ListMap in Scala
Immutable maps Implemented by using a list-based data structure. The Scala List class holds a sequenced, linear list of items. We must import scala.collection.mutable.ListMap for ListMap. ListMap collection used only for a small number of elements.
Syntax:
var listMapName = ListMap("k1"->"v1", "k2"->"v2", "k3"->"v3", ...)
Here, k is key and v is value.
Operation performed by ListMap
Creating an ListMap:
In below code we can see a ListMap is created with values.
Scala
// Scala program to create or print ListMap import scala.collection.immutable.ListMap // Creating object object Geeks { // Main method def main(args : Array[String]) { // Creating ListMap with values var listMap = ListMap( "C" - > "Csharp" , "S" - > "Scala" , "J" - > "Java" ) // Printing ListMap println(listMap) } } |
Output:
Map(C -> Csharp, S -> Scala, J -> Java)
Adding and accessing elements :
A ListMap is created, add elements and access elements also performed.
Scala
// Scala program to Adding and Accessing Elements ListMap import scala.collection.mutable.ListMap // Creating object object Geeks { // Main method def main(args : Array[String]) { // Creating ListMap var listMap = ListMap( "C" - > "Csharp" , "S" - > "Scala" , "J" - > "Java" ) // Iterating elements listMap.foreach { case (key, value) => println (key + " -> " + value) } // Accessing value by using key println(listMap( "S" )) // Adding element var ListMap 2 = listMap + ( "P" - > "Perl" ) ListMap 2 .foreach { case (key, value) => println (key + " -> " + value) } } } |
Output:
J -> Java C -> Csharp S -> Scala Scala P -> Perl C -> Csharp J -> Java S -> Scala
Removing an element from ListMap :
A ListMap is created than removing an element is performed using – sign. Below is the example to removing an element from ListMap.
Scala
// Scala program to removing Element from ListMap import scala.collection.mutable.ListMap // Creating object object Geeks { // Main method def main(args : Array[String]) { // Creating ListMap var listMap = ListMap( "C" - > "Csharp" , "S" - > "Scala" , "J" - > "Java" ) // Iterating elements listMap.foreach { case (key, value) => println (key + " -> " + value) } // Removing an element listMap - = "C" println( "After Removing" ) listMap.foreach { case (key, value) => println (key + " -> " + value) } } } |
Output:
J -> Java C -> Csharp S -> Scala After Removing J -> Java S -> Scala
Creating an empty ListMap:
An empty ListMap is created either by calling its constructor or using ListMap.empty method.
Scala
// Scala program to Create an empty ListMap import scala.collection.mutable.ListMap // Creating object object Geeks { // Main method def main(args : Array[String]) { // Creating an empty list map by calling constructor var ListMap 1 = new ListMap() // Creating an empty list map by using .empty method var ListMap 2 = ListMap.empty // Printing empty ListMap println(emptyListMap 1 ) println(emptyListMap 2 ) } } |
Output:
Map() Map()