Scala SortedMap under the hood

Question

I use SortedMap for storing ordered elements:

val map = SortedMap("Kim" -> 90, "Steve" -> 22, "Alex" -> 12)

My questions are:

What is the implementation stand under SortedMap?
Does SortedMap same to Red black tree?
SortedMap in Java is an interface, why in Scala it can be instantiated?

3. is https://stackoverflow.com/questions/9737352/what-is-the-apply-function-in-scala#9738862 — Reactormonk, Jan 02 '17 at 22:49

score 3 · Accepted Answer · answered Jan 02 '17 at 23:18

3

The default implantation of SortedMap in Scala is a TreeMap which is an immutable Red-Black tree. Not to be confused with Java's java.util.TreeMap which is mutable.

Why SortedMap in Scala can be instantiated? It can't, it's a trait but the SortedMap companion object gives you the flexibility to initialise the object this way.

answered Jan 02 '17 at 23:18

Sleiman Jneidi

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Why `SortedMap` is related to `TreeMap`, this two concepts must be separate like class and trait? – pacman Jan 03 '17 at 00:12
@pacman They are separate, but TreeMap is the default implementation. – Sleiman Jneidi Jan 03 '17 at 10:32
where is the place in scala code where `SortedMap` delegate to `TreeMap`? – pacman Jan 03 '17 at 10:35
@pacman https://github.com/scala/scala/blob/v2.9.3/src/library/scala/collection/immutable/SortedMap.scala#L91 – Sleiman Jneidi Jan 03 '17 at 10:40

Scala SortedMap under the hood

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