/*

  * Copyright (c) 1996, 2010, 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.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</code> 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:

  * <pre>

  *  myString = DateFormat.getDateInstance().format(myDate);

  * </pre>

  * <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.

  * <pre>

  *  DateFormat df = DateFormat.getDateInstance();

  *  for (int i = 0; i < myDate.length; ++i) {

  *    output.println(df.format(myDate[i]) + "; ");

  *  }

  * </pre>

  * <p>To format a date for a different Locale, specify it in the

  * call to {@link #getDateInstance(int, Locale) getDateInstance()}.

  * <pre>

  *  DateFormat df = DateFormat.getDateInstance(DateFormat.LONG, Locale.FRANCE);

  * </pre>

  * <p>You can use a DateFormat to parse also.

  * <pre>

  *  myDate = df.parse(myString);

  * </pre>

  * <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>

  *

  * <h4><a name="synchronization">Synchronization</a></h4>

  *

  * <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</code>.

      * @serial

      */

     protected Calendar calendar;

     /**

      * The number formatter that <code>DateFormat</code> 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</code>.

      * @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</code> whose beginning should be parsed.

      * @return A <code>Date</code> 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</code>.

      * <p>

      * The method attempts to parse text starting at the index given by

      * <code>pos</code>.

      * If parsing succeeds, then the index of <code>pos</code> 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</code> 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</code> is not

      * changed, the error index of <code>pos</code> 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</code>, part of which should be parsed.

      * @param pos A <code>ParsePosition</code> object with index and error

      *            index information as described above.

      * @return A <code>Date</code> parsed from the string. In case of

      *         error, returns null.

      * @exception NullPointerException if <code>pos</code> 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 locale.

      * @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 locale.

      * @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 locale.

      * @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 locale.

      * @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 locale.

      * @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 locale.

      * @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.

      */

     public final static DateFormat getInstance() {

         return getDateTimeInstance(SHORT, SHORT);

     }

     /**

      * Returns an array of all locales for which the

      * <code>get*Instance</code> 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</code> instance equal to

      * {@link java.util.Locale#US Locale.US}.

      *

      * @return An array of locales for which localized

      *         <code>DateFormat</code> 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>

      *  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>

      *  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>

      *  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>

      *  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;

         }

         try {

             // Check whether a provider can provide an implementation that's closer

             // to the requested locale than what the Java runtime itself can provide.

             LocaleServiceProviderPool pool =

                 LocaleServiceProviderPool.getPool(DateFormatProvider.class);

             if (pool.hasProviders()) {

                 DateFormat providersInstance = pool.getLocalizedObject(

                                                     DateFormatGetter.INSTANCE,

                                                     loc,

                                                     timeStyle,

                                                     dateStyle,

                                                     flags);

                 if (providersInstance != null) {

                     return providersInstance;

                 }

             }

             return new SimpleDateFormat(timeStyle, dateStyle, loc);

         } catch (MissingResourceException e) {

             return new SimpleDateFormat("M/d/yy h:mm a");

         }

     }

     /**

      * Create a new date format.

      */

     protected DateFormat() {}

     /**

      * Defines constants that are used as attribute keys in the

      * <code>AttributedCharacterIterator</code> returned

      * from <code>DateFormat.formatToCharacterIterator</code> and as

      * field identifiers in <code>FieldPosition</code>.

      * <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 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</code> constant that corresponds to

          * the <code>Calendar</code> constant <code>calendarField</code>.

          * If there is no direct mapping between the <code>Calendar</code>

          * constant and a <code>Field</code>, null is returned.

          *

          * @throws IllegalArgumentException if <code>calendarField</code> is

          *         not the value of a <code>Calendar</code> 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</code>.

          *

          * @param name the name of the <code>Field</code>

          * @param calendarField the <code>Calendar</code> constant this

          *        <code>Field</code> corresponds to; any value, even one

          *        outside the range of legal <code>Calendar</code> values may

          *        be used, but <code>-1</code> should be used for values

          *        that don't correspond to legal <code>Calendar</code> 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</code> field associated with this

          * attribute. For example, if this represents the hours field of

          * a <code>Calendar</code>, this would return

          * <code>Calendar.HOUR</code>. If there is no corresponding

          * <code>Calendar</code> 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

          */

         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);

     }

     /**

      * Obtains a DateFormat instance from a DateFormatProvider

      * implementation.

      */

     private static class DateFormatGetter

         implements LocaleServiceProviderPool.LocalizedObjectGetter<DateFormatProvider, DateFormat> {

         private static final DateFormatGetter INSTANCE = new DateFormatGetter();

         public DateFormat getObject(DateFormatProvider dateFormatProvider,

                                 Locale locale,

                                 String key,

                                 Object... params) {

             assert params.length == 3;

             int timeStyle = (Integer)params[0];

             int dateStyle = (Integer)params[1];

             int flags = (Integer)params[2];

             switch (flags) {

             case 1:

                 return dateFormatProvider.getTimeInstance(timeStyle, locale);

             case 2:

                 return dateFormatProvider.getDateInstance(dateStyle, locale);

             case 3:

                 return dateFormatProvider.getDateTimeInstance(dateStyle, timeStyle, locale);

             default:

                 assert false : "should not happen";

             }

             return null;

         }

     }

 }