HashMap in Scala

Last Updated : 09 Aug, 2019

HashMap is a part of Scala Collection's. It is used to store element and return a map. A HashMap is a combination of key and value pairs which are stored using a Hash Table data structure. It provides the basic implementation of Map. Syntax:

var hashMapName = HashMap("key1"->"value1", "key2"->"value2", "key3"->"value3", ...)

We must import scala.collection.mutable.HashMap for HashMap.

Operation performed by HashMap

Creating an HashMap: Below is the example to create HashMap. In below code, we can see an empty HashMap is created then a HashMap is created with values.

Scala

// Scala program to create or print HashMap
import scala.collection.mutable.HashMap

// Creating object 
object Geeks 
{ 

    // Main method 
    def main(args: Array[String]) 
    { 
        // Creating empty HashMap
        var hashMap = new HashMap()  
        
        // Creating HashMap with values
        var hashMap2 = HashMap("C"->"Csharp", "S"->"Scala", "J"->"Java")  
        
        // Printing HashMap
        println(hashMap)  
        println(hashMap2)  
    } 
}

Output:

Map()
Map(S -> Scala, J -> Java, C -> Csharp)

Adding and Accessing Elements : In the below example, A HashMap is created. add elements and access elements also performed.

Scala

// Scala program to Adding and Accessing Elements HashMap
import scala.collection.mutable.HashMap

// Creating object 
object Geeks 
{ 

    // Main method 
    def main(args: Array[String]) 
    { 
        // Creating HashMap
        var hashMap = HashMap("C"->"Csharp", "S"->"Scala", "J"->"Java")
        
        // Iterating elements
        hashMap.foreach 
        {  
            case (key, value) => println (key + " -> " + value)         
        }  
        
        // Accessing value by using key 
        println(hashMap("S"))  
        
        // Adding element
        var HashMap2 = hashMap + ("P"->"Perl")  
        HashMap2.foreach 
        {  
            case (key, value) => println (key + " -> " + value)  
        }  
    } 
}

Output:

S -> Scala
J -> Java
C -> Csharp
Scala
S -> Scala
P -> Perl
J -> Java
C -> Csharp

Removing an element from HashMap : A HashMap is created than removing an element is performed using - sign. Below is the example to removing an element from HashMap.

Scala

// Scala program to removing Element HashMap
import scala.collection.mutable.HashMap

// Creating object 
object Geeks 
{ 

    // Main method 
    def main(args: Array[String]) 
    { 
        // Creating HashMap
        var hashMap = HashMap("C"->"Csharp", "S"->"Scala", "J"->"Java")
        
        // Iterating elements
        hashMap.foreach 
        { 
            case (key, value) => println (key + " -> " + value)         
        } 
        
        // Removing an element
        hashMap -= "C"
        
        println("After Removing")
        hashMap.foreach 
        { 
            case (key, value) => println (key + " -> " + value) 
        } 
    } 
}

Output:

S -> Scala
J -> Java
C -> Csharp
After Removing
S -> Scala
J -> Java

TreeSet in Scala

DivyaPareek

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HashMap in Scala

Operation performed by HashMap

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