Eh, is it not that you are mapping the values of an RDD whose keys are
StringStrings, but expecting the keys are Strings? That's also about
what the compiler is saying too.
On Thu, Oct 2, 2014 at 4:15 PM, Robin Keunen <robin.keu...@lampiris.be> wrote:
> Hi all,
>
> I successfully implemented my algorithm in Scala but my team wants it in
> Java. I have a problem with Generics, can anyone help me?
>
> I have a first JavaPairRDD with a structure like ((ean, key), [from, to,
> value])
>
> ean and key are string
> from and to are DateTime
> value is a Double
>
> JavaPairRDD<StringString, List<Serializable>> eanKeyTsParameters =
> javaRDD.mapToPair( ... );
>
> Then I try to do flatMapValues to apply the GenerateTimeSeries Function, it
> takes the from, to and values to generate a List<LongDouble>. Here is the
> error I get when compiling:
>
> error: incompatible types: no instance(s) of type variable(s) U exist so
> that JavaPairRDD<StringString,U> conforms to JavaPairRDD<String,LongDouble>
>
> Here is what IntelliJ tells me:
> flatMapValues( Function<List<Serializable>, Iterable<U>> ) in JavaPairRDD
> cannot be applied to Transformations.GenerateTimeSeries
>
> Here is the problematic transformation:
>
> JavaPairRDD<String, LongDouble> keyLongDouble =
> eanKeyTsParameters.flatMapValues(new
> Transformations.GenerateTimeSeries());
>
> And here is the Function:
>
> import org.apache.spark.api.java.function.Function; [...]
>
> public class Transformations {
> public static class GenerateTimeSeries
> implements Function<List<Serializable>, Iterable<LongDouble>> {
>
> @Override
> public Iterable<LongDouble> call(List<Serializable> args) {
> DateTime start = (DateTime) args.get(0);
> DateTime end = (DateTime) args.get(1);
> Double value = (Double) args.get(2);
> int granularity = 24*60*60*1000; // 1 day
>
> return AggregationUtils.createTimeSeries(start, end, value,
> granularity);
> }
> }
> }
>
> Any idea?
>
> Thanks
>
> --
>
> Robin Keunen
> Software Engineer
> robin.keu...@lampiris.be
> www.lampiris.be
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