Kotlin Programming Cookbook

How to do it…

We will be using the .flatten method of the kotlin.stdlib library. It takes in an array or collection and returns a single list of all elements from all collections/arrays in the given collection/array.

For example, with an array of arrays:

[[1,2,3],[1,2,3],[1,2,3]] -> [1,2,3,1,2,3,1,2,3]

fun main(args: Array<String>) {    val a= arrayOf(arrayOf(1,2,3),arrayOf(1,2,3),arrayOf(1,2,3))    a.flatten().forEach { print(" ${it} ") }}//Output:  1 2 3 1 2 3 1 2 3 

For example, with a list of lists:

[[1,2,3],[1,2,3],[1,2,3]] -> [1,2,3,1,2,3,1,2,3]

fun main(args: Array<String>) {    val a= listOf(listOf(1,2,3),listOf(1,2,3),listOf(1,2,3))    a.flatten().forEach { print(" ${it} ") }}