8176706: Additional Date-Time Formats

Reviewed-by: joehw, rriggs

make/jdk/src/classes/build/tools/cldrconverter/Bundle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,6 +25,9 @@
 
 package build.tools.cldrconverter;
 
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.EnumSet;
@@ -34,6 +37,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
 class Bundle {
@@ -47,21 +51,21 @@ class Bundle {
                                                     FORMATDATA);
     }
 
-    private final static Map<String, Bundle> bundles = new HashMap<>();
+    private static final Map<String, Bundle> bundles = new HashMap<>();
 
-    private final static String[] NUMBER_PATTERN_KEYS = {
+    private static final String[] NUMBER_PATTERN_KEYS = {
         "NumberPatterns/decimal",
         "NumberPatterns/currency",
         "NumberPatterns/percent",
         "NumberPatterns/accounting"
     };
 
-    private final static String[] COMPACT_NUMBER_PATTERN_KEYS = {
+    private static final String[] COMPACT_NUMBER_PATTERN_KEYS = {
         "short.CompactNumberPatterns",
         "long.CompactNumberPatterns"
     };
 
-    private final static String[] NUMBER_ELEMENT_KEYS = {
+    private static final String[] NUMBER_ELEMENT_KEYS = {
         "NumberElements/decimal",
         "NumberElements/group",
         "NumberElements/list",
@@ -77,41 +81,45 @@ class Bundle {
         "NumberElements/currencyGroup",
     };
 
-    private final static String[] TIME_PATTERN_KEYS = {
+    private static final String[] TIME_PATTERN_KEYS = {
         "DateTimePatterns/full-time",
         "DateTimePatterns/long-time",
         "DateTimePatterns/medium-time",
         "DateTimePatterns/short-time",
     };
 
-    private final static String[] DATE_PATTERN_KEYS = {
+    private static final String[] DATE_PATTERN_KEYS = {
         "DateTimePatterns/full-date",
         "DateTimePatterns/long-date",
         "DateTimePatterns/medium-date",
         "DateTimePatterns/short-date",
     };
 
-    private final static String[] DATETIME_PATTERN_KEYS = {
+    private static final String[] DATETIME_PATTERN_KEYS = {
         "DateTimePatterns/full-dateTime",
         "DateTimePatterns/long-dateTime",
         "DateTimePatterns/medium-dateTime",
         "DateTimePatterns/short-dateTime",
     };
 
-    private final static String[] ERA_KEYS = {
+    private static final String[] ERA_KEYS = {
         "long.Eras",
         "Eras",
         "narrow.Eras"
     };
 
+    // DateFormatItem prefix
+    static final String DATEFORMATITEM_KEY_PREFIX = "DateFormatItem.";
+    static final String DATEFORMATITEM_INPUT_REGIONS_PREFIX = "DateFormatItemInputRegions.";
+
     // Keys for individual time zone names
-    private final static String TZ_GEN_LONG_KEY = "timezone.displayname.generic.long";
+    private static final String TZ_GEN_LONG_KEY = "timezone.displayname.generic.long";
-    private final static String TZ_GEN_SHORT_KEY = "timezone.displayname.generic.short";
+    private static final String TZ_GEN_SHORT_KEY = "timezone.displayname.generic.short";
-    private final static String TZ_STD_LONG_KEY = "timezone.displayname.standard.long";
+    private static final String TZ_STD_LONG_KEY = "timezone.displayname.standard.long";
-    private final static String TZ_STD_SHORT_KEY = "timezone.displayname.standard.short";
+    private static final String TZ_STD_SHORT_KEY = "timezone.displayname.standard.short";
-    private final static String TZ_DST_LONG_KEY = "timezone.displayname.daylight.long";
+    private static final String TZ_DST_LONG_KEY = "timezone.displayname.daylight.long";
-    private final static String TZ_DST_SHORT_KEY = "timezone.displayname.daylight.short";
+    private static final String TZ_DST_SHORT_KEY = "timezone.displayname.daylight.short";
-    private final static String[] ZONE_NAME_KEYS = {
+    private static final String[] ZONE_NAME_KEYS = {
         TZ_STD_LONG_KEY,
         TZ_STD_SHORT_KEY,
         TZ_DST_LONG_KEY,
@@ -262,7 +270,7 @@ class Bundle {
         CLDRConverter.handleAliases(myMap);
 
         // another hack: parentsMap is not used for date-time resources.
-        if ("root".equals(id)) {
+        if (isRoot()) {
             parentsMap = null;
         }
 
@@ -287,6 +295,14 @@ class Bundle {
             handleDateTimeFormatPatterns(TIME_PATTERN_KEYS, myMap, parentsMap, calendarType, "TimePatterns");
             handleDateTimeFormatPatterns(DATE_PATTERN_KEYS, myMap, parentsMap, calendarType, "DatePatterns");
             handleDateTimeFormatPatterns(DATETIME_PATTERN_KEYS, myMap, parentsMap, calendarType, "DateTimePatterns");
+
+            // Skeleton
+            handleSkeletonPatterns(myMap, calendarType);
+        }
+
+        // Skeleton input regions
+        if (isRoot()) {
+            skeletonInputRegions(myMap);
         }
 
         // First, weed out any empty timezone or metazone names from myMap.
@@ -647,8 +663,9 @@ class Bundle {
     private void convertDateTimePatternLetter(CalendarType calendarType, char cldrLetter, int count, StringBuilder sb) {
         switch (cldrLetter) {
             case 'u':
-                // Change cldr letter 'u' to 'y', as 'u' is interpreted as
+            case 'U':
-                // "Extended year (numeric)" in CLDR/LDML,
+                // Change cldr letter 'u'/'U' to 'y', as 'u' is interpreted as
+                // "Extended year (numeric)", and 'U' as "Cyclic year" in CLDR/LDML,
                 // which is not supported in SimpleDateFormat and
                 // j.t.f.DateTimeFormatter, so it is replaced with 'y'
                 // as the best approximation
@@ -742,6 +759,19 @@ class Bundle {
         return false;
     }
 
+    private void handleSkeletonPatterns(Map<String, Object> myMap, CalendarType calendarType) {
+        String calendarPrefix = calendarType.keyElementName();
+        myMap.putAll(myMap.entrySet().stream()
+            .filter(e -> e.getKey().startsWith(Bundle.DATEFORMATITEM_KEY_PREFIX))
+            .collect(Collectors.toMap(
+                e -> calendarPrefix + e.getKey(),
+                e -> translateDateFormatLetters(calendarType,
+                        (String)e.getValue(),
+                        this::convertDateTimePatternLetter)
+            ))
+        );
+    }
+
     @FunctionalInterface
     private interface ConvertDateTimeLetters {
         void convert(CalendarType calendarType, char cldrLetter, int count, StringBuilder sb);
@@ -790,4 +820,14 @@ class Bundle {
         }
         return numArray;
     }
+
+    private static void skeletonInputRegions(Map<String, Object> myMap) {
+        myMap.putAll(myMap.entrySet().stream()
+                .filter(e -> e.getKey().startsWith(Bundle.DATEFORMATITEM_INPUT_REGIONS_PREFIX))
+                .collect(Collectors.toMap(
+                        e -> e.getKey(),
+                        e -> ((String)e.getValue()).trim()
+                ))
+        );
+    }
 }

make/jdk/src/classes/build/tools/cldrconverter/CLDRConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -847,20 +847,19 @@ public class CLDRConverter {
         "DateTimePatternChars",
         "PluralRules",
         "DayPeriodRules",
+        "DateFormatItem",
     };
 
     private static Map<String, Object> extractFormatData(Map<String, Object> map, String id) {
         Map<String, Object> formatData = new LinkedHashMap<>();
         for (CalendarType calendarType : CalendarType.values()) {
-            if (calendarType == CalendarType.GENERIC) {
-                continue;
-            }
             String prefix = calendarType.keyElementName();
-            for (String element : FORMAT_DATA_ELEMENTS) {
+            Arrays.stream(FORMAT_DATA_ELEMENTS)
-                String key = prefix + element;
+                .flatMap(elem -> map.keySet().stream().filter(k -> k.startsWith(prefix + elem)))
+                .forEach(key -> {
                     copyIfPresent(map, "java.time." + key, formatData);
                     copyIfPresent(map, key, formatData);
-            }
+                });
         }
 
         for (String key : map.keySet()) {
@@ -868,9 +867,6 @@ public class CLDRConverter {
             if (key.startsWith(CLDRConverter.LOCALE_TYPE_PREFIX_CA)) {
                 String type = key.substring(CLDRConverter.LOCALE_TYPE_PREFIX_CA.length());
                 for (CalendarType calendarType : CalendarType.values()) {
-                    if (calendarType == CalendarType.GENERIC) {
-                        continue;
-                    }
                     if (type.equals(calendarType.lname())) {
                         Object value = map.get(key);
                         String dataKey = key.replace(LOCALE_TYPE_PREFIX_CA,

make/jdk/src/classes/build/tools/cldrconverter/LDMLParseHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -756,6 +756,14 @@ class LDMLParseHandler extends AbstractLDMLHandler<Object> {
                 pushStringEntry(qName, attributes, prefix + "DateTimePatterns/" + attributes.getValue("type") + "-dateTime");
             }
             break;
+        case "dateFormatItem":
+            {
+                // for FormatData
+                String prefix = (currentCalendarType == null) ? "" : currentCalendarType.keyElementName();
+                pushStringEntry(qName, attributes,
+                        prefix + Bundle.DATEFORMATITEM_KEY_PREFIX + attributes.getValue("id"));
+            }
+            break;
         case "localizedPatternChars":
             {
                 // for FormatData
@@ -1113,7 +1121,7 @@ class LDMLParseHandler extends AbstractLDMLHandler<Object> {
                 if (id.equals("root") && key.startsWith("MonthNames")) {
                     value = new DateFormatSymbols(Locale.US).getShortMonths();
                 }
-                return put(entry.getKey(), value);
+                return put(key, value);
             }
         }
         return null;

make/jdk/src/classes/build/tools/cldrconverter/SupplementDataParseHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,8 +27,12 @@ package build.tools.cldrconverter;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.SortedSet;
+import java.util.TreeSet;
+import java.util.stream.Collectors;
 import org.xml.sax.Attributes;
 import org.xml.sax.InputSource;
 import org.xml.sax.SAXException;
@@ -62,10 +66,15 @@ class SupplementDataParseHandler extends AbstractLDMLHandler<Object> {
     // parentLocale.<parent_locale_id>=<child_locale_id>(" "<child_locale_id>)+
     private final Map<String, String> parentLocalesMap;
 
+    // Input Skeleton map for "preferred" and "allowed"
+    // Map<"preferred"/"allowed", Map<"skeleton", SortedSet<"regions">>>
+    private final Map<String, Map<String, SortedSet<String>>> inputSkeletonMap;
+
     SupplementDataParseHandler() {
         firstDayMap = new HashMap<>();
         minDaysMap = new HashMap<>();
         parentLocalesMap = new HashMap<>();
+        inputSkeletonMap = new HashMap<>();
     }
 
     /**
@@ -76,22 +85,25 @@ class SupplementDataParseHandler extends AbstractLDMLHandler<Object> {
      * It returns null when there is no firstDay and minDays for the country
      * although this should not happen because supplementalData.xml includes
      * default value for the world ("001") for firstDay and minDays.
+     *
+     * This method also returns Maps for "preferred" and "allowed" skeletons,
+     * which are grouped by regions. E.g, "h:XX YY ZZ;" which means 'h' pattern
+     * is "preferred"/"allowed" in "XX", "YY", and "ZZ" regions.
      */
     Map<String, Object> getData(String id) {
         Map<String, Object> values = new HashMap<>();
         if ("root".equals(id)) {
-            parentLocalesMap.keySet().forEach(key -> {
+            parentLocalesMap.forEach((k, v) -> values.put(CLDRConverter.PARENT_LOCALE_PREFIX + k, v));
-            values.put(CLDRConverter.PARENT_LOCALE_PREFIX+key,
+            firstDayMap.forEach((k, v) -> values.put(CLDRConverter.CALENDAR_FIRSTDAY_PREFIX + v, k));
-                parentLocalesMap.get(key));
+            minDaysMap.forEach((k, v) -> values.put(CLDRConverter.CALENDAR_MINDAYS_PREFIX + v, k));
-            });
+            inputSkeletonMap.get("preferred").forEach((k, v) ->
-            firstDayMap.keySet().forEach(key -> {
+                    values.merge(Bundle.DATEFORMATITEM_INPUT_REGIONS_PREFIX + "preferred",
-            values.put(CLDRConverter.CALENDAR_FIRSTDAY_PREFIX+firstDayMap.get(key),
+                            k + ":" + v.stream().collect(Collectors.joining(" ")) + ";",
-                key);
+                            (old, newVal) -> old + (String)newVal));
-            });
+            inputSkeletonMap.get("allowed").forEach((k, v) ->
-            minDaysMap.keySet().forEach(key -> {
+                    values.merge(Bundle.DATEFORMATITEM_INPUT_REGIONS_PREFIX + "allowed",
-            values.put(CLDRConverter.CALENDAR_MINDAYS_PREFIX+minDaysMap.get(key),
+                            k + ":" + v.stream().collect(Collectors.joining(" ")) + ";",
-                key);
+                            (old, newVal) -> old + (String)newVal));
-            });
         }
         return values.isEmpty() ? null : values;
     }
@@ -158,11 +170,23 @@ class SupplementDataParseHandler extends AbstractLDMLHandler<Object> {
                     attributes.getValue("locales").replaceAll("_", "-"));
             }
             break;
+        case "hours":
+            if (!isIgnored(attributes)) {
+                var preferred = attributes.getValue("preferred");
+                var allowed = attributes.getValue("allowed").replaceFirst(" .*", "").replaceFirst("b", "B"); // take only the first one, "b" -> "B"
+                var regions = Arrays.stream(attributes.getValue("regions").split(" "))
+                        .map(r -> r.replaceAll("_", "-"))
+                        .collect(Collectors.toSet());
+                var pmap = inputSkeletonMap.computeIfAbsent("preferred", k -> new HashMap<>());
+                var amap = inputSkeletonMap.computeIfAbsent("allowed", k -> new HashMap<>());
+                pmap.computeIfAbsent(preferred, k -> new TreeSet<>()).addAll(regions);
+                amap.computeIfAbsent(allowed, k -> new TreeSet<>()).addAll(regions);
+            }
+            break;
         default:
             // treat anything else as a container
             pushContainer(qName, attributes);
             break;
         }
     }
-
 }

src/java.base/share/classes/java/time/format/DateTimeFormatter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -81,7 +81,6 @@ import java.time.Period;
 import java.time.ZoneId;
 import java.time.ZoneOffset;
 import java.time.chrono.ChronoLocalDateTime;
-import java.time.chrono.ChronoZonedDateTime;
 import java.time.chrono.Chronology;
 import java.time.chrono.IsoChronology;
 import java.time.format.DateTimeFormatterBuilder.CompositePrinterParser;
@@ -718,6 +717,57 @@ public final class DateTimeFormatter {
                 .toFormatter(ResolverStyle.SMART, IsoChronology.INSTANCE);
     }
 
+    //-----------------------------------------------------------------------
+    /**
+     * 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) {
+        return new DateTimeFormatterBuilder().appendLocalized(requestedTemplate)
+                .toFormatter(ResolverStyle.SMART, IsoChronology.INSTANCE);
+    }
+
     //-----------------------------------------------------------------------
     /**
      * The ISO date formatter that formats or parses a date without an

src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -227,6 +227,42 @@ public final class DateTimeFormatterBuilder {
                          CalendarDataUtility.findRegionOverride(locale));
     }
 
+    /**
+     * 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) {
+        Objects.requireNonNull(requestedTemplate, "requestedTemplate");
+        Objects.requireNonNull(chrono, "chrono");
+        Objects.requireNonNull(locale, "locale");
+        Locale override = CalendarDataUtility.findRegionOverride(locale);
+        LocaleProviderAdapter adapter = LocaleProviderAdapter.getAdapter(JavaTimeDateTimePatternProvider.class, override);
+        JavaTimeDateTimePatternProvider provider = adapter.getJavaTimeDateTimePatternProvider();
+        return provider.getJavaTimeDateTimePattern(requestedTemplate,
+                chrono.getCalendarType(),
+                override);
+    }
+
     /**
      * Converts the given FormatStyle to the java.text.DateFormat style.
      *
@@ -1423,6 +1459,84 @@ public final class DateTimeFormatterBuilder {
         return this;
     }
 
+    //-----------------------------------------------------------------------
+    // RegEx pattern for skeleton validity checking
+    private static final Pattern VALID_TEMPLATE_PATTERN = Pattern.compile(
+        "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
+        "m{0,2}" +        // Minute of Hour
+        "s{0,2}" +        // Second of Minute
+        "[vz]{0,4}");     // Zone
+    /**
+     * 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) {
+        Objects.requireNonNull(requestedTemplate, "requestedTemplate");
+        if (!VALID_TEMPLATE_PATTERN.matcher(requestedTemplate).matches()) {
+            throw new IllegalArgumentException("Requested template is invalid: " + requestedTemplate);
+        }
+        appendInternal(new LocalizedPrinterParser(requestedTemplate));
+        return this;
+    }
+
     //-----------------------------------------------------------------------
     /**
      * Appends a character literal to the formatter.
@@ -2378,11 +2492,11 @@ public final class DateTimeFormatterBuilder {
         private final DateTimePrinterParser[] printerParsers;
         private final boolean optional;
 
-        CompositePrinterParser(List<DateTimePrinterParser> printerParsers, boolean optional) {
+        private CompositePrinterParser(List<DateTimePrinterParser> printerParsers, boolean optional) {
             this(printerParsers.toArray(new DateTimePrinterParser[0]), optional);
         }
 
-        CompositePrinterParser(DateTimePrinterParser[] printerParsers, boolean optional) {
+        private CompositePrinterParser(DateTimePrinterParser[] printerParsers, boolean optional) {
             this.printerParsers = printerParsers;
             this.optional = optional;
         }
@@ -2476,7 +2590,7 @@ public final class DateTimeFormatterBuilder {
          * @param padWidth  the width to pad to, 1 or greater
          * @param padChar  the pad character
          */
-        PadPrinterParserDecorator(DateTimePrinterParser printerParser, int padWidth, char padChar) {
+        private PadPrinterParserDecorator(DateTimePrinterParser printerParser, int padWidth, char padChar) {
             // input checked by DateTimeFormatterBuilder
             this.printerParser = printerParser;
             this.padWidth = padWidth;
@@ -2584,7 +2698,7 @@ public final class DateTimeFormatterBuilder {
         private final TemporalField field;
         private final long value;
 
-        DefaultValueParser(TemporalField field, long value) {
+        private DefaultValueParser(TemporalField field, long value) {
             this.field = field;
             this.value = value;
         }
@@ -2608,7 +2722,7 @@ public final class DateTimeFormatterBuilder {
     static final class CharLiteralPrinterParser implements DateTimePrinterParser {
         private final char literal;
 
-        CharLiteralPrinterParser(char literal) {
+        private CharLiteralPrinterParser(char literal) {
             this.literal = literal;
         }
 
@@ -2651,7 +2765,7 @@ public final class DateTimeFormatterBuilder {
     static final class StringLiteralPrinterParser implements DateTimePrinterParser {
         private final String literal;
 
-        StringLiteralPrinterParser(String literal) {
+        private StringLiteralPrinterParser(String literal) {
             this.literal = literal;  // validated by caller
         }
 
@@ -2717,7 +2831,7 @@ public final class DateTimeFormatterBuilder {
          * @param maxWidth  the maximum field width, from minWidth to 19
          * @param signStyle  the positive/negative sign style, not null
          */
-        NumberPrinterParser(TemporalField field, int minWidth, int maxWidth, SignStyle signStyle) {
+        private NumberPrinterParser(TemporalField field, int minWidth, int maxWidth, SignStyle signStyle) {
             // validated by caller
             this.field = field;
             this.minWidth = minWidth;
@@ -3008,7 +3122,7 @@ public final class DateTimeFormatterBuilder {
          * @param baseValue  the base value
          * @param baseDate  the base date
          */
-        ReducedPrinterParser(TemporalField field, int minWidth, int maxWidth,
+        private ReducedPrinterParser(TemporalField field, int minWidth, int maxWidth,
                 int baseValue, ChronoLocalDate baseDate) {
             this(field, minWidth, maxWidth, baseValue, baseDate, 0);
             if (minWidth < 1 || minWidth > 10) {
@@ -3161,7 +3275,7 @@ public final class DateTimeFormatterBuilder {
          * @param maxWidth  the maximum width to output, from 0 to 9
          * @param decimalPoint  whether to output the localized decimal point symbol
          */
-        NanosPrinterParser(int minWidth, int maxWidth, boolean decimalPoint) {
+        private NanosPrinterParser(int minWidth, int maxWidth, boolean decimalPoint) {
             this(minWidth, maxWidth, decimalPoint, 0);
             if (minWidth < 0 || minWidth > 9) {
                 throw new IllegalArgumentException("Minimum width must be from 0 to 9 inclusive but was " + minWidth);
@@ -3183,7 +3297,7 @@ public final class DateTimeFormatterBuilder {
          * @param decimalPoint  whether to output the localized decimal point symbol
          * @param subsequentWidth the subsequentWidth for this instance
          */
-        NanosPrinterParser(int minWidth, int maxWidth, boolean decimalPoint, int subsequentWidth) {
+        private NanosPrinterParser(int minWidth, int maxWidth, boolean decimalPoint, int subsequentWidth) {
             super(NANO_OF_SECOND, minWidth, maxWidth, SignStyle.NOT_NEGATIVE, subsequentWidth);
             this.decimalPoint = decimalPoint;
         }
@@ -3366,7 +3480,7 @@ public final class DateTimeFormatterBuilder {
          * @param maxWidth  the maximum width to output, from 0 to 9
          * @param decimalPoint  whether to output the localized decimal point symbol
          */
-        FractionPrinterParser(TemporalField field, int minWidth, int maxWidth, boolean decimalPoint) {
+        private FractionPrinterParser(TemporalField field, int minWidth, int maxWidth, boolean decimalPoint) {
             this(field, minWidth, maxWidth, decimalPoint, 0);
             Objects.requireNonNull(field, "field");
             if (field.range().isFixed() == false) {
@@ -3393,7 +3507,7 @@ public final class DateTimeFormatterBuilder {
          * @param decimalPoint  whether to output the localized decimal point symbol
          * @param subsequentWidth the subsequentWidth for this instance
          */
-        FractionPrinterParser(TemporalField field, int minWidth, int maxWidth, boolean decimalPoint, int subsequentWidth) {
+        private FractionPrinterParser(TemporalField field, int minWidth, int maxWidth, boolean decimalPoint, int subsequentWidth) {
             super(field, minWidth, maxWidth, SignStyle.NOT_NEGATIVE, subsequentWidth);
             this.decimalPoint = decimalPoint;
             ValueRange range = field.range();
@@ -3583,7 +3697,7 @@ public final class DateTimeFormatterBuilder {
          * @param textStyle  the text style, not null
          * @param provider  the text provider, not null
          */
-        TextPrinterParser(TemporalField field, TextStyle textStyle, DateTimeTextProvider provider) {
+        private TextPrinterParser(TemporalField field, TextStyle textStyle, DateTimeTextProvider provider) {
             // validated by caller
             this.field = field;
             this.textStyle = textStyle;
@@ -3681,7 +3795,7 @@ public final class DateTimeFormatterBuilder {
         private static final long SECONDS_0000_TO_1970 = ((146097L * 5L) - (30L * 365L + 7L)) * 86400L;
         private final int fractionalDigits;
 
-        InstantPrinterParser(int fractionalDigits) {
+        private InstantPrinterParser(int fractionalDigits) {
             this.fractionalDigits = fractionalDigits;
         }
 
@@ -3830,7 +3944,7 @@ public final class DateTimeFormatterBuilder {
          * @param pattern  the pattern
          * @param noOffsetText  the text to use for UTC, not null
          */
-        OffsetIdPrinterParser(String pattern, String noOffsetText) {
+        private OffsetIdPrinterParser(String pattern, String noOffsetText) {
             Objects.requireNonNull(pattern, "pattern");
             Objects.requireNonNull(noOffsetText, "noOffsetText");
             this.type = checkPattern(pattern);
@@ -4312,7 +4426,7 @@ public final class DateTimeFormatterBuilder {
 
         /**  Display in generic time-zone format. True in case of pattern letter 'v' */
         private final boolean isGeneric;
-        ZoneTextPrinterParser(TextStyle textStyle, Set<ZoneId> preferredZones, boolean isGeneric) {
+        private ZoneTextPrinterParser(TextStyle textStyle, Set<ZoneId> preferredZones, boolean isGeneric) {
             super(TemporalQueries.zone(), "ZoneText(" + textStyle + ")");
             this.textStyle = Objects.requireNonNull(textStyle, "textStyle");
             this.isGeneric = isGeneric;
@@ -4484,7 +4598,7 @@ public final class DateTimeFormatterBuilder {
         private final TemporalQuery<ZoneId> query;
         private final String description;
 
-        ZoneIdPrinterParser(TemporalQuery<ZoneId> query, String description) {
+        private ZoneIdPrinterParser(TemporalQuery<ZoneId> query, String description) {
             this.query = query;
             this.description = description;
         }
@@ -4903,7 +5017,7 @@ public final class DateTimeFormatterBuilder {
         /** The text style to output, null means the ID. */
         private final TextStyle textStyle;
 
-        ChronoPrinterParser(TextStyle textStyle) {
+        private ChronoPrinterParser(TextStyle textStyle) {
             // validated by caller
             this.textStyle = textStyle;
         }
@@ -4978,6 +5092,7 @@ public final class DateTimeFormatterBuilder {
 
         private final FormatStyle dateStyle;
         private final FormatStyle timeStyle;
+        private final String requestedTemplate;
 
         /**
          * Constructor.
@@ -4985,10 +5100,23 @@ public final class DateTimeFormatterBuilder {
          * @param dateStyle  the date style to use, may be null
          * @param timeStyle  the time style to use, may be null
          */
-        LocalizedPrinterParser(FormatStyle dateStyle, FormatStyle timeStyle) {
+        private LocalizedPrinterParser(FormatStyle dateStyle, FormatStyle timeStyle) {
-            // validated by caller
+            // params validated by caller
             this.dateStyle = dateStyle;
             this.timeStyle = timeStyle;
+            this.requestedTemplate = null;
+        }
+
+        /**
+         * Constructor.
+         *
+         * @param requestedTemplate the requested template to use, not null
+         */
+        private LocalizedPrinterParser(String requestedTemplate) {
+            // param validated by caller
+            this.dateStyle = null;
+            this.timeStyle = null;
+            this.requestedTemplate = requestedTemplate;
         }
 
         @Override
@@ -5006,7 +5134,8 @@ public final class DateTimeFormatterBuilder {
         /**
          * Gets the formatter to use.
          * <p>
-         * The formatter will be the most appropriate to use for the date and time style in the locale.
+         * The formatter will be the most appropriate to use for the date and time style, or
+         * the requested template for the locale.
          * For example, some locales will use the month name while others will use the number.
          *
          * @param locale  the locale to use, not null
@@ -5015,23 +5144,22 @@ public final class DateTimeFormatterBuilder {
          * @throws IllegalArgumentException if the formatter cannot be found
          */
         private DateTimeFormatter formatter(Locale locale, Chronology chrono) {
-            String key = chrono.getId() + '|' + locale.toString() + '|' + dateStyle + timeStyle;
+            String key = chrono.getId() + '|' + locale.toString() + '|' +
-            DateTimeFormatter formatter = FORMATTER_CACHE.get(key);
+                    (requestedTemplate != null ? requestedTemplate : Objects.toString(dateStyle) + timeStyle);
-            if (formatter == null) {
+
-                String pattern = getLocalizedDateTimePattern(dateStyle, timeStyle, chrono, locale);
+            return FORMATTER_CACHE.computeIfAbsent(key, k ->
-                formatter = new DateTimeFormatterBuilder().appendPattern(pattern).toFormatter(locale);
+                new DateTimeFormatterBuilder()
-                DateTimeFormatter old = FORMATTER_CACHE.putIfAbsent(key, formatter);
+                    .appendPattern(requestedTemplate != null ?
-                if (old != null) {
+                        getLocalizedDateTimePattern(requestedTemplate, chrono, locale) :
-                    formatter = old;
+                        getLocalizedDateTimePattern(dateStyle, timeStyle, chrono, locale))
-                }
+                    .toFormatter(locale));
-            }
-            return formatter;
         }
 
         @Override
         public String toString() {
-            return "Localized(" + (dateStyle != null ? dateStyle : "") + "," +
+            return "Localized(" + (requestedTemplate != null ? requestedTemplate :
-                (timeStyle != null ? timeStyle : "") + ")";
+                (dateStyle != null ? dateStyle : "") + "," +
+                (timeStyle != null ? timeStyle : "")) + ")";
         }
     }
 
@@ -5056,7 +5184,7 @@ public final class DateTimeFormatterBuilder {
          * @param minWidth  the minimum field width, from 1 to 19
          * @param maxWidth  the maximum field width, from minWidth to 19
          */
-        WeekBasedFieldPrinterParser(char chr, int count, int minWidth, int maxWidth) {
+        private WeekBasedFieldPrinterParser(char chr, int count, int minWidth, int maxWidth) {
             this(chr, count, minWidth, maxWidth, 0);
         }
 
@@ -5070,7 +5198,7 @@ public final class DateTimeFormatterBuilder {
          * @param subsequentWidth  the width of subsequent non-negative numbers, 0 or greater,
          * -1 if fixed width due to active adjacent parsing
          */
-        WeekBasedFieldPrinterParser(char chr, int count, int minWidth, int maxWidth,
+        private WeekBasedFieldPrinterParser(char chr, int count, int minWidth, int maxWidth,
                 int subsequentWidth) {
             super(null, minWidth, maxWidth, SignStyle.NOT_NEGATIVE, subsequentWidth);
             this.chr = chr;
@@ -5201,7 +5329,7 @@ public final class DateTimeFormatterBuilder {
          *
          * @param textStyle  the text style, not null
          */
-        DayPeriodPrinterParser(TextStyle textStyle) {
+        private DayPeriodPrinterParser(TextStyle textStyle) {
             // validated by caller
             this.textStyle = textStyle;
         }

src/java.base/share/classes/sun/text/spi/JavaTimeDateTimePatternProvider.java

@@ -27,6 +27,7 @@
 
 package sun.text.spi;
 
+import java.time.DateTimeException;
 import java.util.Locale;
 import java.util.spi.LocaleServiceProvider;
 
@@ -41,10 +42,10 @@ public abstract class JavaTimeDateTimePatternProvider extends LocaleServiceProvi
     }
 
     /**
-     * Gets the formatting pattern for a timeStyle
+     * Returns the formatting pattern for a timeStyle
      * dateStyle, calendarType and locale.
      * Concrete implementation of this method will retrieve
-     * a java.time specific dateTime Pattern from selected Locale Provider.
+     * a java.time specific dateTime Pattern from the selected Locale Provider.
      *
      * @param timeStyle an {@code int} value, representing FormatStyle constant, -1
      * for date-only pattern
@@ -58,4 +59,26 @@ public abstract class JavaTimeDateTimePatternProvider extends LocaleServiceProvi
      * @since 9
      */
     public abstract String getJavaTimeDateTimePattern(int timeStyle, int dateStyle, String calType, Locale locale);
+
+    /**
+     * Returns the formatting pattern for the requested template, calendarType, and locale.
+     * Concrete implementation of this method will retrieve
+     * a java.time specific pattern from selected Locale Provider.
+     *
+     * @param requestedTemplate the requested template, not null
+     * @param calType a {@code String}, non-null representing CalendarType such as "japanese",
+     * "iso8601"
+     * @param locale {@code locale}, non-null
+     * @throws IllegalArgumentException if {@code requestedTemplate} does not match
+     *      the regular expression syntax described in
+     *      {@link java.time.format.DateTimeFormatterBuilder#appendLocalized(String)}.
+     * @throws DateTimeException if a match for the formatting pattern for
+     *      {@code requestedTemplate} is not available
+     * @return  formatting pattern {@code String}
+     * @since 19
+     */
+    public String getJavaTimeDateTimePattern(String requestedTemplate, String calType, Locale locale) {
+        // default implementation throws exception
+        throw new DateTimeException("Formatting pattern is not available for the requested template: " + requestedTemplate);
+    }
 }

src/java.base/share/classes/sun/util/locale/provider/JavaTimeDateTimePatternImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -24,7 +24,10 @@
  */
 package sun.util.locale.provider;
 
+import java.time.DateTimeException;
 import java.util.Locale;
+import java.util.Objects;
+import java.util.Optional;
 import java.util.Set;
 import sun.text.spi.JavaTimeDateTimePatternProvider;
 
@@ -63,10 +66,21 @@ public class JavaTimeDateTimePatternImpl extends JavaTimeDateTimePatternProvider
     @Override
     public String getJavaTimeDateTimePattern(int timeStyle, int dateStyle, String calType, Locale locale) {
         LocaleResources lr = LocaleProviderAdapter.getResourceBundleBased().getLocaleResources(locale);
-        String pattern = lr.getJavaTimeDateTimePattern(
+        return lr.getJavaTimeDateTimePattern(timeStyle, dateStyle, calType);
-                timeStyle, dateStyle, calType);
+    }
-        return pattern;
 
+    @Override
+    public String getJavaTimeDateTimePattern(String requestedTemplate, String calType, Locale locale) {
+        LocaleProviderAdapter lpa = LocaleProviderAdapter.getResourceBundleBased();
+        return ((ResourceBundleBasedAdapter)lpa).getCandidateLocales("", locale).stream()
+                .map(lpa::getLocaleResources)
+                .map(lr -> lr.getLocalizedPattern(requestedTemplate, calType))
+                .filter(Objects::nonNull)
+                .findFirst()
+                .or(() -> calType.equals("generic") ? Optional.empty():
+                        Optional.of(getJavaTimeDateTimePattern(requestedTemplate, "generic", locale)))
+                .orElseThrow(() -> new DateTimeException("Requested template \"" + requestedTemplate +
+                        "\" cannot be resolved in the locale \"" + locale + "\""));
     }
 
     @Override

src/java.base/share/classes/sun/util/locale/provider/LocaleResources.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -46,15 +46,21 @@ import java.text.MessageFormat;
 import java.text.NumberFormat;
 import java.util.Arrays;
 import java.util.Calendar;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Locale;
+import java.util.Map;
 import java.util.Objects;
 import java.util.ResourceBundle;
 import java.util.Set;
 import java.util.TimeZone;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
+import java.util.regex.Pattern;
+import java.util.stream.Stream;
+
 import sun.security.action.GetPropertyAction;
 import sun.util.resources.LocaleData;
 import sun.util.resources.OpenListResourceBundle;
@@ -91,6 +97,10 @@ public class LocaleResources {
     private static final String COMPACT_NUMBER_PATTERNS_CACHEKEY = "CNP";
     private static final String DATE_TIME_PATTERN = "DTP.";
     private static final String RULES_CACHEKEY = "RULE";
+    private static final String SKELETON_PATTERN = "SP.";
+
+    // ResourceBundle key names for skeletons
+    private static final String SKELETON_INPUT_REGIONS_KEY = "DateFormatItemInputRegions";
 
     // TimeZoneNamesBundle exemplar city prefix
     private static final String TZNB_EXCITY_PREFIX = "timezone.excity.";
@@ -98,6 +108,31 @@ public class LocaleResources {
     // null singleton cache value
     private static final Object NULLOBJECT = new Object();
 
+    // RegEx pattern for skeleton validity checking
+    private static final Pattern VALID_SKELETON_PATTERN = Pattern.compile(
+        "(?<date>" +
+        "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
+        "(?<time>" +
+        "B{0,5}" +        // Period/AmPm of Day
+        "[hHjC]{0,2}" +   // Hour of Day/AmPm
+        "m{0,2}" +        // Minute of Hour
+        "s{0,2}" +        // Second of Minute
+        "[vz]{0,4})");    // Zone
+
+    // Input Skeleton map for "preferred" and "allowed"
+    // Map<"preferred"/"allowed", Map<"region", "skeleton">>
+    private static Map<String, Map<String, String>> inputSkeletons;
+
+    // Skeletons for "j" and "C" input skeleton symbols for this locale
+    private String jPattern;
+    private String CPattern;
+
     LocaleResources(ResourceBundleBasedAdapter adapter, Locale locale) {
         this.locale = locale;
         this.localeData = adapter.getLocaleData();
@@ -531,6 +566,202 @@ public class LocaleResources {
         return rb;
     }
 
+    /**
+     * Returns the actual format pattern string based on the requested template
+     * and calendar type for this locale.
+     *
+     * @param requestedTemplate requested template
+     * @param calType calendar type
+     * @throws IllegalArgumentException if the requested template is invalid
+     * @return format pattern string for this locale, null if not found
+     */
+    public String getLocalizedPattern(String requestedTemplate, String calType) {
+        String pattern;
+        String cacheKey = SKELETON_PATTERN + calType + "." + requestedTemplate;
+
+        removeEmptyReferences();
+        ResourceReference data = cache.get(cacheKey);
+
+        if (data == null || ((pattern = (String) data.get()) == null)) {
+            pattern = getLocalizedPatternImpl(requestedTemplate, calType);
+            cache.put(cacheKey,
+                new ResourceReference(cacheKey, pattern != null ? pattern : "", referenceQueue));
+        } else if ("".equals(pattern)) {
+            // non-existent pattern
+            pattern = null;
+        }
+
+        return pattern;
+    }
+
+    private String getLocalizedPatternImpl(String requestedTemplate, String calType) {
+        initSkeletonIfNeeded();
+
+        // input skeleton substitution
+        var skeleton = substituteInputSkeletons(requestedTemplate);
+
+        // validity check
+        var matcher = VALID_SKELETON_PATTERN.matcher(skeleton);
+        if (!matcher.matches()) {
+            throw new IllegalArgumentException("Requested template \"%s\" is invalid".formatted(requestedTemplate) +
+                    (requestedTemplate.equals(skeleton) ? "." : ", which translated into \"%s\"".formatted(skeleton) +
+                            " after the 'j' or 'C' substitution."));
+        }
+
+        // try to match entire requested template first
+        String matched = matchSkeleton(skeleton, calType);
+        if (matched == null) {
+            // 2.6.2.2 Missing Skeleton Fields
+            var dateMatched = matchSkeleton(matcher.group("date"), calType);
+            var timeMatched = matchSkeleton(matcher.group("time"), calType);
+            if (dateMatched != null && timeMatched != null) {
+                // combine both matches
+                var style = switch (requestedTemplate.replaceAll("[^M]+", "").length()) {
+                    case 4 -> requestedTemplate.indexOf('E') >= 0 ? 0 : 1;
+                    case 3 -> 2;
+                    default -> 3;
+                };
+                var dateTimePattern = getDateTimePattern(null, "DateTimePatterns", style, calType);
+                matched = MessageFormat.format(dateTimePattern.replaceAll("'", "''"), timeMatched, dateMatched);
+            }
+        }
+
+        trace("requested: %s, locale: %s, calType: %s, matched: %s\n", requestedTemplate, locale, calType, matched);
+
+        return matched;
+    }
+
+    private String matchSkeleton(String skeleton, String calType) {
+        // Expand it with possible inferred skeleton stream based on its priority
+        var inferred = possibleInferred(skeleton);
+
+        // Search the closest format pattern string from the resource bundle
+        ResourceBundle r = localeData.getDateFormatData(locale);
+        return inferred
+            .map(s -> ("gregory".equals(calType) ? "" : calType + ".") + "DateFormatItem." + s)
+            .map(key -> r.containsKey(key) ? r.getString(key) : null)
+            .filter(Objects::nonNull)
+            .findFirst()
+            .orElse(null);
+    }
+
+    private void initSkeletonIfNeeded() {
+        // "preferred"/"allowed" input skeleton maps
+        if (inputSkeletons == null) {
+            inputSkeletons = new HashMap<>();
+            Pattern p = Pattern.compile("([^:]+):([^;]+);");
+            ResourceBundle r = localeData.getDateFormatData(Locale.ROOT);
+            Stream.of("preferred", "allowed").forEach(type -> {
+                var inputRegionsKey = SKELETON_INPUT_REGIONS_KEY + "." + type;
+                Map<String, String> typeMap = new HashMap<>();
+
+                if (r.containsKey(inputRegionsKey)) {
+                    p.matcher(r.getString(inputRegionsKey)).results()
+                        .forEach(mr ->
+                            Arrays.stream(mr.group(2).split(" "))
+                                .forEach(region -> typeMap.put(region, mr.group(1))));
+                }
+                inputSkeletons.put(type, typeMap);
+            });
+        }
+
+        // j/C patterns for this locale
+        if (jPattern == null) {
+            jPattern = resolveInputSkeleton("preferred");
+            CPattern = resolveInputSkeleton("allowed");
+            // hack: "allowed" contains reversed order for hour/period, e.g, "hB" which should be "Bh" as a skeleton
+            if (CPattern.length() == 2) {
+                var ba = new byte[2];
+                ba[0] = (byte)CPattern.charAt(1);
+                ba[1] = (byte)CPattern.charAt(0);
+                CPattern = new String(ba);
+            }
+        }
+    }
+
+    /**
+     * Resolve locale specific input skeletons. Fall back method is different from usual
+     * resource bundle's, as it has to be "lang-region" -> "region" -> "lang-001" -> "001"
+     * @param type type of the input skeleton
+     * @return resolved skeletons for this locale, defaults to "h" if none found.
+     */
+    private String resolveInputSkeleton(String type) {
+        var regionToSkeletonMap = inputSkeletons.get(type);
+        return regionToSkeletonMap.getOrDefault(locale.getLanguage() + "-" + locale.getCountry(),
+            regionToSkeletonMap.getOrDefault(locale.getCountry(),
+                regionToSkeletonMap.getOrDefault(locale.getLanguage() + "-001",
+                    regionToSkeletonMap.getOrDefault("001", "h"))));
+    }
+
+    /**
+     * Replace 'j' and 'C' input skeletons with locale specific patterns. Note that 'j'
+     * is guaranteed to be replaced with one char [hkHK], while 'C' may be replaced with
+     * multiple chars. Repeat each as much as 'C' count.
+     * @param requestedTemplate requested skeleton
+     * @return skeleton with j/C substituted with concrete patterns
+     */
+    private String substituteInputSkeletons(String requestedTemplate) {
+        var cCount = requestedTemplate.chars().filter(c -> c == 'C').count();
+        return requestedTemplate.replaceAll("j", jPattern)
+                .replaceFirst("C+", CPattern.replaceAll("([hkHK])", "$1".repeat((int)cCount)));
+    }
+
+    /**
+     * Returns a stream of possible skeletons, inferring standalone/format (M/L and/or E/c) patterns
+     * and their styles. (cf. 2.6.2.1 Matching Skeletons)
+     *
+     * @param skeleton original skeleton
+     * @return inferred Stream of skeletons in its priority order
+     */
+    private Stream<String> possibleInferred(String skeleton) {
+        return priorityList(skeleton, "M", "L").stream()
+                .flatMap(s -> priorityList(s, "E", "c").stream())
+                .distinct();
+    }
+
+    /**
+     * Inferring the possible format styles in priority order, based on the original
+     * skeleton length.
+     *
+     * @param skeleton skeleton
+     * @param pChar pattern character string
+     * @param subChar substitute character string
+     * @return list of skeletons
+     */
+    private List<String> priorityList(String skeleton, String pChar, String subChar) {
+        int first = skeleton.indexOf(pChar);
+        int last = skeleton.lastIndexOf(pChar);
+
+        if (first >= 0) {
+            var prefix = skeleton.substring(0, first);
+            var suffix = skeleton.substring(last + 1);
+
+            // Priority are based on this chart. First column is the original count of `pChar`,
+            // then it is followed by inferred skeletons base on priority.
+            //
+            // 1->2->3->4 (number form (1-digit) -> number form (2-digit) -> Abbr. form -> Full form)
+            // 2->1->3->4
+            // 3->4->2->1
+            // 4->3->2->1
+            var o1 = prefix + pChar + suffix;
+            var o2 = prefix + pChar.repeat(2) + suffix;
+            var o3 = prefix + pChar.repeat(3) + suffix;
+            var o4 = prefix + pChar.repeat(4) + suffix;
+            var s1 = prefix + subChar + suffix;
+            var s2 = prefix + subChar.repeat(2) + suffix;
+            var s3 = prefix + subChar.repeat(3) + suffix;
+            var s4 = prefix + subChar.repeat(4) + suffix;
+            return switch (last - first) {
+                case 1 -> List.of(skeleton, o1, o2, o3, o4, s1, s2, s3, s4);
+                case 2 -> List.of(skeleton, o2, o1, o3, o4, s2, s1, s3, s4);
+                case 3 -> List.of(skeleton, o3, o4, o2, o1, s3, s4, s2, s1);
+                default -> List.of(skeleton, o4, o3, o2, o1, s4, s3, s2, s1);
+            };
+        } else {
+            return List.of(skeleton);
+        }
+    }
+
     private String getDateTimePattern(String prefix, String key, int styleIndex, String calendarType) {
         StringBuilder sb = new StringBuilder();
         if (prefix != null) {

test/jdk/java/time/test/java/time/format/Skeletons_en_US.properties

@@ -0,0 +1,51 @@
+H=15
+h=3 PM
+j=3 PM
+C=3 PM
+Hm=15:32
+hm=3:32 PM
+jm=3:32 PM
+Cm=3:32 PM
+Hms=15:32:39
+hms=3:32:39 PM
+jms=3:32:39 PM
+Cms=3:32:39 PM
+Hmv=15:32 PT
+hmv=3:32 PM PT
+jmv=3:32 PM PT
+Cmv=3:32 PM PT
+Hmsv=15:32:39 PT
+hmsv=3:32:39 PM PT
+jmsv=3:32:39 PM PT
+Cmsv=3:32:39 PM PT
+Bh=3 in the afternoon
+Bj=3 in the afternoon
+BC=3 in the afternoon
+Bhm=3:32 in the afternoon
+Bjm=3:32 in the afternoon
+BCm=3:32 in the afternoon
+Bhms=3:32:39 in the afternoon
+Bjms=3:32:39 in the afternoon
+BCms=3:32:39 in the afternoon
+
+M=1
+MMM=Jan
+MEd=Wed, 1/26
+MMMMEd=Wed, Jan 26
+d=26
+y=2022
+yM=1/2022
+yMEd=Wed, 1/26/2022
+yMMM=Jan 2022
+yMMMMEd=Wed, Jan 26, 2022
+GyM=Jan 2022 AD
+GyMEd=Wed, Jan 26, 2022 AD
+GyMMM=Jan 2022 AD
+GyMMMMEd=Wed, Jan 26, 2022 AD
+yQQQ=Q1 2022
+yQQQQ=1st quarter 2022
+
+MMMMEdBh=Wed, Jan 26 at 3 in the afternoon
+MMMMdBh=January 26 at 3 in the afternoon
+MMMdBh=Jan 26, 3 in the afternoon
+MdBh=1/26, 3 in the afternoon

test/jdk/java/time/test/java/time/format/Skeletons_ja.properties

@@ -0,0 +1,43 @@
+H=15時
+h=午後3時
+j=15時
+C=15時
+Hm=15:32
+hm=午後3:32
+jm=15:32
+Cm=15:32
+Hms=15:32:39
+hms=午後3:32:39
+jms=15:32:39
+Cms=15:32:39
+Hmv=15:32 PT
+hmv=午後3:32 PT
+jmv=15:32 PT
+Cmv=15:32 PT
+Hmsv=15:32:39 PT
+hmsv=午後3:32:39 PT
+jmsv=15:32:39 PT
+Cmsv=15:32:39 PT
+Bh=昼3時
+Bhm=昼3:32
+Bhms=昼3:32:39
+
+M=1月
+MMM=1月
+MEd=1/26(水)
+MMMMEd=1月26日(水)
+d=26日
+y=4年
+yM=4/1
+yMEd=4/1/26(水)
+yMMM=4年1月
+yMMMMEd=4年1月26日(水)
+GyM=令和4年1月
+GyMEd=令和4年1月26日(水)
+GyMMM=令和4年1月
+GyMMMMEd=令和4年1月26日(水)
+
+MMMMEdBh=1月26日(水) 昼3時
+MMMMdBh=1月26日 昼3時
+MMMdBh=1月26日 昼3時
+MdBh=1/26 昼3時

test/jdk/java/time/test/java/time/format/TestLocalizedPattern.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package test.java.time.format;
+
+import static org.testng.Assert.assertEquals;
+
+import java.time.DateTimeException;
+import java.time.ZonedDateTime;
+import java.time.ZoneId;
+import java.time.chrono.IsoChronology;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeFormatterBuilder;
+import java.util.List;
+import java.util.Locale;
+import java.util.ResourceBundle;
+
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+
+/**
+ * Test DateTimeFormatter.ofLocalizedPattern() related methods.
+ * @bug 8176706
+ */
+@Test
+public class TestLocalizedPattern {
+
+    private static final ZonedDateTime ZDT =
+            ZonedDateTime.of(2022, 1, 26, 15, 32, 39, 0, ZoneId.of("America/Los_Angeles"));
+
+    private final static List<Locale> SAMPLE_LOCALES = List.of(
+            Locale.US,
+            Locale.forLanguageTag("ja-JP-u-ca-japanese")
+    );
+
+    @DataProvider(name = "validSkeletons")
+    Object[][] data_validSkeletons() {
+        return SAMPLE_LOCALES.stream()
+                .flatMap(l -> {
+                    var rb = ResourceBundle.getBundle("test.java.time.format.Skeletons", l);
+                    return rb.keySet().stream().map(key -> new Object[]{key, rb.getString(key), l});
+                })
+                .toList()
+                .toArray(new Object[0][0]);
+    }
+
+    @DataProvider(name = "invalidSkeletons")
+    Object[][] data_invalidSkeletons() {
+        return new Object[][] {
+            {"afo"}, {"hB"}, {"uMMM"}, {"MMMMMM"}, {"BhmsyMMM"},
+        };
+    }
+
+    @DataProvider(name = "unavailableSkeletons")
+    Object[][] data_unavailableSkeletons() {
+        return new Object[][] {
+            {"yyyyyy"}, {"BBh"}, {"yMMMMEdBBh"},
+        };
+    }
+
+    @Test(dataProvider = "validSkeletons")
+    public void test_ofLocalizedPattern(String skeleton, String expected, Locale l) {
+        var dtf = DateTimeFormatter.ofLocalizedPattern(skeleton).localizedBy(l);
+        assertEquals(dtf.format(ZDT), expected);
+    }
+
+    @Test(dataProvider = "invalidSkeletons", expectedExceptions = IllegalArgumentException.class)
+    public void test_ofLocalizedPattern_invalid(String skeleton) {
+        DateTimeFormatter.ofLocalizedPattern(skeleton);
+    }
+
+    @Test(dataProvider = "invalidSkeletons", expectedExceptions = IllegalArgumentException.class)
+    public void test_appendLocalized_invalid(String skeleton) {
+        new DateTimeFormatterBuilder().appendLocalized(skeleton);
+    }
+
+    @Test(dataProvider = "unavailableSkeletons", expectedExceptions = DateTimeException.class)
+    public void test_ofLocalizedPattern_unavailable(String skeleton) {
+        DateTimeFormatter.ofLocalizedPattern(skeleton).format(ZDT);
+    }
+
+    @Test(dataProvider = "unavailableSkeletons", expectedExceptions = DateTimeException.class)
+    public void test_getLocalizedDateTimePattern_unavailable(String skeleton) {
+        DateTimeFormatterBuilder.getLocalizedDateTimePattern(skeleton, IsoChronology.INSTANCE, Locale.US);
+    }
+}