In Kotlin, how to check contains one or another value?

Question

In Kotlin we can do:

val arr = intArrayOf(1,2,3) if (2 in arr)    println("in list") 

But if I want to check if 2 or 3 are in arr, what is the most idiomatic way to do it other than:

if (2 in arr || 3 in arr)    println("in list") 

Answer 1

I'd use any() extension method:

arrayOf(1, 2, 3).any { it == 2 || it == 3 } 

This way, you traverse the array only once and you don't create a set instance just to check whether it's empty or not (like in one of other answers to this question).

Answer 2

This is the shortest and most idiomatic way I can think of using any and in:

val values = setOf(2, 3) val array = intArrayOf(1, 2, 3)  array.any { it in values } 

Of course you can use a functional reference for the in operator as well:

array.any(values::contains) 

I use setOf for the first collection because order does not matter.

Edit: I switched values and array, because of alex.dorokhow's answer. The order doesn't matter for the check to work but for performance.

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_{The OP wanted the most idiomatic way of solving this. If you are after a more efficient way, go for aga's answer.}