CODEWITHSUNDEEP
eclipsescala
Hemanth Annavarapu
Hemanth Annavarapu

Reputation: 917

Scala on Eclipse gives errors on Map operations

I am trying to write a word Count program using Maps in Scala. From various sources on the internet, I found that 'contains', adding elements to the Map using '+' and updating the existing values are valid. But Eclipse gives me errors when I try to use those operations in my code:

object wc {

 def main(args:Array[String])={
  val story = """ Once upon a time there was a poor lady with a son who was lazy
                  she was worried how she will grow up and
                  survive after she goes """

  count(story.split("\n ,.".toCharArray()))

 }

 def count(s:Array[String])={

    var count = scala.collection.mutable.Map
    for(i <- 0 until s.size){
     if(count.contains(s(i))) {
       count(s(i)) = count(s(i))+1

     }
     else count = count + (s(i),1)
    } 
    println(count)

 }
}

these are the error messages I get in eclipse: 1.) enter image description here

2.) enter image description here

3.) enter image description here

I tried these operations on REPL and they were working fine without any errors. Any help would be appreciated. Thank you!

Upvotes: 1

Views: 84

Answers (1)

Andy Hayden
Andy Hayden

Reputation: 375475

You need to instantiate a typed mutable Map (otherwise you're looking for the contains attribute on Map.type; which isn't there):

 def count(s: Array[String]) ={
   var count = scala.collection.mutable.Map[String, Int]()
   for(i <- 0 until s.size){
     if (count.contains(s(i))) {
       // count += s(i) -> (count(s(i)) + 1)
       // can be rewritten as
       count(s(i)) += 1    
     }
     else count += s(i) -> 1
   }
   println(count)
}

Note: I also fixed up the lines updating count.

Perhaps this is better written as a groupBy:

a.groupBy({s: String => s}).mapValues(_.length)

val a = List("a", "a", "b", "c", "c", "c")

scala> a.groupBy({s: String => s}).mapValues(_.length)
Map("b" -> 1, "a" -> 2, "c" -> 3): Map[String, Int]

Upvotes: 2

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