GetClassOnAnnotation
Calling getClass() on an annotation may return a proxy class

Category
JDK
Severity
ERROR
Maturity

The problem

Instances of an annotation interface generally return a random proxy class when getClass() is called on them; to get the actual annotation type use annotationType().

In the following example, calling getClass() on the annotation instance returns a proxy class like com.sun.proxy.$Proxy1, while annotationType() returns Deprecated.

@Deprecated
public class Test {
  static void printAnnotationClass(Annotation annotation) {
    System.err.println(annotation.getClass());
    System.err.println(annotation.annotationType());
  }

  public static void main(String[] args) {
    printAnnotationClass(Test.class.getAnnotation(Deprecated.class));
  }
}

Prints:

class com.sun.proxy.$Proxy1
interface java.lang.Deprecated

Suppression

Suppress false positives by adding an @SuppressWarnings("GetClassOnAnnotation") annotation to the enclosing element.