content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * 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
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  /*
   * (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.util.Calendar;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Locale;
  import java.util.Map;
  import java.util.MissingResourceException;
  import java.util.TimeZone;
  import libcore.icu.ICU;
  
  /**
   * {@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 &rarr; text), parsing (text &rarr; 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:
   * <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><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>
   *
   * <h3><a name="synchronization">Synchronization</a></h3>
   *
   * <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          Calendar
   * @see          java.util.GregorianCalendar
   * @see          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 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(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 {@link Locale.Category#FORMAT FORMAT} locale.
       * <p>This is equivalent to calling
       * {@link #getTimeInstance(int, Locale) getTimeInstance(DEFAULT,
       *     Locale.getDefault(Locale.Category.FORMAT))}.
       * @see Locale#getDefault(Locale.Category)
       * @see 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 Locale.Category#FORMAT FORMAT} locale.
       * <p>This is equivalent to calling
       * {@link #getTimeInstance(int, Locale) getTimeInstance(style,
       *     Locale.getDefault(Locale.Category.FORMAT))}.
       * @see Locale#getDefault(Locale.Category)
       * @see 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 Locale.Category#FORMAT FORMAT} locale.
       * <p>This is equivalent to calling
       * {@link #getDateInstance(int, Locale) getDateInstance(DEFAULT,
       *     Locale.getDefault(Locale.Category.FORMAT))}.
       * @see Locale#getDefault(Locale.Category)
       * @see 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 Locale.Category#FORMAT FORMAT} locale.
       * <p>This is equivalent to calling
       * {@link #getDateInstance(int, Locale) getDateInstance(style,
       *     Locale.getDefault(Locale.Category.FORMAT))}.
       * @see Locale#getDefault(Locale.Category)
       * @see 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 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 Locale#getDefault(Locale.Category)
       * @see 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 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 Locale#getDefault(Locale.Category)
       * @see 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);
      }
  
      // Android-changed: Added support for overriding locale default 12 / 24 hour preference.
      /**
       * {@code null}: use Locale default. {@code true}: force 24-hour format.
       * {@code false} force 12-hour format.
       * @hide
       */
      public static Boolean is24Hour;
  
      /**
       * Override the time formatting behavior for SHORT and MEDIUM time formats.
       * {@code null}: use Locale default. {@code true}: force 24-hour format.
       * {@code false} force 12-hour format.
       *
       * @hide for internal use only.
       */
      public static final void set24HourTimePref(Boolean is24Hour) {
          DateFormat.is24Hour = is24Hour;
      }
  
      // Android-changed: Remove reference to DateFormatProvider.
      /**
       * Returns an array of all locales for which the
       * <code>get*Instance</code> methods of this class can return
       * localized instances.
       *
       * @return An array of locales for which localized
       *         <code>DateFormat</code> instances are available.
       */
      public static Locale[] getAvailableLocales()
      {
          // Android-changed: Removed used of DateFormatProvider. Switched to use ICU.
          return ICU.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 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(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(Calendar) setCalendar()}.
       *
       * @param lenient when {@code true}, parsing is lenient
       * @see 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 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;
          }
  
          // BEGIN Android-changed: Remove use of DateFormatProvider and LocaleProviderAdapter.
          /*
          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;
          */
          try {
              return new SimpleDateFormat(timeStyle, dateStyle, loc);
          } catch (MissingResourceException e) {
              return new SimpleDateFormat("M/d/yy h:mm a");
          }
          // END Android-changed: Remove use of DateFormatProvider and LocaleProviderAdapter.
      }
  
      /**
       * 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 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</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 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() == 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 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() != 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);
      }
  }
  