spark flatMapToPair to create keys of different type

问题

For the following codes using spark java API:

JavaPairRDD<TypeOne,Long> pairs = originalRows.flatMapToPair(new PairFlatMapFunction<OriginalType,TypeOne,Long>()

it takes the RDD, named OriginalType and maps it into pairs with key type of TypeOne.

I am wondering that is it possible to takes OriginalType and during the map step, maps it into two types of key? Like TypeOne and TypeTwo. Or I must use two map steps to realize this...

回答1:

You can create an Interface or Generic class that both types will implement/inherit and use this instead of the specific type.

public interface IType { }

public class TypeOne implements IType { }

public class TypeTwo implements IType { }

JavaPairRDD<IType,Long> pairs = originalRows.flatMapToPair(new PairFlatMapFunction<OriginalType,IType,Long>()

来源：https://stackoverflow.com/questions/29260756/spark-flatmaptopair-to-create-keys-of-different-type