Creating a class that can format string input inside EditText into a phone number. However, the input return isn’t appending the “-“.

    internal class PhoneNumberFormatter : TextFormatter {

    override fun format(input: String): String {
        // logic to format phone #

        val textLength = input.length;
        if (input.endsWith("-") || input.endsWith(" ") || input.endsWith(" "))
            return ""
        if (textLength == 4) {
            if (!input.contains("-")) {
                StringBuilder(input).append("-").toString()
            }
        } else if (textLength == 8) {
            if (input.contains("-")) {
                StringBuilder(input).insert(input.length - 1, "-").toString()
                }
            }

        return input
    }
}