[FIXED] format number with locale to fixed decimal places

Issue

What's the correct way to format a number with a given locale AND with given decimal places.

If I'd have the following code:

fun main() {
    val number = BigDecimal("1000");
    println(formatNumber(number,Locale("de","DE"),2)) // should print 1.000,00
    println(formatNumber(number,Locale("de","CH"),3)) // should print 1'000.000
}

How should formatNumber be implemented?

I've found 2 common ways to format numbers in kotlin on the internet, but both don't fully satisfy the needs:

DecimalFormat

fun formatNumber(number: BigDecimal, locale: Locale, decimalPlaces: Int) = DecimalFormat("#,###."+("0".repeat(decimalPlaces))).format(number)

Drawback: Lacks localization

NumberFormat

fun formatNumber(number: BigDecimal, locale: Locale, decimalPlaces: Int) = NumberFormat.getNumberInstance(locale).format(number)

Drawback: Lacks Decimal places

Is there a way that ticks all boxes? I feel like NumberFormat should be the way to go, but I can't figure out how to specify the decimal places..

Solution

You can set the maximumFractionDigits and minimumFractionDigits on the number format:

fun formatNumber(number: BigDecimal, locale: Locale, decimalPlaces: Int) =
    with(NumberFormat.getNumberInstance(locale)) {
        maximumFractionDigits = decimalPlaces
        minimumFractionDigits = decimalPlaces
        format(number)
    }

Answered By - Sweeper