Steps

1. How to initialize a HashMap with 3 elements using Tuples of key and value

The code below shows how to initialize a HashMap with 3 elements using Tuples of key and value.

import scala.collection.immutable.HashMap
println("Step 1: How to initialize a HashMap with 3 elements using Tuples of key and value")
val hashMap1: HashMap[String, String] = HashMap(("PD","Plain Donut"),("SD","Strawberry Donut"),("CD","Chocolate Donut"))
println(s"Elements of hashMap1 = $hashMap1")

You should see the following output when you run your Scala application in IntelliJ:

Step 1: How to initialize a HashMap with 3 elements using Tuples of key and value
Elements of hashMap1 = Map(PD -> Plain Donut, SD -> Strawberry Donut, CD -> Chocolate Donut)

2. How to initialize HashMap using key -> value notation

The code below shows how to initialize HashMap using key -> value notation.

println("\nStep 2: How to initialize HashMap using key -> value notation")
val hashMap2: HashMap[String, String] = HashMap("VD"-> "Vanilla Donut", "GD" -> "Glazed Donut")
println(s"Elements of hashMap2 = $hashMap2")

You should see the following output when you run your Scala application in IntelliJ:

Step 2: How to initialize HashMap using key -> value notation
Elements of hashMap2 = Map(GD -> Glazed Donut, VD -> Vanilla Donut)

3. How to access elements in HashMap by specific key

The code below shows mow to access elements in HashMap by specific key.

println("\nStep 3: How to access elements in HashMap by specific key")
println(s"Element by key VD = ${hashMap2("VD")}")
println(s"Element by key GD = ${hashMap2("GD")}")

You should see the following output when you run your Scala application in IntelliJ:

Step 3: How to access elements in HashMap by specific key
Element by key VD = Vanilla Donut
Element by key GD = Glazed Donut

4. How to add elements to HashMap using +

The code below shows how to add elements to HashMap using +

println("\nStep 4: How to add elements to HashMap using +")
val hashMap3: HashMap[String, String] = hashMap1 + ("KD" -> "Krispy Kreme Donut")
println(s"Element in hashMap3 = $hashMap3")

You should see the following output when you run your Scala application in IntelliJ:

Step 4: How to add elements to HashMap using +
Element in hashMap3 = Map(PD -> Plain Donut, SD -> Strawberry Donut, KD -> Krispy Kreme Donut, CD -> Chocolate Donut)

5. How to add two HashMap together using ++

The code below shows how to add two HashMap together using ++

println("\nStep 5: How to add two HashMap together using ++")
val hashMap4: Map[String, String] = hashMap1 ++ hashMap2
println(s"Elements in hashMap4 = $hashMap4")

You should see the following output when you run your Scala application in IntelliJ:

Step 5: How to add two HashMap together using ++
Elements in hashMap4 = Map(PD -> Plain Donut, GD -> Glazed Donut, SD -> Strawberry Donut, VD -> Vanilla Donut, CD -> Chocolate Donut)

6. How to remove key and its value from HashMap using -

The code below shows how to remove key and its value from HashMap using -

println("\nStep 6: How to remove key and its value from HashMap using -")
val hashMap5: Map[String, String] = hashMap4 - ("CD")
println(s"HashMap without the key CD and its value = $hashMap5")

You should see the following output when you run your Scala application in IntelliJ:

Step 6: How to remove key and its value from HashMap using -
HashMap without the key CD and its value = Map(PD -> Plain Donut, GD -> Glazed Donut, SD -> Strawberry Donut, VD -> Vanilla Donut)

7. How to initialize an empty HashMap

The code below shows how to initialize an empty HashMap.

println("\nStep 7: How to initialize an empty HashMap")
val emptyHashMap: HashMap[String,String] = HashMap.empty[String,String]
println(s"Empty HashMap = $emptyHashMap")

You should see the following output when you run your Scala application in IntelliJ:

Step 7: How to initialize an empty HashMap
Empty HashMap = Map()