What Is Scala List?

What is a collection in Scala?

Scala has a rich set of collection library.

Collections are containers of things.

Those containers can be sequenced, linear sets of items like List, Tuple, Option, Map, etc.

The collections may have an arbitrary number of elements or be bounded to zero or one element (e.g., Option).

Collections may be strict or lazy..

How do you write a loop in Scala?

In Scala, for-loop allows you to filter some elements from the given collection using one or more if statements in for-loop. Syntax: for(i<- List if condition1; if condition2; if condition3; ...) { // code.. }

What is map in Scala?

Scala map is a collection of key/value pairs. Any value can be retrieved based on its key. Keys are unique in the Map, but values need not be unique. Maps are also called Hash tables. There are two kinds of Maps, the immutable and the mutable.

What is the difference between SEQ and list in Scala?

A Seq is an Iterable that has a defined order of elements. Sequences provide a method apply() for indexing, ranging from 0 up to the length of the sequence. Seq has many subclasses including Queue, Range, List, Stack, and LinkedList. A List is a Seq that is implemented as an immutable linked list.

What is flatMap Scala?

Advertisements. flatMap() method is method of TraversableLike trait, it takes a predicate, applies it to each element of the collection and returns a new collection of elements returned by the predicate.

What does ::: mean in Scala?

In general: :: – adds an element at the beginning of a list and returns a list with the added element. ::: – concatenates two lists and returns the concatenated list.

What is foldLeft in Scala?

foldLeft() method is a member of TraversableOnce trait, it is used to collapse elements of collections. It navigates elements from Left to Right order. It is primarily used in recursive functions and prevents stack overflow exceptions.

How do you define a list in Scala?

Syntax for defining a Scala List. val variable_name: List[type] = List(item1, item2, item3) or val variable_name = List(item1, item2, item3) A list in Scala is mostly like a Scala array. However, the Scala List is immutable and represents a linked list data structure. On the other hand, Scala array is flat and mutable.

What is difference between Array and List in Scala?

The Scala List class holds a sequenced, linear list of items. Following are the point of difference between lists and array in Scala: Lists are immutable whereas arrays are mutable in Scala. Lists represents a linked list whereas arrays are flat.

How do you declare an empty list in Scala?

As mentioned in an above answer, the Scala List is an immutable collection. You can create an empty list with . empty[A] . Then you can use a method :+ , +: or :: in order to add element to the list.

Is Scala list ordered?

An ordering is imposed. With Scala, we use the sorted function. A List is immutable, so sorted returns a sorted copy of the list. With the Ordering class, we access common sort types.

How do you create a set in Scala?

Let’s see how to create a set.import scala.collection.immutable._object MainObject{def main(args:Array[String]){val set1 = Set() // An empty set.val games = Set(“Cricket”,”Football”,”Hocky”,”Golf”) // Creating a set with elements.println(set1)println(games)}More items…

What is Array in Scala?

Advertisements. Scala provides a data structure, the array, which stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.

How do you add elements to a list in Scala?

How to add elements to a List in Scala (List, ListBuffer)Prepending elements to Scala Lists. One thing you can do when working with a Scala List is to create a new List from an existing List . … Use a ListBuffer when you want a “List” you can modify. … Scala REPL example. … More functional ways to work with Scala lists.

How do you create an array in Scala?

In Scala arrays are immutable objects. You create an array like this: var myArray : Array[String] = new Array[String](10); First you declare variable var myArray to be of type Array[String] .