lastIndexOf
Returns last index of element, or -1 if the array does not contain element.
fun <T> Array<out T>.lastIndexOf(element: T): Int(source)
val fruits = arrayOf("apple", "banana", "apple", "cherry")
val lastIndex = fruits.lastIndexOf("apple")
println("Last index of \"apple\" is $lastIndex") // Output: Last index of "apple" is 2