CODEWITHSUNDEEP
scalaclasscastexception
Georg Heiler
Georg Heiler

Reputation: 17676

Scala access Map[String, Any] with nested data structures

I have s simple map like

  val parameters: Map[String, Any] = Map("digits" -> Seq(1, 2, 3, 4, 5, 6, 7, 8,

an want to multiply each number by 3 like shown below

class PrintMap extends App {
  val conf: SparkConf = new SparkConf()
    .setAppName("sparkApiSample")
    .setMaster("local[*]")

  val session: SparkSession = SparkSession
    .builder()
    .config(conf)
    .getOrCreate()

  val parameters: Map[String, Any] = Map("digits" -> Seq(1, 2, 3, 4, 5, 6, 7, 8, 9, 0))

  val numbers: Seq[Int] = parameters("digits").asInstanceOf[Seq[Int]]
  val rdd = session.sparkContext.parallelize(numbers)

  val result = Map("result" -> rdd.map(x => x * 3).collect())

  // want to "access / print the contents of the Array at result
  result.get("result") match {
    case Some(x) => x.asInstanceOf[Seq[Any]].foreach(println)
    case None => println("error occurred")
  }

Why does it result in the following exception and how could I actually access the map? java.lang.ClassCastException: [I cannot be cast to scala.collection.Seq

Upvotes: 1

Views: 308

Answers (1)

A Spoty Spot
A Spoty Spot

Reputation: 746

Collect on an RDD returns an Array. Array does not extend Seq. So your x cannot be cast to a Seq.

eg.)

Array(2).asInstanceOf[Seq[Int]]

Throws the same exception.

Instead your result should be of type: Map[String, Array[Int]]

So instead just use x.toSeq isntead of x.asInstanceOf[Seq[Int]]

EDIT: "[I" in your stack means Array of Int.

It occurred to me as I was writing this, I'm guessing the reason you're using any is because each your have a bunch of different parameters and return types in your array. If this is the case it'd be handy see a slightly more complete example.

Upvotes: 3

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