How to Merge Two Maps in Kotlin - Step by Step Examples

How to Merge Two Maps in Kotlin ?

Answer

To merge two maps in Kotlin, you can use the plus operator to create a new map that combines the contents of both maps. This method provides a concise and convenient way to merge maps.

✐ Examples

1 Merging Two Maps Using the plus Operator

We can merge two maps in Kotlin using the plus operator, which creates a new map that includes all key-value pairs from both maps.

For example,

We start by declaring and initializing two maps named map1 and map2 with some key-value pairs. In this example, both maps have string keys and integer values.
We create a new map named mergedMap that combines the contents of map1 and map2 using the plus operator.
We print the merged map to the console using the println function to verify the merge.

Kotlin Program

fun main() {
    // Declare and initialize two maps
    val map1 = mapOf("one" to 1, "two" to 2)
    val map2 = mapOf("three" to 3, "four" to 4)

    // Merge the maps using the plus operator
    val mergedMap = map1 + map2

    // Print the merged map
    println("Merged Map: $mergedMap")
}

Output

Merged Map: {one=1, two=2, three=3, four=4}

2 Merging Two Maps with Overlapping Keys Using the plus Operator

We can merge two maps in Kotlin and handle overlapping keys using the plus operator. If a key exists in both maps, the value from the second map will overwrite the value in the first map.

For example,

We start by declaring and initializing two maps named map1 and map2 with some key-value pairs. In this example, both maps have string keys and integer values, and there is an overlapping key.
We create a new map named mergedMap that combines the contents of map1 and map2 using the plus operator. The value from map2 will overwrite the value from map1 for overlapping keys.
We print the merged map to the console using the println function to verify the merge.

Kotlin Program

fun main() {
    // Declare and initialize two maps with overlapping keys
    val map1 = mapOf("one" to 1, "two" to 2)
    val map2 = mapOf("two" to 22, "three" to 3)

    // Merge the maps using the plus operator
    val mergedMap = map1 + map2

    // Print the merged map
    println("Merged Map: $mergedMap")
}

Output

Merged Map: {one=1, two=22, three=3}

3 Merging Two Mutable Maps Using putAll Method

We can also merge two mutable maps in Kotlin using the putAll method, which adds all key-value pairs from one map to another.

For example,

We start by declaring and initializing two mutable maps named map1 and map2 with some key-value pairs. In this example, both maps have string keys and integer values.
We use the putAll method to add all key-value pairs from map2 to map1.
We print the merged map to the console using the println function to verify the merge.

Kotlin Program

fun main() {
    // Declare and initialize two mutable maps
    val map1 = mutableMapOf("one" to 1, "two" to 2)
    val map2 = mutableMapOf("three" to 3, "four" to 4)

    // Merge map2 into map1 using putAll
    map1.putAll(map2)

    // Print the merged map
    println("Merged Map: $map1")
}

Output

Merged Map: {one=1, two=2, three=3, four=4}

Summary

In this tutorial, we learned How to Merge Two Maps in Kotlin language with well detailed examples.

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How to Merge Two Maps in Kotlin - Step by Step Examples