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So i already did the following: val mutablePersonsAgeChanged = mutablePersons.If you want to iterate the indices as a range, you can use the attribute lastIndex of IntArray in order to avoid an IndexOutOfBoundsException. We propose a view enumerate whose value type is a struct with 2 members index and value representing respectively the position and value of the elements in the adapted. Returns a list containing the results of applying the given transform function to each element and its index of the original collection. For traversing collection elements, the Kotlin standard library supports the commonly used mechanism of iterators objects that provide access to the elements sequentially without exposing the underlying structure of the collection. Lists support all common operations for element retrieval: elementAt(), first(), last(), and others listed in Retrieve single elements. C++ Standard proposal P2164 proposes to add views::enumerate, which would provide a view of a range giving both reference-to-element and index-of-element to a user iterating it. Index access to the elements of lists provides a powerful set of operations for lists. The idea is to iterate over a range of valid indices with a range expression. The standard approach to iterate over characters of a string is with index-based for-loop.

Array.mapIndexed( transform: (index: Int, T) -> R ): List (source) inline fun ByteArray.mapIndexed( transform: (index: Int, Byte) -> R ): List (source) inline fun ShortArray.mapIndexed( transform: (index: Int, Short) -> R ): List (source) inline fun IntArray. This article explores different ways to iterate over characters of a string in Kotlin.

transform - function that takes the index of an element and the element itself and returns the result of the transform applied to the element. I did it in the following way: val personA = Person("john", 25) Returns a list containing the results of applying the given transform function to each element and its index in the original array. So i created a new List and create a mutableList from it because i want to change their age. I have a data class which is: data class Person (var name : String, var age : Int)Īnd i want to create a List which contains the Person with the multiplied age multiplied per 2, only on even items. In this tutorial, we’re going to look at the different types of loops supported by Kotlin: repeat for loop while loop do.while loop Let’s start by looking at the repeat statement. They allow for repeated execution of one or more statements until a condition is met. I'm playing a little bit with Kotlin and i don't understand this so, maybe someone can explain it to me. Introduction Loops are one of the basic constructs of any programming language.