is there a way to sort only a ArrayList subrange?

# announcements

[elect]

is there a way to sort only a ArrayList subrange?

[Vampire]

fun main() {
    val x = mutableListOf(5, 4, 3, 2, 1)
    println(x)
    x.subList(1, 4).sort()
    println(x)
}

=>

[5, 4, 3, 2, 1]
[5, 2, 3, 4, 1]

[CLOVIS]

I thought subList copied the list 🤔 that's very good to know

[stephanmg]

from the documentation it looks like there is no copying

[stephanmg]

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-list/sub-list.html

[stephanmg]

?

[Vampire]

Actually https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-array-list/sub-list.html as he asked about ArrayList, but it is basically the same, yes. 🙂

[Vampire]

Returns a view of the portion of this list between the specified fromIndex (inclusive) and toIndex (exclusive). The returned list is backed by this list, so non-structural changes in the returned list are reflected in this list, and vice-versa.

Structural changes in the base list make the behavior of the view undefined.

[Vampire]

I think slice would give you an independent list

[elect]

perfect, thanks @Vampire

[stephanmg]

and slice copies?

[Vampire]

Yes:

fun main() {
    val x = mutableListOf(5, 4, 3, 2, 1)
    println(x)
    val slice: List<Int> = x.slice(1..3)
    println(slice)
    (slice as MutableList).sort()
    println(slice)
    println(x)
}

=>

[5, 4, 3, 2, 1]
[4, 3, 2]
[2, 3, 4]
[5, 4, 3, 2, 1]

[stephanmg]

ha okay, great