How to Get the Value Associated with a Key in a Map in Kotlin

How to Get the Value Associated with a Key in a Map in Kotlin ?

Answer

To get the value associated with a key in a map in Kotlin, you can use the get method or the square bracket notation. These methods allow you to access the value directly using the key.

✐ Examples

1 Getting the Value Associated with a Key Using get Method

We can get the value associated with a key in a map in Kotlin using the get method, which returns the value associated with the specified key.

For example,

We start by declaring and initializing a mutable map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the get method to access the value associated with the key 'two'. The get method returns the value associated with the specified key.
We store the value in a variable named value.
We print the value to the console using the println function.

Kotlin Program

fun main() {
    // Declare and initialize a mutable map
    val myMap: MutableMap<String, Int> = mutableMapOf(
        "one" to 1,
        "two" to 2,
        "three" to 3
    )

    // Get the value associated with a key using get method
    val value = myMap.get("two")

    // Print the value
    println("The value associated with key 'two' is: $value")
}

Output

The value associated with key 'two' is: 2

2 Getting the Value Associated with a Key Using Square Bracket Notation

We can get the value associated with a key in a map in Kotlin using the square bracket notation, which returns the value associated with the specified key.

For example,

We start by declaring and initializing a mutable map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the square bracket notation to access the value associated with the key 'three'. The square bracket notation returns the value associated with the specified key.
We store the value in a variable named value.
We print the value to the console using the println function.

Kotlin Program

fun main() {
    // Declare and initialize a mutable map
    val myMap: MutableMap<String, Int> = mutableMapOf(
        "one" to 1,
        "two" to 2,
        "three" to 3
    )

    // Get the value associated with a key using square bracket notation
    val value = myMap["three"]

    // Print the value
    println("The value associated with key 'three' is: $value")
}

Output

The value associated with key 'three' is: 3

3 Handling Key Not Found Using get Method

We can handle the case where a key is not found in a map in Kotlin using the get method, which returns null if the key is not present.

For example,

We start by declaring and initializing a mutable map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the get method to attempt to access the value associated with the key 'four'. The get method returns null if the key is not found.
We store the value in a variable named value.
We check if the value is null and print an appropriate message to the console using the println function.

Kotlin Program

fun main() {
    // Declare and initialize a mutable map
    val myMap: MutableMap<String, Int> = mutableMapOf(
        "one" to 1,
        "two" to 2,
        "three" to 3
    )

    // Attempt to get the value associated with a non-existent key
    val value = myMap.get("four")

    // Print the result
    if (value == null) {
        println("Key 'four' not found in the map.")
    } else {
        println("The value associated with key 'four' is: $value")
    }
}

Output

Key 'four' not found in the map.

Summary

In this tutorial, we learned How to Get the Value Associated with a Key in a Map in Kotlin language with well detailed examples.

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How to Get the Value Associated with a Key in a Map in Kotlin