I have an enumerator and a custom annotation that represents the enumerator's description:
public @interface Description {
String name() default "";
}
Enumerator:
public enum KeyIntermediaryService {
@Description(name="Descrizione WorldCheckService")
WORLDCHECKSERVICE,
@Description(name="blabla")
WORLDCHECKDOWNLOAD,
@Description(name="")
WORLDCHECKTERRORISM,
// ...
}
How can I get the enumerator description from within another class?
Like this, e.g. to get the description for the WORLDCHECKSERVICE enum value:
Description description = KeyIntermediaryService.class
.getField(KeyIntermediaryService.WORLDCHECKSERVICE.name())
.getAnnotation(Description.class);
System.out.println(description.name());
You would have to change your annotation's retention policy to runtime though:
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
@interface Description {
String name() default "";
}
@Retention(RetentionPolicy.RUNTIME) the reason for getting a NullPointer with my code? I mean could you elaborate the use and reason to use it more.
CLASS, i.e. the annotation will not be available for inspection at runtime.Followed the link Is it possible to read the value of a annotation in java? to produce the following code -
public static void main(String[] args) {
for (Field field : KeyIntermediaryService.class.getFields()) {
Description description = field.getAnnotation(Description.class);
System.out.println(description.name());
}
}
Ya but this code would produce an NPE, unless as specifed by @Robby in his answer that you need to change your annotation to have a @Retention(RetentionPolicy.RUNTIME) marked for Description.
The reason for that being stated in the answer here - How do different retention policies affect my annotations?
java.lang.reflect.Field