Summary

Grouping separator in java.text.DecimalFormat/DecimalFormatSymbols should identify generic and monetary instances.

Problem

Some languages have two distinct characters for the grouping separator. For example, the number 1_500 should be formatted to "1 500" as a generic number, and "1.500" for currency in German in Austria. Currently, JDK assumes there is one single character for the grouping separator per locale, so it cannot handle the de-AT case.

Solution

A monetary grouping separator is added to DecimalFormatSymbols. It is used in DecimalFormat for patterns with a currency sign symbol U+00A4. Public get and set methods should be provided for applications, which will be on par with get/setMonetaryDecimalSeparator() methods. Initial values for the field will be obtained from the CLDR locale data.

Specification

In java.text.DecimalFormat class description, change the following rows in the chart of "Special Pattern Characters":

The "Meaning" column of ',' should read:

Grouping separator or monetary grouping separator

The "Meaning" column of ¤ (\u00A4) should read:

Currency sign, replaced by currency symbol. If doubled, replaced by international currency symbol. If present in a pattern, the monetary decimal/grouping separators are used instead of the decimal/grouping separators.

Add the following new getter/setter methods in java.text.DecimalFormatSymbols class:

/**
 * Gets the character used for grouping separator for currencies.
 * May be different from {@code grouping separator} in some locales,
 * e.g, German in Austria.
 *
 * @since 15
 * @return the monetary grouping separator
 */
public char getMonetaryGroupingSeparator()

 /**
 * Sets the character used for grouping separator for currencies.
 * Invocation of this method will not affect the normal
 * {@code grouping separator}.
 *
 * @param monetaryGroupingSeparator the monetary grouping separator
 * @see #setGroupingSeparator(char)
 * @since 15
 */
public void setMonetaryGroupingSeparator(char monetaryGroupingSeparator)

Add the following new serializable field in java.text.DecimalFormatSymbols class:

/**
 * The grouping separator used when formatting currency values.
 *
 * @serial
 * @since 15
 */
private  char    monetaryGroupingSeparator;

Add the following sentence in the method description of java.text.DecimalFormatSymbols.readObject(), after the perMillText, percentText, minusSignText explanation :

 * If {@code serialVersionOnStream} is less than 5, it initializes
 * {@code monetaryGroupingSeparator} using {@code groupingSeparator}.

Add the following list item in the field description of java.text.DecimalFormatSymbols.serialVersionOnStream, after the perMillText, percentText, minusSignText list item:

 * <li><b>5</b>: Versions written by Java SE 15 or later, which include
 *      new {@code monetaryGroupingSeparator} field.

Replace the occurrences of "thousand separator(s)" with "grouping separator(s)" in DecimalFormat and DecimalFormatSymbols classes, as the former is old (and incorrect) usage of the separator name.