src/java.base/share/classes/java/util/GregorianCalendar.java
changeset 47216 71c04702a3d5
parent 45881 aaec0fbe17ae
child 54206 003cc64366da
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/util/GregorianCalendar.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,3298 @@
+/*
+ * Copyright (c) 1996, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * (C) Copyright Taligent, Inc. 1996-1998 - 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 java.time.Instant;
+import java.time.ZonedDateTime;
+import java.time.temporal.ChronoField;
+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.
+ *
+ * <h3><a id="week_and_year">Week Of Year and Week Year</a></h3>
+ *
+ * <p>Values calculated for the {@link Calendar#WEEK_OF_YEAR
+ * WEEK_OF_YEAR} field range from 1 to 53. The first week of a
+ * calendar year is the earliest seven day period starting on {@link
+ * Calendar#getFirstDayOfWeek() getFirstDayOfWeek()} that contains at
+ * least {@link Calendar#getMinimalDaysInFirstWeek()
+ * getMinimalDaysInFirstWeek()} days from that year. It thus depends
+ * on the values of {@code getMinimalDaysInFirstWeek()}, {@code
+ * getFirstDayOfWeek()}, and the day of the week of January 1. Weeks
+ * between week 1 of one year and week 1 of the following year
+ * (exclusive) are numbered sequentially from 2 to 52 or 53 (except
+ * for year(s) involved in the Julian-Gregorian transition).
+ *
+ * <p>The {@code getFirstDayOfWeek()} and {@code
+ * getMinimalDaysInFirstWeek()} values are initialized using
+ * locale-dependent resources when constructing a {@code
+ * GregorianCalendar}. <a id="iso8601_compatible_setting">The week
+ * determination is compatible</a> with the ISO 8601 standard when {@code
+ * getFirstDayOfWeek()} is {@code MONDAY} and {@code
+ * getMinimalDaysInFirstWeek()} is 4, which values are used in locales
+ * where the standard is preferred. These values can explicitly be set by
+ * calling {@link Calendar#setFirstDayOfWeek(int) setFirstDayOfWeek()} and
+ * {@link Calendar#setMinimalDaysInFirstWeek(int)
+ * setMinimalDaysInFirstWeek()}.
+ *
+ * <p>A <a id="week_year"><em>week year</em></a> is in sync with a
+ * {@code WEEK_OF_YEAR} cycle. All weeks between the first and last
+ * weeks (inclusive) have the same <em>week year</em> value.
+ * Therefore, the first and last days of a week year may have
+ * different calendar year values.
+ *
+ * <p>For example, January 1, 1998 is a Thursday. If {@code
+ * getFirstDayOfWeek()} is {@code MONDAY} and {@code
+ * getMinimalDaysInFirstWeek()} is 4 (ISO 8601 standard compatible
+ * setting), then week 1 of 1998 starts on December 29, 1997, and ends
+ * on January 4, 1998. The week year is 1998 for the last three days
+ * of calendar year 1997. If, however, {@code getFirstDayOfWeek()} is
+ * {@code SUNDAY}, 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 and their week year is 1997.
+ *
+ * <h4>Week Of Month</h4>
+ *
+ * <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.
+ *
+ * <h4>Default Fields Values</h4>
+ *
+ * <p>The <code>clear</code> method sets calendar field(s)
+ * undefined. <code>GregorianCalendar</code> uses the following
+ * default value for each calendar field if its value is undefined.
+ *
+ * <table class="striped" style="text-align: left; width: 66%;">
+ * <caption style="display:none">GregorianCalendar default field values</caption>
+ *   <thead>
+ *     <tr>
+ *       <th scope="col">
+ *          Field
+ *       </th>
+ *       <th scope="col">
+            Default Value
+ *       </th>
+ *     </tr>
+ *   </thead>
+ *   <tbody>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>ERA</code>
+ *       </th>
+ *       <td>
+ *              <code>AD</code>
+ *       </td>
+ *     </tr>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>YEAR</code>
+ *       </th>
+ *       <td>
+ *              <code>1970</code>
+ *       </td>
+ *     </tr>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>MONTH</code>
+ *       </th>
+ *       <td>
+ *              <code>JANUARY</code>
+ *       </td>
+ *     </tr>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>DAY_OF_MONTH</code>
+ *       </th>
+ *       <td>
+ *              <code>1</code>
+ *       </td>
+ *     </tr>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>DAY_OF_WEEK</code>
+ *       </th>
+ *       <td>
+ *              <code>the first day of week</code>
+ *       </td>
+ *     </tr>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>WEEK_OF_MONTH</code>
+ *       </th>
+ *       <td>
+ *              <code>0</code>
+ *       </td>
+ *     </tr>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>DAY_OF_WEEK_IN_MONTH</code>
+ *       </th>
+ *       <td>
+ *              <code>1</code>
+ *       </td>
+ *     </tr>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>AM_PM</code>
+ *       </th>
+ *       <td>
+ *              <code>AM</code>
+ *       </td>
+ *     </tr>
+ *     <tr>
+ *       <th scope="row">
+ *              <code>HOUR, HOUR_OF_DAY, MINUTE, SECOND, MILLISECOND</code>
+ *       </th>
+ *       <td>
+ *              <code>0</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 Saving 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
+ * @author David Goldsmith, Mark Davis, Chen-Lieh Huang, Alan Liu
+ * @since 1.1
+ */
+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
+    @SuppressWarnings("FieldNameHidesFieldInSuperclass")
+    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
+     * {@link Locale.Category#FORMAT FORMAT} locale.
+     */
+    public GregorianCalendar() {
+        this(TimeZone.getDefaultRef(), Locale.getDefault(Locale.Category.FORMAT));
+        setZoneShared(true);
+    }
+
+    /**
+     * Constructs a <code>GregorianCalendar</code> based on the current time
+     * in the given time zone with the default
+     * {@link Locale.Category#FORMAT FORMAT} locale.
+     *
+     * @param zone the given time zone.
+     */
+    public GregorianCalendar(TimeZone zone) {
+        this(zone, Locale.getDefault(Locale.Category.FORMAT));
+    }
+
+    /**
+     * 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);
+
+        // Set AM_PM and HOUR here to set their stamp values before
+        // setting HOUR_OF_DAY (6178071).
+        if (hourOfDay >= 12 && hourOfDay <= 23) {
+            // If hourOfDay is a valid PM hour, set the correct PM values
+            // so that it won't throw an exception in case it's set to
+            // non-lenient later.
+            this.internalSet(AM_PM, PM);
+            this.internalSet(HOUR, hourOfDay - 12);
+        } else {
+            // The default value for AM_PM is AM.
+            // We don't care any out of range value here for leniency.
+            this.internalSet(HOUR, hourOfDay);
+        }
+        // The stamp values of AM_PM and HOUR must be COMPUTED. (6440854)
+        setFieldsComputed(HOUR_MASK|AM_PM_MASK);
+
+        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);
+    }
+
+    /**
+     * Constructs an empty GregorianCalendar.
+     *
+     * @param zone    the given time zone
+     * @param aLocale the given locale
+     * @param flag    the flag requesting an empty instance
+     */
+    GregorianCalendar(TimeZone zone, Locale locale, boolean flag) {
+        super(zone, locale);
+        gdate = (BaseCalendar.Date) gcal.newCalendarDate(getZone());
+    }
+
+/////////////////
+// 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 julianCal = getJulianCalendarSystem();
+        d = (BaseCalendar.Date) julianCal.newCalendarDate(TimeZone.NO_TIMEZONE);
+        julianCal.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;
+    }
+
+    /**
+     * Returns {@code "gregory"} as the calendar type.
+     *
+     * @return {@code "gregory"}
+     * @since 1.8
+     */
+    @Override
+    public String getCalendarType() {
+        return "gregory";
+    }
+
+    /**
+     * 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)
+     */
+    @Override
+    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.
+     */
+    @Override
+    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.
+     */
+    @Override
+    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 = month/12;
+            } 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,  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)
+     */
+    @Override
+    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
+     */
+    @Override
+    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 rolledValue = getRolledValue(internalGet(field), amount, min, max);
+                int hourOfDay = rolledValue;
+                if (field == HOUR && internalGet(AM_PM) == PM) {
+                    hourOfDay += 12;
+                }
+
+                // Create the current date/time value to perform wall-clock-based
+                // roll.
+                CalendarDate d = calsys.getCalendarDate(time, getZone());
+                d.setHours(hourOfDay);
+                time = calsys.getTime(d);
+
+                // If we stay on the same wall-clock time, try the next or previous hour.
+                if (internalGet(HOUR_OF_DAY) == d.getHours()) {
+                    hourOfDay = getRolledValue(rolledValue, amount > 0 ? +1 : -1, min, max);
+                    if (field == HOUR && internalGet(AM_PM) == PM) {
+                        hourOfDay += 12;
+                    }
+                    d.setHours(hourOfDay);
+                    time = calsys.getTime(d);
+                }
+                // Get the new hourOfDay value which might have changed due to a DST transition.
+                hourOfDay = d.getHours();
+                // Update the hour related fields
+                internalSet(HOUR_OF_DAY, hourOfDay);
+                internalSet(AM_PM, hourOfDay / 12);
+                internalSet(HOUR, hourOfDay % 12);
+
+                // 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)) {
+                    int weekYear = getWeekYear();
+                    if (weekYear == 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
+                        // in the calendar year
+                        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--;
+                        }
+                    } else {
+                        // When WEEK_OF_YEAR and YEAR are out of sync,
+                        // adjust woy and amount to stay in the calendar year.
+                        if (weekYear > y) {
+                            if (amount < 0) {
+                                amount++;
+                            }
+                            woy = max;
+                        } else {
+                            if (amount > 0) {
+                                amount -= woy - max;
+                            }
+                            woy = min;
+                        }
+                    }
+                    set(field, getRolledValue(woy, amount, min, max));
+                    return;
+                }
+
+                // 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 = BaseCalendar.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:
+            {
+                if (!isCutoverYear(cdate.getNormalizedYear())) {
+                    // If the week of year is in the same year, we can
+                    // just change DAY_OF_WEEK.
+                    int weekOfYear = internalGet(WEEK_OF_YEAR);
+                    if (weekOfYear > 1 && weekOfYear < 52) {
+                        set(WEEK_OF_YEAR, weekOfYear); // update stamp[WEEK_OF_YEAR]
+                        max = SATURDAY;
+                        break;
+                    }
+                }
+
+                // We need to handle it in a different way around year
+                // boundaries and in the cutover year. Note that
+                // changing era and year values violates the roll
+                // rule: not changing larger calendar fields...
+                amount %= 7;
+                if (amount == 0) {
+                    return;
+                }
+                long fd = getCurrentFixedDate();
+                long dowFirst = BaseCalendar.getDayOfWeekDateOnOrBefore(fd, getFirstDayOfWeek());
+                fd += amount;
+                if (fd < dowFirst) {
+                    fd += 7;
+                } else if (fd >= dowFirst + 7) {
+                    fd -= 7;
+                }
+                BaseCalendar.Date d = getCalendarDate(fd);
+                set(ERA, (d.getNormalizedYear() <= 0 ? BCE : CE));
+                set(d.getYear(), d.getMonth() - 1, d.getDayOfMonth());
+                return;
+            }
+
+        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() 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)
+     */
+    @Override
+    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() 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)
+     */
+    @Override
+    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() 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)
+     */
+    @Override
+    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() 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)
+     */
+    @Override
+    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() 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
+     */
+    @Override
+    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() 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.
+     *
+     * <p>This method calculates the maximum value of {@link
+     * Calendar#WEEK_OF_YEAR WEEK_OF_YEAR} based on the {@link
+     * Calendar#YEAR YEAR} (calendar year) value, not the <a
+     * href="#week_year">week year</a>. Call {@link
+     * #getWeeksInWeekYear()} to get the maximum value of {@code
+     * WEEK_OF_YEAR} in the week year of this {@code GregorianCalendar}.
+     *
+     * @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
+     */
+    @Override
+    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();
+                }
+                int maxDayOfYear = getActualMaximum(DAY_OF_YEAR);
+                gc.set(DAY_OF_YEAR, maxDayOfYear);
+                value = gc.get(WEEK_OF_YEAR);
+                if (internalGet(YEAR) != gc.getWeekYear()) {
+                    gc.set(DAY_OF_YEAR, maxDayOfYear - 7);
+                    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 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));
+    }
+
+    @Override
+    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;
+    }
+
+    @Override
+    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;
+    }
+
+    @Override
+    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);
+        }
+    }
+
+    /**
+     * Returns {@code true} indicating this {@code GregorianCalendar}
+     * supports week dates.
+     *
+     * @return {@code true} (always)
+     * @see #getWeekYear()
+     * @see #setWeekDate(int,int,int)
+     * @see #getWeeksInWeekYear()
+     * @since 1.7
+     */
+    @Override
+    public final boolean isWeekDateSupported() {
+        return true;
+    }
+
+    /**
+     * Returns the <a href="#week_year">week year</a> represented by this
+     * {@code GregorianCalendar}. The dates in the weeks between 1 and the
+     * maximum week number of the week year have the same week year value
+     * that may be one year before or after the {@link Calendar#YEAR YEAR}
+     * (calendar year) value.
+     *
+     * <p>This method calls {@link Calendar#complete()} before
+     * calculating the week year.
+     *
+     * @return the week year represented by this {@code GregorianCalendar}.
+     *         If the {@link Calendar#ERA ERA} value is {@link #BC}, the year is
+     *         represented by 0 or a negative number: BC 1 is 0, BC 2
+     *         is -1, BC 3 is -2, and so on.
+     * @throws IllegalArgumentException
+     *         if any of the calendar fields is invalid in non-lenient mode.
+     * @see #isWeekDateSupported()
+     * @see #getWeeksInWeekYear()
+     * @see Calendar#getFirstDayOfWeek()
+     * @see Calendar#getMinimalDaysInFirstWeek()
+     * @since 1.7
+     */
+    @Override
+    public int getWeekYear() {
+        int year = get(YEAR); // implicitly calls complete()
+        if (internalGetEra() == BCE) {
+            year = 1 - year;
+        }
+
+        // Fast path for the Gregorian calendar years that are never
+        // affected by the Julian-Gregorian transition
+        if (year > gregorianCutoverYear + 1) {
+            int weekOfYear = internalGet(WEEK_OF_YEAR);
+            if (internalGet(MONTH) == JANUARY) {
+                if (weekOfYear >= 52) {
+                    --year;
+                }
+            } else {
+                if (weekOfYear == 1) {
+                    ++year;
+                }
+            }
+            return year;
+        }
+
+        // General (slow) path
+        int dayOfYear = internalGet(DAY_OF_YEAR);
+        int maxDayOfYear = getActualMaximum(DAY_OF_YEAR);
+        int minimalDays = getMinimalDaysInFirstWeek();
+
+        // Quickly check the possibility of year adjustments before
+        // cloning this GregorianCalendar.
+        if (dayOfYear > minimalDays && dayOfYear < (maxDayOfYear - 6)) {
+            return year;
+        }
+
+        // Create a clone to work on the calculation
+        GregorianCalendar cal = (GregorianCalendar) clone();
+        cal.setLenient(true);
+        // Use GMT so that intermediate date calculations won't
+        // affect the time of day fields.
+        cal.setTimeZone(TimeZone.getTimeZone("GMT"));
+        // Go to the first day of the year, which is usually January 1.
+        cal.set(DAY_OF_YEAR, 1);
+        cal.complete();
+
+        // Get the first day of the first day-of-week in the year.
+        int delta = getFirstDayOfWeek() - cal.get(DAY_OF_WEEK);
+        if (delta != 0) {
+            if (delta < 0) {
+                delta += 7;
+            }
+            cal.add(DAY_OF_YEAR, delta);
+        }
+        int minDayOfYear = cal.get(DAY_OF_YEAR);
+        if (dayOfYear < minDayOfYear) {
+            if (minDayOfYear <= minimalDays) {
+                --year;
+            }
+        } else {
+            cal.set(YEAR, year + 1);
+            cal.set(DAY_OF_YEAR, 1);
+            cal.complete();
+            int del = getFirstDayOfWeek() - cal.get(DAY_OF_WEEK);
+            if (del != 0) {
+                if (del < 0) {
+                    del += 7;
+                }
+                cal.add(DAY_OF_YEAR, del);
+            }
+            minDayOfYear = cal.get(DAY_OF_YEAR) - 1;
+            if (minDayOfYear == 0) {
+                minDayOfYear = 7;
+            }
+            if (minDayOfYear >= minimalDays) {
+                int days = maxDayOfYear - dayOfYear + 1;
+                if (days <= (7 - minDayOfYear)) {
+                    ++year;
+                }
+            }
+        }
+        return year;
+    }
+
+    /**
+     * Sets this {@code GregorianCalendar} to the date given by the
+     * date specifiers - <a href="#week_year">{@code weekYear}</a>,
+     * {@code weekOfYear}, and {@code dayOfWeek}. {@code weekOfYear}
+     * follows the <a href="#week_and_year">{@code WEEK_OF_YEAR}
+     * numbering</a>.  The {@code dayOfWeek} value must be one of the
+     * {@link Calendar#DAY_OF_WEEK DAY_OF_WEEK} values: {@link
+     * Calendar#SUNDAY SUNDAY} to {@link Calendar#SATURDAY SATURDAY}.
+     *
+     * <p>Note that the numeric day-of-week representation differs from
+     * the ISO 8601 standard, and that the {@code weekOfYear}
+     * numbering is compatible with the standard when {@code
+     * getFirstDayOfWeek()} is {@code MONDAY} and {@code
+     * getMinimalDaysInFirstWeek()} is 4.
+     *
+     * <p>Unlike the {@code set} method, all of the calendar fields
+     * and the instant of time value are calculated upon return.
+     *
+     * <p>If {@code weekOfYear} is out of the valid week-of-year
+     * range in {@code weekYear}, the {@code weekYear}
+     * and {@code weekOfYear} values are adjusted in lenient
+     * mode, or an {@code IllegalArgumentException} is thrown in
+     * non-lenient mode.
+     *
+     * @param weekYear    the week year
+     * @param weekOfYear  the week number based on {@code weekYear}
+     * @param dayOfWeek   the day of week value: one of the constants
+     *                    for the {@link #DAY_OF_WEEK DAY_OF_WEEK} field:
+     *                    {@link Calendar#SUNDAY SUNDAY}, ...,
+     *                    {@link Calendar#SATURDAY SATURDAY}.
+     * @exception IllegalArgumentException
+     *            if any of the given date specifiers is invalid,
+     *            or if any of the calendar fields are inconsistent
+     *            with the given date specifiers in non-lenient mode
+     * @see GregorianCalendar#isWeekDateSupported()
+     * @see Calendar#getFirstDayOfWeek()
+     * @see Calendar#getMinimalDaysInFirstWeek()
+     * @since 1.7
+     */
+    @Override
+    public void setWeekDate(int weekYear, int weekOfYear, int dayOfWeek) {
+        if (dayOfWeek < SUNDAY || dayOfWeek > SATURDAY) {
+            throw new IllegalArgumentException("invalid dayOfWeek: " + dayOfWeek);
+        }
+
+        // To avoid changing the time of day fields by date
+        // calculations, use a clone with the GMT time zone.
+        GregorianCalendar gc = (GregorianCalendar) clone();
+        gc.setLenient(true);
+        int era = gc.get(ERA);
+        gc.clear();
+        gc.setTimeZone(TimeZone.getTimeZone("GMT"));
+        gc.set(ERA, era);
+        gc.set(YEAR, weekYear);
+        gc.set(WEEK_OF_YEAR, 1);
+        gc.set(DAY_OF_WEEK, getFirstDayOfWeek());
+        int days = dayOfWeek - getFirstDayOfWeek();
+        if (days < 0) {
+            days += 7;
+        }
+        days += 7 * (weekOfYear - 1);
+        if (days != 0) {
+            gc.add(DAY_OF_YEAR, days);
+        } else {
+            gc.complete();
+        }
+
+        if (!isLenient() &&
+            (gc.getWeekYear() != weekYear
+             || gc.internalGet(WEEK_OF_YEAR) != weekOfYear
+             || gc.internalGet(DAY_OF_WEEK) != dayOfWeek)) {
+            throw new IllegalArgumentException();
+        }
+
+        set(ERA, gc.internalGet(ERA));
+        set(YEAR, gc.internalGet(YEAR));
+        set(MONTH, gc.internalGet(MONTH));
+        set(DAY_OF_MONTH, gc.internalGet(DAY_OF_MONTH));
+
+        // to avoid throwing an IllegalArgumentException in
+        // non-lenient, set WEEK_OF_YEAR internally
+        internalSet(WEEK_OF_YEAR, weekOfYear);
+        complete();
+    }
+
+    /**
+     * Returns the number of weeks in the <a href="#week_year">week year</a>
+     * represented by this {@code GregorianCalendar}.
+     *
+     * <p>For example, if this {@code GregorianCalendar}'s date is
+     * December 31, 2008 with <a href="#iso8601_compatible_setting">the ISO
+     * 8601 compatible setting</a>, this method will return 53 for the
+     * period: December 29, 2008 to January 3, 2010 while {@link
+     * #getActualMaximum(int) getActualMaximum(WEEK_OF_YEAR)} will return
+     * 52 for the period: December 31, 2007 to December 28, 2008.
+     *
+     * @return the number of weeks in the week year.
+     * @see Calendar#WEEK_OF_YEAR
+     * @see #getWeekYear()
+     * @see #getActualMaximum(int)
+     * @since 1.7
+     */
+    @Override
+    public int getWeeksInWeekYear() {
+        GregorianCalendar gc = getNormalizedCalendar();
+        int weekYear = gc.getWeekYear();
+        if (weekYear == gc.internalGet(YEAR)) {
+            return gc.getActualMaximum(WEEK_OF_YEAR);
+        }
+
+        // Use the 2nd week for calculating the max of WEEK_OF_YEAR
+        if (gc == this) {
+            gc = (GregorianCalendar) gc.clone();
+        }
+        gc.setWeekDate(weekYear, 2, internalGet(DAY_OF_WEEK));
+        return gc.getActualMaximum(WEEK_OF_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.
+     */
+    private transient 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
+     */
+    @Override
+    protected void computeFields() {
+        int mask;
+        if (isPartiallyNormalized()) {
+            // Determine which calendar fields need to be computed.
+            mask = getSetStateFields();
+            int fieldMask = ~mask & ALL_FIELDS;
+            // We have to call computTime in case calsys == null in
+            // order to set calsys and cdate. (6263644)
+            if (fieldMask != 0 || calsys == null) {
+                mask |= computeFields(fieldMask,
+                                      mask & (ZONE_OFFSET_MASK|DST_OFFSET_MASK));
+                assert mask == ALL_FIELDS;
+            }
+        } else {
+            mask = ALL_FIELDS;
+            computeFields(mask, 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 tzMask a bit mask to specify which time zone offset
+     * fields to be used for time calculations
+     * @return a new field mask that indicates what field values have
+     * actually been set.
+     */
+    private int computeFields(int fieldMask, int tzMask) {
+        int zoneOffset = 0;
+        TimeZone tz = getZone();
+        if (zoneOffsets == null) {
+            zoneOffsets = new int[2];
+        }
+        if (tzMask != (ZONE_OFFSET_MASK|DST_OFFSET_MASK)) {
+            if (tz instanceof ZoneInfo) {
+                zoneOffset = ((ZoneInfo)tz).getOffsets(time, zoneOffsets);
+            } else {
+                zoneOffset = tz.getOffset(time);
+                zoneOffsets[0] = tz.getRawOffset();
+                zoneOffsets[1] = zoneOffset - zoneOffsets[0];
+            }
+        }
+        if (tzMask != 0) {
+            if (isFieldSet(tzMask, ZONE_OFFSET)) {
+                zoneOffsets[0] = internalGet(ZONE_OFFSET);
+            }
+            if (isFieldSet(tzMask, DST_OFFSET)) {
+                zoneOffsets[1] = internalGet(DST_OFFSET);
+            }
+            zoneOffset = zoneOffsets[0] + zoneOffsets[1];
+        }
+
+        // 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) {
+            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 (gregorianCutoverYearJulian <= gregorianCutoverYear) {
+                    // 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  = fixedDateJan1 - 365;
+                if (normalizedYear > (cutoverYear + 1)) {
+                    if (CalendarUtils.isGregorianLeapYear(normalizedYear - 1)) {
+                        --prevJan1;
+                    }
+                } else if (normalizedYear <= gregorianCutoverYearJulian) {
+                    if (CalendarUtils.isJulianLeapYear(normalizedYear - 1)) {
+                        --prevJan1;
+                    }
+                } else {
+                    BaseCalendar calForJan1 = calsys;
+                    //int prevYear = normalizedYear - 1;
+                    int prevYear = getCalendarDate(fixedDec31).getNormalizedYear();
+                    if (prevYear == gregorianCutoverYear) {
+                        calForJan1 = getCutoverCalendarSystem();
+                        if (calForJan1 == jcal) {
+                            prevJan1 = calForJan1.getFixedDate(prevYear,
+                                                               BaseCalendar.JANUARY,
+                                                               1,
+                                                               null);
+                        } else {
+                            prevJan1 = gregorianCutoverDate;
+                            calForJan1 = gcal;
+                        }
+                    } else if (prevYear <= gregorianCutoverYearJulian) {
+                        calForJan1 = getJulianCalendarSystem();
+                        prevJan1 = calForJan1.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 = BaseCalendar.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;
+                    if (nextYear > gregorianCutoverYear
+                        || gregorianCutoverYearJulian == gregorianCutoverYear
+                        || nextYear == gregorianCutoverYearJulian) {
+                        nextJan1 = calForJan1.getFixedDate(nextYear,
+                                                           BaseCalendar.JANUARY,
+                                                           1,
+                                                           null);
+                    } else {
+                        nextJan1 = gregorianCutoverDate;
+                        calForJan1 = gcal;
+                    }
+
+                    long nextJan1st = BaseCalendar.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 int getWeekNumber(long fixedDay1, long fixedDate) {
+        // We can always use `gcal' since Julian and Gregorian are the
+        // same thing for this calculation.
+        long fixedDay1st = Gregorian.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.
+     */
+    @Override
+    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 = jfd;
+            } else {
+                jfd = fixedDate + getFixedDate(getJulianCalendarSystem(), year, fieldMask);
+                gfd = fixedDate + getFixedDate(gcal, year, fieldMask);
+            }
+
+            // Now we have to determine which calendar date it is.
+
+            // If the date is relative from the beginning of the year
+            // in the Julian calendar, then use jfd;
+            if (isFieldSet(fieldMask, DAY_OF_YEAR) || isFieldSet(fieldMask, WEEK_OF_YEAR)) {
+                if (gregorianCutoverYear == gregorianCutoverYearJulian) {
+                    fixedDate = jfd;
+                    break calculateFixedDate;
+                } else if (year == gregorianCutoverYear) {
+                    fixedDate = gfd;
+                    break calculateFixedDate;
+                }
+            }
+
+            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];
+        }
+        int tzMask = fieldMask & (ZONE_OFFSET_MASK|DST_OFFSET_MASK);
+        if (tzMask != (ZONE_OFFSET_MASK|DST_OFFSET_MASK)) {
+            if (zone instanceof ZoneInfo) {
+                ((ZoneInfo)zone).getOffsetsByWall(millis, zoneOffsets);
+            } else {
+                int gmtOffset = isFieldSet(fieldMask, ZONE_OFFSET) ?
+                                    internalGet(ZONE_OFFSET) : zone.getRawOffset();
+                zone.getOffsets(millis - gmtOffset, zoneOffsets);
+            }
+        }
+        if (tzMask != 0) {
+            if (isFieldSet(tzMask, ZONE_OFFSET)) {
+                zoneOffsets[0] = internalGet(ZONE_OFFSET);
+            }
+            if (isFieldSet(tzMask, DST_OFFSET)) {
+                zoneOffsets[1] = internalGet(DST_OFFSET);
+            }
+        }
+
+        // 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(), tzMask);
+
+        if (!isLenient()) {
+            for (int field = 0; field < FIELD_COUNT; field++) {
+                if (!isExternallySet(field)) {
+                    continue;
+                }
+                if (originalFields[field] != internalGet(field)) {
+                    String s = originalFields[field] + " -> " + internalGet(field);
+                    // Restore the original field values
+                    System.arraycopy(originalFields, 0, fields, 0, fields.length);
+                    throw new IllegalArgumentException(getFieldName(field) + ": " + s);
+                }
+            }
+        }
+        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 = BaseCalendar.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 = BaseCalendar.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 = BaseCalendar.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 = BaseCalendar.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 = BaseCalendar.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 = BaseCalendar.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 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.
+     */
+    private static synchronized 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() {
+        if (gregorianCutoverYearJulian < gregorianCutoverYear) {
+            return gcal;
+        }
+        return getJulianCalendarSystem();
+    }
+
+    /**
+     * Determines if the specified year (normalized) is the Gregorian
+     * cutover year. This object must have been normalized.
+     */
+    private 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 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 juliancal = getJulianCalendarSystem();
+        return juliancal.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 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 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 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 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 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 int monthLength(int month) {
+        int year = internalGet(YEAR);
+        if (internalGetEra() == BCE) {
+            year = 1 - year;
+        }
+        return monthLength(month, year);
+    }
+
+    private 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 int yearLength(int year) {
+        return isLeapYear(year) ? 366 : 365;
+    }
+
+    /**
+     * Returns the length (in days) of the year provided by
+     * internalGet(YEAR).
+     */
+    private 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 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 long getCurrentFixedDate() {
+        return (calsys == gcal) ? cachedFixedDate : calsys.getFixedDate(cdate);
+    }
+
+    /**
+     * Returns the new value after 'roll'ing the specified value and amount.
+     */
+    private static 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 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);
+    }
+
+    /**
+     * Converts this object to a {@code ZonedDateTime} that represents
+     * the same point on the time-line as this {@code GregorianCalendar}.
+     * <p>
+     * Since this object supports a Julian-Gregorian cutover date and
+     * {@code ZonedDateTime} does not, it is possible that the resulting year,
+     * month and day will have different values.  The result will represent the
+     * correct date in the ISO calendar system, which will also be the same value
+     * for Modified Julian Days.
+     *
+     * @return a zoned date-time representing the same point on the time-line
+     *  as this gregorian calendar
+     * @since 1.8
+     */
+    public ZonedDateTime toZonedDateTime() {
+        return ZonedDateTime.ofInstant(Instant.ofEpochMilli(getTimeInMillis()),
+                                       getTimeZone().toZoneId());
+    }
+
+    /**
+     * Obtains an instance of {@code GregorianCalendar} with the default locale
+     * from a {@code ZonedDateTime} object.
+     * <p>
+     * Since {@code ZonedDateTime} does not support a Julian-Gregorian cutover
+     * date and uses ISO calendar system, the return GregorianCalendar is a pure
+     * Gregorian calendar and uses ISO 8601 standard for week definitions,
+     * which has {@code MONDAY} as the {@link Calendar#getFirstDayOfWeek()
+     * FirstDayOfWeek} and {@code 4} as the value of the
+     * {@link Calendar#getMinimalDaysInFirstWeek() MinimalDaysInFirstWeek}.
+     * <p>
+     * {@code ZoneDateTime} can store points on the time-line further in the
+     * future and further in the past than {@code GregorianCalendar}. In this
+     * scenario, this method will throw an {@code IllegalArgumentException}
+     * exception.
+     *
+     * @param zdt  the zoned date-time object to convert
+     * @return  the gregorian calendar representing the same point on the
+     *  time-line as the zoned date-time provided
+     * @exception NullPointerException if {@code zdt} is null
+     * @exception IllegalArgumentException if the zoned date-time is too
+     * large to represent as a {@code GregorianCalendar}
+     * @since 1.8
+     */
+    public static GregorianCalendar from(ZonedDateTime zdt) {
+        GregorianCalendar cal = new GregorianCalendar(TimeZone.getTimeZone(zdt.getZone()));
+        cal.setGregorianChange(new Date(Long.MIN_VALUE));
+        cal.setFirstDayOfWeek(MONDAY);
+        cal.setMinimalDaysInFirstWeek(4);
+        try {
+            cal.setTimeInMillis(Math.addExact(Math.multiplyExact(zdt.toEpochSecond(), 1000),
+                                              zdt.get(ChronoField.MILLI_OF_SECOND)));
+        } catch (ArithmeticException ex) {
+            throw new IllegalArgumentException(ex);
+        }
+        return cal;
+    }
+}