Find Last occurrence index value of outer list in Kotlin-CodePudding

Hey i have nested list and i wanted to find last occurrence index value of outer list. I tried to search in Kotlin Doc. I tried some code but I failed. So how can I do this in my case in efficient way.

fun main() {
    val value = listOf(
        Group(0, mutableListOf(GroupValue(true, "1"))),
        Group(1, mutableListOf(GroupValue(true, "2"))),
        Group(2, mutableListOf(GroupValue(false, "3"))),
        Group(3, mutableListOf(GroupValue(true, "4"))),
        Group(4, mutableListOf(GroupValue(false, "5"))),
        Group(5, mutableListOf(GroupValue(true, "6"))),
        Group(6, mutableListOf(GroupValue(true, "6"), GroupValue(false, "7"))),
        Group(7, mutableListOf(GroupValue(true, "6"), GroupValue(false, "7"))),
        Group(8, mutableListOf(GroupValue(true, "6"), GroupValue(true, "7"), GroupValue(false, "7"))),
        Group(9, mutableListOf(GroupValue(false, "6"), GroupValue(true, "7"))),
        Group(10, mutableListOf(GroupValue(true, "7")))
    )

    val result = value.asSequence().flatMap { it.value }.indexOfLast { conversationItems ->
        conversationItems?.isRead == false
    }
    println("result $result")

}

Group

data class Group(
    val key: Int,
    val value: MutableList<GroupValue?>
)

GroupValue

data class GroupValue(
    val isRead: Boolean? = null,
    val id: String? = null
)

Getting output of above code is

result 13

Expected Output

result 9

I don't know what i am doing wrong in above logic

CodePudding user response：

13 is correct since you used flatMap, which turns all your lists into a single list and you're getting the index of an item in that bigger, combined list.

From what you said you expected, I'm guessing you want the index of the outer list for the last Group containing a false isRead GroupValue. I would do that like this:

val result = value.indexOfLast { group ->
    group.value.any { it?.isRead == false }
}