如何在Kotlin中将字符串数字格式化为逗号？

import java.text.NumberFormat
import java.util.Locale

fun formatNumberWithCommas(numberString: String): String {
    val number = numberString.toDoubleOrNull()
    return if (number != null) {
        val numberFormat = NumberFormat.getNumberInstance(Locale.getDefault())
        numberFormat.format(number)
    } else {
        "Invalid number"
    }
}

fun main() {
    val numberString = "1234567.89"
    val formattedNumber = formatNumberWithCommas(numberString)
    println(formattedNumber) // Output: 1,234,567.89
}