How to create a list in scala

How do I create 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.

How do I create a string list in Scala?

Five ways to create a Scala List
  1. Lisp style.
  2. Java style.
  3. Using the List class range method.
  4. Using the List class fill method.
  5. Using the List class tabulate method.

What is a list in Scala?

A list is a collection which contains immutable data. 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 I create a dynamic list in Scala?

But it seems Scala Arrays & Lists doesn’t provide any methods for adding items dynamically due to the immutable nature. But just as Java (and C/C++/C#/etc.) arrays, you can’t change the size of an array. So you need another collection, which is backed by an array, but does allow resizing.

How do I create 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.

How do I add elements to a Scala list?

How to add elements to a List in Scala (List, ListBuffer)
  1. 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 .
  2. Use a ListBuffer when you want a “List” you can modify.
  3. Scala REPL example.
  4. More functional ways to work with Scala lists.

How do I convert a ListBuffer to list in Scala?

  1. L += e appends the element e in constant time;
  2. e +=: L prepends the element e in constant time;
  3. L. toList returns a list with the contents of the ListBuffer in constant time. You should not use the ListBuffer after converting it to a list.

How do you find the length of a list in Scala?

Related Articles. The length() method is utilized to find the length of the list. Return Type: It returns the length of the list stated.

How do you write a loop in Scala?

Scala for-loop Example by using yield keyword
  1. object MainObject {
  2. def main(args: Array[String]) {
  3. var result = for( a <- 1 to 10) yield a.
  4. for(i<-result){
  5. println(i)
  6. }
  7. }
  8. }

How do you write if else in Scala?

Syntax. if(Boolean_expression 1){ //Executes when the Boolean expression 1 is true } else if(Boolean_expression 2){ //Executes when the Boolean expression 2 is true } else if(Boolean_expression 3){ //Executes when the Boolean expression 3 is true } else { //Executes when the none of the above condition is true. }

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] .

What is Array in Scala?

Array is a special kind of collection in scala. it is a fixed size data structure that stores elements of the same data type. The index of the first element of an array is zero and the last element is the total number of elements minus one.

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 array string in Scala?

Array is a special kind of collection in Scala. On the one hand, Scala arrays correspond one-to-one to Java arrays. That is, a Scala array Array[Int] is represented as a Java int[] , an Array[Double] is represented as a Java double[] and a Array[String] is represented as a Java String[] .

How do you use a range in Scala?

For example, “1, 2, 3,” is a range, as is “5, 8, 11, 14.” To create a range in Scala, use the predefined methods to and by. Ranges are represented in constant space, because they can be defined by just three numbers: their start, their end, and the stepping value.

What is a collection in Scala?

Scala Collections are the containers that hold sequenced linear set of items like List, Set, Tuple, Option, Map etc. Collections may be strict or lazy. The memory is not allocated until they are accessed. Collections can be mutable or immutable.

How do you declare a variable in Scala?

The variable is declared with the following syntax in Scala as follows: val or val variable_name: variable_datatype = value; In the above syntax, the variable can be defined in one of two ways by using either the ‘var’ or ‘val’ keyword. It consists of ‘variable_name’ as your new variable, followed by a colon.

Which is used to collect data in Scala?

Scala provides rich set of collection library. It contains classes and traits to collect data. These collections can be mutable or immutable. You can use them according to your requirement.

Some Significant Methods of Traversable Trait.

Method Description
def head: A It returns the first element of collection.

How do I create a global variable in Scala?

3. Declaring Scala Variables
  1. val x:Int=7. val name:String=”Ayushi” val x:Int=7 val name:String=”Ayushi”
  2. var name:String=”Ayushi” name=”Megha” var name:String=”Ayushi” name=”Megha”
  3. val x=1+2. var name=”Ayushi” val x=1+2 var name=”Ayushi”
  4. val x:Int=7. val x:Int. val x:Int=7 val x:Int.

What does <- mean in Scala?

Scala allows the use of underscores (denoted as ‘_’) to be used as placeholders for one or more parameters. Multiple underscores means multiple parameters and not the use of same parameter repeatedly. Hence, this syntax is used when you want to take 1 or more parameters only once.

What is method in Scala?

A Scala method is a part of a class which has a name, a signature, optionally some annotations, and some bytecode where as a function in Scala is a complete object which can be assigned to a variable. In other words, a function, which is defined as a member of some object, is called a method.