<not computed> on collection output in Scala

Question

When I tried to println MapView I have been got a message MapView(<not computed>)

val phonebook = Map("Jim" -> 555, "Daniel" -> 789)
println(phonebook)           // Map(Jim -> 555, Daniel -> 789)

val filteredMap = phonebook.filterKeys(_.startsWith("J"))
println(filteredMap("Jim"))  // 555
println(filteredMap)         // MapView(<not computed>)

If I defined filteredMap as following

val filteredMap = phonebook.view.filterKeys(_.startsWith("J"))

then nothing have been changed. Scala version is 2.13.2

Why mapview cannot be printed and what is the best way to fix it?

Answer 1

Add .toMap to convert your mapView into a static map. As suggested by @ Luis Miguel Mejía Suárez

val filteredMap = phonebook.view.filterKeys(_.startsWith("J")).toMap