How to Get the Size (Number of Key-Value Pairs) of a Map in Kotlin

How to Get the Size (Number of Key-Value Pairs) of a Map in Kotlin ?

Answer

To get the size (number of key-value pairs) of a map in Kotlin, you can use the size property. This property returns the number of elements in the map.

✐ Examples

1 Getting the Size of a Map Using size Property

We can get the size of a map in Kotlin using the size property, which provides the number of key-value pairs in the map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the size property to get the number of key-value pairs in the map.
We store the size in a variable named mapSize.
We print the size to the console using the println function to verify the number of key-value pairs in the map.

Kotlin Program

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

    // Get the size of the map
    val mapSize = myMap.size

    // Print the size
    println("Size of the map: $mapSize")
}

Output

Size of the map: 3

2 Getting the Size of an Empty Map

We can also get the size of an empty map in Kotlin using the size property, which returns 0 when the map is empty.

For example,

We start by declaring an empty map named emptyMap with string keys and integer values.
We use the size property to get the number of key-value pairs in the empty map.
We store the size in a variable named emptyMapSize.
We print the size to the console using the println function to verify that the map is empty.

Kotlin Program

fun main() {
    // Declare an empty map
    val emptyMap = mapOf<String, Int>()

    // Get the size of the empty map
    val emptyMapSize = emptyMap.size

    // Print the size
    println("Size of the empty map: $emptyMapSize")
}

Output

Size of the empty map: 0

3 Getting the Size of a Map After Adding Elements

We can get the size of a map in Kotlin after adding elements using the size property, which provides the updated number of key-value pairs in the map.

For example,

We start by declaring an empty mutable map named dynamicMap with string keys and integer values.
We add some key-value pairs to the map using the map's put method.
We use the size property to get the number of key-value pairs in the map after adding elements.
We store the size in a variable named dynamicMapSize.
We print the size to the console using the println function to verify the updated number of key-value pairs in the map.

Kotlin Program

fun main() {
    // Declare an empty mutable map
    val dynamicMap = mutableMapOf<String, Int>()

    // Add elements to the map
    dynamicMap["one"] = 1
    dynamicMap["two"] = 2
    dynamicMap["three"] = 3

    // Get the size of the map after adding elements
    val dynamicMapSize = dynamicMap.size

    // Print the size
    println("Size of the map after adding elements: $dynamicMapSize")
}

Output

Size of the map after adding elements: 3

Summary

In this tutorial, we learned How to Get the Size (Number of Key-Value Pairs) of a Map in Kotlin language with well detailed examples.

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How to Get the Size (Number of Key-Value Pairs) of a Map in Kotlin