Hi all,
I am currently developing some feature extractors in the DKPro framework and I
have come across a problem with the Class type in the following method in
org.apache.uima.fit.util.JCasUtil:
public static <T extends Annotation> List<T> selectCovered(JCas jCas, final
Class<T> type,
int begin, int end) {
return cast(CasUtil.selectCovered(jCas.getCas(), getType(jCas, type),
begin, end));
}
In my type system I have a base type „Proposition" that extends „Annotation"
and two more types which are derived from the base type: „Conclusion“ and
„Premise". If I use the base type for the generic type parameter T in this
method above, it works fine. If I use one of the sub-types of the base type, I
get the following error:
- Bound mismatch: The generic method selectCovered(JCas, Class<T>, int,
int) of type JCasUtil is not applicable for the arguments (JCas,
Class<Conclusion>, int, int). The
inferred type Conclusion is not a valid substitute for the bounded
parameter <T extends Annotation>
Background is that I would like to use one abstract feature extractor for
common code which is parameterized with <T extends Proposition> and the two
concrete sub-class FE’s, which are parameterized with the two sub-types.
Maybe I have some misunderstanding regarding the use of Generics here. Could it
be that in the definition of selectCovered() the clause <T extends Annotation>
allows only direct sub-types of Annotation? Interestingly enough, if I don’t
parameterize the sub-class FEs, I don’t get any errors.
Thanks a lot.
Cheers,
Martin
