Kotlin way of converting country codes to emoji flags

FlagToEmoji.kt

import java.util.Locale

fun countryCodeToEmojiFlag(countryCode: String) {
    return countryCode
        .toUpperCase(Locale.US)
        .map { char ->
          Character.codePointAt("$char", 0) - 0x41 + 0x1F1E6
        }
        .map { codePoint ->
          Character.toChars(codePoint)
        }
        .joinToString(separator = "") { charArray ->
          String(charArray)
        }
}

Thanks, very useful!
Two small corrections: Declare return type : String, and use uppercase() since toUpperCase() has been deprecated.

fun countryCodeToEmojiFlag(countryCode: String): String {
    return countryCode
        .uppercase(Locale.US)
        .map { char ->
          Character.codePointAt("$char", 0) - 0x41 + 0x1F1E6
        }
        .map { codePoint ->
          Character.toChars(codePoint)
        }
        .joinToString(separator = "") { charArray ->
          String(charArray)
        }
}