Join our newsletter for the latest updates.
Kotlin Program to Join Two Lists

Kotlin Program to Join Two Lists

In this program, you'll learn different techniques to join two lists in Kotlin.

Example 1: Join Two Lists using addAll()

import java.util.ArrayList

fun main(args: Array<String>) {

    val list1 = ArrayList<String>()
    list1.add("a")

    val list2 = ArrayList<String>()
    list2.add("b")

    val joined = ArrayList<String>()

    joined.addAll(list1)
    joined.addAll(list2)

    println("list1: $list1")
    println("list2: $list2")
    println("joined: $joined")

}

When you run the program, the output will be:

list1: [a]
list2: [b]
joined: [a, b]

In the above program, we used List's addAll() method to join lists list1 and list2 to the joined list.


Example 2: Join Two Lists using union()

import java.util.ArrayList;
import org.apache.commons.collections.ListUtils;

fun main(args: Array<String>) {

    val list1 = ArrayList<String>()
    list1.add("a")

    val list2 = ArrayList<String>()
    list2.add("b")

    val joined = ListUtils.union(list1, list2)

    println("list1: $list1")
    println("list2: $list2")
    println("joined: $joined")

}

The output of this program is the same.

In the above program, we used union() method to join the given lists to joined.

Here's the equivalent Java code: Java Program to join two lists.