Quarkus GraalVM native image DateTimeFormatter and Localization - date

Question

I tried to use localization in java to print date with local style.
I already make a similar functionality with numbers and currencies but I failed to apply the same behavior to date.
As I learning when I posted this topics few days ago, GraalVM Quarkus Locale in native mode , use localization in native mode need to use create an "#AutomaticFeature".
This trick works for numbers and currencies :
#AutomaticFeature
public class NativeNumberFormatFeature implements Feature {
#Override
public void beforeAnalysis(BeforeAnalysisAccess access) {
ImageSingletons
.lookup(RuntimeClassInitializationSupport.class)
.initializeAtBuildTime(NumberFormatSupport.class, this.getClass().getName());
ImageSingletons.add(NumberFormatSupport.class, new NumberFormatSupport());
}
}
public class NumberFormatSupport {
private Map<Locale, NumberFormat> numberInstancesByLocale;
private Map<Locale, Map<String, NumberFormat>> currencyInstancesByLocale;
public NumberFormatSupport() {
numberInstancesByLocale = new HashMap<>();
currencyInstancesByLocale = new HashMap<>();
for (Locale locale : Locale.getAvailableLocales()) {
numberInstancesByLocale.put(locale, NumberFormat.getNumberInstance(locale));
currencyInstancesByLocale.put(locale, new HashMap<>());
for (Currency currency : Currency.getAvailableCurrencies()) {
currencyInstancesByLocale.get(locale).put(currency.getCurrencyCode(), NumberFormat.getCurrencyInstance(locale));
currencyInstancesByLocale.get(locale).get(currency.getCurrencyCode()).setCurrency(currency);
}
}
}
public NumberFormat getNumberFormat(Locale locale) {
return (NumberFormat) numberInstancesByLocale.get(locale).clone();
}
public NumberFormat getCurrencyFormat(Locale locale, Currency currency) {
return (NumberFormat) currencyInstancesByLocale.get(locale).get(currency.getCurrencyCode()).clone();
}
}
But it's not works with DateTimeFormatter :
#AutomaticFeature
public class NativeDateFormatterFeature implements Feature {
#Override
public void beforeAnalysis(BeforeAnalysisAccess access) {
ImageSingletons
.lookup(RuntimeClassInitializationSupport.class)
.initializeAtBuildTime(DateFormatterSupport.class, this.getClass().getName());
ImageSingletons.add(DateFormatterSupport.class, new DateFormatterSupport());
}
}
public class DateFormatterSupport {
private Map<Locale, DateTimeFormatter> dateTimeFormatterByLocale;
public DateFormatterSupport() {
dateTimeFormatterByLocale = Arrays.stream(Locale.getAvailableLocales()).collect(Collectors.toMap(
Function.identity(),
l -> DateTimeFormatter.ofLocalizedDate(FormatStyle.MEDIUM).withLocale(l)));
}
public DateTimeFormatter get(Locale locale) {
return dateTimeFormatterByLocale.get(locale);
}
}
In development mode all is ok but in native mode, locale is ignore. Style is always le same, month name isn't translate.
I was looking for a solution on google but i didn't find anything so I ask on StackOverflow.
I am at your disposal if needed.
Regards,
Stéphane.

Answer 1

I don't understand why, but the following solution works :
public class DateFormatterSupport {
private Map<Locale, DateTimeFormatter> dateTimeFormatterByLocale;
public DateFormatterSupport() {
dateTimeFormatterByLocale = Arrays.stream(Locale.getAvailableLocales()).collect(Collectors.toMap(
Function.identity(),
l -> DateTimeFormatter.ofLocalizedDate(FormatStyle.MEDIUM).withLocale(l)));
Arrays.stream(Locale.getAvailableLocales()).forEach(locale -> {
dateTimeFormatterByLocale.get(locale).format(LocalDate.now());
});
}
public DateTimeFormatter get(Locale locale) {
return dateTimeFormatterByLocale.get(locale);
}
}