/*
 * @(#)GregorianCalendar.java	1.84 04/04/25
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

/*
 * (C) Copyright Taligent, Inc. 1996-1998 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996-1998 - 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.util;

import java.io.IOException;
import java.io.ObjectInputStream;
import sun.util.calendar.BaseCalendar;
import sun.util.calendar.CalendarDate;
import sun.util.calendar.CalendarSystem;
import sun.util.calendar.CalendarUtils;
import sun.util.calendar.Era;
import sun.util.calendar.Gregorian;
import sun.util.calendar.JulianCalendar;
import sun.util.calendar.ZoneInfo;

/**
 * <code>GregorianCalendar</code> is a concrete subclass of
 * <code>Calendar</code> and provides the standard calendar system
 * used by most of the world.
 *
 * <p> <code>GregorianCalendar</code> is a hybrid calendar that
 * supports both the Julian and Gregorian calendar systems with the
 * support of a single discontinuity, which corresponds by default to
 * the Gregorian date when the Gregorian calendar was instituted
 * (October 15, 1582 in some countries, later in others).  The cutover
 * date may be changed by the caller by calling {@link
 * #setGregorianChange(Date) setGregorianChange()}.
 *
 * <p>
 * Historically, in those countries which adopted the Gregorian calendar first,
 * October 4, 1582 (Julian) was thus followed by October 15, 1582 (Gregorian). This calendar models
 * this correctly.  Before the Gregorian cutover, <code>GregorianCalendar</code>
 * implements the Julian calendar.  The only difference between the Gregorian
 * and the Julian calendar is the leap year rule. The Julian calendar specifies
 * leap years every four years, whereas the Gregorian calendar omits century
 * years which are not divisible by 400.
 *
 * <p>
 * <code>GregorianCalendar</code> implements <em>proleptic</em> Gregorian and
 * Julian calendars. That is, dates are computed by extrapolating the current
 * rules indefinitely far backward and forward in time. As a result,
 * <code>GregorianCalendar</code> may be used for all years to generate
 * meaningful and consistent results. However, dates obtained using
 * <code>GregorianCalendar</code> are historically accurate only from March 1, 4
 * AD onward, when modern Julian calendar rules were adopted.  Before this date,
 * leap year rules were applied irregularly, and before 45 BC the Julian
 * calendar did not even exist.
 *
 * <p>
 * Prior to the institution of the Gregorian calendar, New Year's Day was
 * March 25. To avoid confusion, this calendar always uses January 1. A manual
 * adjustment may be made if desired for dates that are prior to the Gregorian
 * changeover and which fall between January 1 and March 24.
 *
 * <p>Values calculated for the <code>WEEK_OF_YEAR</code> field range from 1 to
 * 53.  Week 1 for a year is the earliest seven day period starting on
 * <code>getFirstDayOfWeek()</code> that contains at least
 * <code>getMinimalDaysInFirstWeek()</code> days from that year.  It thus
 * depends on the values of <code>getMinimalDaysInFirstWeek()</code>,
 * <code>getFirstDayOfWeek()</code>, and the day of the week of January 1.
 * Weeks between week 1 of one year and week 1 of the following year are
 * numbered sequentially from 2 to 52 or 53 (as needed).

 * <p>For example, January 1, 1998 was a Thursday.  If
 * <code>getFirstDayOfWeek()</code> is <code>MONDAY</code> and
 * <code>getMinimalDaysInFirstWeek()</code> is 4 (these are the values
 * reflecting ISO 8601 and many national standards), then week 1 of 1998 starts
 * on December 29, 1997, and ends on January 4, 1998.  If, however,
 * <code>getFirstDayOfWeek()</code> is <code>SUNDAY</code>, then week 1 of 1998
 * starts on January 4, 1998, and ends on January 10, 1998; the first three days
 * of 1998 then are part of week 53 of 1997.
 *
 * <p>Values calculated for the <code>WEEK_OF_MONTH</code> field range from 0
 * to 6.  Week 1 of a month (the days with <code>WEEK_OF_MONTH =
 * 1</code>) is the earliest set of at least
 * <code>getMinimalDaysInFirstWeek()</code> contiguous days in that month,
 * ending on the day before <code>getFirstDayOfWeek()</code>.  Unlike
 * week 1 of a year, week 1 of a month may be shorter than 7 days, need
 * not start on <code>getFirstDayOfWeek()</code>, and will not include days of
 * the previous month.  Days of a month before week 1 have a
 * <code>WEEK_OF_MONTH</code> of 0.
 *
 * <p>For example, if <code>getFirstDayOfWeek()</code> is <code>SUNDAY</code>
 * and <code>getMinimalDaysInFirstWeek()</code> is 4, then the first week of
 * January 1998 is Sunday, January 4 through Saturday, January 10.  These days
 * have a <code>WEEK_OF_MONTH</code> of 1.  Thursday, January 1 through
 * Saturday, January 3 have a <code>WEEK_OF_MONTH</code> of 0.  If
 * <code>getMinimalDaysInFirstWeek()</code> is changed to 3, then January 1
 * through January 3 have a <code>WEEK_OF_MONTH</code> of 1.
 *
 * <p>The <code>clear</code> methods set calendar field(s)
 * undefined. <code>GregorianCalendar</code> uses the following
 * default value for each calendar field if its value is undefined.
 *
 * <table cellpadding="0" cellspacing="3" border="0"
 *	  summary="GregorianCalendar default field values" 
 *	  style="text-align: left; width: 66%;">
 *   <tbody>
 *     <tr>
 *       <th style="vertical-align: top; background-color: rgb(204, 204, 255);
 *	     text-align: center;">Field<br>
 *       </th>
 *       <th style="vertical-align: top; background-color: rgb(204, 204, 255);
 *	     text-align: center;">Default Value<br>
 *       </th>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: middle;">
 *		<code>ERA<br></code>
 *	 </td>
 *       <td style="vertical-align: middle;">
 *		<code>AD<br></code>
 *	 </td>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: middle; background-color: rgb(238, 238, 255);">
 *		<code>YEAR<br></code>
 *	 </td>
 *       <td style="vertical-align: middle; background-color: rgb(238, 238, 255);">
 *		<code>1970<br></code>
 *	 </td>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: middle;">
 *		<code>MONTH<br></code>
 *	 </td>
 *       <td style="vertical-align: middle;">
 *		<code>JANUARY<br></code>
 *	 </td>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: top; background-color: rgb(238, 238, 255);">
 *		<code>DAY_OF_MONTH<br></code>
 *	 </td>
 *       <td style="vertical-align: top; background-color: rgb(238, 238, 255);">
 *		<code>1<br></code>
 *	 </td>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: middle;">
 *		<code>DAY_OF_WEEK<br></code>
 *	 </td>
 *       <td style="vertical-align: middle;">
 *		<code>the first day of week<br></code>
 *	 </td>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: top; background-color: rgb(238, 238, 255);">
 *		<code>WEEK_OF_MONTH<br></code>
 *       </td>
 *       <td style="vertical-align: top; background-color: rgb(238, 238, 255);">
 *		<code>0<br></code>
 *       </td>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: top;">
 *		<code>DAY_OF_WEEK_IN_MONTH<br></code>
 *       </td>
 *       <td style="vertical-align: top;">
 *		<code>1<br></code>
 *       </td>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: middle; background-color: rgb(238, 238, 255);">
 *		<code>AM_PM<br></code>
 *       </td>
 *       <td style="vertical-align: middle; background-color: rgb(238, 238, 255);">
 *		<code>AM<br></code>
 *       </td>
 *     </tr>
 *     <tr>
 *       <td style="vertical-align: middle;">
 *		<code>HOUR, HOUR_OF_DAY, MINUTE, SECOND, MILLISECOND<br></code>
 *       </td>
 *       <td style="vertical-align: middle;">
 *		<code>0<br></code>
 *       </td>
 *     </tr>
 *   </tbody>
 * </table>
 * <br>Default values are not applicable for the fields not listed above.
 *
 * <p>
 * <strong>Example:</strong>
 * <blockquote>
 * <pre>
 * // get the supported ids for GMT-08:00 (Pacific Standard Time)
 * String[] ids = TimeZone.getAvailableIDs(-8 * 60 * 60 * 1000);
 * // if no ids were returned, something is wrong. get out.
 * if (ids.length == 0)
 *     System.exit(0);
 *
 *  // begin output
 * System.out.println("Current Time");
 *
 * // create a Pacific Standard Time time zone
 * SimpleTimeZone pdt = new SimpleTimeZone(-8 * 60 * 60 * 1000, ids[0]);
 *
 * // set up rules for daylight savings time
 * pdt.setStartRule(Calendar.APRIL, 1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
 * pdt.setEndRule(Calendar.OCTOBER, -1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
 *
 * // create a GregorianCalendar with the Pacific Daylight time zone
 * // and the current date and time
 * Calendar calendar = new GregorianCalendar(pdt);
 * Date trialTime = new Date();
 * calendar.setTime(trialTime);
 *
 * // print out a bunch of interesting things
 * System.out.println("ERA: " + calendar.get(Calendar.ERA));
 * System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
 * System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
 * System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
 * System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
 * System.out.println("DATE: " + calendar.get(Calendar.DATE));
 * System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
 * System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
 * System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
 * System.out.println("DAY_OF_WEEK_IN_MONTH: "
 *                    + calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
 * System.out.println("AM_PM: " + calendar.get(Calendar.AM_PM));
 * System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
 * System.out.println("HOUR_OF_DAY: " + calendar.get(Calendar.HOUR_OF_DAY));
 * System.out.println("MINUTE: " + calendar.get(Calendar.MINUTE));
 * System.out.println("SECOND: " + calendar.get(Calendar.SECOND));
 * System.out.println("MILLISECOND: " + calendar.get(Calendar.MILLISECOND));
 * System.out.println("ZONE_OFFSET: "
 *                    + (calendar.get(Calendar.ZONE_OFFSET)/(60*60*1000)));
 * System.out.println("DST_OFFSET: "
 *                    + (calendar.get(Calendar.DST_OFFSET)/(60*60*1000)));

 * System.out.println("Current Time, with hour reset to 3");
 * calendar.clear(Calendar.HOUR_OF_DAY); // so doesn't override
 * calendar.set(Calendar.HOUR, 3);
 * System.out.println("ERA: " + calendar.get(Calendar.ERA));
 * System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
 * System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
 * System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
 * System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
 * System.out.println("DATE: " + calendar.get(Calendar.DATE));
 * System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
 * System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
 * System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
 * System.out.println("DAY_OF_WEEK_IN_MONTH: "
 *                    + calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
 * System.out.println("AM_PM: " + calendar.get(Calendar.AM_PM));
 * System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
 * System.out.println("HOUR_OF_DAY: " + calendar.get(Calendar.HOUR_OF_DAY));
 * System.out.println("MINUTE: " + calendar.get(Calendar.MINUTE));
 * System.out.println("SECOND: " + calendar.get(Calendar.SECOND));
 * System.out.println("MILLISECOND: " + calendar.get(Calendar.MILLISECOND));
 * System.out.println("ZONE_OFFSET: "
 *        + (calendar.get(Calendar.ZONE_OFFSET)/(60*60*1000))); // in hours
 * System.out.println("DST_OFFSET: "
 *        + (calendar.get(Calendar.DST_OFFSET)/(60*60*1000))); // in hours
 * </pre>
 * </blockquote>
 *
 * @see          TimeZone
 * @version      1.84
 * @author David Goldsmith, Mark Davis, Chen-Lieh Huang, Alan Liu
 * @since JDK1.1
 */
public class GregorianCalendar extends Calendar {
    /*
     * Implementation Notes
     *
     * The epoch is the number of days or milliseconds from some defined
     * starting point. The epoch for java.util.Date is used here; that is,
     * milliseconds from January 1, 1970 (Gregorian), midnight UTC.  Other
     * epochs which are used are January 1, year 1 (Gregorian), which is day 1
     * of the Gregorian calendar, and December 30, year 0 (Gregorian), which is
     * day 1 of the Julian calendar.
     *
     * We implement the proleptic Julian and Gregorian calendars.  This means we
     * implement the modern definition of the calendar even though the
     * historical usage differs.  For example, if the Gregorian change is set
     * to new Date(Long.MIN_VALUE), we have a pure Gregorian calendar which
     * labels dates preceding the invention of the Gregorian calendar in 1582 as
     * if the calendar existed then.
     *
     * Likewise, with the Julian calendar, we assume a consistent
     * 4-year leap year rule, even though the historical pattern of
     * leap years is irregular, being every 3 years from 45 BCE
     * through 9 BCE, then every 4 years from 8 CE onwards, with no
     * leap years in-between.  Thus date computations and functions
     * such as isLeapYear() are not intended to be historically
     * accurate.
     */

//////////////////
// Class Variables
//////////////////

    /**
     * Value of the <code>ERA</code> field indicating
     * the period before the common era (before Christ), also known as BCE.
     * The sequence of years at the transition from <code>BC</code> to <code>AD</code> is
     * ..., 2 BC, 1 BC, 1 AD, 2 AD,...
     *
     * @see #ERA
     */
    public static final int BC = 0;

    /**
     * Value of the {@link #ERA} field indicating
     * the period before the common era, the same value as {@link #BC}.
     *
     * @see #CE
     */
    static final int BCE = 0;

    /**
     * Value of the <code>ERA</code> field indicating
     * the common era (Anno Domini), also known as CE.
     * The sequence of years at the transition from <code>BC</code> to <code>AD</code> is
     * ..., 2 BC, 1 BC, 1 AD, 2 AD,...
     *
     * @see #ERA
     */
    public static final int AD = 1;

    /**
     * Value of the {@link #ERA} field indicating
     * the common era, the same value as {@link #AD}.
     *
     * @see #BCE
     */
    static final int CE = 1;

    private static final int EPOCH_OFFSET   = 719163; // Fixed date of January 1, 1970 (Gregorian)
    private static final int EPOCH_YEAR     = 1970;

    static final int MONTH_LENGTH[]
        = {31,28,31,30,31,30,31,31,30,31,30,31}; // 0-based
    static final int LEAP_MONTH_LENGTH[]
        = {31,29,31,30,31,30,31,31,30,31,30,31}; // 0-based

    // Useful millisecond constants.  Although ONE_DAY and ONE_WEEK can fit
    // into ints, they must be longs in order to prevent arithmetic overflow
    // when performing (bug 4173516).
    private static final int  ONE_SECOND = 1000;
    private static final int  ONE_MINUTE = 60*ONE_SECOND;
    private static final int  ONE_HOUR   = 60*ONE_MINUTE;
    private static final long ONE_DAY    = 24*ONE_HOUR;
    private static final long ONE_WEEK   = 7*ONE_DAY;

    /*
     * <pre>
     *                            Greatest       Least 
     * Field name        Minimum   Minimum     Maximum     Maximum
     * ----------        -------   -------     -------     -------
     * ERA                     0         0           1           1
     * YEAR                    1         1   292269054   292278994
     * MONTH                   0         0          11          11
     * WEEK_OF_YEAR            1         1          52*         53
     * WEEK_OF_MONTH           0         0           4*          6
     * DAY_OF_MONTH            1         1          28*         31
     * DAY_OF_YEAR             1         1         365*        366
     * DAY_OF_WEEK             1         1           7           7
     * DAY_OF_WEEK_IN_MONTH   -1        -1           4*          6
     * AM_PM                   0         0           1           1
     * HOUR                    0         0          11          11
     * HOUR_OF_DAY             0         0          23          23
     * MINUTE                  0         0          59          59
     * SECOND                  0         0          59          59
     * MILLISECOND             0         0         999         999
     * ZONE_OFFSET        -13:00    -13:00       14:00       14:00
     * DST_OFFSET           0:00      0:00        0:20        2:00
     * </pre>
     * *: depends on the Gregorian change date
     */
    static final int MIN_VALUES[] = {
        BCE,		// ERA
	1,		// YEAR
	JANUARY,	// MONTH
	1,		// WEEK_OF_YEAR
	0,		// WEEK_OF_MONTH
	1,		// DAY_OF_MONTH
	1,		// DAY_OF_YEAR
	SUNDAY,		// DAY_OF_WEEK
	1,		// DAY_OF_WEEK_IN_MONTH
	AM,		// AM_PM
	0,		// HOUR
	0,		// HOUR_OF_DAY
	0,		// MINUTE
	0,		// SECOND
	0,		// MILLISECOND
	-13*ONE_HOUR,	// ZONE_OFFSET (UNIX compatibility)
	0		// DST_OFFSET
    };
    static final int LEAST_MAX_VALUES[] = {
        CE,		// ERA
	292269054,	// YEAR
	DECEMBER,	// MONTH
	52,		// WEEK_OF_YEAR
	4,		// WEEK_OF_MONTH
	28,		// DAY_OF_MONTH
	365,		// DAY_OF_YEAR
	SATURDAY,	// DAY_OF_WEEK
	4,		// DAY_OF_WEEK_IN
	PM,		// AM_PM
	11,		// HOUR
	23,		// HOUR_OF_DAY
	59,		// MINUTE
	59,		// SECOND
	999,		// MILLISECOND
	14*ONE_HOUR,	// ZONE_OFFSET
	20*ONE_MINUTE	// DST_OFFSET (historical least maximum)
    };
    static final int MAX_VALUES[] = {
        CE,		// ERA
	292278994,	// YEAR
	DECEMBER,	// MONTH
	53,		// WEEK_OF_YEAR
	6,		// WEEK_OF_MONTH
	31,		// DAY_OF_MONTH
	366,		// DAY_OF_YEAR
	SATURDAY,	// DAY_OF_WEEK
	6,		// DAY_OF_WEEK_IN
	PM,		// AM_PM
	11,		// HOUR
	23,		// HOUR_OF_DAY
	59,		// MINUTE
	59,		// SECOND
	999,		// MILLISECOND
	14*ONE_HOUR,	// ZONE_OFFSET
	2*ONE_HOUR	// DST_OFFSET (double summer time)
    };

    // Proclaim serialization compatibility with JDK 1.1
    static final long serialVersionUID = -8125100834729963327L;

    // Reference to the sun.util.calendar.Gregorian instance (singleton).
    private static final Gregorian gcal =
				CalendarSystem.getGregorianCalendar();

    // Reference to the JulianCalendar instance (singleton), set as needed. See
    // getJulianCalendarSystem().
    private static JulianCalendar jcal;

    // JulianCalendar eras. See getJulianCalendarSystem().
    private static Era[] jeras;

    // The default value of gregorianCutover.
    static final long DEFAULT_GREGORIAN_CUTOVER = -12219292800000L;

/////////////////////
// Instance Variables
/////////////////////

    /**
     * The point at which the Gregorian calendar rules are used, measured in
     * milliseconds from the standard epoch.  Default is October 15, 1582
     * (Gregorian) 00:00:00 UTC or -12219292800000L.  For this value, October 4,
     * 1582 (Julian) is followed by October 15, 1582 (Gregorian).  This
     * corresponds to Julian day number 2299161.
     * @serial
     */
    private long gregorianCutover = DEFAULT_GREGORIAN_CUTOVER;

    /**
     * The fixed date of the gregorianCutover.
     */
    private transient long gregorianCutoverDate =
    	(((DEFAULT_GREGORIAN_CUTOVER + 1)/ONE_DAY) - 1) + EPOCH_OFFSET;	// == 577736

    /**
     * The normalized year of the gregorianCutover in Gregorian, with
     * 0 representing 1 BCE, -1 representing 2 BCE, etc.
     */
    private transient int gregorianCutoverYear = 1582;

    /**
     * The normalized year of the gregorianCutover in Julian, with 0
     * representing 1 BCE, -1 representing 2 BCE, etc.
     */
    private transient int gregorianCutoverYearJulian = 1582;

    /**
     * gdate always has a sun.util.calendar.Gregorian.Date instance to
     * avoid overhead of creating it. The assumption is that most
     * applications will need only Gregorian calendar calculations.
     */
    private transient BaseCalendar.Date gdate;

    /**
     * Reference to either gdate or a JulianCalendar.Date
     * instance. After calling complete(), this value is guaranteed to
     * be set.
     */
    private transient BaseCalendar.Date cdate;

    /**
     * The CalendarSystem used to calculate the date in cdate. After
     * calling complete(), this value is guaranteed to be set and
     * consistent with the cdate value.
     */
    private transient BaseCalendar calsys;

    /**
     * Temporary int[2] to get time zone offsets. zoneOffsets[0] gets
     * the GMT offset value and zoneOffsets[1] gets the DST saving
     * value.
     */
    private transient int[] zoneOffsets;

    /**
     * Temporary storage for saving original fields[] values in
     * non-lenient mode.
     */
    private transient int[] originalFields;

///////////////
// Constructors
///////////////

    /**
     * Constructs a default <code>GregorianCalendar</code> using the current time
     * in the default time zone with the default locale.
     */
    public GregorianCalendar() {
        this(TimeZone.getDefaultRef(), Locale.getDefault());
	setZoneShared(true);
    }

    /**
     * Constructs a <code>GregorianCalendar</code> based on the current time
     * in the given time zone with the default locale.
     *
     * @param zone the given time zone.
     */
    public GregorianCalendar(TimeZone zone) {
        this(zone, Locale.getDefault());
    }

    /**
     * Constructs a <code>GregorianCalendar</code> based on the current time
     * in the default time zone with the given locale.
     *
     * @param aLocale the given locale.
     */
    public GregorianCalendar(Locale aLocale) {
        this(TimeZone.getDefaultRef(), aLocale);
	setZoneShared(true);
    }

    /**
     * Constructs a <code>GregorianCalendar</code> based on the current time
     * in the given time zone with the given locale.
     *
     * @param zone the given time zone.
     * @param aLocale the given locale.
     */
    public GregorianCalendar(TimeZone zone, Locale aLocale) {
        super(zone, aLocale);
	gdate = (BaseCalendar.Date) gcal.newCalendarDate(zone);
        setTimeInMillis(System.currentTimeMillis());
    }

    /**
     * Constructs a <code>GregorianCalendar</code> with the given date set
     * in the default time zone with the default locale.
     *
     * @param year the value used to set the <code>YEAR</code> calendar field in the calendar.
     * @param month the value used to set the <code>MONTH</code> calendar field in the calendar.
     * Month value is 0-based. e.g., 0 for January.
     * @param dayOfMonth the value used to set the <code>DAY_OF_MONTH</code> calendar field in the calendar.
     */
    public GregorianCalendar(int year, int month, int dayOfMonth) {
	this(year, month, dayOfMonth, 0, 0, 0, 0);
    }

    /**
     * Constructs a <code>GregorianCalendar</code> with the given date
     * and time set for the default time zone with the default locale.
     *
     * @param year the value used to set the <code>YEAR</code> calendar field in the calendar.
     * @param month the value used to set the <code>MONTH</code> calendar field in the calendar.
     * Month value is 0-based. e.g., 0 for January.
     * @param dayOfMonth the value used to set the <code>DAY_OF_MONTH</code> calendar field in the calendar.
     * @param hourOfDay the value used to set the <code>HOUR_OF_DAY</code> calendar field
     * in the calendar.
     * @param minute the value used to set the <code>MINUTE</code> calendar field
     * in the calendar.
     */
    public GregorianCalendar(int year, int month, int dayOfMonth, int hourOfDay,
                             int minute) {
	this(year, month, dayOfMonth, hourOfDay, minute, 0, 0);
    }

    /**
     * Constructs a GregorianCalendar with the given date
     * and time set for the default time zone with the default locale.
     *
     * @param year the value used to set the <code>YEAR</code> calendar field in the calendar.
     * @param month the value used to set the <code>MONTH</code> calendar field in the calendar.
     * Month value is 0-based. e.g., 0 for January.
     * @param dayOfMonth the value used to set the <code>DAY_OF_MONTH</code> calendar field in the calendar.
     * @param hourOfDay the value used to set the <code>HOUR_OF_DAY</code> calendar field
     * in the calendar.
     * @param minute the value used to set the <code>MINUTE</code> calendar field
     * in the calendar.
     * @param second the value used to set the <code>SECOND</code> calendar field
     * in the calendar.
     */
    public GregorianCalendar(int year, int month, int dayOfMonth, int hourOfDay,
                             int minute, int second) {
	this(year, month, dayOfMonth, hourOfDay, minute, second, 0);
    }

    /**
     * Constructs a <code>GregorianCalendar</code> with the given date
     * and time set for the default time zone with the default locale.
     *
     * @param year the value used to set the <code>YEAR</code> calendar field in the calendar.
     * @param month the value used to set the <code>MONTH</code> calendar field in the calendar.
     * Month value is 0-based. e.g., 0 for January.
     * @param dayOfMonth the value used to set the <code>DAY_OF_MONTH</code> calendar field in the calendar.
     * @param hourOfDay the value used to set the <code>HOUR_OF_DAY</code> calendar field
     * in the calendar.
     * @param minute the value used to set the <code>MINUTE</code> calendar field
     * in the calendar.
     * @param second the value used to set the <code>SECOND</code> calendar field
     * in the calendar.
     * @param millis the value used to set the <code>MILLISECOND</code> calendar field
     */
    GregorianCalendar(int year, int month, int dayOfMonth,
		      int hourOfDay, int minute, int second, int millis) {
        super();
	gdate = (BaseCalendar.Date) gcal.newCalendarDate(getZone());
        this.set(YEAR, year);
        this.set(MONTH, month);
        this.set(DAY_OF_MONTH, dayOfMonth);
        this.set(HOUR_OF_DAY, hourOfDay);
        this.set(MINUTE, minute);
        this.set(SECOND, second);
	// should be changed to set() when this constructor is made
	// public.
	this.internalSet(MILLISECOND, millis);
    }
 
/////////////////
// Public methods
/////////////////

    /**
     * Sets the <code>GregorianCalendar</code> change date. This is the point when the switch
     * from Julian dates to Gregorian dates occurred. Default is October 15,
     * 1582 (Gregorian). Previous to this, dates will be in the Julian calendar.
     * <p>
     * To obtain a pure Julian calendar, set the change date to
     * <code>Date(Long.MAX_VALUE)</code>.  To obtain a pure Gregorian calendar,
     * set the change date to <code>Date(Long.MIN_VALUE)</code>.
     *
     * @param date the given Gregorian cutover date.
     */
    public void setGregorianChange(Date date) {
	long cutoverTime = date.getTime();
	if (cutoverTime == gregorianCutover) {
	    return;
	}
	// Before changing the cutover date, make sure to have the
	// time of this calendar.
	complete();
	setGregorianChange(cutoverTime);
    }

    private void setGregorianChange(long cutoverTime) {
        gregorianCutover = cutoverTime;
        gregorianCutoverDate = CalendarUtils.floorDivide(cutoverTime, ONE_DAY)
				+ EPOCH_OFFSET;

	// To provide the "pure" Julian calendar as advertised.
	// Strictly speaking, the last millisecond should be a
	// Gregorian date. However, the API doc specifies that setting
	// the cutover date to Long.MAX_VALUE will make this calendar
	// a pure Julian calendar. (See 4167995)
	if (cutoverTime == Long.MAX_VALUE) {
	    gregorianCutoverDate++;
	}

	BaseCalendar.Date d = getGregorianCutoverDate();

	// Set the cutover year (in the Gregorian year numbering)
        gregorianCutoverYear = d.getYear();

	BaseCalendar jcal = getJulianCalendarSystem();
	d = (BaseCalendar.Date) jcal.newCalendarDate(TimeZone.NO_TIMEZONE);
	jcal.getCalendarDateFromFixedDate(d, gregorianCutoverDate - 1);
	gregorianCutoverYearJulian = d.getNormalizedYear();

	if (time < gregorianCutover) {
	    // The field values are no longer valid under the new
	    // cutover date.
	    setUnnormalized();
	}
    }

    /**
     * Gets the Gregorian Calendar change date.  This is the point when the
     * switch from Julian dates to Gregorian dates occurred. Default is
     * October 15, 1582 (Gregorian). Previous to this, dates will be in the Julian
     * calendar.
     *
     * @return the Gregorian cutover date for this <code>GregorianCalendar</code> object.
     */
    public final Date getGregorianChange() {
        return new Date(gregorianCutover);
    }

    /**
     * Determines if the given year is a leap year. Returns <code>true</code> if
     * the given year is a leap year. To specify BC year numbers,
     * <code>1 - year number</code> must be given. For example, year BC 4 is
     * specified as -3.
     *
     * @param year the given year.
     * @return <code>true</code> if the given year is a leap year; <code>false</code> otherwise.
     */
    public boolean isLeapYear(int year) {
	if ((year & 3) != 0) {
	    return false;
	}

        if (year > gregorianCutoverYear) {
            return (year%100 != 0) || (year%400 == 0); // Gregorian
	}
	if (year < gregorianCutoverYearJulian) {
            return true; // Julian
	}
	boolean gregorian;
	// If the given year is the Gregorian cutover year, we need to
	// determine which calendar system to be applied to February in the year.
	if (gregorianCutoverYear == gregorianCutoverYearJulian) {
	    BaseCalendar.Date d = getCalendarDate(gregorianCutoverDate); // Gregorian
	    gregorian = d.getMonth() < BaseCalendar.MARCH;
	} else {
	    gregorian = year == gregorianCutoverYear;
	}
	return gregorian ? (year%100 != 0) || (year%400 == 0) : true;
    }

    /**
     * Compares this <code>GregorianCalendar</code> to the specified
     * <code>Object</code>. The result is <code>true</code> if and
     * only if the argument is a <code>GregorianCalendar</code> object
     * that represents the same time value (millisecond offset from
     * the <a href="Calendar.html#Epoch">Epoch</a>) under the same
     * <code>Calendar</code> parameters and Gregorian change date as
     * this object.
     *
     * @param obj the object to compare with.
     * @return <code>true</code> if this object is equal to <code>obj</code>
     * <code>false</code> otherwise.
     * @see Calendar#compareTo(Calendar)
     */
    public boolean equals(Object obj) {
        return obj instanceof GregorianCalendar &&
	    super.equals(obj) &&
            gregorianCutover == ((GregorianCalendar)obj).gregorianCutover;
    }
    
    /**
     * Generates the hash code for this <code>GregorianCalendar</code> object.
     */
    public int hashCode() {
        return super.hashCode() ^ (int)gregorianCutoverDate;
    }

    /**
     * Adds the specified (signed) amount of time to the given calendar field,
     * based on the calendar's rules.
     *
     * <p><em>Add rule 1</em>. The value of <code>field</code>
     * after the call minus the value of <code>field</code> before the
     * call is <code>amount</code>, modulo any overflow that has occurred in
     * <code>field</code>. Overflow occurs when a field value exceeds its
     * range and, as a result, the next larger field is incremented or
     * decremented and the field value is adjusted back into its range.</p>
     *
     * <p><em>Add rule 2</em>. If a smaller field is expected to be
     * invariant, but it is impossible for it to be equal to its
     * prior value because of changes in its minimum or maximum after
     * <code>field</code> is changed, then its value is adjusted to be as close
     * as possible to its expected value. A smaller field represents a
     * smaller unit of time. <code>HOUR</code> is a smaller field than
     * <code>DAY_OF_MONTH</code>. No adjustment is made to smaller fields
     * that are not expected to be invariant. The calendar system
     * determines what fields are expected to be invariant.</p>
     *
     * @param field the calendar field.
     * @param amount the amount of date or time to be added to the field.
     * @exception IllegalArgumentException if <code>field</code> is
     * <code>ZONE_OFFSET</code>, <code>DST_OFFSET</code>, or unknown,
     * or if any calendar fields have out-of-range values in
     * non-lenient mode.
     */
    public void add(int field, int amount) {
	// If amount == 0, do nothing even the given field is out of
	// range. This is tested by JCK.
        if (amount == 0) {
	    return;   // Do nothing!
	}

	if (field < 0 || field >= ZONE_OFFSET) {
	    throw new IllegalArgumentException();
	}

	// Sync the time and calendar fields.
        complete();

        if (field == YEAR) {
            int year = internalGet(YEAR);
            if (internalGetEra() == CE) {
                year += amount;
                if (year > 0) {
                    set(YEAR, year);
                } else { // year <= 0
                    set(YEAR, 1 - year);
                    // if year == 0, you get 1 BCE.
                    set(ERA, BCE);
                }
            }
            else { // era == BCE
                year -= amount;
                if (year > 0) {
                    set(YEAR, year);
                } else { // year <= 0
                    set(YEAR, 1 - year);
                    // if year == 0, you get 1 CE
                    set(ERA, CE);
                }
            }
            pinDayOfMonth();
        } else if (field == MONTH) {
            int month = internalGet(MONTH) + amount;
	    int year = internalGet(YEAR);
	    int y_amount;

	    if (month >= 0) {
                y_amount = month12;
	    } else {
                y_amount = (month+1)/12 - 1;
	    }
	    if (y_amount != 0) {
                if (internalGetEra() == CE) {
                    year += y_amount;
                    if (year > 0) {
                        set(YEAR, year);
                    } else { // year <= 0
                        set(YEAR, 1 - year);
                        // if year == 0, you get 1 BCE
                        set(ERA, BCE);
                    }
                }
                else { // era == BCE
                    year -= y_amount;
                    if (year > 0) {
                        set(YEAR, year);
                    } else { // year <= 0
                        set(YEAR, 1 - year);
                        // if year == 0, you get 1 CE
                        set(ERA, CE);
                    }
                }
            }

            if (month >= 0) {
                set(MONTH, (int) (month % 12));
            } else {
		// month < 0
                month %= 12;
                if (month < 0) {
		    month += 12;
		}
                set(MONTH, JANUARY + month);
            }
            pinDayOfMonth();
        } else if (field == ERA) {
            int era = internalGet(ERA) + amount;
            if (era < 0) {
		era = 0;
	    }
            if (era > 1) {
		era = 1;
	    }
            set(ERA, era);
        } else {
	    long delta = amount;
	    long timeOfDay = 0;
	    switch (field) {
	    // Handle the time fields here. Convert the given
	    // amount to milliseconds and call setTimeInMillis.
            case HOUR:
            case HOUR_OF_DAY:
                delta *= 60 * 60 * 1000;	// hours to minutes
                break;

            case MINUTE:
                delta *= 60 * 1000;		// minutes to seconds
                break;

            case SECOND:
                delta *= 1000;			// seconds to milliseconds
                break;

            case MILLISECOND:
                break;

	    // Handle week, day and AM_PM fields which involves
	    // time zone offset change adjustment. Convert the
	    // given amount to the number of days.
            case WEEK_OF_YEAR:
            case WEEK_OF_MONTH:
            case DAY_OF_WEEK_IN_MONTH:
                delta *= 7;
		break;

            case DAY_OF_MONTH: // synonym of DATE
            case DAY_OF_YEAR:
            case DAY_OF_WEEK:
		break;

	    case AM_PM:
		// Convert the amount to the number of days (delta)
		// and +12 or -12 hours (timeOfDay).
		delta = amount / 2;
		timeOfDay = 12 * (amount % 2);
		break;
	    }

	    // The time fields don't require time zone offset change
	    // adjustment.
	    if (field >= HOUR) {
		setTimeInMillis(time + delta);
		return;
	    }

	    // The rest of the fields (week, day or AM_PM fields)
	    // require time zone offset (both GMT and DST) change
	    // adjustment.

	    // Translate the current time to the fixed date and time
	    // of the day.
	    long fd = getCurrentFixedDate();
	    timeOfDay += internalGet(HOUR_OF_DAY);
	    timeOfDay *= 60;
	    timeOfDay += internalGet(MINUTE);
	    timeOfDay *= 60;
	    timeOfDay += internalGet(SECOND);
	    timeOfDay *= 1000;
	    timeOfDay += internalGet(MILLISECOND);
	    if (timeOfDay >= ONE_DAY) {
		fd++;
		timeOfDay -= ONE_DAY;
	    } else if (timeOfDay < 0) {
		fd--;
		timeOfDay += ONE_DAY;
	    }

	    fd += delta; // fd is the expected fixed date after the calculation
	    int zoneOffset = internalGet(ZONE_OFFSET) + internalGet(DST_OFFSET);
	    setTimeInMillis((fd - EPOCH_OFFSET) * ONE_DAY + timeOfDay - zoneOffset);
	    zoneOffset -= internalGet(ZONE_OFFSET) + internalGet(DST_OFFSET);
	    // If the time zone offset has changed, then adjust the difference.
	    if (zoneOffset != 0) {
		setTimeInMillis(time + zoneOffset);
		long fd2 = getCurrentFixedDate();
		// If the adjustment has changed the date, then take
		// the previous one.
		if (fd2 != fd) {
		    setTimeInMillis(time - zoneOffset);
		}
	    }
	}
    }

    /**
     * Adds or subtracts (up/down) a single unit of time on the given time
     * field without changing larger fields. 
     * <p>
     * <em>Example</em>: Consider a <code>GregorianCalendar</code>
     * originally set to December 31, 1999. Calling {@link #roll(int,boolean) roll(Calendar.MONTH, true)}
     * sets the calendar to January 31, 1999.  The <code>YEAR</code> field is unchanged
     * because it is a larger field than <code>MONTH</code>.</p>
     *
     * @param up indicates if the value of the specified calendar field is to be
     * rolled up or rolled down. Use <code>true</code> if rolling up, <code>false</code> otherwise.
     * @exception IllegalArgumentException if <code>field</code> is
     * <code>ZONE_OFFSET</code>, <code>DST_OFFSET</code>, or unknown,
     * or if any calendar fields have out-of-range values in
     * non-lenient mode.
     * @see #add(int,int)
     * @see #set(int,int)
     */
    public void roll(int field, boolean up) {
        roll(field, up ? +1 : -1);
    }

    /**
     * Adds a signed amount to the specified calendar field without changing larger fields.
     * A negative roll amount means to subtract from field without changing 
     * larger fields. If the specified amount is 0, this method performs nothing.
     *
     * <p>This method calls {@link #complete()} before adding the
     * amount so that all the calendar fields are normalized. If there
     * is any calendar field having an out-of-range value in non-lenient mode, then an
     * <code>IllegalArgumentException</code> is thrown.
     *
     * <p>
     * <em>Example</em>: Consider a <code>GregorianCalendar</code>
     * originally set to August 31, 1999. Calling <code>roll(Calendar.MONTH,
     * 8)</code> sets the calendar to April 30, <strong>1999</strong>. Using a
     * <code>GregorianCalendar</code>, the <code>DAY_OF_MONTH</code> field cannot
     * be 31 in the month April. <code>DAY_OF_MONTH</code> is set to the closest possible
     * value, 30. The <code>YEAR</code> field maintains the value of 1999 because it
     * is a larger field than <code>MONTH</code>.
     * <p>
     * <em>Example</em>: Consider a <code>GregorianCalendar</code>
     * originally set to Sunday June 6, 1999. Calling
     * <code>roll(Calendar.WEEK_OF_MONTH, -1)</code> sets the calendar to
     * Tuesday June 1, 1999, whereas calling
     * <code>add(Calendar.WEEK_OF_MONTH, -1)</code> sets the calendar to
     * Sunday May 30, 1999. This is because the roll rule imposes an
     * additional constraint: The <code>MONTH</code> must not change when the
     * <code>WEEK_OF_MONTH</code> is rolled. Taken together with add rule 1,
     * the resultant date must be between Tuesday June 1 and Saturday June
     * 5. According to add rule 2, the <code>DAY_OF_WEEK</code>, an invariant
     * when changing the <code>WEEK_OF_MONTH</code>, is set to Tuesday, the
     * closest possible value to Sunday (where Sunday is the first day of the
     * week).</p>
     *
     * @param field the calendar field.
     * @param amount the signed amount to add to <code>field</code>.
     * @exception IllegalArgumentException if <code>field</code> is
     * <code>ZONE_OFFSET</code>, <code>DST_OFFSET</code>, or unknown,
     * or if any calendar fields have out-of-range values in
     * non-lenient mode.
     * @see #roll(int,boolean)
     * @see #add(int,int)
     * @see #set(int,int)
     * @since 1.2
     */
    public void roll(int field, int amount) {
	// If amount == 0, do nothing even the given field is out of
	// range. This is tested by JCK.
        if (amount == 0) {
	    return;
	}

	if (field < 0 || field >= ZONE_OFFSET) {
	    throw new IllegalArgumentException();
	}

	// Sync the time and calendar fields.
	complete();

	int min = getMinimum(field);
	int max = getMaximum(field);

        switch (field) {
        case AM_PM:
        case ERA:
        case YEAR:
        case MINUTE:
        case SECOND:
        case MILLISECOND:
            // These fields are handled simply, since they have fixed minima
            // and maxima.  The field DAY_OF_MONTH is almost as simple.  Other
            // fields are complicated, since the range within they must roll
            // varies depending on the date.
            break;

        case HOUR:
        case HOUR_OF_DAY:
	    {
		int unit = max + 1; // 12 or 24 hours
		int h = internalGet(field);
		int nh = (h + amount) % unit;
		if (nh < 0) {
		    nh += unit;
		}
		time += ONE_HOUR * (nh - h);

		// The day might have changed, which could happen if
		// the daylight saving time transition brings it to
		// the next day, although it's very unlikely. But we
		// have to make sure not to change the larger fields.
		CalendarDate d = calsys.getCalendarDate(time, getZone());
		if (internalGet(DAY_OF_MONTH) != d.getDayOfMonth()) {
		    d.setDate(internalGet(YEAR),
			      internalGet(MONTH) + 1,
			      internalGet(DAY_OF_MONTH));
		    if (field == HOUR) {
			assert (internalGet(AM_PM) == PM);
			d.addHours(+12); // restore PM
		    }
		    time = calsys.getTime(d);
		}
		internalSet(field, d.getHours() % unit);

		// Time zone offset and/or daylight saving might have changed.
		int zoneOffset = d.getZoneOffset();
		int saving = d.getDaylightSaving();
		internalSet(ZONE_OFFSET, zoneOffset - saving);
		internalSet(DST_OFFSET, saving);
		return;
	    }

        case MONTH:
            // Rolling the month involves both pinning the final value to [0, 11]
            // and adjusting the DAY_OF_MONTH if necessary.  We only adjust the
            // DAY_OF_MONTH if, after updating the MONTH field, it is illegal.
            // E.g., <jan31>.roll(MONTH, 1) -> <feb28> or <feb29>.
            {
		if (!isCutoverYear(cdate.getNormalizedYear())) {
		    int mon = (internalGet(MONTH) + amount) % 12;
		    if (mon < 0) {
			mon += 12;
		    }
		    set(MONTH, mon);
                
		    // Keep the day of month in the range.  We don't want to spill over
		    // into the next month; e.g., we don't want jan31 + 1 mo -> feb31 ->
		    // mar3.
		    int monthLen = monthLength(mon);
		    if (internalGet(DAY_OF_MONTH) > monthLen) {
			set(DAY_OF_MONTH, monthLen);
		    }
		} else {
		    // We need to take care of different lengths in
		    // year and month due to the cutover.
		    int yearLength = getActualMaximum(MONTH) + 1;
		    int mon = (internalGet(MONTH) + amount) % yearLength;
		    if (mon < 0) {
			mon += yearLength;
		    }
		    set(MONTH, mon);
		    int monthLen = getActualMaximum(DAY_OF_MONTH);
		    if (internalGet(DAY_OF_MONTH) > monthLen) {
			set(DAY_OF_MONTH, monthLen);
		    }
		}
		return;
            }

        case WEEK_OF_YEAR:
	    {
		int y = cdate.getNormalizedYear();
		max = getActualMaximum(WEEK_OF_YEAR);
		set(DAY_OF_WEEK, internalGet(DAY_OF_WEEK));
		int woy = internalGet(WEEK_OF_YEAR);
		int value = woy + amount;
		if (!isCutoverYear(y)) {
		    // If the new value is in between min and max
		    // (exclusive), then we can use the value.
		    if (value > min && value < max) {
			set(WEEK_OF_YEAR, value);
			return;
		    }
		    long fd = getCurrentFixedDate();
		    // Make sure that the min week has the current DAY_OF_WEEK
		    long day1 = fd - (7 * (woy - min));
		    if (calsys.getYearFromFixedDate(day1) != y) {
			min++;
		    }

		    // Make sure the same thing for the max week
		    fd += 7 * (max - internalGet(WEEK_OF_YEAR));
		    if (calsys.getYearFromFixedDate(fd) != y) {
			max--;
		    }
		    break;
		}

		// Handle cutover here.
		long fd = getCurrentFixedDate();
		BaseCalendar cal;
		if (gregorianCutoverYear == gregorianCutoverYearJulian) {
		    cal = getCutoverCalendarSystem();
		} else if (y == gregorianCutoverYear) {
		    cal = gcal;
		} else {
		    cal = getJulianCalendarSystem();
		}
		long day1 = fd - (7 * (woy - min));
		// Make sure that the min week has the current DAY_OF_WEEK
		if (cal.getYearFromFixedDate(day1) != y) {
		    min++;
		}

		// Make sure the same thing for the max week
		fd += 7 * (max - woy);
		cal = (fd >= gregorianCutoverDate) ? gcal : getJulianCalendarSystem();
		if (cal.getYearFromFixedDate(fd) != y) {
		    max--;
		}
		// value: the new WEEK_OF_YEAR which must be converted
		// to month and day of month.
		value = getRolledValue(woy, amount, min, max) - 1;
		BaseCalendar.Date d = getCalendarDate(day1 + value * 7);
		set(MONTH, d.getMonth() - 1);
		set(DAY_OF_MONTH, d.getDayOfMonth());
		return;
	    }

        case WEEK_OF_MONTH:
	    {
		boolean isCutoverYear = isCutoverYear(cdate.getNormalizedYear());
		// dow: relative day of week from first day of week
		int dow = internalGet(DAY_OF_WEEK) - getFirstDayOfWeek();
		if (dow < 0) {
		    dow += 7;
		}

		long fd = getCurrentFixedDate();
		long month1;	 // fixed date of the first day (usually 1) of the month
		int monthLength; // actual month length
		if (isCutoverYear) {
		    month1 = getFixedDateMonth1(cdate, fd);
		    monthLength = actualMonthLength();
		} else {
		    month1 = fd - internalGet(DAY_OF_MONTH) + 1;
		    monthLength = calsys.getMonthLength(cdate);
		}

		// the first day of week of the month.
		long monthDay1st = calsys.getDayOfWeekDateOnOrBefore(month1 + 6,
								     getFirstDayOfWeek());
		// if the week has enough days to form a week, the
		// week starts from the previous month.
		if ((int)(monthDay1st - month1) >= getMinimalDaysInFirstWeek()) {
		    monthDay1st -= 7;
		}
		max = getActualMaximum(field);

		// value: the new WEEK_OF_MONTH value
		int value = getRolledValue(internalGet(field), amount, 1, max) - 1;

		// nfd: fixed date of the rolled date
		long nfd = monthDay1st + value * 7 + dow;

		// Unlike WEEK_OF_YEAR, we need to change day of week if the
		// nfd is out of the month.
		if (nfd < month1) {
		    nfd = month1;
		} else if (nfd >= (month1 + monthLength)) {
		    nfd = month1 + monthLength - 1;
		}
		int dayOfMonth;
		if (isCutoverYear) {
		    // If we are in the cutover year, convert nfd to
		    // its calendar date and use dayOfMonth.
		    BaseCalendar.Date d = getCalendarDate(nfd);
		    dayOfMonth = d.getDayOfMonth();
		} else {
		    dayOfMonth = (int)(nfd - month1) + 1;
		}
		set(DAY_OF_MONTH, dayOfMonth);
		return;
	    }

        case DAY_OF_MONTH:
	    {
		if (!isCutoverYear(cdate.getNormalizedYear())) {
		    max = calsys.getMonthLength(cdate);
		    break;
		}

		// Cutover year handling
		long fd = getCurrentFixedDate();
		long month1 = getFixedDateMonth1(cdate, fd);
		// It may not be a regular month. Convert the date and range to
		// the relative values, perform the roll, and
		// convert the result back to the rolled date.
		int value = getRolledValue((int)(fd - month1), amount, 0, actualMonthLength() - 1);
		BaseCalendar.Date d = getCalendarDate(month1 + value);
		assert d.getMonth()-1 == internalGet(MONTH);
		set(DAY_OF_MONTH, d.getDayOfMonth());
		return;
	    }

        case DAY_OF_YEAR:
	    {
		max = getActualMaximum(field);
		if (!isCutoverYear(cdate.getNormalizedYear())) {
		    break;
		}

		// Handle cutover here.
		long fd = getCurrentFixedDate();
		long jan1 = fd - internalGet(DAY_OF_YEAR) + 1;
		int value = getRolledValue((int)(fd - jan1) + 1, amount, min, max);
		BaseCalendar.Date d = getCalendarDate(jan1 + value - 1);
		set(MONTH, d.getMonth() - 1);
		set(DAY_OF_MONTH, d.getDayOfMonth());
		return;
	    }

        case DAY_OF_WEEK:
	    set(WEEK_OF_YEAR, internalGet(WEEK_OF_YEAR));
	    max = SATURDAY;
	    break;

        case DAY_OF_WEEK_IN_MONTH:
            {
		min = 1; // after normalized, min should be 1.
		if (!isCutoverYear(cdate.getNormalizedYear())) {
		    int dom = internalGet(DAY_OF_MONTH);
		    int monthLength = calsys.getMonthLength(cdate);
		    int lastDays = monthLength % 7;
		    max = monthLength / 7;
		    int x = (dom - 1) % 7;
		    if (x < lastDays) {
			max++;
		    }
		    set(DAY_OF_WEEK, internalGet(DAY_OF_WEEK));
		    break;
		}

		// Cutover year handling
		long fd = getCurrentFixedDate();
		long month1 = getFixedDateMonth1(cdate, fd);
		int monthLength = actualMonthLength();
		int lastDays = monthLength % 7;
		max = monthLength / 7;
		int x = (int)(fd - month1) % 7;
		if (x < lastDays) {
		    max++;
		}
		int value = getRolledValue(internalGet(field), amount, min, max) - 1;
		fd = month1 + value * 7 + x;
		BaseCalendar cal = (fd >= gregorianCutoverDate) ? gcal : getJulianCalendarSystem();
		BaseCalendar.Date d = (BaseCalendar.Date) cal.newCalendarDate(TimeZone.NO_TIMEZONE);
		cal.getCalendarDateFromFixedDate(d, fd);
		set(DAY_OF_MONTH, d.getDayOfMonth());
		return;
            }
	}

	set(field, getRolledValue(internalGet(field), amount, min, max));
    }

    /**
     * Returns the minimum value for the given calendar field of this
     * <code>GregorianCalendar</code> instance. The minimum value is
     * defined as the smallest value returned by the {@link
     * Calendar#get(int) get} method for any possible time value,
     * taking into consideration the current values of the
     * {@link Calendar#getFirstDayOfWeek() getFirstDayOfWeek},
     * {@link Calendar#getMinimalDaysInFirstWeek() getMinimalDaysInFirstWeek},
     * {@link #getGregorianChange(Date) getGregorianChange} and
     * {@link Calendar#getTimeZone() getTimeZone} methods.
     *
     * @param field the calendar field.
     * @return the minimum value for the given calendar field.
     * @see #getMaximum(int)
     * @see #getGreatestMinimum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMinimum(int)
     * @see #getActualMaximum(int)
     */
    public int getMinimum(int field) {
        return MIN_VALUES[field];
    }

    /**
     * Returns the maximum value for the given calendar field of this
     * <code>GregorianCalendar</code> instance. The maximum value is
     * defined as the largest value returned by the {@link
     * Calendar#get(int) get} method for any possible time value,
     * taking into consideration the current values of the
     * {@link Calendar#getFirstDayOfWeek() getFirstDayOfWeek},
     * {@link Calendar#getMinimalDaysInFirstWeek() getMinimalDaysInFirstWeek},
     * {@link #getGregorianChange(Date) getGregorianChange} and
     * {@link Calendar#getTimeZone() getTimeZone} methods.
     *
     * @param field the calendar field.
     * @return the maximum value for the given calendar field.
     * @see #getMinimum(int)
     * @see #getGreatestMinimum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMinimum(int)
     * @see #getActualMaximum(int)
     */
    public int getMaximum(int field) {
	switch (field) {
	case MONTH:
        case DAY_OF_MONTH:
        case DAY_OF_YEAR:
        case WEEK_OF_YEAR:
        case WEEK_OF_MONTH:
        case DAY_OF_WEEK_IN_MONTH:
	case YEAR:
	    {
		// On or after Gregorian 200-3-1, Julian and Gregorian
		// calendar dates are the same or Gregorian dates are
		// larger (i.e., there is a "gap") after 300-3-1.
		if (gregorianCutoverYear > 200) {
		    break;
		}
		// There might be "overlapping" dates.
		GregorianCalendar gc = (GregorianCalendar) clone();
		gc.setLenient(true);
		gc.setTimeInMillis(gregorianCutover);
		int v1 = gc.getActualMaximum(field);
		gc.setTimeInMillis(gregorianCutover-1);
		int v2 = gc.getActualMaximum(field);
		return Math.max(MAX_VALUES[field], Math.max(v1, v2));
	    }
	}
        return MAX_VALUES[field];
    }

    /**
     * Returns the highest minimum value for the given calendar field
     * of this <code>GregorianCalendar</code> instance. The highest
     * minimum value is defined as the largest value returned by
     * {@link #getActualMinimum(int)} for any possible time value,
     * taking into consideration the current values of the
     * {@link Calendar#getFirstDayOfWeek() getFirstDayOfWeek},
     * {@link Calendar#getMinimalDaysInFirstWeek() getMinimalDaysInFirstWeek},
     * {@link #getGregorianChange(Date) getGregorianChange} and
     * {@link Calendar#getTimeZone() getTimeZone} methods.
     *
     * @param field the calendar field.
     * @return the highest minimum value for the given calendar field.
     * @see #getMinimum(int)
     * @see #getMaximum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMinimum(int)
     * @see #getActualMaximum(int)
     */
    public int getGreatestMinimum(int field) {
	if (field == DAY_OF_MONTH) {
	    BaseCalendar.Date d = getGregorianCutoverDate();
	    long mon1 = getFixedDateMonth1(d, gregorianCutoverDate);
	    d = getCalendarDate(mon1);
	    return Math.max(MIN_VALUES[field], d.getDayOfMonth());
	}
        return MIN_VALUES[field];
    }

    /**
     * Returns the lowest maximum value for the given calendar field
     * of this <code>GregorianCalendar</code> instance. The lowest
     * maximum value is defined as the smallest value returned by
     * {@link #getActualMaximum(int)} for any possible time value,
     * taking into consideration the current values of the
     * {@link Calendar#getFirstDayOfWeek() getFirstDayOfWeek},
     * {@link Calendar#getMinimalDaysInFirstWeek() getMinimalDaysInFirstWeek},
     * {@link #getGregorianChange(Date) getGregorianChange} and
     * {@link Calendar#getTimeZone() getTimeZone} methods.
     *
     * @param field the calendar field
     * @return the lowest maximum value for the given calendar field.
     * @see #getMinimum(int)
     * @see #getMaximum(int)
     * @see #getGreatestMinimum(int)
     * @see #getActualMinimum(int)
     * @see #getActualMaximum(int)
     */
    public int getLeastMaximum(int field) {
	switch (field) {
	case MONTH:
        case DAY_OF_MONTH:
        case DAY_OF_YEAR:
        case WEEK_OF_YEAR:
        case WEEK_OF_MONTH:
        case DAY_OF_WEEK_IN_MONTH:
	case YEAR:
	    {
		GregorianCalendar gc = (GregorianCalendar) clone();
		gc.setLenient(true);
		gc.setTimeInMillis(gregorianCutover);
		int v1 = gc.getActualMaximum(field);
		gc.setTimeInMillis(gregorianCutover-1);
		int v2 = gc.getActualMaximum(field);
		return Math.min(LEAST_MAX_VALUES[field], Math.min(v1, v2));
	    }
	}
        return LEAST_MAX_VALUES[field];
    }

    /**
     * Returns the minimum value that this calendar field could have,
     * taking into consideration the given time value and the current
     * values of the
     * {@link Calendar#getFirstDayOfWeek() getFirstDayOfWeek},
     * {@link Calendar#getMinimalDaysInFirstWeek() getMinimalDaysInFirstWeek},
     * {@link #getGregorianChange(Date) getGregorianChange} and
     * {@link Calendar#getTimeZone() getTimeZone} methods.
     *
     * <p>For example, if the Gregorian change date is January 10,
     * 1970 and the date of this <code>GregorianCalendar</code> is
     * January 20, 1970, the actual minimum value of the
     * <code>DAY_OF_MONTH</code> field is 10 because the previous date
     * of January 10, 1970 is December 27, 1996 (in the Julian
     * calendar). Therefore, December 28, 1969 to January 9, 1970
     * don't exist.
     *
     * @param field the calendar field
     * @return the minimum of the given field for the time value of
     * this <code>GregorianCalendar</code>
     * @see #getMinimum(int)
     * @see #getMaximum(int)
     * @see #getGreatestMinimum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMaximum(int)
     * @since 1.2
     */
    public int getActualMinimum(int field) {
	if (field == DAY_OF_MONTH) {
	    GregorianCalendar gc = getNormalizedCalendar();
	    int year = gc.cdate.getNormalizedYear();
	    if (year == gregorianCutoverYear || year == gregorianCutoverYearJulian) {
		long month1 = getFixedDateMonth1(gc.cdate, gc.calsys.getFixedDate(gc.cdate));
		BaseCalendar.Date d = getCalendarDate(month1);
		return d.getDayOfMonth();
	    }
	}
        return getMinimum(field);
    }

    /**
     * Returns the maximum value that this calendar field could have,
     * taking into consideration the given time value and the current
     * values of the
     * {@link Calendar#getFirstDayOfWeek() getFirstDayOfWeek},
     * {@link Calendar#getMinimalDaysInFirstWeek() getMinimalDaysInFirstWeek},
     * {@link #getGregorianChange(Date) getGregorianChange} and
     * {@link Calendar#getTimeZone() getTimeZone} methods.
     * For example, if the date of this instance is February 1, 2004,
     * the actual maximum value of the <code>DAY_OF_MONTH</code> field
     * is 29 because 2004 is a leap year, and if the date of this
     * instance is February 1, 2005, it's 28.
     *
     * @param field the calendar field
     * @return the maximum of the given field for the time value of
     * this <code>GregorianCalendar</code>
     * @see #getMinimum(int)
     * @see #getMaximum(int)
     * @see #getGreatestMinimum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMinimum(int)
     * @since 1.2
     */
    public int getActualMaximum(int field) {
	final int fieldsForFixedMax = ERA_MASK|DAY_OF_WEEK_MASK|HOUR_MASK|AM_PM_MASK|
	    HOUR_OF_DAY_MASK|MINUTE_MASK|SECOND_MASK|MILLISECOND_MASK|
	    ZONE_OFFSET_MASK|DST_OFFSET_MASK;
	if ((fieldsForFixedMax & (1<<field)) != 0) {
	    return getMaximum(field);
	}

	GregorianCalendar gc = getNormalizedCalendar();
	BaseCalendar.Date date = gc.cdate;
	BaseCalendar cal = gc.calsys;
	int normalizedYear = date.getNormalizedYear();

	int value = -1;
        switch (field) {
	case MONTH:
	    {
		if (!gc.isCutoverYear(normalizedYear)) {
		    value = DECEMBER;
		    break;
		}

		// January 1 of the next year may or may not exist.
		long nextJan1;
		do {
		    nextJan1 = gcal.getFixedDate(++normalizedYear, BaseCalendar.JANUARY, 1, null);
		} while (nextJan1 < gregorianCutoverDate);
		BaseCalendar.Date d = (BaseCalendar.Date) date.clone();
		cal.getCalendarDateFromFixedDate(d, nextJan1 - 1);
		value = d.getMonth() - 1;
	    }
	    break;

        case DAY_OF_MONTH:
	    {
		value = cal.getMonthLength(date);
		if (!gc.isCutoverYear(normalizedYear) || date.getDayOfMonth() == value) {
		    break;
		}

		// Handle cutover year.
		long fd = gc.getCurrentFixedDate();
		if (fd >= gregorianCutoverDate) {
		    break;
		}
		int monthLength = gc.actualMonthLength();
		long monthEnd = gc.getFixedDateMonth1(gc.cdate, fd) + monthLength - 1;
		// Convert the fixed date to its calendar date.
		BaseCalendar.Date d = gc.getCalendarDate(monthEnd);
		value = d.getDayOfMonth();
	    }		    
	    break;

        case DAY_OF_YEAR:
	    {
		if (!gc.isCutoverYear(normalizedYear)) {
		    value = cal.getYearLength(date);
		    break;
		}

		// Handle cutover year.
		long jan1;
		if (gregorianCutoverYear == gregorianCutoverYearJulian) {
		    BaseCalendar cocal = gc.getCutoverCalendarSystem();
		    jan1 = cocal.getFixedDate(normalizedYear, 1, 1, null);
		} else if (normalizedYear == gregorianCutoverYearJulian) {
		    jan1 = cal.getFixedDate(normalizedYear, 1, 1, null);
		} else {
		    jan1 = gregorianCutoverDate;
		}
		// January 1 of the next year may or may not exist.
		long nextJan1 = gcal.getFixedDate(++normalizedYear, 1, 1, null);
		if (nextJan1 < gregorianCutoverDate) {
		    nextJan1 = gregorianCutoverDate;
		}
		assert jan1 <= cal.getFixedDate(date.getNormalizedYear(), date.getMonth(),
						date.getDayOfMonth(), date);
		assert nextJan1 >= cal.getFixedDate(date.getNormalizedYear(), date.getMonth(),
						date.getDayOfMonth(), date);
		value = (int)(nextJan1 - jan1);
	    }
	    break;

        case WEEK_OF_YEAR:
	    {
		if (!gc.isCutoverYear(normalizedYear)) {
		    // Get the day of week of January 1 of the year
		    CalendarDate d = cal.newCalendarDate(TimeZone.NO_TIMEZONE);
		    d.setDate(date.getYear(), BaseCalendar.JANUARY, 1);
		    int dayOfWeek = cal.getDayOfWeek(d);
		    // Normalize the day of week with the firstDayOfWeek value
		    dayOfWeek -= getFirstDayOfWeek();
		    if (dayOfWeek < 0) {
			dayOfWeek += 7;
		    }
		    value = 52;
		    int magic = dayOfWeek + getMinimalDaysInFirstWeek() - 1;
		    if ((magic == 6) ||
			(date.isLeapYear() && (magic == 5 || magic == 12))) {
			value++;
		    }
		    break;
		}

		if (gc == this) {
		    gc = (GregorianCalendar) gc.clone();
		}
		gc.set(DAY_OF_YEAR, getActualMaximum(DAY_OF_YEAR));
		value = gc.get(WEEK_OF_YEAR);
	    }
	    break;

        case WEEK_OF_MONTH:
	    {
		if (!gc.isCutoverYear(normalizedYear)) {
		    CalendarDate d = cal.newCalendarDate(null);
		    d.setDate(date.getYear(), date.getMonth(), 1);
		    int dayOfWeek = cal.getDayOfWeek(d);
		    int monthLength = cal.getMonthLength(d);
		    dayOfWeek -= getFirstDayOfWeek();
		    if (dayOfWeek < 0) {
			dayOfWeek += 7;
		    }
		    int nDaysFirstWeek = 7 - dayOfWeek; // # of days in the first week
		    value = 3;
		    if (nDaysFirstWeek >= getMinimalDaysInFirstWeek()) {
			value++;
		    }
		    monthLength -= nDaysFirstWeek + 7 * 3;
		    if (monthLength > 0) {
			value++;
			if (monthLength > 7) {
			    value++;
			}
		    }
		    break;
		}

		// Cutover year handling
		if (gc == this) {
		    gc = (GregorianCalendar) gc.clone();
		}
		int y = gc.internalGet(YEAR);
		int m = gc.internalGet(MONTH);
		do {
		    value = gc.get(WEEK_OF_MONTH);
		    gc.add(WEEK_OF_MONTH, +1);
		} while (gc.get(YEAR) == y && gc.get(MONTH) == m);
	    }
	    break;

        case DAY_OF_WEEK_IN_MONTH:
	    {
		// may be in the Gregorian cutover month
		int ndays, dow1;
		int dow = date.getDayOfWeek();
		if (!gc.isCutoverYear(normalizedYear)) {
		    BaseCalendar.Date d = (BaseCalendar.Date) date.clone();
		    ndays = cal.getMonthLength(d);
		    d.setDayOfMonth(1);
		    cal.normalize(d);
		    dow1 = d.getDayOfWeek();
		} else {
		    // Let a cloned GregorianCalendar take care of the cutover cases.
		    if (gc == this) {
			gc = (GregorianCalendar) clone();
		    }
		    ndays = gc.actualMonthLength();
		    gc.set(DAY_OF_MONTH, gc.getActualMinimum(DAY_OF_MONTH));
		    dow1 = gc.get(DAY_OF_WEEK);
		}
		int x = dow - dow1;
		if (x < 0) {
		    x += 7;
		}
		ndays -= x;
		value = (ndays + 6) / 7;
	    }
	    break;

	case YEAR:
            /* The year computation is no different, in principle, from the
             * others, however, the range of possible maxima is large.  In
             * addition, the way we know we've exceeded the range is different.
             * For these reasons, we use the special case code below to handle
             * this field.
             *
             * The actual maxima for YEAR depend on the type of calendar:
             *
             *     Gregorian = May 17, 292275056 BCE - Aug 17, 292278994 CE
             *     Julian    = Dec  2, 292269055 BCE - Jan  3, 292272993 CE
             *     Hybrid    = Dec  2, 292269055 BCE - Aug 17, 292278994 CE
             *
             * We know we've exceeded the maximum when either the month, date,
             * time, or era changes in response to setting the year.  We don't
             * check for month, date, and time here because the year and era are
             * sufficient to detect an invalid year setting.  NOTE: If code is
             * added to check the month and date in the future for some reason,
             * Feb 29 must be allowed to shift to Mar 1 when setting the year.
             */
	    {
		if (gc == this) {
		    gc = (GregorianCalendar) clone();
		}

		// Calculate the millisecond offset from the beginning
		// of the year of this calendar and adjust the max
		// year value if we are beyond the limit in the max
		// year.
		long current = gc.getYearOffsetInMillis();

		if (gc.internalGetEra() == CE) {
		    gc.setTimeInMillis(Long.MAX_VALUE);
		    value = gc.get(YEAR);
		    long maxEnd = gc.getYearOffsetInMillis();
		    if (current > maxEnd) {
			value--;
		    }
		} else {
		    CalendarSystem mincal = gc.getTimeInMillis() >= gregorianCutover ?
			gcal : getJulianCalendarSystem();
		    CalendarDate d = mincal.getCalendarDate(Long.MIN_VALUE, getZone());
		    long maxEnd = (cal.getDayOfYear(d) - 1) * 24 + d.getHours();
		    maxEnd *= 60;
		    maxEnd += d.getMinutes();
		    maxEnd *= 60;
		    maxEnd += d.getSeconds();
		    maxEnd *= 1000;
		    maxEnd += d.getMillis();
		    value = d.getYear();
		    if (value <= 0) {
			assert mincal == gcal;
			value = 1 - value;
		    }
		    if (current < maxEnd) {
			value--;
		    }
		}
	    }
	    break;

	default:
	    throw new ArrayIndexOutOfBoundsException(field);
	}
	return value;
    }

    /**
     * Returns the millisecond offset from the beginning of this
     * year. This Calendar object must have been normalized.
     */
    private final long getYearOffsetInMillis() {
	long t = (internalGet(DAY_OF_YEAR) - 1) * 24;
	t += internalGet(HOUR_OF_DAY);
	t *= 60;
	t += internalGet(MINUTE);
	t *= 60;
	t += internalGet(SECOND);
	t *= 1000;
	return t + internalGet(MILLISECOND) -
	    (internalGet(ZONE_OFFSET) + internalGet(DST_OFFSET));
    }

    public Object clone()
    {
	GregorianCalendar other = (GregorianCalendar) super.clone();

	other.gdate = (BaseCalendar.Date) gdate.clone();
	if (cdate != null) {
	    if (cdate != gdate) {
		other.cdate = (BaseCalendar.Date) cdate.clone();
	    } else {
		other.cdate = other.gdate;
	    }
	}
	other.originalFields = null;
	other.zoneOffsets = null;
	return other;
    }

    public TimeZone getTimeZone() {
	TimeZone zone = super.getTimeZone();
	// To share the zone by CalendarDates
	gdate.setZone(zone);
	if (cdate != null && cdate != gdate) {
	    cdate.setZone(zone);
	}
	return zone;
    }

    public void setTimeZone(TimeZone zone) {
	super.setTimeZone(zone);
	// To share the zone by CalendarDates
	gdate.setZone(zone);
	if (cdate != null && cdate != gdate) {
	    cdate.setZone(zone);
	}
    }

//////////////////////
// Proposed public API
//////////////////////

    /**
     * Returns the year that corresponds to the <code>WEEK_OF_YEAR</code> field.
     * This may be one year before or after the Gregorian or Julian year stored
     * in the <code>YEAR</code> field.  For example, January 1, 1999 is considered
     * Friday of week 53 of 1998 (if minimal days in first week is
     * 2 or less, and the first day of the week is Sunday).  Given
     * these same settings, the ISO year of January 1, 1999 is
     * 1998.
     * 
     * <p>This method calls {@link Calendar#complete} before
     * calculating the week-based year.
     *
     * @return the year corresponding to the <code>WEEK_OF_YEAR</code> field, which
     * may be one year before or after the <code>YEAR</code> field.
     * @see #YEAR
     * @see #WEEK_OF_YEAR
     */
    /*
    public int getWeekBasedYear() {
        complete();
	// TODO: Below doesn't work for gregorian cutover...
        int weekOfYear = internalGet(WEEK_OF_YEAR);
        int year = internalGet(YEAR);
        if (internalGet(MONTH) == Calendar.JANUARY) {
            if (weekOfYear >= 52) {
                --year;
            }
        } else {
            if (weekOfYear == 1) {
                ++year;
            }
        }
        return year;
    }
    */


/////////////////////////////
// Time => Fields computation
/////////////////////////////

    /**
     * The fixed date corresponding to gdate. If the value is
     * Long.MIN_VALUE, the fixed date value is unknown. Currently,
     * Julian calendar dates are not cached.
     */
    transient private long cachedFixedDate = Long.MIN_VALUE;

    /**
     * Converts the time value (millisecond offset from the <a
     * href="Calendar.html#Epoch">Epoch</a>) to calendar field values.
     * The time is <em>not</em>
     * recomputed first; to recompute the time, then the fields, call the
     * <code>complete</code> method.
     *
     * @see Calendar#complete
     */
    protected void computeFields() {
	int mask = 0;
	if (isPartiallyNormalized()) {
	    // Determine which calendar fields need to be computed.
	    mask = getSetStateFields();
	    int fieldMask = ~mask & ALL_FIELDS;
	    mask |= computeFields(fieldMask,
				  (mask & (ZONE_OFFSET_MASK|DST_OFFSET_MASK))
				  == (ZONE_OFFSET_MASK|DST_OFFSET_MASK) ? fields : null,
				  ZONE_OFFSET);
	    assert mask == ALL_FIELDS;
	} else {
	    // Specify all fields
	    mask = ALL_FIELDS;
	    computeFields(mask, null, 0);
	}
	// After computing all the fields, set the field state to `COMPUTED'.
	setFieldsComputed(mask);
    }

    /**
     * This computeFields implements the conversion from UTC
     * (millisecond offset from the Epoch) to calendar
     * field values. fieldMask specifies which fields to change the
     * setting state to COMPUTED, although all fields are set to
     * the correct values. This is required to fix 4685354.
     *
     * @param fieldMask a bit mask to specify which fields to change
     * the setting state.
     * @param offsets an <code>int</code> array having time zone
     * offset values at 'time', or <code>null</code> if time zone
     * offsets are not known. The <code>int</code> array must be
     * either <code>zoneOffsets[]</code> or <code>fields[]</code>.
     * @param index an index to <code>offsets[]</code>. Must be 0 for
     * <code>zoneOffsets[]</code> or <code>ZONE_OFFSET</code> for
     * <code>fields[]</code>.
     * @return a new field mask that indicates what field values have
     * actually been set.
     */
    private int computeFields(int fieldMask, int[] offsets, int index) {
	int zoneOffset;
	if (offsets != null) {
	    zoneOffset = offsets[index] + offsets[index + 1];
	} else {
	    TimeZone tz = getZone();
	    if (zoneOffsets == null) {
		zoneOffsets = new int[2];
	    }
	    if (tz instanceof ZoneInfo) {
		zoneOffset = ((ZoneInfo)tz).getOffsets(time, zoneOffsets);
	    } else {
		zoneOffset = tz.getOffset(time);
		zoneOffsets[0] = tz.getRawOffset();
		zoneOffsets[1] = zoneOffset - zoneOffsets[0];
	    }
	}

	// By computing time and zoneOffset separately, we can take
	// the wider range of time+zoneOffset than the previous
	// implementation.
	long fixedDate = zoneOffset / ONE_DAY;
	int timeOfDay = zoneOffset % (int)ONE_DAY;
	fixedDate += time / ONE_DAY;
	timeOfDay += (int) (time % ONE_DAY);
	if (timeOfDay >= ONE_DAY) {
	    timeOfDay -= ONE_DAY;
	    ++fixedDate;
	} else {
	    while (timeOfDay < 0) {
		timeOfDay += ONE_DAY;
		--fixedDate;
	    }
	}
	fixedDate += EPOCH_OFFSET;

	int era = CE;
	int year;
	if (fixedDate >= gregorianCutoverDate) {
	    // Handle Gregorian dates.
	    assert cachedFixedDate == Long.MIN_VALUE || gdate.isNormalized()
			: "cache control: not normalized";
	    assert cachedFixedDate == Long.MIN_VALUE ||
		   gcal.getFixedDate(gdate.getNormalizedYear(),
					  gdate.getMonth(),
					  gdate.getDayOfMonth(), gdate)
				== cachedFixedDate
			: "cache control: inconsictency" +
			  ", cachedFixedDate=" + cachedFixedDate +
			  ", computed=" +
		          gcal.getFixedDate(gdate.getNormalizedYear(),
						 gdate.getMonth(),
						 gdate.getDayOfMonth(),
						 gdate) +
			  ", date=" + gdate;

	    // See if we can use gdate to avoid date calculation.
	    if (fixedDate != cachedFixedDate) {
		gcal.getCalendarDateFromFixedDate(gdate, fixedDate);
		cachedFixedDate = fixedDate;
	    }

	    year = gdate.getYear();
	    if (year <= 0) {
		year = 1 - year;
		era = BCE;
	    }
	    calsys = gcal;
	    cdate = gdate;
	    assert cdate.getDayOfWeek() > 0 : "dow="+cdate.getDayOfWeek()+", date="+cdate;
	} else {
	    // Handle Julian calendar dates.
	    calsys = getJulianCalendarSystem();
	    cdate = (BaseCalendar.Date) jcal.newCalendarDate(getZone());
	    jcal.getCalendarDateFromFixedDate(cdate, fixedDate);
	    Era e = cdate.getEra();
	    if (e == jeras[0]) {
		era = BCE;
	    }
	    year = cdate.getYear();
	}

	// Always set the ERA and YEAR values.
        internalSet(ERA, era);
	internalSet(YEAR, year);
	int mask = fieldMask | (ERA_MASK|YEAR_MASK);

	int month =  cdate.getMonth() - 1; // 0-based
	int dayOfMonth = cdate.getDayOfMonth();

	// Set the basic date fields.
	if ((fieldMask & (MONTH_MASK|DAY_OF_MONTH_MASK|DAY_OF_WEEK_MASK))
	    != 0) {
	    internalSet(MONTH, month);
	    internalSet(DAY_OF_MONTH, dayOfMonth);
	    internalSet(DAY_OF_WEEK, cdate.getDayOfWeek());
	    mask |= MONTH_MASK|DAY_OF_MONTH_MASK|DAY_OF_WEEK_MASK;
	}

	if ((fieldMask & (HOUR_OF_DAY_MASK|AM_PM_MASK|HOUR_MASK
			  |MINUTE_MASK|SECOND_MASK|MILLISECOND_MASK)) != 0) {
	    if (timeOfDay != 0) {
		int hours = timeOfDay / ONE_HOUR;
		internalSet(HOUR_OF_DAY, hours);
		internalSet(AM_PM, hours / 12); // Assume AM == 0
		internalSet(HOUR, hours % 12);
		int r = timeOfDay % ONE_HOUR;
		internalSet(MINUTE, r / ONE_MINUTE);
		r %= ONE_MINUTE;
		internalSet(SECOND, r / ONE_SECOND);
		internalSet(MILLISECOND, r % ONE_SECOND);
	    } else {
		internalSet(HOUR_OF_DAY, 0);
		internalSet(AM_PM, AM);
		internalSet(HOUR, 0);
		internalSet(MINUTE, 0);
		internalSet(SECOND, 0);
		internalSet(MILLISECOND, 0);
	    }
	    mask |= (HOUR_OF_DAY_MASK|AM_PM_MASK|HOUR_MASK
		     |MINUTE_MASK|SECOND_MASK|MILLISECOND_MASK);
	}

	if ((fieldMask & (ZONE_OFFSET_MASK|DST_OFFSET_MASK)) != 0) {
	    // Avoid setting fields[] to fields[]
	    if (offsets != fields) {
		internalSet(ZONE_OFFSET, zoneOffsets[0]);
		internalSet(DST_OFFSET, zoneOffsets[1]);
	    }
	    mask |= (ZONE_OFFSET_MASK|DST_OFFSET_MASK);
	}

	if ((fieldMask & (DAY_OF_YEAR_MASK|WEEK_OF_YEAR_MASK|WEEK_OF_MONTH_MASK|DAY_OF_WEEK_IN_MONTH_MASK)) != 0) {
	    int normalizedYear = cdate.getNormalizedYear();
	    long fixedDateJan1 = calsys.getFixedDate(normalizedYear, 1, 1, cdate);
	    int dayOfYear = (int)(fixedDate - fixedDateJan1) + 1;
	    long fixedDateMonth1 = fixedDate - dayOfMonth + 1;
	    int cutoverGap = 0;
	    int cutoverYear = (calsys == gcal) ? gregorianCutoverYear : gregorianCutoverYearJulian;
	    int relativeDayOfMonth = dayOfMonth - 1;

	    // If we are in the cutover year, we need some special handling.
	    if (normalizedYear == cutoverYear) {
		// Need to take care of the "missing" days.
		if (getCutoverCalendarSystem() == jcal) {
		    // We need to find out where we are. The cutover
		    // gap could even be more than one year.  (One
		    // year difference in ~48667 years.)
		    fixedDateJan1 = getFixedDateJan1(cdate, fixedDate);
		    if (fixedDate >= gregorianCutoverDate) {
			fixedDateMonth1 = getFixedDateMonth1(cdate, fixedDate);
		    }
		}
		int realDayOfYear = (int)(fixedDate - fixedDateJan1) + 1;
		cutoverGap = dayOfYear - realDayOfYear;
		dayOfYear = realDayOfYear;
		relativeDayOfMonth = (int)(fixedDate - fixedDateMonth1);
	    }
	    internalSet(DAY_OF_YEAR, dayOfYear);
	    internalSet(DAY_OF_WEEK_IN_MONTH, relativeDayOfMonth / 7 + 1);

	    int weekOfYear = getWeekNumber(fixedDateJan1, fixedDate);

	    // The spec is to calculate WEEK_OF_YEAR in the
	    // ISO8601-style. This creates problems, though.
	    if (weekOfYear == 0) {
		// If the date belongs to the last week of the
		// previous year, use the week number of "12/31" of
		// the "previous" year. Again, if the previous year is
		// the Gregorian cutover year, we need to take care of
		// it.  Usually the previous day of January 1 is
		// December 31, which is not always true in
		// GregorianCalendar.
		long fixedDec31 = fixedDateJan1 - 1;
		long prevJan1;
		if (normalizedYear > (cutoverYear + 1)) {
		    prevJan1 = fixedDateJan1 - 365;
		    if (CalendarUtils.isGregorianLeapYear(normalizedYear - 1)) {
			--prevJan1;
		    }
		} else {
		    BaseCalendar calForJan1 = calsys;
		    int prevYear = normalizedYear - 1;
		    if (prevYear == cutoverYear) {
			calForJan1 = getCutoverCalendarSystem();
		    }
		    prevJan1 = calForJan1.getFixedDate(prevYear,
						       BaseCalendar.JANUARY,
						       1,
						       null);
		    while (prevJan1 > fixedDec31) {
			prevJan1 = getJulianCalendarSystem().getFixedDate(--prevYear,
								    BaseCalendar.JANUARY,
								    1,
								    null);
		    }
		}
		weekOfYear = getWeekNumber(prevJan1, fixedDec31);
	    } else {
		if (normalizedYear > gregorianCutoverYear ||
		    normalizedYear < (gregorianCutoverYearJulian - 1)) {
		    // Regular years
		    if (weekOfYear >= 52) {
			long nextJan1 = fixedDateJan1 + 365;
			if (cdate.isLeapYear()) {
			    nextJan1++;
			}
			long nextJan1st = calsys.getDayOfWeekDateOnOrBefore(nextJan1 + 6,
									    getFirstDayOfWeek());
			int ndays = (int)(nextJan1st - nextJan1);
			if (ndays >= getMinimalDaysInFirstWeek() && fixedDate >= (nextJan1st - 7)) {
			    // The first days forms a week in which the date is included.
			    weekOfYear = 1;
			}
		    }
		} else {
		    BaseCalendar calForJan1 = calsys;
		    int nextYear = normalizedYear + 1;
		    if (nextYear == (gregorianCutoverYearJulian + 1) &&
			nextYear < gregorianCutoverYear) {
			// In case the gap is more than one year.
			nextYear = gregorianCutoverYear;
		    }
		    if (nextYear == gregorianCutoverYear) {
			calForJan1 = getCutoverCalendarSystem();
		    }
		    long nextJan1 = calForJan1.getFixedDate(nextYear,
							    BaseCalendar.JANUARY,
							    1,
							    null);
		    if (nextJan1 < fixedDate) {
			nextJan1 = gregorianCutoverDate;
			calForJan1 = gcal;
		    }
		    long nextJan1st = calForJan1.getDayOfWeekDateOnOrBefore(nextJan1 + 6,
									    getFirstDayOfWeek());
		    int ndays = (int)(nextJan1st - nextJan1);
		    if (ndays >= getMinimalDaysInFirstWeek() && fixedDate >= (nextJan1st - 7)) {
			// The first days forms a week in which the date is included.
			weekOfYear = 1;
		    }
		}
	    }
	    internalSet(WEEK_OF_YEAR, weekOfYear);
	    internalSet(WEEK_OF_MONTH, getWeekNumber(fixedDateMonth1, fixedDate));
	    mask |= (DAY_OF_YEAR_MASK|WEEK_OF_YEAR_MASK|WEEK_OF_MONTH_MASK|DAY_OF_WEEK_IN_MONTH_MASK);
	}
	return mask;
    }

    /**
     * Returns the number of weeks in a period between fixedDay1 and
     * fixedDate. The getFirstDayOfWeek-getMinimalDaysInFirstWeek rule
     * is applied to calculate the number of weeks.
     *
     * @param fixedDay1 the fixed date of the first day of the period
     * @param fixedDate the fixed date of the last day of the period
     * @return the number of weeks of the given period
     */
    private final int getWeekNumber(long fixedDay1, long fixedDate) {
	// We can always use `gcal' since Julian and Gregorian are the
	// same thing for this calculation.
	long fixedDay1st = gcal.getDayOfWeekDateOnOrBefore(fixedDay1 + 6,
							   getFirstDayOfWeek());
	int ndays = (int)(fixedDay1st - fixedDay1);
	assert ndays <= 7;
	if (ndays >= getMinimalDaysInFirstWeek()) {
	    fixedDay1st -= 7;
	}
	int normalizedDayOfPeriod = (int)(fixedDate - fixedDay1st);
	if (normalizedDayOfPeriod >= 0) {
	    return normalizedDayOfPeriod / 7 + 1;
	}
	return CalendarUtils.floorDivide(normalizedDayOfPeriod, 7) + 1;
    }

    /**
     * Converts calendar field values to the time value (millisecond
     * offset from the <a href="Calendar.html#Epoch">Epoch</a>).
     *
     * @exception IllegalArgumentException if any calendar fields are invalid.
     */
    protected void computeTime() {
	// In non-lenient mode, perform brief checking of calendar
	// fields which have been set externally. Through this
	// checking, the field values are stored in originalFields[]
	// to see if any of them are normalized later.
        if (!isLenient()) {
	    if (originalFields == null) {
		originalFields = new int[FIELD_COUNT];
	    }
	    for (int field = 0; field < FIELD_COUNT; field++) {
		int value = internalGet(field);
		if (isExternallySet(field)) {
		    // Quick validation for any out of range values
		    if (value < getMinimum(field) || value > getMaximum(field)) {
			throw new IllegalArgumentException(getFieldName(field));
		    }
		}
		originalFields[field] = value;
	    }
	}

	// Let the super class determine which calendar fields to be
	// used to calculate the time.
	int fieldMask = selectFields();

        // The year defaults to the epoch start. We don't check
        // fieldMask for YEAR because YEAR is a mandatory field to
        // determine the date.
        int year = isSet(YEAR) ? internalGet(YEAR) : EPOCH_YEAR;

        int era = internalGetEra();
	if (era == BCE) {
	    year = 1 - year;
	} else if (era != CE) {
	    // Even in lenient mode we disallow ERA values other than CE & BCE.
	    // (The same normalization rule as add()/roll() could be
	    // applied here in lenient mode. But this checking is kept
	    // unchanged for compatibility as of 1.5.)
	    throw new IllegalArgumentException("Invalid era");
	}
	    
	// If year is 0 or negative, we need to set the ERA value later.
	if (year <= 0 && !isSet(ERA)) {
	    fieldMask |= ERA_MASK;
	    setFieldsComputed(ERA_MASK);
	}

        // Calculate the time of day. We rely on the convention that
        // an UNSET field has 0.
        long timeOfDay = 0;
	if (isFieldSet(fieldMask, HOUR_OF_DAY)) {
	    timeOfDay += (long) internalGet(HOUR_OF_DAY);
	} else {
	    timeOfDay += internalGet(HOUR);
	    // The default value of AM_PM is 0 which designates AM.
	    if (isFieldSet(fieldMask, AM_PM)) {
		timeOfDay += 12 * internalGet(AM_PM);
	    }
        }
        timeOfDay *= 60;
	timeOfDay += internalGet(MINUTE);
        timeOfDay *= 60;
	timeOfDay += internalGet(SECOND);
        timeOfDay *= 1000;
	timeOfDay += internalGet(MILLISECOND);

	// Convert the time of day to the number of days and the
	// millisecond offset from midnight.
	long fixedDate = timeOfDay / ONE_DAY;
	timeOfDay %= ONE_DAY;
	while (timeOfDay < 0) {
	    timeOfDay += ONE_DAY;
	    --fixedDate;
	}

	// Calculate the fixed date since January 1, 1 (Gregorian).
	calculateFixedDate: {
	    long gfd, jfd;
	    if (year > gregorianCutoverYear && year > gregorianCutoverYearJulian) {
		gfd = fixedDate + getFixedDate(gcal, year, fieldMask);
		if (gfd >= gregorianCutoverDate) {
		    fixedDate = gfd;
		    break calculateFixedDate;
		}
		jfd = fixedDate + getFixedDate(getJulianCalendarSystem(), year, fieldMask);
	    } else if (year < gregorianCutoverYear && year < gregorianCutoverYearJulian) {
		jfd = fixedDate + getFixedDate(getJulianCalendarSystem(), year, fieldMask);
		if (jfd < gregorianCutoverDate) {
		    fixedDate = jfd;
		    break calculateFixedDate;
		}
		gfd = fixedDate + getFixedDate(gcal, year, fieldMask);
	    } else {
		gfd = fixedDate + getFixedDate(gcal, year, fieldMask);
		jfd = fixedDate + getFixedDate(getJulianCalendarSystem(), year, fieldMask);
	    }
	    // Now we have to determine which calendar date it is.
	    if (gfd >= gregorianCutoverDate) {
		if (jfd >= gregorianCutoverDate) {
		    fixedDate = gfd;
		} else {
		    // The date is in an "overlapping" period. No way
		    // to disambiguate it. Determine it using the
		    // previous date calculation.
		    if (calsys == gcal || calsys == null) {
			fixedDate = gfd;
		    } else {
			fixedDate = jfd;
		    }
		}
	    } else {
		if (jfd < gregorianCutoverDate) {
		    fixedDate = jfd;
		} else {
		    // The date is in a "missing" period.
		    if (!isLenient()) {
			throw new IllegalArgumentException("the specified date doesn't exist");
		    }
		    // Take the Julian date for compatibility, which
		    // will produce a Gregorian date.
		    fixedDate = jfd;
		}
	    }
	}

        // millis represents local wall-clock time in milliseconds.
        long millis = (fixedDate - EPOCH_OFFSET) * ONE_DAY + timeOfDay;

        // Compute the time zone offset and DST offset.  There are two potential
        // ambiguities here.  We'll assume a 2:00 am (wall time) switchover time
        // for discussion purposes here.
        // 1. The transition into DST.  Here, a designated time of 2:00 am - 2:59 am
        //    can be in standard or in DST depending.  However, 2:00 am is an invalid
        //    representation (the representation jumps from 1:59:59 am Std to 3:00:00 am DST).
        //    We assume standard time.
        // 2. The transition out of DST.  Here, a designated time of 1:00 am - 1:59 am
        //    can be in standard or DST.  Both are valid representations (the rep
        //    jumps from 1:59:59 DST to 1:00:00 Std).
        //    Again, we assume standard time.
        // We use the TimeZone object, unless the user has explicitly set the ZONE_OFFSET
        // or DST_OFFSET fields; then we use those fields.
        TimeZone zone = getZone();
	if (zoneOffsets == null) {
	    zoneOffsets = new int[2];
	}
	if (zone instanceof ZoneInfo) {
	    if ((fieldMask & (ZONE_OFFSET_MASK|DST_OFFSET_MASK))
		!= (ZONE_OFFSET_MASK|DST_OFFSET_MASK)) {
		((ZoneInfo)zone).getOffsetsByWall(millis, zoneOffsets);
	    }
	    if (isFieldSet(fieldMask, ZONE_OFFSET)) {
		zoneOffsets[0] = internalGet(ZONE_OFFSET);
	    }
	    if (isFieldSet(fieldMask, DST_OFFSET)) {
		zoneOffsets[1] = internalGet(DST_OFFSET);
	    }
	} else {
	    zoneOffsets[0] = isFieldSet(fieldMask, ZONE_OFFSET) ?
				internalGet(ZONE_OFFSET) : zone.getRawOffset();
	    if (isFieldSet(fieldMask, DST_OFFSET)) {
		zoneOffsets[1] = internalGet(DST_OFFSET);
	    } else {
		zoneOffsets[1] = zone.getOffsets(millis - (long)zoneOffsets[0], null)
		    - zoneOffsets[0];
	    }
	}

	// Adjust the time zone offset values to get the UTC time.
	millis -= zoneOffsets[0] + zoneOffsets[1];

	// Set this calendar's time in milliseconds
	time = millis;

	int mask = computeFields(fieldMask | getSetStateFields(), null, 0);

	if (!isLenient()) {
	    for (int field = 0; field < FIELD_COUNT; field++) {
		if (!isExternallySet(field)) {
		    continue;
		}
		if (originalFields[field] != internalGet(field)) {
		    // Restore the original field values
		    System.arraycopy(originalFields, 0, fields, 0, fields.length);
		    throw new IllegalArgumentException(getFieldName(field));
		}
	    }
	}
	setFieldsNormalized(mask);
    }

    /**
     * Computes the fixed date under either the Gregorian or the
     * Julian calendar, using the given year and the specified calendar fields.
     *
     * @param cal the CalendarSystem to be used for the date calculation
     * @param year the normalized year number, with 0 indicating the
     * year 1 BCE, -1 indicating 2 BCE, etc.
     * @param fieldMask the calendar fields to be used for the date calculation
     * @return the fixed date
     * @see Calendar#selectFields
     */
    private long getFixedDate(BaseCalendar cal, int year, int fieldMask) {
	int month = JANUARY;
	if (isFieldSet(fieldMask, MONTH)) {
            // No need to check if MONTH has been set (no isSet(MONTH)
            // call) since its unset value happens to be JANUARY (0).
	    month = internalGet(MONTH);

            // If the month is out of range, adjust it into range
	    if (month > DECEMBER) {
		year += month / 12;
		month %= 12;
	    } else if (month < JANUARY) {
                int[] rem = new int[1];
                year += CalendarUtils.floorDivide(month, 12, rem);
                month = rem[0];
            }
	}

	// Get the fixed date since Jan 1, 1 (Gregorian). We are on
	// the first day of either `month' or January in 'year'.
	long fixedDate = cal.getFixedDate(year, month + 1, 1,
					  cal == gcal ? gdate : null);
	if (isFieldSet(fieldMask, MONTH)) {
	    // Month-based calculations
            if (isFieldSet(fieldMask, DAY_OF_MONTH)) {
		// We are on the first day of the month. Just add the
		// offset if DAY_OF_MONTH is set. If the isSet call
		// returns false, that means DAY_OF_MONTH has been
		// selected just because of the selected
		// combination. We don't need to add any since the
		// default value is the 1st.
		if (isSet(DAY_OF_MONTH)) {
		    // To avoid underflow with DAY_OF_MONTH-1, add
		    // DAY_OF_MONTH, then subtract 1.
		    fixedDate += internalGet(DAY_OF_MONTH);
		    fixedDate--;
		}
            } else {
                if (isFieldSet(fieldMask, WEEK_OF_MONTH)) {
		    long firstDayOfWeek = cal.getDayOfWeekDateOnOrBefore(fixedDate + 6,
									 getFirstDayOfWeek());
                    // If we have enough days in the first week, then
                    // move to the previous week.
                    if ((firstDayOfWeek - fixedDate) >= getMinimalDaysInFirstWeek()) {
			firstDayOfWeek -= 7;
		    }
		    if (isFieldSet(fieldMask, DAY_OF_WEEK)) {
			firstDayOfWeek = cal.getDayOfWeekDateOnOrBefore(firstDayOfWeek + 6,
									internalGet(DAY_OF_WEEK));
		    }
		    // In lenient mode, we treat days of the previous
		    // months as a part of the specified
		    // WEEK_OF_MONTH. See 4633646.
		    fixedDate = firstDayOfWeek + 7 * (internalGet(WEEK_OF_MONTH) - 1);
                } else {
		    int dayOfWeek;
		    if (isFieldSet(fieldMask, DAY_OF_WEEK)) {
			dayOfWeek = internalGet(DAY_OF_WEEK);
		    } else {
			dayOfWeek = getFirstDayOfWeek();
		    }
                    // We are basing this on the day-of-week-in-month.  The only
                    // trickiness occurs if the day-of-week-in-month is
                    // negative.
		    int dowim;
		    if (isFieldSet(fieldMask, DAY_OF_WEEK_IN_MONTH)) {
			dowim = internalGet(DAY_OF_WEEK_IN_MONTH);
		    } else {
			dowim = 1;
		    }
		    if (dowim >= 0) {
			fixedDate = cal.getDayOfWeekDateOnOrBefore(fixedDate + (7 * dowim) - 1,
								   dayOfWeek);
		    } else {
			// Go to the first day of the next week of
			// the specified week boundary.
			int lastDate = monthLength(month, year) + (7 * (dowim + 1));
			// Then, get the day of week date on or before the last date.
			fixedDate = cal.getDayOfWeekDateOnOrBefore(fixedDate + lastDate - 1,
								   dayOfWeek);
                    }
                }
            }
        } else {
	    if (year == gregorianCutoverYear && cal == gcal
		&& fixedDate < gregorianCutoverDate
		&& gregorianCutoverYear != gregorianCutoverYearJulian) {
		// January 1 of the year doesn't exist.  Use
		// gregorianCutoverDate as the first day of the
		// year.
		fixedDate = gregorianCutoverDate;
	    }
	    // We are on the first day of the year.
            if (isFieldSet(fieldMask, DAY_OF_YEAR)) {
		// Add the offset, then subtract 1. (Make sure to avoid underflow.)
                fixedDate += internalGet(DAY_OF_YEAR);
		fixedDate--;
            } else {
		long firstDayOfWeek = cal.getDayOfWeekDateOnOrBefore(fixedDate + 6,
								     getFirstDayOfWeek());
		// If we have enough days in the first week, then move
		// to the previous week.
		if ((firstDayOfWeek - fixedDate) >= getMinimalDaysInFirstWeek()) {
		    firstDayOfWeek -= 7;
		}
		if (isFieldSet(fieldMask, DAY_OF_WEEK)) {
		    int dayOfWeek = internalGet(DAY_OF_WEEK);
		    if (dayOfWeek != getFirstDayOfWeek()) {
			firstDayOfWeek = cal.getDayOfWeekDateOnOrBefore(firstDayOfWeek + 6,
									dayOfWeek);
		    }
		}
		fixedDate = firstDayOfWeek + 7 * ((long)internalGet(WEEK_OF_YEAR) - 1);
            }
        }

        return fixedDate;
    }

    /**
     * Returns this object if it's normalized (all fields and time are
     * in sync). Otherwise, a cloned object is returned after calling
     * complete() in lenient mode.
     */
    private final GregorianCalendar getNormalizedCalendar() {
	GregorianCalendar gc;
	if (isFullyNormalized()) {
	    gc = this;
	} else {
	    // Create a clone and normalize the calendar fields
	    gc = (GregorianCalendar) this.clone();
	    gc.setLenient(true);
	    gc.complete();
	}
	return gc;
    }

    /**
     * Returns the Julian calendar system instance (singleton). 'jcal'
     * and 'jeras' are set upon the return.
     */
    synchronized private static final BaseCalendar getJulianCalendarSystem() {
	if (jcal == null) {
	    jcal = (JulianCalendar) CalendarSystem.forName("julian");
	    jeras = jcal.getEras();
	}
	return jcal;
    }

    /**
     * Returns the calendar system for dates before the cutover date
     * in the cutover year. If the cutover date is January 1, the
     * method returns Gregorian. Otherwise, Julian.
     */
    private BaseCalendar getCutoverCalendarSystem() {
	CalendarDate date = getGregorianCutoverDate();
	if (date.getMonth() == BaseCalendar.JANUARY
	    && date.getDayOfMonth() == 1) {
	    return gcal;
	}
	return getJulianCalendarSystem();
    }

    /**
     * Determines if the specified year (normalized) is the Gregorian
     * cutover year. This object must have been normalized.
     */
    private final boolean isCutoverYear(int normalizedYear) {
	int cutoverYear = (calsys == gcal) ? gregorianCutoverYear : gregorianCutoverYearJulian;
	return normalizedYear == cutoverYear;
    }

    /**
     * Returns the fixed date of the first day of the year (usually
     * January 1) before the specified date.
     *
     * @param date the date for which the first day of the year is
     * calculated. The date has to be in the cut-over year (Gregorian
     * or Julian).
     * @param fixedDate the fixed date representation of the date
     */
    private final long getFixedDateJan1(BaseCalendar.Date date, long fixedDate) {
	assert date.getNormalizedYear() == gregorianCutoverYear ||
	    date.getNormalizedYear() == gregorianCutoverYearJulian;
	if (gregorianCutoverYear != gregorianCutoverYearJulian) {
	    if (fixedDate >= gregorianCutoverDate) {
		// Dates before the cutover date don't exist
		// in the same (Gregorian) year. So, no
		// January 1 exists in the year. Use the
		// cutover date as the first day of the year.
		return gregorianCutoverDate;
	    }
	}
	// January 1 of the normalized year should exist.
	BaseCalendar jcal = getJulianCalendarSystem();
	return jcal.getFixedDate(date.getNormalizedYear(), BaseCalendar.JANUARY, 1, null);
    }

    /**
     * Returns the fixed date of the first date of the month (usually
     * the 1st of the month) before the specified date.
     *
     * @param date the date for which the first day of the month is
     * calculated. The date has to be in the cut-over year (Gregorian
     * or Julian).
     * @param fixedDate the fixed date representation of the date
     */
    private final long getFixedDateMonth1(BaseCalendar.Date date, long fixedDate) {
	assert date.getNormalizedYear() == gregorianCutoverYear ||
	    date.getNormalizedYear() == gregorianCutoverYearJulian;
	BaseCalendar.Date gCutover = getGregorianCutoverDate();
	if (gCutover.getMonth() == BaseCalendar.JANUARY
	    && gCutover.getDayOfMonth() == 1) {
	    // The cutover happened on January 1.
	    return fixedDate - date.getDayOfMonth() + 1;
	}

	long fixedDateMonth1;
	// The cutover happened sometime during the year.
	if (date.getMonth() == gCutover.getMonth()) {
	    // The cutover happened in the month.
	    BaseCalendar.Date jLastDate = getLastJulianDate();
	    if (gregorianCutoverYear == gregorianCutoverYearJulian
		&& gCutover.getMonth() == jLastDate.getMonth()) {
		// The "gap" fits in the same month.
		fixedDateMonth1 = jcal.getFixedDate(date.getNormalizedYear(),
						    date.getMonth(),
						    1,
						    null);
	    } else {
		// Use the cutover date as the first day of the month.
		fixedDateMonth1 = gregorianCutoverDate;
	    }
	} else {
	    // The cutover happened before the month.
	    fixedDateMonth1 = fixedDate - date.getDayOfMonth() + 1;
	}

	return fixedDateMonth1;
    }

    /**
     * Returns a CalendarDate produced from the specified fixed date.
     *
     * @param fd the fixed date
     */
    private final BaseCalendar.Date getCalendarDate(long fd) {
	BaseCalendar cal = (fd >= gregorianCutoverDate) ? gcal : getJulianCalendarSystem();
	BaseCalendar.Date d = (BaseCalendar.Date) cal.newCalendarDate(TimeZone.NO_TIMEZONE);
	cal.getCalendarDateFromFixedDate(d, fd);
	return d;
    }

    /**
     * Returns the Gregorian cutover date as a BaseCalendar.Date. The
     * date is a Gregorian date.
     */
    private final BaseCalendar.Date getGregorianCutoverDate() {
	return getCalendarDate(gregorianCutoverDate);
    }

    /**
     * Returns the day before the Gregorian cutover date as a
     * BaseCalendar.Date. The date is a Julian date.
     */
    private final BaseCalendar.Date getLastJulianDate() {
	return getCalendarDate(gregorianCutoverDate - 1);
    }

    /**
     * Returns the length of the specified month in the specified
     * year. The year number must be normalized.
     *
     * @see #isLeapYear(int)
     */
    private final int monthLength(int month, int year) {
        return isLeapYear(year) ? LEAP_MONTH_LENGTH[month] : MONTH_LENGTH[month];
    }

    /**
     * Returns the length of the specified month in the year provided
     * by internalGet(YEAR).
     *
     * @see #isLeapYear(int)
     */
    private final int monthLength(int month) {
        int year = internalGet(YEAR);
        if (internalGetEra() == BCE) {
            year = 1 - year;
        }
        return monthLength(month, year);
    }

    private final int actualMonthLength() {
        int year = cdate.getNormalizedYear();
	if (year != gregorianCutoverYear && year != gregorianCutoverYearJulian) {
	    return calsys.getMonthLength(cdate);
	}
	BaseCalendar.Date date = (BaseCalendar.Date) cdate.clone();
	long fd = calsys.getFixedDate(date);
	long month1 = getFixedDateMonth1(date, fd);
	long next1 = month1 + calsys.getMonthLength(date);
	if (next1 < gregorianCutoverDate) {
	    return (int)(next1 - month1);
	}
	if (cdate != gdate) {
	    date = (BaseCalendar.Date) gcal.newCalendarDate(TimeZone.NO_TIMEZONE);
	}
	gcal.getCalendarDateFromFixedDate(date, next1);
	next1 = getFixedDateMonth1(date, next1);
	return (int)(next1 - month1);
    }

    /**
     * Returns the length (in days) of the specified year. The year
     * must be normalized.
     */
    private final int yearLength(int year) {
        return isLeapYear(year) ? 366 : 365;
    }

    /**
     * Returns the length (in days) of the year provided by
     * internalGet(YEAR).
     */
    private final int yearLength() {
        int year = internalGet(YEAR);
        if (internalGetEra() == BCE) {
            year = 1 - year;
        }
        return yearLength(year);
    }

    /**
     * After adjustments such as add(MONTH), add(YEAR), we don't want the
     * month to jump around.  E.g., we don't want Jan 31 + 1 month to go to Mar
     * 3, we want it to go to Feb 28.  Adjustments which might run into this
     * problem call this method to retain the proper month.
     */
    private final void pinDayOfMonth() {
	int year = internalGet(YEAR);
	int monthLen;
	if (year > gregorianCutoverYear || year < gregorianCutoverYearJulian) {
	    monthLen = monthLength(internalGet(MONTH));
	} else {
	    GregorianCalendar gc = getNormalizedCalendar();
	    monthLen = gc.getActualMaximum(DAY_OF_MONTH);
	}
	int dom = internalGet(DAY_OF_MONTH);
	if (dom > monthLen) {
	    set(DAY_OF_MONTH, monthLen);
	}
    }

    /**
     * Returns the fixed date value of this object. The time value and
     * calendar fields must be in synch.
     */
    private final long getCurrentFixedDate() {
	assert isTimeSet && areFieldsSet
	    && ((calsys == gcal) ? cachedFixedDate != Long.MIN_VALUE : true);
	return (calsys == gcal) ? cachedFixedDate : calsys.getFixedDate(cdate);
    }

    /**
     * Returns the new value after 'roll'ing the specified value and amount.
     */
    private static final int getRolledValue(int value, int amount, int min, int max) {
	assert value >= min && value <= max;
	int range = max - min + 1;
	amount %= range;
	int n = value + amount;
	if (n > max) {
	    n -= range;
	} else if (n < min) {
	    n += range;
	}
	assert n >= min && n <= max;
	return n;
    }

    /**
     * Returns the ERA.  We need a special method for this because the
     * default ERA is CE, but a zero (unset) ERA is BCE.
     */
    private final int internalGetEra() {
        return isSet(ERA) ? internalGet(ERA) : CE;
    }

    /**
     * Updates internal state.
     */
    private void readObject(ObjectInputStream stream)
	    throws IOException, ClassNotFoundException {
	stream.defaultReadObject();
	if (gdate == null) {
	    gdate = (BaseCalendar.Date) gcal.newCalendarDate(getZone());
	    cachedFixedDate = Long.MIN_VALUE;
	}
	setGregorianChange(gregorianCutover);
    }
}