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  1. JDK
  2. JDK-8243445

Additional Date-Time Formats

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Details

    • CSR
    • Status: Closed
    • P4
    • Resolution: Approved
    • 19
    • core-libs
    • None
    • source
    • minimal
    • These are additions of new methods to final classes.
    • Java API
    • SE

    Description

      Summary

      Support additional custom locale date/time formats defined in CLDR.

      Problem

      Currently java.time.format.DateTimeFormatter supports 4 pre-defined format styles, for example, FormatStyle.FULL/LONG/MEDIUM/SHORT. Users cannot use localized formats in a more flexible manner, such as a format that contains only year and month. For example, consider getting the title string for a typical month for a calendar user interface. Currently, the typical way is to assume an explicit pattern, such as DateTimeFormatter.ofPattern("MMM y") which is proven to be incorrect for some locales.

      Solution

      Provide a method analogous to java.time.format.DateTimeFormatter#ofPattern that takes the template based on Skeleton patterns defined in CLDR. It returns the localized formatter based on passed skeletons. Also, add supporting methods in java.time.format.DateTimeFormatterBuilder class that are the basis for the method in DateTimeFormatter.

      Specification

      Add the following method to java.time.format.DateTimeFormatter class:

      /**
       * Creates a locale specific formatter derived from the requested template for
       * the ISO chronology. The requested template is a series of typical pattern
       * symbols in canonical order from the largest date or time unit to the smallest,
       * which can be expressed with the following regular expression:
       * {@snippet :
       *      "G{0,5}" +        // Era
       *      "y*" +            // Year
       *      "Q{0,5}" +        // Quarter
       *      "M{0,5}" +        // Month
       *      "w*" +            // Week of Week Based Year
       *      "E{0,5}" +        // Day of Week
       *      "d{0,2}" +        // Day of Month
       *      "B{0,5}" +        // Period/AmPm of Day
       *      "[hHjC]{0,2}" +   // Hour of Day/AmPm (refer to LDML for 'j' and 'C')
       *      "m{0,2}" +        // Minute of Hour
       *      "s{0,2}" +        // Second of Minute
       *      "[vz]{0,4}"       // Zone
       * }
       * All pattern symbols are optional, and each pattern symbol represents a field,
       * for example, 'M' represents the Month field. The number of the pattern symbol letters follows the
       * same presentation, such as "number" or "text" as in the <a href="#patterns">Patterns for
       * Formatting and Parsing</a> section. Other pattern symbols in the requested template are
       * invalid.
       * <p>
       * The mapping of the requested template to the closest of the available localized formats
       * is defined by the
       * <a href="https://www.unicode.org/reports/tr35/tr35-dates.html#availableFormats_appendItems">
       * Unicode LDML specification</a>. For example, the formatter created from the requested template
       * {@code yMMM} will format the date '2020-06-16' to 'Jun 2020' in the {@link Locale#US US locale}.
       * <p>
       * The locale is determined from the formatter. The formatter returned directly by
       * this method uses the {@link Locale#getDefault() default FORMAT locale}.
       * The locale can be controlled using {@link DateTimeFormatter#withLocale(Locale) withLocale(Locale)}
       * on the result of this method.
       * <p>
       * The returned formatter has no override zone.
       * It uses {@link ResolverStyle#SMART SMART} resolver style.
       *
       * @param requestedTemplate the requested template, not null
       * @return the formatter based on the {@code requestedTemplate} pattern, not null
       * @throws IllegalArgumentException if {@code requestedTemplate} is invalid
       * @see #ofPattern(String)
       * @since 19
       */
      public static DateTimeFormatter ofLocalizedPattern(String requestedTemplate)

      Add the following methods to java.time.format.DateTimeFormatterBuilder class:

      /**
       * Appends a localized pattern to the formatter using the requested template.
       * <p>
       * This appends a localized section to the builder, suitable for outputting
       * a date, time or date-time combination. The format of the localized
       * section is lazily looked up based on three items:
       * <ul>
       * <li>the {@code requestedTemplate} specified to this method
       * <li>the {@code Locale} of the {@code DateTimeFormatter}
       * <li>the {@code Chronology} of the {@code DateTimeFormatter} unless overridden
       * </ul>
       * During formatting, the chronology is obtained from the temporal object
       * being formatted, which may have been overridden by
       * {@link DateTimeFormatter#withChronology(Chronology)}.
       * <p>
       * During parsing, if a chronology has already been parsed, then it is used.
       * Otherwise the default from {@code DateTimeFormatter.withChronology(Chronology)}
       * is used, with {@code IsoChronology} as the fallback.
       * <p>
       * The requested template is a series of typical pattern
       * symbols in canonical order from the largest date or time unit to the smallest,
       * which can be expressed with the following regular expression:
       * {@snippet :
       *      "G{0,5}" +        // Era
       *      "y*" +            // Year
       *      "Q{0,5}" +        // Quarter
       *      "M{0,5}" +        // Month
       *      "w*" +            // Week of Week Based Year
       *      "E{0,5}" +        // Day of Week
       *      "d{0,2}" +        // Day of Month
       *      "B{0,5}" +        // Period/AmPm of Day
       *      "[hHjC]{0,2}" +   // Hour of Day/AmPm (refer to LDML for 'j' and 'C')
       *      "m{0,2}" +        // Minute of Hour
       *      "s{0,2}" +        // Second of Minute
       *      "[vz]{0,4}"       // Zone
       * }
       * All pattern symbols are optional, and each pattern symbol represents a field,
       * for example, 'M' represents the Month field. The number of the pattern symbol letters follows the
       * same presentation, such as "number" or "text" as in the
       * <a href="./DateTimeFormatter.html#patterns">Patterns for Formatting and Parsing</a> section.
       * Other pattern symbols in the requested template are invalid.
       * <p>
       * The mapping of the requested template to the closest of the available localized formats
       * is defined by the
       * <a href="https://www.unicode.org/reports/tr35/tr35-dates.html#availableFormats_appendItems">
       * Unicode LDML specification</a>. For example, the formatter created from the requested template
       * {@code yMMM} will format the date '2020-06-16' to 'Jun 2020' in the {@link Locale#US US locale}.
       *
       * @param requestedTemplate the requested template to use, not null
       * @return this, for chaining, not null
       * @throws IllegalArgumentException if {@code requestedTemplate} is invalid
       * @see #appendPattern(String)
       * @since 19
       */
      public DateTimeFormatterBuilder appendLocalized(String requestedTemplate)
      
      /**
       * Returns the formatting pattern for the requested template for a locale and chronology.
       * The locale and chronology are used to lookup the locale specific format
       * for the requested template.
       * <p>
       * If the locale contains the "rg" (region override)
       * <a href="../../util/Locale.html#def_locale_extension">Unicode extensions</a>,
       * the formatting pattern is overridden with the one appropriate for the region.
       * <p>
       * Refer to {@link #appendLocalized(String)} for the detail of {@code requestedTemplate}
       * argument.
       *
       * @param requestedTemplate the requested template, not null
       * @param chrono  the Chronology, non-null
       * @param locale  the locale, non-null
       * @return the locale and Chronology specific formatting pattern
       * @throws IllegalArgumentException if {@code requestedTemplate} does not match
       *      the regular expression syntax described in {@link #appendLocalized(String)}.
       * @throws DateTimeException if a match for the localized pattern for
       *      {@code requestedTemplate} is not available
       * @see #appendLocalized(String) 
       * @since 19
       */
      public static String getLocalizedDateTimePattern(String requestedTemplate,
                                                       Chronology chrono, Locale locale)

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              naoto Naoto Sato
              naoto Naoto Sato
              Joe Wang, Roger Riggs
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              Dates

                Created:
                Updated:
                Resolved: