List Class, Part 1 (Scala 3 Video)

Scala List Class

The List class is an immutable, singly-linked list. You can use it (a) when you need a small, immutable sequential collection, and (b) when you need a larger sequence, and you’ll only be prepending elements, and accessing its head and tail elements (using methods like map and filter, which always begin at the first element and start marching through each subsequent element is also okay).

If you want an immutable sequence class where you want fast, random access to any element in the sequence, use Vector instead. (See the video for List and Vector performance information.)

List class basics

// creating a List
val nums = List(1, 2, 3, 4, 5)

// accessing List elements
nums(0)
nums(1)

// accessing List elements in a for-loop
for n <- nums do println(n)

// creating a new list from an existing list,
// using a for-expression
val names = List("bert", "ernie")
val capNames = for name <- names yield name.capitalize

// the `map` method is the same as that for-expression
val capNames = names.map(_.capitalize)

More information

For many more List class details, see my Scala List class examples page.