Question

I don’t understand this with Scala hasmaps:
How do I create a value or update one if it does not exist?

I am tryng to count the number of characters in a list of Strings.

I’ve tried this code but it doesn’t work :

 def times(chars: List[Char]): List[(Char, Int)] = {
     val map = new HashMap[Char, Int]()
     chars.foreach(
        (c : Char) => {
           map.update(c, map.get(c) + 1)
        })
 } 

I understand the returning type isn’t correct.
But is my foreach loop wrong?
Is there a prettier way to write it?

Answer 1

I think this will answer your question:

scala> "abaccdba".groupBy(identity).mapValues(_.length)
res3: scala.collection.immutable.Map[Char,Int] = Map(b -> 2, d -> 1, a -> 3, c -> 2)

Oh, and btw HashMap has a method getOrElseUpdate as to your original question