kotlin find index of item compare string code example

Example 1: how to get index of item in arraylist in kotlin

val b: List<Int> = a.mapIndexed { i, b -> if (b) i else null }.filterNotNull().toList()
val c: List<Int> = a.withIndex().filter { it.value }.map { it.index }

Example 2: kotlin element at index in string

val hello = "Hello World"

    // Using get() function
    val W = hello.get(6)

    // Using indexing
    val e = hello[1]