Why is this Kotlin code not working? (If str[index] in list then print)

import kotlin.reflect

fun main(args: Array<String>) {
    
    val cons = listOf("B","C","D", "F", "G", "H", "J", "K", "M", "N", "P", "Q", "R", "S", "T", "V", "W", "X", "Y", "Z",)
        
    var str = "JBIKCA"
    
       for (item in str.indices) {
        val j = (str[item])
         if (j in cons){
          println(j)
         }             
    }

Apologies for the basic question but this is my first time with the language.

Correct Output should be:

J
B
K
C

>Solution :

The problem is that j is a Char where cons contains String elements.

Simply convert the characters to string before checking. You can also more simply iterate str using for..in

for (j in str) {
    if (j.toString() in cons) {
        println(j)
    }
}