The post “Compact Number Formatting Comes to JDK 12” demonstrated the support added to NumberFormat in JDK 12 to support compact number formatting. The examples shown in that post only used the instances of NumberFormat returned by invocations of NumberFormat‘s new overloaded getCompactNumberInstance(-) methods and so therefore did not specify characteristics such as minimum fractional digits and maximum fractional digits. The results, in some cases, are less than desirable. Fortunately, NumberFormat does allow for minimum and maximum fractional digits to be specified and this post demonstrates how that can improve the output of the compact number formatting available with JDK 12.
The code listing introduced in the original “Compact Number Formatting Comes to JDK 12” post (and which is available on GitHub) has been updated to demonstrate use of NumberFormat.setMinimumFractionDigits(int). An excerpt of that code is shown next and is followed by the accompanying output.
/**
* Generates standardized map of labels to Compact Number Format
* instances described by the labels. The instances of {@code NumberFormat}
* are created with Locale and Style only and with the provided number
* of minimum fractional digits.
*
* @return Mapping of label to an instance of a Compact Number Format
* consisting of a Locale, Style, and specified minimum number of fractional
* digits that is described by the label.
*/
private static Map<String, NumberFormat> generateCompactNumberFormats(
final int minimumNumberFractionDigits)
{
var numberFormats = generateCompactNumberFormats();
numberFormats.forEach((label, numberFormat) ->
numberFormat.setMinimumFractionDigits(minimumNumberFractionDigits));
return numberFormats;
}
/**
* Demonstrates compact number formatting in a variety of locales
* and number formats against the provided {@code long} value and
* with a minimum fractional digits of 1 specified.
* @param numberToFormat Value of type {@code long} that is to be
* formatted using compact number formatting and a variety of
* locales and number formats and with a single minimal fractional
* digit.
*/
private static void demonstrateCompactNumberFormattingOneFractionalDigitMinimum(
final long numberToFormat)
{
final Map<String, NumberFormat> numberFormats = generateCompactNumberFormats(1);
out.println(
"Demonstrating Compact Number Formatting on long '" + numberToFormat
+ "' with 1 minimum fraction digit:");
numberFormats.forEach((label, numberFormat) ->
out.println("\t" + label + ": " + numberFormat.format(numberToFormat))
);
}Demonstrating Compact Number Formatting on long '15' with 1 minimum fraction digit: Default: 15 US/Long: 15 UK/Short: 15 UK/Long: 15 FR/Short: 15 FR/Long: 15 DE/Short: 15 DE/Long: 15 IT/Short: 15 IT/Long: 15 Demonstrating Compact Number Formatting on long '150' with 1 minimum fraction digit: Default: 150 US/Long: 150 UK/Short: 150 UK/Long: 150 FR/Short: 150 FR/Long: 150 DE/Short: 150 DE/Long: 150 IT/Short: 150 IT/Long: 150 Demonstrating Compact Number Formatting on long '1500' with 1 minimum fraction digit: Default: 1.5K US/Long: 1.5 thousand UK/Short: 1.5K UK/Long: 1.5 thousand FR/Short: 1,5 k FR/Long: 1,5 millier DE/Short: 1.500 DE/Long: 1,5 Tausend IT/Short: 1.500 IT/Long: 1,5 mille Demonstrating Compact Number Formatting on long '15000' with 1 minimum fraction digit: Default: 15.0K US/Long: 15.0 thousand UK/Short: 15.0K UK/Long: 15.0 thousand FR/Short: 15,0 k FR/Long: 15,0 mille DE/Short: 15.000 DE/Long: 15,0 Tausend IT/Short: 15.000 IT/Long: 15,0 mila Demonstrating Compact Number Formatting on long '150000' with 1 minimum fraction digit: Default: 150.0K US/Long: 150.0 thousand UK/Short: 150.0K UK/Long: 150.0 thousand FR/Short: 150,0 k FR/Long: 150,0 mille DE/Short: 150.000 DE/Long: 150,0 Tausend IT/Short: 150.000 IT/Long: 150,0 mila Demonstrating Compact Number Formatting on long '1500000' with 1 minimum fraction digit: Default: 1.5M US/Long: 1.5 million UK/Short: 1.5M UK/Long: 1.5 million FR/Short: 1,5 M FR/Long: 1,5 million DE/Short: 1,5 Mio. DE/Long: 1,5 Million IT/Short: 1,5 Mln IT/Long: 1,5 milione Demonstrating Compact Number Formatting on long '15000000' with 1 minimum fraction digit: Default: 15.0M US/Long: 15.0 million UK/Short: 15.0M UK/Long: 15.0 million FR/Short: 15,0 M FR/Long: 15,0 million DE/Short: 15,0 Mio. DE/Long: 15,0 Millionen IT/Short: 15,0 Mln IT/Long: 15,0 milioni
As the example and output shown above demonstrate, use of NumberFormat.setMinimumFractionDigits(int) leads to compact number formatted output that is likely to be more aesthetically pleasing in many cases. There is a recent discussion “Compact Number Formatting and Fraction Digits” on the OpenJDK core-libs-dev mailing list that also discusses this ability to customize the compact number formatting output.
Published on Java Code Geeks with permission by Dustin Marx, partner at our JCG program. See the original article here: Using Minimum Fractional Digits with JDK 12 Compact Number Formatting Opinions expressed by Java Code Geeks contributors are their own. |
