CODEWITHSUNDEEP
scala
Surender Raja
Surender Raja

Reputation: 3599

How to return a Map with Value Type as String in scala

 object passingmapstomethod {

  def main(args:Array[String])={

val custs = Map(100->"surender",101->"raja")
val txns = Map(100->"USA", 101->"UK")

    println(join(custs,txns))

}

  def join[K,A,B,C](custs:Map[K,A],txns:Map[K,B]) :Map[K, C]=
  {

   for((k,va) <- custs; vb <- txns.get(k)) yield k -> va.toString()+"|"+ vb.toString()

 }

}

Expected Output is 

 Map(101 -> raja|UK , 100 -> surender|USA)

But while running this I get error as 

◾Implicit conversion found:  ⇒ any2stringadd(): any2stringadd[(K, String)]
◾type mismatch; found : scala.collection.mutable.Iterable[String] required: scala.collection.mutable.Map[K,C]
◾Implicit conversion found:  ⇒ option2Iterable(): Iterable[String]
◾Implicit conversion found:  ⇒ ArrowAssoc(): ArrowAssoc[K]

Upvotes: 1

Views: 280

Answers (1)

Pablo Francisco P&#233;rez Hidalgo
Pablo Francisco P&#233;rez Hidalgo

Reputation: 27692

You have three options:

(A) Remove the parametric type C from join as your return value will be always String:

def join[K,A,B](custs:Map[K,A],txns:Map[K,B]) :Map[K, String]= {
    for((k,va) <- custs; vb <- txns.get(k)) yield k -> va.toString()+"|"+ vb.toString()
}

(B) Add a generic combiner function and keep the method parametric:

def join[K,A,B, C](custs:Map[K,A],txns:Map[K,B], combiner: (A, B) => C) :Map[K, C]= {
    for((k,va) <- custs; vb <- txns.get(k)) yield k -> combiner(va, vb)
}

(C) Always return a tuple, thus removing the parametric type C too; and use mapValues over its result in order to combine the tuple elements:

def join[K,A,B](custs:Map[K,A],txns:Map[K,B]) :Map[K, C]= {
    for((k,va) <- custs; vb <- txns.get(k)) yield k -> (va, vb)
}

Upvotes: 3

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