[FREEMARKER-125] ExtendedDecimalFormatParser ignores DecimalFormatSymbolsProvider

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.28, 2.3.29
• Fix Version/s: 2.3.30
• Component/s: engine
• Assignee: Unassigned
• Reporter: Adrian Schmid
• Created: 19/Dec/19 13:40
• Updated: 07/Mar/20 14:20
• Resolved: 12/Jan/20 22:00

Description

We have customers that operate in multiple regions of Switzerland and use the locales de-CH, fr-CH and it-CH.

The standard fr-CH number format changed when we upgraded from java 8 to java 11.

old:
1'000.00 (single quote as thousands separator and dot as decimal separator)
new:
1 000,00 (nonbreaking space as thousands separator and comma as decimal separator)

To "fix" the issue we implemented a custom DecimalFormatSymbolsProvider to use the de-CH DecimalFormatSymbols for all swiss locales:

public class SwissDecimalFormatSymbolsProvider extends DecimalFormatSymbolsProvider {
    @Override
    public Locale[] getAvailableLocales() {
        return new Locale[] {
            Locale.forLanguageTag("de-CH"),
            Locale.forLanguageTag("fr-CH"),
            Locale.forLanguageTag("it-CH")
        };
    }

    @Override
    public DecimalFormatSymbols getInstance(Locale locale) {
        return new DecimalFormatSymbols(Locale.forLanguageTag("de-CH"));
    }
}

This works everywhere as expected except for when people use a "custom" freemarker number format.

E.g.
number?currency -> 1'000.00 CHF (correct de-CH DecimalFormatSymbols)
number?string(",##0.00") -> 1 000,00 (wrong fr-CH DecimalFormatSymbols)

I looked at the source code of the constructor of ExtendedDecimalFormatParser and DecimalFormatSymbols are "retrieved" by using the constructor of the DecimalFormatSymbols class.

private ExtendedDecimalFormatParser(String formatString, Locale locale) {
    src = formatString;
    this.symbols = new DecimalFormatSymbols(locale);
}

This initialises DecimalFormatSymbols for the current locale ("fr-CH") instead of applying DecimalFormatSymbolsProviders.

/**
 * Create a DecimalFormatSymbols object for the given locale.
 * This constructor can only construct instances for the locales
 * supported by the Java runtime environment, not for those
 * supported by installed
 * {@link java.text.spi.DecimalFormatSymbolsProvider DecimalFormatSymbolsProvider}
 * implementations. For full locale coverage, use the
 * {@link #getInstance(Locale) getInstance} method.
 * If the specified locale contains the {@link java.util.Locale#UNICODE_LOCALE_EXTENSION}
 * for the numbering system, the instance is initialized with the specified numbering
 * system if the JRE implementation supports it. For example,
 * <pre>
 * NumberFormat.getNumberInstance(Locale.forLanguageTag("th-TH-u-nu-thai"))
 * </pre>
 * This may return a {@code NumberFormat} instance with the Thai numbering system,
 * instead of the Latin numbering system.
 *
 * @param locale the desired locale
 * @exception NullPointerException if <code>locale</code> is null
 */
public DecimalFormatSymbols( Locale locale ) {
    initialize( locale );
}