Map

Map

A Map stores key-value pairs and gives fast lookup by key, created with Map("a" -> 1, "b" -> 2) using the -> arrow syntax. Map(...) is immutable by default, and keys must be unique. Accessing a missing key with map(key) throws, so .get(key) (returning an Option) or .getOrElse are the safer alternatives.

Warning: Accessing a missing key with map(key) throws a NoSuchElementException -- use .get(key) or .getOrElse(key, default) for safety.

Example: Map

object Main extends App {
  val ages = Map("Alice" -> 30, "Bob" -> 25)

  println(ages("Alice"))
  println(ages.getOrElse("Cara", -1))

  for ((name, age) <- ages) {
    println(s"$name is $age")
  }
}