How to Swap Keys and Values in a Map in Kotlin - Step by Step Examples

How to Swap Keys and Values in a Map in Kotlin ?

Answer

To swap keys and values in a map in Kotlin, you can iterate over the original map and insert each key-value pair into a new map with the value as the key and the key as the value. This method allows you to create a new map with swapped key-value pairs.

✐ Examples

1 Swapping Keys and Values in a Map of Integers

We can swap keys and values in a map of integers in Kotlin by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value.

For example,

We start by declaring and initializing a map of integers named originalMap.
We declare an empty mutable map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

Kotlin Program

fun main() {
    // Declare and initialize a map of integers
    val originalMap = mapOf(1 to 10, 2 to 20, 3 to 30, 4 to 40, 5 to 50)

    // Declare an empty mutable map to store the swapped key-value pairs
    val swappedMap = mutableMapOf<Int, Int>()

    // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
    for ((key, value) in originalMap) {
        swappedMap[value] = key
    }

    // Print the resulting map
    println("Swapped map of integers:")
    for ((key, value) in swappedMap) {
        println("$key: $value")
    }
}

Output

Swapped map of integers:
10: 1
20: 2
30: 3
40: 4
50: 5

2 Swapping Keys and Values in a Map of Strings

We can swap keys and values in a map of strings in Kotlin by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value.

For example,

We start by declaring and initializing a map of strings named originalMap.
We declare an empty mutable map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

Kotlin Program

fun main() {
    // Declare and initialize a map of strings
    val originalMap = mapOf("one" to "uno", "two" to "dos", "three" to "tres", "four" to "cuatro", "five" to "cinco")

    // Declare an empty mutable map to store the swapped key-value pairs
    val swappedMap = mutableMapOf<String, String>()

    // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
    for ((key, value) in originalMap) {
        swappedMap[value] = key
    }

    // Print the resulting map
    println("Swapped map of strings:")
    for ((key, value) in swappedMap) {
        println("$key: $value")
    }
}

Output

Swapped map of strings:
uno: one
dos: two
tres: three
cuatro: four
cinco: five

3 Swapping Keys and Values in a Map of Mixed Types

We can swap keys and values in a map with mixed key and value types in Kotlin by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value. This example demonstrates swapping keys of type Int with values of type String.

For example,

We start by declaring and initializing a map with mixed types named originalMap.
We declare an empty mutable map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

Kotlin Program

fun main() {
    // Declare and initialize a map with mixed types
    val originalMap = mapOf(1 to "one", 2 to "two", 3 to "three", 4 to "four", 5 to "five")

    // Declare an empty mutable map to store the swapped key-value pairs
    val swappedMap = mutableMapOf<String, Int>()

    // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
    for ((key, value) in originalMap) {
        swappedMap[value] = key
    }

    // Print the resulting map
    println("Swapped map of mixed types:")
    for ((key, value) in swappedMap) {
        println("$key: $value")
    }
}

Output

Swapped map of mixed types:
one: 1
two: 2
three: 3
four: 4
five: 5

Summary

In this tutorial, we learned How to Swap Keys and Values in a Map in Kotlin language with well detailed examples.

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How to Swap Keys and Values in a Map in Kotlin - Step by Step Examples