CODEWITHSUNDEEP
javaannotations
Denim Datta
Denim Datta

Reputation: 3802

How to get values of different Annotations

How can i print the Annotation values for different Annotation?

I have the following two Annotation

@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Author 
{
    String name() default "--Unknown--";
    String date() default "--Unknown--";
}

and

@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Revision 
{
    int version() default 0;
    String modifiedBy() default "--Unknown--";
}

now one class use both this annotations, and inside this class I want to display the annotation values for both the annotations

@Author(
        name = "Panther",
        date = "22.04.2013"
        )

@Revision(
        version = 2,
        modifiedBy = "Black", 
        )
public class AnnotationTest
{
    public static void main(String[] args)
    {
        AnnotationTest b = new AnnotationTest();
        for(Annotation a : AnnotationTest.class.getDeclaredAnnotations())
        {
            // for Author display name and date
            // for revision display version and modifiedBy
        }
    }
}

is there any way to do that?

Upvotes: 2

Views: 481

Answers (2)

Reimeus
Reimeus

Reputation: 159754

You can use instanceof:

for (Annotation a : AnnotationTest.class.getDeclaredAnnotations()) {
   if (a instanceof Author) {
      Author author = (Author) a;
      System.out.println("Author Name: " + author.name());
      System.out.println("Date: " + author.date());

   } else if (a instanceof Revision) {
      Revision revision = (Revision) a;
      System.out.println("Version: " + revision.version());
      System.out.println("Modified By: " + revision.modifiedBy());
   } 
}

Upvotes: 3

rmalchow
rmalchow

Reputation: 2769

the answer is very simple:

a.getClass().getAnnotation(Author.class).name();

this is generic, so getAnnotation will return the type you asked for, then you can get the fields directly.

Upvotes: 1

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