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	/*
	* Copyright (c) 1996, 2021, 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. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* 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.
	*/

	/*
	* (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
	* (C) Copyright IBM Corp. 1996 - All Rights Reserved
	*
	* The original version of this source code and documentation is copyrighted
	* and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
	* materials are provided under terms of a License Agreement between Taligent
	* and Sun. This technology is protected by multiple US and International
	* patents. This notice and attribution to Taligent may not be removed.
	* Taligent is a registered trademark of Taligent, Inc.
	*
	*/

	package java.text;

	import java.io.InvalidObjectException;
	import java.text.spi.DateFormatProvider;
	import java.util.Calendar;
	import java.util.Date;
	import java.util.GregorianCalendar;
	import java.util.HashMap;
	import java.util.Locale;
	import java.util.Map;
	import java.util.MissingResourceException;
	import java.util.ResourceBundle;
	import java.util.TimeZone;
	import java.util.spi.LocaleServiceProvider;
	import sun.util.locale.provider.LocaleProviderAdapter;
	import sun.util.locale.provider.LocaleServiceProviderPool;

	/**
	* {@code DateFormat} is an abstract class for date/time formatting subclasses which
	* formats and parses dates or time in a language-independent manner.
	* The date/time formatting subclass, such as {@link SimpleDateFormat}, allows for
	* formatting (i.e., date → text), parsing (text → date), and
	* normalization. The date is represented as a {@code Date} object or
	* as the milliseconds since January 1, 1970, 00:00:00 GMT.
	*
	* <p>{@code DateFormat} provides many class methods for obtaining default date/time
	* formatters based on the default or a given locale and a number of formatting
	* styles. The formatting styles include {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, and {@link #SHORT}. More
	* detail and examples of using these styles are provided in the method
	* descriptions.
	*
	* <p>{@code DateFormat} helps you to format and parse dates for any locale.
	* Your code can be completely independent of the locale conventions for
	* months, days of the week, or even the calendar format: lunar vs. solar.
	*
	* <p>To format a date for the current Locale, use one of the
	* static factory methods:
	* <blockquote>
	* <pre>{@code
	* myString = DateFormat.getDateInstance().format(myDate);
	* }</pre>
	* </blockquote>
	* <p>If you are formatting multiple dates, it is
	* more efficient to get the format and use it multiple times so that
	* the system doesn't have to fetch the information about the local
	* language and country conventions multiple times.
	* <blockquote>
	* <pre>{@code
	* DateFormat df = DateFormat.getDateInstance();
	* for (int i = 0; i < myDate.length; ++i) {
	* output.println(df.format(myDate[i]) + "; ");
	* }
	* }</pre>
	* </blockquote>
	* <p>To format a date for a different Locale, specify it in the
	* call to {@link #getDateInstance(int, Locale) getDateInstance()}.
	* <blockquote>
	* <pre>{@code
	* DateFormat df = DateFormat.getDateInstance(DateFormat.LONG, Locale.FRANCE);
	* }</pre>
	* </blockquote>
	*
	* <p>If the specified locale contains "ca" (calendar), "rg" (region override),
	* and/or "tz" (timezone) <a href="../util/Locale.html#def_locale_extension">Unicode
	* extensions</a>, the calendar, the country and/or the time zone for formatting
	* are overridden. If both "ca" and "rg" are specified, the calendar from the "ca"
	* extension supersedes the implicit one from the "rg" extension.
	*
	* <p>You can use a DateFormat to parse also.
	* <blockquote>
	* <pre>{@code
	* myDate = df.parse(myString);
	* }</pre>
	* </blockquote>
	* <p>Use {@code getDateInstance} to get the normal date format for that country.
	* There are other static factory methods available.
	* Use {@code getTimeInstance} to get the time format for that country.
	* Use {@code getDateTimeInstance} to get a date and time format. You can pass in
	* different options to these factory methods to control the length of the
	* result; from {@link #SHORT} to {@link #MEDIUM} to {@link #LONG} to {@link #FULL}. The exact result depends
	* on the locale, but generally:
	* <ul><li>{@link #SHORT} is completely numeric, such as {@code 12.13.52} or {@code 3:30pm}
	* <li>{@link #MEDIUM} is longer, such as {@code Jan 12, 1952}
	* <li>{@link #LONG} is longer, such as {@code January 12, 1952} or {@code 3:30:32pm}
	* <li>{@link #FULL} is pretty completely specified, such as
	* {@code Tuesday, April 12, 1952 AD or 3:30:42pm PST}.
	* </ul>
	*
	* <p>You can also set the time zone on the format if you wish.
	* If you want even more control over the format or parsing,
	* (or want to give your users more control),
	* you can try casting the {@code DateFormat} you get from the factory methods
	* to a {@link SimpleDateFormat}. This will work for the majority
	* of countries; just remember to put it in a {@code try} block in case you
	* encounter an unusual one.
	*
	* <p>You can also use forms of the parse and format methods with
	* {@link ParsePosition} and {@link FieldPosition} to
	* allow you to
	* <ul><li>progressively parse through pieces of a string.
	* <li>align any particular field, or find out where it is for selection
	* on the screen.
	* </ul>
	*
	* <h2><a id="synchronization">Synchronization</a></h2>
	*
	* <p>
	* Date formats are not synchronized.
	* It is recommended to create separate format instances for each thread.
	* If multiple threads access a format concurrently, it must be synchronized
	* externally.
	* @apiNote Consider using {@link java.time.format.DateTimeFormatter} as an
	* immutable and thread-safe alternative.
	*
	* @implSpec
	* <ul><li>The {@link #format(Date, StringBuffer, FieldPosition)} and
	* {@link #parse(String, ParsePosition)} methods may throw
	* {@code NullPointerException}, if any of their parameter is {@code null}.
	* The subclass may provide its own implementation and specification about
	* {@code NullPointerException}.</li>
	* <li>The {@link #setCalendar(Calendar)}, {@link
	* #setNumberFormat(NumberFormat)} and {@link #setTimeZone(TimeZone)} methods
	* do not throw {@code NullPointerException} when their parameter is
	* {@code null}, but any subsequent operations on the same instance may throw
	* {@code NullPointerException}.</li>
	* <li>The {@link #getCalendar()}, {@link #getNumberFormat()} and
	* {@link getTimeZone()} methods may return {@code null}, if the respective
	* values of this instance is set to {@code null} through the corresponding
	* setter methods. For Example: {@link #getTimeZone()} may return {@code null},
	* if the {@code TimeZone} value of this instance is set as
	* {@link #setTimeZone(java.util.TimeZone) setTimeZone(null)}.</li>
	* </ul>
	*
	* @see Format
	* @see NumberFormat
	* @see SimpleDateFormat
	* @see java.util.Calendar
	* @see java.util.GregorianCalendar
	* @see java.util.TimeZone
	* @see java.time.format.DateTimeFormatter
	* @author Mark Davis, Chen-Lieh Huang, Alan Liu
	* @since 1.1
	*/
	public abstract class DateFormat extends Format {

	/**
	* The {@link Calendar} instance used for calculating the date-time fields
	* and the instant of time. This field is used for both formatting and
	* parsing.
	*
	* <p>Subclasses should initialize this field to a {@link Calendar}
	* appropriate for the {@link Locale} associated with this
	* {@code DateFormat}.
	* @serial
	*/
	protected Calendar calendar;

	/**
	* The number formatter that {@code DateFormat} uses to format numbers
	* in dates and times. Subclasses should initialize this to a number format
	* appropriate for the locale associated with this {@code DateFormat}.
	* @serial
	*/
	protected NumberFormat numberFormat;

	/**
	* Useful constant for ERA field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int ERA_FIELD = 0;
	/**
	* Useful constant for YEAR field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int YEAR_FIELD = 1;
	/**
	* Useful constant for MONTH field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int MONTH_FIELD = 2;
	/**
	* Useful constant for DATE field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int DATE_FIELD = 3;
	/**
	* Useful constant for one-based HOUR_OF_DAY field alignment.
	* Used in FieldPosition of date/time formatting.
	* HOUR_OF_DAY1_FIELD is used for the one-based 24-hour clock.
	* For example, 23:59 + 01:00 results in 24:59.
	*/
	public static final int HOUR_OF_DAY1_FIELD = 4;
	/**
	* Useful constant for zero-based HOUR_OF_DAY field alignment.
	* Used in FieldPosition of date/time formatting.
	* HOUR_OF_DAY0_FIELD is used for the zero-based 24-hour clock.
	* For example, 23:59 + 01:00 results in 00:59.
	*/
	public static final int HOUR_OF_DAY0_FIELD = 5;
	/**
	* Useful constant for MINUTE field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int MINUTE_FIELD = 6;
	/**
	* Useful constant for SECOND field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int SECOND_FIELD = 7;
	/**
	* Useful constant for MILLISECOND field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int MILLISECOND_FIELD = 8;
	/**
	* Useful constant for DAY_OF_WEEK field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int DAY_OF_WEEK_FIELD = 9;
	/**
	* Useful constant for DAY_OF_YEAR field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int DAY_OF_YEAR_FIELD = 10;
	/**
	* Useful constant for DAY_OF_WEEK_IN_MONTH field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int DAY_OF_WEEK_IN_MONTH_FIELD = 11;
	/**
	* Useful constant for WEEK_OF_YEAR field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int WEEK_OF_YEAR_FIELD = 12;
	/**
	* Useful constant for WEEK_OF_MONTH field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int WEEK_OF_MONTH_FIELD = 13;
	/**
	* Useful constant for AM_PM field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int AM_PM_FIELD = 14;
	/**
	* Useful constant for one-based HOUR field alignment.
	* Used in FieldPosition of date/time formatting.
	* HOUR1_FIELD is used for the one-based 12-hour clock.
	* For example, 11:30 PM + 1 hour results in 12:30 AM.
	*/
	public static final int HOUR1_FIELD = 15;
	/**
	* Useful constant for zero-based HOUR field alignment.
	* Used in FieldPosition of date/time formatting.
	* HOUR0_FIELD is used for the zero-based 12-hour clock.
	* For example, 11:30 PM + 1 hour results in 00:30 AM.
	*/
	public static final int HOUR0_FIELD = 16;
	/**
	* Useful constant for TIMEZONE field alignment.
	* Used in FieldPosition of date/time formatting.
	*/
	public static final int TIMEZONE_FIELD = 17;

	// Proclaim serial compatibility with 1.1 FCS
	@java.io.Serial
	private static final long serialVersionUID = 7218322306649953788L;

	/**
	* Formats the given {@code Object} into a date-time string. The formatted
	* string is appended to the given {@code StringBuffer}.
	*
	* @param obj Must be a {@code Date} or a {@code Number} representing a
	* millisecond offset from the <a href="../util/Calendar.html#Epoch">Epoch</a>.
	* @param toAppendTo The string buffer for the returning date-time string.
	* @param fieldPosition keeps track on the position of the field within
	* the returned string. For example, given a date-time text
	* {@code "1996.07.10 AD at 15:08:56 PDT"}, if the given {@code fieldPosition}
	* is {@link DateFormat#YEAR_FIELD}, the begin index and end index of
	* {@code fieldPosition} will be set to 0 and 4, respectively.
	* Notice that if the same date-time field appears more than once in a
	* pattern, the {@code fieldPosition} will be set for the first occurrence
	* of that date-time field. For instance, formatting a {@code Date} to the
	* date-time string {@code "1 PM PDT (Pacific Daylight Time)"} using the
	* pattern {@code "h a z (zzzz)"} and the alignment field
	* {@link DateFormat#TIMEZONE_FIELD}, the begin index and end index of
	* {@code fieldPosition} will be set to 5 and 8, respectively, for the
	* first occurrence of the timezone pattern character {@code 'z'}.
	* @return the string buffer passed in as {@code toAppendTo},
	* with formatted text appended.
	* @throws IllegalArgumentException if the {@code Format} cannot format
	* the given {@code obj}.
	* @see java.text.Format
	*/
	public final StringBuffer format(Object obj, StringBuffer toAppendTo,
	FieldPosition fieldPosition)
	{
	if (obj instanceof Date)
	return format( (Date)obj, toAppendTo, fieldPosition );
	else if (obj instanceof Number)
	return format( new Date(((Number)obj).longValue()),
	toAppendTo, fieldPosition );
	else
	throw new IllegalArgumentException("Cannot format given Object as a Date");
	}

	/**
	* Formats a {@link Date} into a date-time string. The formatted
	* string is appended to the given {@code StringBuffer}.
	*
	* @param date a Date to be formatted into a date-time string.
	* @param toAppendTo the string buffer for the returning date-time string.
	* @param fieldPosition keeps track on the position of the field within
	* the returned string. For example, given a date-time text
	* {@code "1996.07.10 AD at 15:08:56 PDT"}, if the given {@code fieldPosition}
	* is {@link DateFormat#YEAR_FIELD}, the begin index and end index of
	* {@code fieldPosition} will be set to 0 and 4, respectively.
	* Notice that if the same date-time field appears more than once in a
	* pattern, the {@code fieldPosition} will be set for the first occurrence
	* of that date-time field. For instance, formatting a {@code Date} to the
	* date-time string {@code "1 PM PDT (Pacific Daylight Time)"} using the
	* pattern {@code "h a z (zzzz)"} and the alignment field
	* {@link DateFormat#TIMEZONE_FIELD}, the begin index and end index of
	* {@code fieldPosition} will be set to 5 and 8, respectively, for the
	* first occurrence of the timezone pattern character {@code 'z'}.
	* @return the string buffer passed in as {@code toAppendTo}, with formatted
	* text appended.
	*/
	public abstract StringBuffer format(Date date, StringBuffer toAppendTo,
	FieldPosition fieldPosition);

	/**
	* Formats a {@link Date} into a date-time string.
	*
	* @param date the time value to be formatted into a date-time string.
	* @return the formatted date-time string.
	*/
	public final String format(Date date)
	{
	return format(date, new StringBuffer(),
	DontCareFieldPosition.INSTANCE).toString();
	}

	/**
	* Parses text from the beginning of the given string to produce a date.
	* The method may not use the entire text of the given string.
	* <p>
	* See the {@link #parse(String, ParsePosition)} method for more information
	* on date parsing.
	*
	* @param source A {@code String} whose beginning should be parsed.
	* @return A {@code Date} parsed from the string.
	* @throws ParseException if the beginning of the specified string
	* cannot be parsed.
	*/
	public Date parse(String source) throws ParseException
	{
	ParsePosition pos = new ParsePosition(0);
	Date result = parse(source, pos);
	if (pos.index == 0)
	throw new ParseException("Unparseable date: \"" + source + "\"" ,
	pos.errorIndex);
	return result;
	}

	/**
	* Parse a date/time string according to the given parse position. For
	* example, a time text {@code "07/10/96 4:5 PM, PDT"} will be parsed into a {@code Date}
	* that is equivalent to {@code Date(837039900000L)}.
	*
	* <p> By default, parsing is lenient: If the input is not in the form used
	* by this object's format method but can still be parsed as a date, then
	* the parse succeeds. Clients may insist on strict adherence to the
	* format by calling {@link #setLenient(boolean) setLenient(false)}.
	*
	* <p>This parsing operation uses the {@link #calendar} to produce
	* a {@code Date}. As a result, the {@code calendar}'s date-time
	* fields and the {@code TimeZone} value may have been
	* overwritten, depending on subclass implementations. Any {@code
	* TimeZone} value that has previously been set by a call to
	* {@link #setTimeZone(java.util.TimeZone) setTimeZone} may need
	* to be restored for further operations.
	*
	* @param source The date/time string to be parsed
	*
	* @param pos On input, the position at which to start parsing; on
	* output, the position at which parsing terminated, or the
	* start position if the parse failed.
	*
	* @return A {@code Date}, or {@code null} if the input could not be parsed
	*/
	public abstract Date parse(String source, ParsePosition pos);

	/**
	* Parses text from a string to produce a {@code Date}.
	* <p>
	* The method attempts to parse text starting at the index given by
	* {@code pos}.
	* If parsing succeeds, then the index of {@code pos} is updated
	* to the index after the last character used (parsing does not necessarily
	* use all characters up to the end of the string), and the parsed
	* date is returned. The updated {@code pos} can be used to
	* indicate the starting point for the next call to this method.
	* If an error occurs, then the index of {@code pos} is not
	* changed, the error index of {@code pos} is set to the index of
	* the character where the error occurred, and null is returned.
	* <p>
	* See the {@link #parse(String, ParsePosition)} method for more information
	* on date parsing.
	*
	* @param source A {@code String}, part of which should be parsed.
	* @param pos A {@code ParsePosition} object with index and error
	* index information as described above.
	* @return A {@code Date} parsed from the string. In case of
	* error, returns null.
	* @throws NullPointerException if {@code source} or {@code pos} is null.
	*/
	public Object parseObject(String source, ParsePosition pos) {
	return parse(source, pos);
	}

	/**
	* Constant for full style pattern.
	*/
	public static final int FULL = 0;
	/**
	* Constant for long style pattern.
	*/
	public static final int LONG = 1;
	/**
	* Constant for medium style pattern.
	*/
	public static final int MEDIUM = 2;
	/**
	* Constant for short style pattern.
	*/
	public static final int SHORT = 3;
	/**
	* Constant for default style pattern. Its value is MEDIUM.
	*/
	public static final int DEFAULT = MEDIUM;

	/**
	* Gets the time formatter with the default formatting style
	* for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
	* <p>This is equivalent to calling
	* {@link #getTimeInstance(int, Locale) getTimeInstance(DEFAULT,
	* Locale.getDefault(Locale.Category.FORMAT))}.
	* @see java.util.Locale#getDefault(java.util.Locale.Category)
	* @see java.util.Locale.Category#FORMAT
	* @return a time formatter.
	*/
	public static final DateFormat getTimeInstance()
	{
	return get(DEFAULT, 0, 1, Locale.getDefault(Locale.Category.FORMAT));
	}

	/**
	* Gets the time formatter with the given formatting style
	* for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
	* <p>This is equivalent to calling
	* {@link #getTimeInstance(int, Locale) getTimeInstance(style,
	* Locale.getDefault(Locale.Category.FORMAT))}.
	* @see java.util.Locale#getDefault(java.util.Locale.Category)
	* @see java.util.Locale.Category#FORMAT
	* @param style the given formatting style. For example,
	* SHORT for "h:mm a" in the US locale.
	* @return a time formatter.
	*/
	public static final DateFormat getTimeInstance(int style)
	{
	return get(style, 0, 1, Locale.getDefault(Locale.Category.FORMAT));
	}

	/**
	* Gets the time formatter with the given formatting style
	* for the given locale.
	* @param style the given formatting style. For example,
	* SHORT for "h:mm a" in the US locale.
	* @param aLocale the given locale.
	* @return a time formatter.
	*/
	public static final DateFormat getTimeInstance(int style,
	Locale aLocale)
	{
	return get(style, 0, 1, aLocale);
	}

	/**
	* Gets the date formatter with the default formatting style
	* for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
	* <p>This is equivalent to calling
	* {@link #getDateInstance(int, Locale) getDateInstance(DEFAULT,
	* Locale.getDefault(Locale.Category.FORMAT))}.
	* @see java.util.Locale#getDefault(java.util.Locale.Category)
	* @see java.util.Locale.Category#FORMAT
	* @return a date formatter.
	*/
	public static final DateFormat getDateInstance()
	{
	return get(0, DEFAULT, 2, Locale.getDefault(Locale.Category.FORMAT));
	}

	/**
	* Gets the date formatter with the given formatting style
	* for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
	* <p>This is equivalent to calling
	* {@link #getDateInstance(int, Locale) getDateInstance(style,
	* Locale.getDefault(Locale.Category.FORMAT))}.
	* @see java.util.Locale#getDefault(java.util.Locale.Category)
	* @see java.util.Locale.Category#FORMAT
	* @param style the given formatting style. For example,
	* SHORT for "M/d/yy" in the US locale.
	* @return a date formatter.
	*/
	public static final DateFormat getDateInstance(int style)
	{
	return get(0, style, 2, Locale.getDefault(Locale.Category.FORMAT));
	}

	/**
	* Gets the date formatter with the given formatting style
	* for the given locale.
	* @param style the given formatting style. For example,
	* SHORT for "M/d/yy" in the US locale.
	* @param aLocale the given locale.
	* @return a date formatter.
	*/
	public static final DateFormat getDateInstance(int style,
	Locale aLocale)
	{
	return get(0, style, 2, aLocale);
	}

	/**
	* Gets the date/time formatter with the default formatting style
	* for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
	* <p>This is equivalent to calling
	* {@link #getDateTimeInstance(int, int, Locale) getDateTimeInstance(DEFAULT,
	* DEFAULT, Locale.getDefault(Locale.Category.FORMAT))}.
	* @see java.util.Locale#getDefault(java.util.Locale.Category)
	* @see java.util.Locale.Category#FORMAT
	* @return a date/time formatter.
	*/
	public static final DateFormat getDateTimeInstance()
	{
	return get(DEFAULT, DEFAULT, 3, Locale.getDefault(Locale.Category.FORMAT));
	}

	/**
	* Gets the date/time formatter with the given date and time
	* formatting styles for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
	* <p>This is equivalent to calling
	* {@link #getDateTimeInstance(int, int, Locale) getDateTimeInstance(dateStyle,
	* timeStyle, Locale.getDefault(Locale.Category.FORMAT))}.
	* @see java.util.Locale#getDefault(java.util.Locale.Category)
	* @see java.util.Locale.Category#FORMAT
	* @param dateStyle the given date formatting style. For example,
	* SHORT for "M/d/yy" in the US locale.
	* @param timeStyle the given time formatting style. For example,
	* SHORT for "h:mm a" in the US locale.
	* @return a date/time formatter.
	*/
	public static final DateFormat getDateTimeInstance(int dateStyle,
	int timeStyle)
	{
	return get(timeStyle, dateStyle, 3, Locale.getDefault(Locale.Category.FORMAT));
	}

	/**
	* Gets the date/time formatter with the given formatting styles
	* for the given locale.
	* @param dateStyle the given date formatting style.
	* @param timeStyle the given time formatting style.
	* @param aLocale the given locale.
	* @return a date/time formatter.
	*/
	public static final DateFormat
	getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
	{
	return get(timeStyle, dateStyle, 3, aLocale);
	}

	/**
	* Get a default date/time formatter that uses the SHORT style for both the
	* date and the time.
	*
	* @return a date/time formatter
	*/
	public static final DateFormat getInstance() {
	return getDateTimeInstance(SHORT, SHORT);
	}

	/**
	* Returns an array of all locales for which the
	* {@code get*Instance} methods of this class can return
	* localized instances.
	* The returned array represents the union of locales supported by the Java
	* runtime and by installed
	* {@link java.text.spi.DateFormatProvider DateFormatProvider} implementations.
	* It must contain at least a {@code Locale} instance equal to
	* {@link java.util.Locale#US Locale.US}.
	*
	* @return An array of locales for which localized
	* {@code DateFormat} instances are available.
	*/
	public static Locale[] getAvailableLocales()
	{
	LocaleServiceProviderPool pool =
	LocaleServiceProviderPool.getPool(DateFormatProvider.class);
	return pool.getAvailableLocales();
	}

	/**
	* Set the calendar to be used by this date format. Initially, the default
	* calendar for the specified or default locale is used.
	*
	* <p>Any {@link java.util.TimeZone TimeZone} and {@linkplain
	* #isLenient() leniency} values that have previously been set are
	* overwritten by {@code newCalendar}'s values.
	*
	* @param newCalendar the new {@code Calendar} to be used by the date format
	*/
	public void setCalendar(Calendar newCalendar)
	{
	this.calendar = newCalendar;
	}

	/**
	* Gets the calendar associated with this date/time formatter.
	*
	* @return the calendar associated with this date/time formatter.
	*/
	public Calendar getCalendar()
	{
	return calendar;
	}

	/**
	* Allows you to set the number formatter.
	* @param newNumberFormat the given new NumberFormat.
	*/
	public void setNumberFormat(NumberFormat newNumberFormat)
	{
	this.numberFormat = newNumberFormat;
	}

	/**
	* Gets the number formatter which this date/time formatter uses to
	* format and parse a time.
	* @return the number formatter which this date/time formatter uses.
	*/
	public NumberFormat getNumberFormat()
	{
	return numberFormat;
	}

	/**
	* Sets the time zone for the calendar of this {@code DateFormat} object.
	* This method is equivalent to the following call.
	* <blockquote><pre>{@code
	* getCalendar().setTimeZone(zone)
	* }</pre></blockquote>
	*
	* <p>The {@code TimeZone} set by this method is overwritten by a
	* {@link #setCalendar(java.util.Calendar) setCalendar} call.
	*
	* <p>The {@code TimeZone} set by this method may be overwritten as
	* a result of a call to the parse method.
	*
	* @param zone the given new time zone.
	*/
	public void setTimeZone(TimeZone zone)
	{
	calendar.setTimeZone(zone);
	}

	/**
	* Gets the time zone.
	* This method is equivalent to the following call.
	* <blockquote><pre>{@code
	* getCalendar().getTimeZone()
	* }</pre></blockquote>
	*
	* @return the time zone associated with the calendar of DateFormat.
	*/
	public TimeZone getTimeZone()
	{
	return calendar.getTimeZone();
	}

	/**
	* Specify whether or not date/time parsing is to be lenient. With
	* lenient parsing, the parser may use heuristics to interpret inputs that
	* do not precisely match this object's format. With strict parsing,
	* inputs must match this object's format.
	*
	* <p>This method is equivalent to the following call.
	* <blockquote><pre>{@code
	* getCalendar().setLenient(lenient)
	* }</pre></blockquote>
	*
	* <p>This leniency value is overwritten by a call to {@link
	* #setCalendar(java.util.Calendar) setCalendar()}.
	*
	* @param lenient when {@code true}, parsing is lenient
	* @see java.util.Calendar#setLenient(boolean)
	*/
	public void setLenient(boolean lenient)
	{
	calendar.setLenient(lenient);
	}

	/**
	* Tell whether date/time parsing is to be lenient.
	* This method is equivalent to the following call.
	* <blockquote><pre>{@code
	* getCalendar().isLenient()
	* }</pre></blockquote>
	*
	* @return {@code true} if the {@link #calendar} is lenient;
	* {@code false} otherwise.
	* @see java.util.Calendar#isLenient()
	*/
	public boolean isLenient()
	{
	return calendar.isLenient();
	}

	/**
	* Overrides hashCode
	*/
	public int hashCode() {
	return numberFormat.hashCode();
	// just enough fields for a reasonable distribution
	}

	/**
	* Overrides equals
	*/
	public boolean equals(Object obj) {
	if (this == obj) return true;
	if (obj == null \|\| getClass() != obj.getClass()) return false;
	DateFormat other = (DateFormat) obj;
	return (// calendar.equivalentTo(other.calendar) // THIS API DOESN'T EXIST YET!
	calendar.getFirstDayOfWeek() == other.calendar.getFirstDayOfWeek() &&
	calendar.getMinimalDaysInFirstWeek() == other.calendar.getMinimalDaysInFirstWeek() &&
	calendar.isLenient() == other.calendar.isLenient() &&
	calendar.getTimeZone().equals(other.calendar.getTimeZone()) &&
	numberFormat.equals(other.numberFormat));
	}

	/**
	* Overrides Cloneable
	*/
	public Object clone()
	{
	DateFormat other = (DateFormat) super.clone();
	other.calendar = (Calendar) calendar.clone();
	other.numberFormat = (NumberFormat) numberFormat.clone();
	return other;
	}

	/**
	* Creates a DateFormat with the given time and/or date style in the given
	* locale.
	* @param timeStyle a value from 0 to 3 indicating the time format,
	* ignored if flags is 2
	* @param dateStyle a value from 0 to 3 indicating the time format,
	* ignored if flags is 1
	* @param flags either 1 for a time format, 2 for a date format,
	* or 3 for a date/time format
	* @param loc the locale for the format
	*/
	private static DateFormat get(int timeStyle, int dateStyle,
	int flags, Locale loc) {
	if ((flags & 1) != 0) {
	if (timeStyle < 0 \|\| timeStyle > 3) {
	throw new IllegalArgumentException("Illegal time style " + timeStyle);
	}
	} else {
	timeStyle = -1;
	}
	if ((flags & 2) != 0) {
	if (dateStyle < 0 \|\| dateStyle > 3) {
	throw new IllegalArgumentException("Illegal date style " + dateStyle);
	}
	} else {
	dateStyle = -1;
	}

	LocaleProviderAdapter adapter = LocaleProviderAdapter.getAdapter(DateFormatProvider.class, loc);
	DateFormat dateFormat = get(adapter, timeStyle, dateStyle, loc);
	if (dateFormat == null) {
	dateFormat = get(LocaleProviderAdapter.forJRE(), timeStyle, dateStyle, loc);
	}
	return dateFormat;
	}

	private static DateFormat get(LocaleProviderAdapter adapter, int timeStyle, int dateStyle, Locale loc) {
	DateFormatProvider provider = adapter.getDateFormatProvider();
	DateFormat dateFormat;
	if (timeStyle == -1) {
	dateFormat = provider.getDateInstance(dateStyle, loc);
	} else {
	if (dateStyle == -1) {
	dateFormat = provider.getTimeInstance(timeStyle, loc);
	} else {
	dateFormat = provider.getDateTimeInstance(dateStyle, timeStyle, loc);
	}
	}
	return dateFormat;
	}

	/**
	* Create a new date format.
	*/
	protected DateFormat() {}

	/**
	* Defines constants that are used as attribute keys in the
	* {@code AttributedCharacterIterator} returned
	* from {@code DateFormat.formatToCharacterIterator} and as
	* field identifiers in {@code FieldPosition}.
	* <p>
	* The class also provides two methods to map
	* between its constants and the corresponding Calendar constants.
	*
	* @since 1.4
	* @see java.util.Calendar
	*/
	public static class Field extends Format.Field {

	// Proclaim serial compatibility with 1.4 FCS
	@java.io.Serial
	private static final long serialVersionUID = 7441350119349544720L;

	// table of all instances in this class, used by readResolve
	private static final Map<String, Field> instanceMap = new HashMap<>(18);
	// Maps from Calendar constant (such as Calendar.ERA) to Field
	// constant (such as Field.ERA).
	private static final Field[] calendarToFieldMapping =
	new Field[Calendar.FIELD_COUNT];

	/** Calendar field. */
	private int calendarField;

	/**
	* Returns the {@code Field} constant that corresponds to
	* the {@code Calendar} constant {@code calendarField}.
	* If there is no direct mapping between the {@code Calendar}
	* constant and a {@code Field}, null is returned.
	*
	* @throws IllegalArgumentException if {@code calendarField} is
	* not the value of a {@code Calendar} field constant.
	* @param calendarField Calendar field constant
	* @return Field instance representing calendarField.
	* @see java.util.Calendar
	*/
	public static Field ofCalendarField(int calendarField) {
	if (calendarField < 0 \|\| calendarField >=
	calendarToFieldMapping.length) {
	throw new IllegalArgumentException("Unknown Calendar constant "
	+ calendarField);
	}
	return calendarToFieldMapping[calendarField];
	}

	/**
	* Creates a {@code Field}.
	*
	* @param name the name of the {@code Field}
	* @param calendarField the {@code Calendar} constant this
	* {@code Field} corresponds to; any value, even one
	* outside the range of legal {@code Calendar} values may
	* be used, but {@code -1} should be used for values
	* that don't correspond to legal {@code Calendar} values
	*/
	protected Field(String name, int calendarField) {
	super(name);
	this.calendarField = calendarField;
	if (this.getClass() == DateFormat.Field.class) {
	instanceMap.put(name, this);
	if (calendarField >= 0) {
	// assert(calendarField < Calendar.FIELD_COUNT);
	calendarToFieldMapping[calendarField] = this;
	}
	}
	}

	/**
	* Returns the {@code Calendar} field associated with this
	* attribute. For example, if this represents the hours field of
	* a {@code Calendar}, this would return
	* {@code Calendar.HOUR}. If there is no corresponding
	* {@code Calendar} constant, this will return -1.
	*
	* @return Calendar constant for this field
	* @see java.util.Calendar
	*/
	public int getCalendarField() {
	return calendarField;
	}

	/**
	* Resolves instances being deserialized to the predefined constants.
	*
	* @throws InvalidObjectException if the constant could not be
	* resolved.
	* @return resolved DateFormat.Field constant
	*/
	@Override
	@java.io.Serial
	protected Object readResolve() throws InvalidObjectException {
	if (this.getClass() != DateFormat.Field.class) {
	throw new InvalidObjectException("subclass didn't correctly implement readResolve");
	}

	Object instance = instanceMap.get(getName());
	if (instance != null) {
	return instance;
	} else {
	throw new InvalidObjectException("unknown attribute name");
	}
	}

	//
	// The constants
	//

	/**
	* Constant identifying the era field.
	*/
	public static final Field ERA = new Field("era", Calendar.ERA);

	/**
	* Constant identifying the year field.
	*/
	public static final Field YEAR = new Field("year", Calendar.YEAR);

	/**
	* Constant identifying the month field.
	*/
	public static final Field MONTH = new Field("month", Calendar.MONTH);

	/**
	* Constant identifying the day of month field.
	*/
	public static final Field DAY_OF_MONTH = new
	Field("day of month", Calendar.DAY_OF_MONTH);

	/**
	* Constant identifying the hour of day field, where the legal values
	* are 1 to 24.
	*/
	public static final Field HOUR_OF_DAY1 = new Field("hour of day 1",-1);

	/**
	* Constant identifying the hour of day field, where the legal values
	* are 0 to 23.
	*/
	public static final Field HOUR_OF_DAY0 = new
	Field("hour of day", Calendar.HOUR_OF_DAY);

	/**
	* Constant identifying the minute field.
	*/
	public static final Field MINUTE =new Field("minute", Calendar.MINUTE);

	/**
	* Constant identifying the second field.
	*/
	public static final Field SECOND =new Field("second", Calendar.SECOND);

	/**
	* Constant identifying the millisecond field.
	*/
	public static final Field MILLISECOND = new
	Field("millisecond", Calendar.MILLISECOND);

	/**
	* Constant identifying the day of week field.
	*/
	public static final Field DAY_OF_WEEK = new
	Field("day of week", Calendar.DAY_OF_WEEK);

	/**
	* Constant identifying the day of year field.
	*/
	public static final Field DAY_OF_YEAR = new
	Field("day of year", Calendar.DAY_OF_YEAR);

	/**
	* Constant identifying the day of week field.
	*/
	public static final Field DAY_OF_WEEK_IN_MONTH =
	new Field("day of week in month",
	Calendar.DAY_OF_WEEK_IN_MONTH);

	/**
	* Constant identifying the week of year field.
	*/
	public static final Field WEEK_OF_YEAR = new
	Field("week of year", Calendar.WEEK_OF_YEAR);

	/**
	* Constant identifying the week of month field.
	*/
	public static final Field WEEK_OF_MONTH = new
	Field("week of month", Calendar.WEEK_OF_MONTH);

	/**
	* Constant identifying the time of day indicator
	* (e.g. "a.m." or "p.m.") field.
	*/
	public static final Field AM_PM = new
	Field("am pm", Calendar.AM_PM);

	/**
	* Constant identifying the hour field, where the legal values are
	* 1 to 12.
	*/
	public static final Field HOUR1 = new Field("hour 1", -1);

	/**
	* Constant identifying the hour field, where the legal values are
	* 0 to 11.
	*/
	public static final Field HOUR0 = new
	Field("hour", Calendar.HOUR);

	/**
	* Constant identifying the time zone field.
	*/
	public static final Field TIME_ZONE = new Field("time zone", -1);
	}
	}

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