CODEWITHSUNDEEP
javascalainner-classes
Georg Heiler
Georg Heiler

Reputation: 17676

how to port java inner function in Scala?

How can I port a java inner function from here which fully is contained in to Scala?

JavaPairRDD<Envelope, HashSet<Point>> castedResult = joinListResultAfterAggregation.mapValues(new Function<HashSet<Geometry>,HashSet<Point>>()
            {
                @Override
                public HashSet<Point> call(HashSet<Geometry> spatialObjects) throws Exception {
                    HashSet<Point> castedSpatialObjects = new HashSet<Point>();
                    Iterator spatialObjectIterator = spatialObjects.iterator();
                    while(spatialObjectIterator.hasNext())
                    {
                        castedSpatialObjects.add((Point)spatialObjectIterator.next());
                    }
                    return castedSpatialObjects;
                }

            });
            return castedResult;

My approach as outlined below would not compile due to some NotinferredU

val castedResult = joinListResultAfterAggregation.mapValues(new Function[java.util.HashSet[Geometry], java.util.HashSet[Point]]() {
    def call(spatialObjects: java.util.HashSet[Geometry]): java.util.HashSet[Point] = {
      val castedSpatialObjects = new java.util.HashSet[Point]
      val spatialObjectIterator = spatialObjects.iterator
      while (spatialObjectIterator.hasNext) castedSpatialObjects.add(spatialObjectIterator.next.asInstanceOf[Point])
      castedSpatialObjects
    }
  })

Upvotes: 0

Views: 86

Answers (2)

Alexey Romanov
Alexey Romanov

Reputation: 170723

When asking a question about compilation errors please provide the exact error, especially when your code doesn't stand on its own.

The inner function itself is fine; my guess would be that due to changes above joinListResultAfterAggregation isn't a JavaPairRDD anymore, but a normal RDD[(Envelope, Something)] (where Something could be java.util.HashSet, scala.collection.Set or some subtype), so its mapValues takes a Scala function, not a org.apache.spark.api.java.function.Function. Scala functions are written as lambdas: spatialObjects: Something => ... (the body will depend on what Something actually is, and the argument type can be omitted in some circumstances).

Upvotes: 1

aks
aks

Reputation: 1029

How about this ?

val castedResult = joinListResultAfterAggregation.mapValues(spatialObjects => {
                        spatialObjects.map(obj => (Point) obj)
                   })

Upvotes: 1

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