I am running into some issues I didn't expect porting some Kotlin code that I wrote into Kotlin Multiplatform. It works in a standalone Kotlin app, but not in Kotlin Multiplatform, and I'm assuming they have to be written differently in common.kt? Any suggestions on how to fix these common uses:

fun convertHexToBitString(dataString: String) : String {
            val binaryArray: MutableList<String> = arrayListOf()
            dataString.toCharArray().forEach {
                val binValue =
                    if (it.isDigit()) {
                        String.format("%4s",
                                       Integer.toBinaryString(Character.getNumericValue(it)))
                                       .replace(' ', '0')
                    } else {
                        when(it.toUpperCase()) {
                            'A' -> "1010"
                            'B' -> "1011"
                            'C' -> "1100"
                            'D' -> "1101"
                            'E' -> "1110"
                            'F' -> "1111"
                            else -> "Invalid hexadecimal digit in string."
                        }
                    }
                binaryArray.add(binValue)
            }
            return binaryArray.joinToString("")

it.isDigit() is not working in common.kt, nor is Character.getNumericValue, and neither is String.format(). Are any of these accessible through another means in Kotlin Multiplatform?

isDigit

is only available in Jvm and Native. See https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/is-digit.html. If you’re not targeting JS you can use expect/actual functions for jvm and native. If you need js support you’ll need to implement the function yourself on that platform.

String.format

is also available only on JVM.

Also I think

arrayListOf()

is jvm-only but you can use

mutableListOf()

instead.