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Java example source code file (DateFormat.java)

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Java - Java tags/keywords

calendar, date, dateformat, default, field, fieldposition, illegalargumentexception, invalidobjectexception, locale, numberformat, object, parseposition, short, stringbuffer, util

The DateFormat.java Java example source code

/*
 * Copyright (c) 1996, 2013, 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>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>
  • {@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>
  • progressively parse through pieces of a string. * <li>align any particular field, or find out where it is for selection * on the screen. * </ul> * * <h3>Synchronization * * <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. * * @see Format * @see NumberFormat * @see SimpleDateFormat * @see java.util.Calendar * @see java.util.GregorianCalendar * @see java.util.TimeZone * @author Mark Davis, Chen-Lieh Huang, Alan Liu */ 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 final static int ERA_FIELD = 0; /** * Useful constant for YEAR field alignment. * Used in FieldPosition of date/time formatting. */ public final static int YEAR_FIELD = 1; /** * Useful constant for MONTH field alignment. * Used in FieldPosition of date/time formatting. */ public final static int MONTH_FIELD = 2; /** * Useful constant for DATE field alignment. * Used in FieldPosition of date/time formatting. */ public final static 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 final static 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 final static int HOUR_OF_DAY0_FIELD = 5; /** * Useful constant for MINUTE field alignment. * Used in FieldPosition of date/time formatting. */ public final static int MINUTE_FIELD = 6; /** * Useful constant for SECOND field alignment. * Used in FieldPosition of date/time formatting. */ public final static int SECOND_FIELD = 7; /** * Useful constant for MILLISECOND field alignment. * Used in FieldPosition of date/time formatting. */ public final static int MILLISECOND_FIELD = 8; /** * Useful constant for DAY_OF_WEEK field alignment. * Used in FieldPosition of date/time formatting. */ public final static int DAY_OF_WEEK_FIELD = 9; /** * Useful constant for DAY_OF_YEAR field alignment. * Used in FieldPosition of date/time formatting. */ public final static int DAY_OF_YEAR_FIELD = 10; /** * Useful constant for DAY_OF_WEEK_IN_MONTH field alignment. * Used in FieldPosition of date/time formatting. */ public final static int DAY_OF_WEEK_IN_MONTH_FIELD = 11; /** * Useful constant for WEEK_OF_YEAR field alignment. * Used in FieldPosition of date/time formatting. */ public final static int WEEK_OF_YEAR_FIELD = 12; /** * Useful constant for WEEK_OF_MONTH field alignment. * Used in FieldPosition of date/time formatting. */ public final static int WEEK_OF_MONTH_FIELD = 13; /** * Useful constant for AM_PM field alignment. * Used in FieldPosition of date/time formatting. */ public final static 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 final static 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 final static int HOUR0_FIELD = 16; /** * Useful constant for TIMEZONE field alignment. * Used in FieldPosition of date/time formatting. */ public final static int TIMEZONE_FIELD = 17; // Proclaim serial compatibility with 1.1 FCS private static final long serialVersionUID = 7218322306649953788L; /** * Overrides Format. * Formats a time object into a time string. Examples of time objects * are a time value expressed in milliseconds and a Date object. * @param obj must be a Number or a Date. * @param toAppendTo the string buffer for the returning time string. * @return the string buffer passed in as toAppendTo, with formatted text appended. * @param fieldPosition keeps track of the position of the field * within the returned string. * On input: an alignment field, * if desired. On output: the offsets of the alignment field. For * example, given a time text "1996.07.10 AD at 15:08:56 PDT", * if the given fieldPosition is DateFormat.YEAR_FIELD, the * begin index and end index of fieldPosition will be set to * 0 and 4, respectively. * Notice that if the same time field appears * more than once in a pattern, the fieldPosition will be set for the first * occurrence of that time field. For instance, formatting a Date to * the time string "1 PM PDT (Pacific Daylight Time)" using the pattern * "h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD, * the begin index and end index of fieldPosition will be set to * 5 and 8, respectively, for the first occurrence of the timezone * pattern character 'z'. * @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 Date into a date/time string. * @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 of the position of the field * within the returned string. * On input: an alignment field, * if desired. On output: the offsets of the alignment field. For * example, given a time text "1996.07.10 AD at 15:08:56 PDT", * if the given fieldPosition is DateFormat.YEAR_FIELD, the * begin index and end index of fieldPosition will be set to * 0 and 4, respectively. * Notice that if the same time field appears * more than once in a pattern, the fieldPosition will be set for the first * occurrence of that time field. For instance, formatting a Date to * the time string "1 PM PDT (Pacific Daylight Time)" using the pattern * "h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD, * the begin index and end index of fieldPosition will be set to * 5 and 8, respectively, for the first occurrence of the timezone * pattern character 'z'. * @return the string buffer passed in as toAppendTo, with formatted text appended. */ public abstract StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition); /** * Formats a Date into a date/time string. * @param date the time value to be formatted into a time string. * @return the formatted 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. * @exception 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. * @exception NullPointerException if <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 final static 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 final static 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 final static 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 final static 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 final static 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 final static 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 final static 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 final static 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 final static 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 final static 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>
    {@code
         * getCalendar().setTimeZone(zone)
         * }</pre>
         *
         * <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>
    {@code
         * getCalendar().getTimeZone()
         * }</pre>
         *
         * @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>
    {@code
         * getCalendar().setLenient(lenient)
         * }</pre>
         *
         * <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>
    {@code
         * getCalendar().isLenient()
         * }</pre>
         *
         * @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
            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 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
            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 final static Field ERA = new Field("era", Calendar.ERA);
    
            /**
             * Constant identifying the year field.
             */
            public final static Field YEAR = new Field("year", Calendar.YEAR);
    
            /**
             * Constant identifying the month field.
             */
            public final static Field MONTH = new Field("month", Calendar.MONTH);
    
            /**
             * Constant identifying the day of month field.
             */
            public final static 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 final static 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 final static Field HOUR_OF_DAY0 = new
                   Field("hour of day", Calendar.HOUR_OF_DAY);
    
            /**
             * Constant identifying the minute field.
             */
            public final static Field MINUTE =new Field("minute", Calendar.MINUTE);
    
            /**
             * Constant identifying the second field.
             */
            public final static Field SECOND =new Field("second", Calendar.SECOND);
    
            /**
             * Constant identifying the millisecond field.
             */
            public final static Field MILLISECOND = new
                    Field("millisecond", Calendar.MILLISECOND);
    
            /**
             * Constant identifying the day of week field.
             */
            public final static Field DAY_OF_WEEK = new
                    Field("day of week", Calendar.DAY_OF_WEEK);
    
            /**
             * Constant identifying the day of year field.
             */
            public final static Field DAY_OF_YEAR = new
                    Field("day of year", Calendar.DAY_OF_YEAR);
    
            /**
             * Constant identifying the day of week field.
             */
            public final static 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 final static Field WEEK_OF_YEAR = new
                  Field("week of year", Calendar.WEEK_OF_YEAR);
    
            /**
             * Constant identifying the week of month field.
             */
            public final static 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 final static Field AM_PM = new
                                Field("am pm", Calendar.AM_PM);
    
            /**
             * Constant identifying the hour field, where the legal values are
             * 1 to 12.
             */
            public final static Field HOUR1 = new Field("hour 1", -1);
    
            /**
             * Constant identifying the hour field, where the legal values are
             * 0 to 11.
             */
            public final static Field HOUR0 = new
                                Field("hour", Calendar.HOUR);
    
            /**
             * Constant identifying the time zone field.
             */
            public final static Field TIME_ZONE = new Field("time zone", -1);
        }
    }
    

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