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From Martin Wunderlich <martin...@gmx.net>
Subject Re: Question on JCasUtil's selectCovered(...)
Date Mon, 03 Aug 2015 16:35:22 GMT
It is. No idea where this one came from. 



> Am 03.08.2015 um 10:29 schrieb Richard Eckart de Castilho <rec@apache.org>:
> Looks like a duplicate post?
> -- Richard
> On 31.07.2015, at 20:27, Martin Wunderlich <martin@wunderlich.com> wrote:
>> 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

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