Kotlin program converts a hash map (HashMap) to a list (List)

Kotlin Comprehensive Examples

In this program, you will learn different methods to convert a map to a list in Kotlin.

Example: Convert map to list

import java.util.ArrayList
import java.util.HashMap
fun main(args: Array<String>) {
　　　　val map = HashMap<Int, String>()
　　　　map.put(1, "a")
　　　　map.put(2, "b")
　　　　map.put(3, "c")
　　　　map.put(4, "d")
　　　　map.put(5, "e")
　　　　val keyList = ArrayList(map.keys)
　　　　val valueList = ArrayList(map.values)
　　　　println("Key List: $keyList")
　　　　println("Value List: $valueList")
}

When running the program, the output is:

Key List: [1,　2,　3,　4,　5]
Value List: [a, b, c, d, e]

In the above program, we have a named integer and string map. Since the map contains a key-value pair, we need two lists to store them, namely keyList and valueList.

We use the map's keySet() method to get all keys and create an ArrayList key list from them. Similarly, we use the map's values() method to get all values and create an ArrayList valueList.

The following is the equivalent Java code:Java Program to Convert Map to List.

Kotlin Comprehensive Examples