How to Copy a Map in Kotlin - Step by Step Examples

How to Copy a Map in Kotlin ?

Answer

To copy a map in Kotlin, you can use the `toMap()` method or the `copy` function to create a new map with the same key-value pairs as the original map. These methods provide straightforward ways to duplicate a map.

✐ Examples

1 Copying a Map Using the toMap() Method

We can copy a map in Kotlin using the `toMap()` method, which creates a new map with the same key-value pairs as the original map.

For example,

We start by declaring and initializing a map named originalMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the toMap() method to create a new map named copiedMap that contains the same key-value pairs as originalMap.
We print the copied map to the console using the println function to verify the copy.

Kotlin Program

fun main() {
    // Declare and initialize a map
    val originalMap = mapOf("one" to 1, "two" to 2, "three" to 3)

    // Copy the map using the toMap() method
    val copiedMap = originalMap.toMap()

    // Print the copied map
    println("Copied Map: $copiedMap")
}

Output

Copied Map: {one=1, two=2, three=3}

2 Copying a Mutable Map Using the toMutableMap() Method

We can also copy a mutable map in Kotlin using the `toMutableMap()` method, which creates a new mutable map with the same key-value pairs as the original map.

For example,

We start by declaring and initializing a mutable map named originalMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the toMutableMap() method to create a new mutable map named copiedMap that contains the same key-value pairs as originalMap.
We print the copied map to the console using the println function to verify the copy.

Kotlin Program

fun main() {
    // Declare and initialize a mutable map
    val originalMap = mutableMapOf("one" to 1, "two" to 2, "three" to 3)

    // Copy the map using the toMutableMap() method
    val copiedMap = originalMap.toMutableMap()

    // Print the copied map
    println("Copied Map: $copiedMap")
}

Output

Copied Map: {one=1, two=2, three=3}

3 Copying a Map and Modifying Values

We can copy a map in Kotlin and modify its values during the copying process by iterating over the original map and applying transformations to the values.

For example,

We start by declaring and initializing a map named originalMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the mapValues function to create a new map named copiedMap, modifying the values during the copying process (e.g., multiplying each value by 2).
We print the copied map to the console using the println function to verify the copy.

Kotlin Program

fun main() {
    // Declare and initialize a map
    val originalMap = mapOf("one" to 1, "two" to 2, "three" to 3)

    // Copy the map and modify values
    val copiedMap = originalMap.mapValues { it.value * 2 }

    // Print the copied map
    println("Copied Map: $copiedMap")
}

Output

Copied Map: {one=2, two=4, three=6}

Summary

In this tutorial, we learned How to Copy a Map in Kotlin language with well detailed examples.

◀ Previous Next ▶

Kotlin Tutorials

Kotlin How-Tos

How to Copy a Map in Kotlin - Step by Step Examples