How to create a Map with Initial Key-Value Pairs in Kotlin - Step by Step Examples

How to create a Map with Initial Key-Value Pairs in Kotlin ?

Answer

To create a map with initial key-value pairs in Kotlin, you can use the mapOf function. This creates a new map object with predefined key-value pairs.

✐ Examples

1 Creating a Map with Initial Key-Value Pairs Using mapOf

We can create a map in Kotlin with initial key-value pairs using the mapOf function, which initializes a map with predefined key-value pairs.

For example,

We start by declaring a variable named myMap. This variable will hold our map with initial key-value pairs.
We use the mapOf function to create a new map object. In Kotlin, the mapOf function allows us to specify key-value pairs directly within the function call.
The newly created map is now assigned to the myMap variable. In this example, the map has string keys and integer values.
We can now perform various operations on this map, such as adding more key-value pairs, checking for the presence of keys, and retrieving values.

Kotlin Program

fun main() {
    // Declare a map with initial key-value pairs
    val myMap: Map<String, Int> = mapOf(
        "one" to 1,
        "two" to 2,
        "three" to 3
    )

    // Operations on the map
    for ((key, value) in myMap) {
        println("$key: $value")
    }
}

Output

one: 1
two: 2
three: 3

2 Creating a Map with Different Key-Value Types

We can create a map in Kotlin with initial key-value pairs of different types using the mapOf function.

For example,

We start by declaring a variable named studentGrades. This variable will hold our map with initial key-value pairs where keys are strings (student names) and values are characters (grades).
We use the mapOf function to create a new map object. In Kotlin, the mapOf function allows us to specify key-value pairs directly within the function call.
The newly created map is now assigned to the studentGrades variable. In this example, the map has string keys and char values representing grades.
We can now perform various operations on this map, such as adding more key-value pairs, checking for the presence of keys, and retrieving values.

Kotlin Program

fun main() {
    // Declare a map with initial key-value pairs
    val studentGrades: Map<String, Char> = mapOf(
        "Alice" to 'A',
        "Bob" to 'B',
        "Charlie" to 'C'
    )

    // Operations on the map
    for ((key, value) in studentGrades) {
        println("$key: $value")
    }
}

Output

Alice: A
Bob: B
Charlie: C

3 Creating a Map with Integer Keys and Float Values

We can create a map in Kotlin with initial key-value pairs where keys are integers and values are floats using the mapOf function.

For example,

We start by declaring a variable named productPrices. This variable will hold our map with initial key-value pairs where keys are integers (product IDs) and values are floats (prices).
We use the mapOf function to create a new map object. In Kotlin, the mapOf function allows us to specify key-value pairs directly within the function call.
The newly created map is now assigned to the productPrices variable. In this example, the map has integer keys and float values.
We can now perform various operations on this map, such as adding more key-value pairs, checking for the presence of keys, and retrieving values.

Kotlin Program

fun main() {
    // Declare a map with initial key-value pairs
    val productPrices: Map<Int, Float> = mapOf(
        101 to 29.99f,
        102 to 39.99f,
        103 to 49.99f
    )

    // Operations on the map
    for ((key, value) in productPrices) {
        println("Product $key: $value")
    }
}

Output

Product 101: 29.99
Product 102: 39.99
Product 103: 49.99

Summary

In this tutorial, we learned How to create a Map with Initial Key-Value Pairs in Kotlin language with well detailed examples.

◀ Previous Next ▶

Kotlin Tutorials

Kotlin How-Tos

How to create a Map with Initial Key-Value Pairs in Kotlin - Step by Step Examples