Flattening Lists and Arrays in Kotlin
With the flatten method in Kotlin, you can turn a list of lists and array of arrays into a single list of all elements.
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fun simpleFlattenedList(list: List<List<Any>>): List<Any> {
return list.flatten()
}
fun flattenedArray(array: Array<Array<Int>>): List<Int> {
return array.flatten()
}
fun main(args: Array<String>) {
println(simpleFlattenedList(listOf(listOf(1, 2, 3), listOf("one", "two", "three"))))
// [1, 2, 3, one, two, three]
println(flattenedArray(arrayOf(arrayOf(1), arrayOf(2, 3), arrayOf(4, 5))))
// [1, 2, 3, 4, 5]
}
When flatten is called on a List or Array, a new list is created and every value on the passed argument is iterated over once and added into a new flat List.