In Which Data Structure We Can Hold Key-Value Pairs Kotlin?


Heather Bennett

In Kotlin, there are several data structures that allow us to hold key-value pairs. These data structures are essential for organizing and retrieving data efficiently. In this article, we will explore some of the commonly used data structures in Kotlin that can handle key-value pairs.

1. Map:
The Map interface in Kotlin is designed specifically for holding key-value pairs.

It is an unordered collection of elements where each element is stored as a pair consisting of a key and a value. The keys in a map are always unique, ensuring that there are no duplicate keys present.

To create a map in Kotlin, you can use the mutableMapOf() function. Let’s take a look at an example:

val myMap = mutableMapOf("key1" to "value1", "key2" to "value2", "key3" to "value3")

You can access the values associated with specific keys using the square bracket notation:

val value = myMap["key1"]

2. HashMap:
A HashMap is an implementation of the Map interface in Kotlin that provides constant-time performance for basic operations like get and put. It allows null values and one null key.

Creating a HashMap in Kotlin is similar to creating a Map:

val myHashMap = hashMapOf("key1" to "value1", "key2" to "value2", "key3" to "value3")

Similarly, you can retrieve values using square brackets:

val value = myHashMap["key2"]

3. LinkedHashMap:
A LinkedHashMap is another implementation of the Map interface in Kotlin.

It maintains the order of elements based on their insertion. This means that when you iterate over a LinkedHashMap, the elements will be returned in the order they were inserted.

Creating a LinkedHashMap is similar to creating a HashMap:

val myLinkedHashMap = linkedMapOf("key1" to "value1", "key2" to "value2", "key3" to "value3")

As with other maps, you can retrieve values using square brackets:

val value = myLinkedHashMap["key3"]

4. SortedMap:
A SortedMap is an interface that extends the Map interface and provides a sorting order for its elements based on their keys. All keys in a SortedMap must implement the Comparable interface or be supplied with a custom Comparator.

To create a SortedMap in Kotlin, you can use the sortedMapOf() function:

val mySortedMap = sortedMapOf("key1" to "value1", "key2" to "value2", "key3" to "value3")

Accessing values in a SortedMap is similar to other maps:

val value = mySortedMap["key2"]

In conclusion, Kotlin provides several data structures such as Map, HashMap, LinkedHashMap, and SortedMap that are suitable for holding key-value pairs. Depending on your requirements, you can choose the appropriate data structure that fits your needs. These data structures offer efficient ways of accessing and manipulating key-value pairs in your Kotlin applications.


  • Kotlin provides various data structures for holding key-value pairs.
  • Map is an unordered collection of key-value pairs.
  • HashMap provides constant-time performance for basic operations.
  • LinkedHashMap maintains the order of insertion.
  • SortedMap provides a sorting order based on keys.

Now that you have a better understanding of these data structures, you can choose the one that best suits your needs when working with key-value pairs in Kotlin. Happy coding!

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