ListMap in Scala
Last Updated :
04 Aug, 2021
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
import scala.collection.immutable.ListMap
object Geeks
{
def main(args : Array[String])
{
var listMap = ListMap( "C" - > "Csharp" , "S" - > "Scala" , "J" - > "Java" )
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
import scala.collection.mutable.ListMap
object Geeks
{
def main(args : Array[String])
{
var listMap = ListMap( "C" - > "Csharp" , "S" - > "Scala" , "J" - > "Java" )
listMap.foreach
{
case (key, value) => println (key + " -> " + value)
}
println(listMap( "S" ))
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
import scala.collection.mutable.ListMap
object Geeks
{
def main(args : Array[String])
{
var listMap = ListMap( "C" - > "Csharp" , "S" - > "Scala" , "J" - > "Java" )
listMap.foreach
{
case (key, value) => println (key + " -> " + value)
}
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
import scala.collection.mutable.ListMap
object Geeks
{
def main(args : Array[String])
{
var ListMap 1 = new ListMap()
var ListMap 2 = ListMap.empty
println(emptyListMap 1 )
println(emptyListMap 2 )
}
}
|
Output:
Map()
Map()
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