Always getting the last item in a list using split - arrays

Question

As of right now i retrieve the first item in my list that i generate by using split, but i also want the last item in a seperate function.
The problem ist the list is generated from an ocr and is never the same length or size.
is there a way in kotlin to always get the last item?
This is the code for getting the first :
fun String.firstLine(): String {
if (this.isEmpty()) return ""
return this.split("\n").get(0)
}

Answer 1

You can do something like this:
fun String.firstAndLast() = split("\n").let { it.first() to it.last() }
fun main() {
val s = "first line\nsecond line\nlast line"
val (first, last) = s.firstAndLast()
println(first)
println(last)
}
output is:
first line
last line
The fun will split, then use the resulting list and get only the first and last element, returning a Pair<String, String>, which can be easily deconstructed with val (first, last), then those values can be used separately.
Edit: for the penultimate as well, I don't think that a list might be a good idea. I personally would go with an object of sorts, or with a Triple.
Class way:
class NoNameIdeas(
val first: String = "",
val penultimate: String = "",
val last: String = ""
) {
companion object {
fun fromString(string: String): NoNameIdeas {
val l = string.split("\n")
val first = l.first()
return when (l.size) {
1 -> NoNameIdeas(first = first)
2 -> NoNameIdeas(first = first, penultimate = "what should this be?", last = l.last())
else -> NoNameIdeas(first = first, penultimate = l[l.lastIndex - 1], last = l.last())
}
}
}
}
fun main() {
val string = "first line\nsecond line\nsecond last\nlast line"
val result = NoNameIdeas.fromString(string)
println(result.first)
println(result.penultimate)
println(result.last)
}
As you can guess, I have no idea how to name this object. Another issues is, what should we do with the penultimate, if we only have 2 lines in total? It can be the same as the first, or it can be empty, or it can be the same as the last. That is your decision, it also might never happen, only you know what data you have.
Another way of doing it without a class, but by using a triple:
Triple way:
fun main() {
val string = "first line\nsecond line\nsecond last\nlast line"
val result = string.firstPenultimateAndLast()
println(result.first)
println(result.second)
println(result.third)
}
fun String.firstPenultimateAndLast(): Triple<String, String, String> {
val l = split("\n")
val first = l.first()
var penultimate = "" //same as the class, what happens when we only have 2 lines?
var last = l.first() //if we only have 1, then I guess that the first is the last as well, will get a new value otherwise
when (l.size) {
2 -> last = l.last()
else -> {
penultimate = l[lastIndex - 1]
last = l.last()
}
}
return Triple(first, penultimate, last)
}