Programming in Kotlin - Part 31: Lists | Ray Wenderlich

Learn how to use Lists in Kotlin to store an ordered collection of data.

This is a companion discussion topic for the original entry at

Hi Kev and all,

I have the following code. But when I remove from the list, it does not get removed inside a function. What is that I am missing here? Thanks in advance.


fun main() {

var nameList = mutableListOf<String>()
var nameArray = arrayOf("Good","Great","Fine")

var ptrToList : ( List) → Int =:: printAllNames

println("\n ----------------------")

fun printAllNames( mylist : List ) : Int {
for (name in mylist) {
if (name == “Ugly”) {
var itemToRemove = mylist.indexOf(name)
println("Index: $itemToRemove ")

return 0


My first thought is that you can’t remove items from a list while in a for loop. If you create an iterator you can remove the item from the iterator. I think the easiest solution is:

val newList = nameList.filter{it != "Ugly"}
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First of all thank you for the quick response!!!

Ok got it now. Also it appears that if I do filter it then it has to be stored on a NEW list rather than the same list. Why is that? :slight_smile:

Reason I am asking because I have created a pointer like this ‘var ptrToList : ( List) → Int =:: printAllNames’

So when I remove an item from the function it should remove it?

Thank you and looking forward to your clarification.

That is the way that the filter function works. A lot of these types of method try to not change the original list but just return a new one.
If you just want to remove you can try something like this. (Not tested):

val iterator = nameList.asIterable()
    while (iterator.hasNext()) {
        if ( == "Ugly") {
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That worked great! Thank you!! I think doing this way will be faster comparing to copying the result to a new list and then returning it and that’s why I wanted to acheive this method.

Also great timing on response. Enjoying the course so far. Nice work! Thanks Kevin! :slight_smile:

Glad to hear it worked and that you liked the course!

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