Question: What Is A Collection In Scala?

How do I create an empty list in Scala?

You can create an empty list with .

Then you can use a method :+ , +: or :: in order to add element to the list.

Per default collections in scala are immutable, so you have a + method which returns a new list with the element added to it..

Does Scala have immutable collections?

Set – It is a collection of elements that are of the same type but do not contain the same elements. By default, scala uses an immutable set. Scala provides mutable and immutable versions of Set.

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.

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 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.

Which are valid collection types in the Scala standard library?

Packagesscala.collection.immutable – Immutable, sequential data-structures such as Vector , List , Range , HashMap or HashSet.scala.collection.mutable – Mutable, sequential data-structures such as ArrayBuffer , StringBuilder , HashMap or HashSet.

What is the 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.

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.

What is Scala API?

The Scala API is somewhat similar to the Java API. It uses a frame on the left to display package names; clicking on a package name brings up a display of that package in the frame on the right. The and icons indicate whether the item is an object or a class (or both); indicates a trait.

How can we convert mutable map to immutable Scala?

Map(x. toList: _*) in 2.7. You can use myMap. toMap to convert an a mutable map into immutable in Scala 2.8 and later versions.

Is Scala set ordered?

You do not care about order in the Set. So you use a HashSet . (That is the default when using the Set.

Which is the top most collection type in the Scala collections hierarchy?

TraversableTraversable. Traversable is the top of the Collection hierarchy. It defines a lot of the great operations that the Scala Collections has to offer. The only abstract method Traversable contains, is a foreach method.

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 constructor in Scala?

Constructors are used to initializing the object’s state. Like methods, a constructor also contains a collection of statements(i.e. instructions) that are executed at the time of Object creation. Scala supports two types of constructors: Primary Constructor. Auxiliary Constructor.

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…

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] .

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.

What is Scala used for?

What is Scala used for? A lot of things, ranging from machine learning to web apps. As a high-level general purpose language, Scala boasts an extensive range of possible applications. Scala allows developers to make good use of standard JVM features and Java libraries.