Hello all, not sure if this is a noob question but...

# getting-started

[Alejandro Rios]

Hello all, not sure if this is a noob question but here it goes:

How can I get the difference between two List/ArrayList regardless of the order of the sentence? I mean, for example these two lists

val first = listOf(1, 2, 3, 4, 5)
 val second = listOf(1, 2, 3)

If I use first.minus(second) I’ll get [4, 5] but If I use second.minus(first) I’ll get []

[Paul Griffith]

You can convert to sets and get the symmetric difference, though there's no convenient standard library function, interestingly

[Paul Griffith]

https://stackoverflow.com/q/65361494

[Alejandro Rios]

Found this one:
https://www.rosettacode.org/wiki/Category:Kotlin

[Alejandro Rios]

Thanks @Paul Griffith

[Javier]

They have added recently the intersect function to the stdlib, I think they should add the opposite too

[ilya.gorbunov]

@Javier, No intersect was not added recently, it's been there quite a long time

[ilya.gorbunov]

@Alejandro Rios There's a request about adding symmetric difference to stdlib, https://youtrack.jetbrains.com/issue/KT-11330, but we're not sure about its use cases. Can you describe yours?

[Javier]

Maybe union was? Don't remember then.

I am going to like that issue, I had the difference as extension function since 2019.

[Alejandro Rios]

That's really cool, thanks for the update

[ilya.gorbunov]

@Javier How do you use your extension function in your code? What tasks do you solve with it?

[Javier]

For example in an android app, we had multiple lists of quizzes, generally a pair of lists, and was a requirement to get the difference of quizzes to show them to the user.