an empty List is printed.

Thanks,
Mohan


On Sat, Jan 4, 2014 at 12:24 AM, Alex Buckley <alex.buckley at oracle.com>wrote:

> On 12/24/2013 4:53 AM, Mohan Radhakrishnan wrote:
>
>> Tried to subscribe using
>> http://mail.openjdk.java.net/mailman/listinfo/type-annotations-dev
>>
>
> Your confirmation mail (the one you send in response to the challenge) was
> received by the list, but for some reason it was not processed. I have
> subscribed you by hand - you should have received a welcome mail.
>
>
>  I could compile the processor code with b113. But with b120 it doesn't.
>>
>
> Please be more specific. The code below compiled with b113 but does not
> compile with b120? What compile-time error is given?
>
>
>  Is this code supposed to print the annotation element values ? I am also
>> trying to get the annotations applied on the bound 'Integer'.
>>
>
> You are calling typeParameterElement.getAnnotationMirrors(), which
> returns annotations that are directly present on the element. But the
> element - the declaration of a type parameter called T - is completely
> unannotated, so there are no element values to print out.
>
> As for the bound Integer, you are calling typeMirror.getAnnotationsByType(...)
> in the right way. I would expect to see @TypeUse(2) and @TypeUse(3) in the
> output.
>
> Alex
>
>
>  --------------Source--------------
>>     @TypeUse(value = 0) @TypeUse(value = 1)class Test1< T extends
>> @TypeUse(value = 2) @TypeUse(value = 3) Integer> {
>>
>>          /**
>>           * A type annotation is permitted in front of a constructor
>> declaration, where declaration annotations are already
>>           permitted.
>>           */
>>          @TypeUse(value = 0) <S> Test1(String s){
>>
>>          }
>>      }
>>
>> }
>>
>> --------------------Processor code---------------------------
>>
>> for (TypeParameterElement typeParameterElement : ((TypeElement)
>> e).getTypeParameters()) {
>>
>>              for( AnnotationMirror am  :
>> typeParameterElement.getAnnotationMirrors() ){
>>
>>                  System.out.println( "Annotation [" + am + "] [" +
>> typeParameterElement  + "]");
>>
>>                  for(Map.Entry< ? extends ExecutableElement, ? extends
>> AnnotationValue> m : am.getElementValues().entrySet()){
>>
>>                      System.out.println( "[" + m.getKey() +"][" +
>> m.getValue() + "]");
>>
>>                  }
>>
>>              }
>>
>>              for (TypeMirror typeMirror :
>> typeParameterElement.getBounds()) {
>>
>>                  System.out.println( "Annotation [" +
>> Arrays.asList(typeMirror.getAnnotationsByType(
>> RepeatableAnnotation.TypeUse.class))
>> + "] [" + typeMirror  + "]");
>>
>>              }
>>          }
>>      }
>>
>> Thanks.
>>
>>
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