1 /*
   2  * Copyright (c) 1996, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 /*
  27  * (C) Copyright Taligent, Inc. 1996-1998 - All Rights Reserved
  28  * (C) Copyright IBM Corp. 1996-1998 - All Rights Reserved
  29  *
  30  *   The original version of this source code and documentation is copyrighted
  31  * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
  32  * materials are provided under terms of a License Agreement between Taligent
  33  * and Sun. This technology is protected by multiple US and International
  34  * patents. This notice and attribution to Taligent may not be removed.
  35  *   Taligent is a registered trademark of Taligent, Inc.
  36  *
  37  */
  38 
  39 package java.util;
  40 
  41 import java.io.IOException;
  42 import java.io.ObjectInputStream;
  43 import java.io.ObjectOutputStream;
  44 import java.io.OptionalDataException;
  45 import java.io.Serializable;
  46 import java.security.AccessControlContext;
  47 import java.security.AccessController;
  48 import java.security.PermissionCollection;
  49 import java.security.PrivilegedActionException;
  50 import java.security.PrivilegedExceptionAction;
  51 import java.security.ProtectionDomain;
  52 import java.text.DateFormat;
  53 import java.text.DateFormatSymbols;
  54 import java.time.Instant;
  55 import java.util.concurrent.ConcurrentHashMap;
  56 import java.util.concurrent.ConcurrentMap;
  57 import sun.util.BuddhistCalendar;
  58 import sun.util.calendar.ZoneInfo;
  59 import sun.util.locale.provider.CalendarDataUtility;
  60 import sun.util.locale.provider.LocaleProviderAdapter;
  61 import sun.util.locale.provider.TimeZoneNameUtility;
  62 import sun.util.spi.CalendarProvider;
  63 
  64 /**
  65  * The <code>Calendar</code> class is an abstract class that provides methods
  66  * for converting between a specific instant in time and a set of {@link
  67  * #fields calendar fields} such as <code>YEAR</code>, <code>MONTH</code>,
  68  * <code>DAY_OF_MONTH</code>, <code>HOUR</code>, and so on, and for
  69  * manipulating the calendar fields, such as getting the date of the next
  70  * week. An instant in time can be represented by a millisecond value that is
  71  * an offset from the <a id="Epoch"><em>Epoch</em></a>, January 1, 1970
  72  * 00:00:00.000 GMT (Gregorian).
  73  *
  74  * <p>The class also provides additional fields and methods for
  75  * implementing a concrete calendar system outside the package. Those
  76  * fields and methods are defined as <code>protected</code>.
  77  *
  78  * <p>
  79  * Like other locale-sensitive classes, <code>Calendar</code> provides a
  80  * class method, <code>getInstance</code>, for getting a generally useful
  81  * object of this type. <code>Calendar</code>'s <code>getInstance</code> method
  82  * returns a <code>Calendar</code> object whose
  83  * calendar fields have been initialized with the current date and time:
  84  * <blockquote>
  85  * <pre>
  86  *     Calendar rightNow = Calendar.getInstance();
  87  * </pre>
  88  * </blockquote>
  89  *
  90  * <p>A <code>Calendar</code> object can produce all the calendar field values
  91  * needed to implement the date-time formatting for a particular language and
  92  * calendar style (for example, Japanese-Gregorian, Japanese-Traditional).
  93  * <code>Calendar</code> defines the range of values returned by
  94  * certain calendar fields, as well as their meaning.  For example,
  95  * the first month of the calendar system has value <code>MONTH ==
  96  * JANUARY</code> for all calendars.  Other values are defined by the
  97  * concrete subclass, such as <code>ERA</code>.  See individual field
  98  * documentation and subclass documentation for details.
  99  *
 100  * <h3>Getting and Setting Calendar Field Values</h3>
 101  *
 102  * <p>The calendar field values can be set by calling the <code>set</code>
 103  * methods. Any field values set in a <code>Calendar</code> will not be
 104  * interpreted until it needs to calculate its time value (milliseconds from
 105  * the Epoch) or values of the calendar fields. Calling the
 106  * <code>get</code>, <code>getTimeInMillis</code>, <code>getTime</code>,
 107  * <code>add</code> and <code>roll</code> involves such calculation.
 108  *
 109  * <h4>Leniency</h4>
 110  *
 111  * <p><code>Calendar</code> has two modes for interpreting the calendar
 112  * fields, <em>lenient</em> and <em>non-lenient</em>.  When a
 113  * <code>Calendar</code> is in lenient mode, it accepts a wider range of
 114  * calendar field values than it produces.  When a <code>Calendar</code>
 115  * recomputes calendar field values for return by <code>get()</code>, all of
 116  * the calendar fields are normalized. For example, a lenient
 117  * <code>GregorianCalendar</code> interprets <code>MONTH == JANUARY</code>,
 118  * <code>DAY_OF_MONTH == 32</code> as February 1.
 119 
 120  * <p>When a <code>Calendar</code> is in non-lenient mode, it throws an
 121  * exception if there is any inconsistency in its calendar fields. For
 122  * example, a <code>GregorianCalendar</code> always produces
 123  * <code>DAY_OF_MONTH</code> values between 1 and the length of the month. A
 124  * non-lenient <code>GregorianCalendar</code> throws an exception upon
 125  * calculating its time or calendar field values if any out-of-range field
 126  * value has been set.
 127  *
 128  * <h4><a id="first_week">First Week</a></h4>
 129  *
 130  * <code>Calendar</code> defines a locale-specific seven day week using two
 131  * parameters: the first day of the week and the minimal days in first week
 132  * (from 1 to 7).  These numbers are taken from the locale resource data or the
 133  * locale itself when a <code>Calendar</code> is constructed. If the designated
 134  * locale contains "fw" and/or "rg" <a href="./Locale.html#def_locale_extension">
 135  * Unicode extensions</a>, the first day of the week will be obtained according to
 136  * those extensions. If both "fw" and "rg" are specified, the value from "fw"
 137  * extension supersedes the implicit one from "rg" extension.
 138  * They may also be specified explicitly through the methods for setting their
 139  * values.
 140  *
 141  * <p>When setting or getting the <code>WEEK_OF_MONTH</code> or
 142  * <code>WEEK_OF_YEAR</code> fields, <code>Calendar</code> must determine the
 143  * first week of the month or year as a reference point.  The first week of a
 144  * month or year is defined as the earliest seven day period beginning on
 145  * <code>getFirstDayOfWeek()</code> and containing at least
 146  * <code>getMinimalDaysInFirstWeek()</code> days of that month or year.  Weeks
 147  * numbered ..., -1, 0 precede the first week; weeks numbered 2, 3,... follow
 148  * it.  Note that the normalized numbering returned by <code>get()</code> may be
 149  * different.  For example, a specific <code>Calendar</code> subclass may
 150  * designate the week before week 1 of a year as week <code><i>n</i></code> of
 151  * the previous year.
 152  *
 153  * <h4>Calendar Fields Resolution</h4>
 154  *
 155  * When computing a date and time from the calendar fields, there
 156  * may be insufficient information for the computation (such as only
 157  * year and month with no day of month), or there may be inconsistent
 158  * information (such as Tuesday, July 15, 1996 (Gregorian) -- July 15,
 159  * 1996 is actually a Monday). <code>Calendar</code> will resolve
 160  * calendar field values to determine the date and time in the
 161  * following way.
 162  *
 163  * <p><a id="resolution">If there is any conflict in calendar field values,
 164  * <code>Calendar</code> gives priorities to calendar fields that have been set
 165  * more recently.</a> The following are the default combinations of the
 166  * calendar fields. The most recent combination, as determined by the
 167  * most recently set single field, will be used.
 168  *
 169  * <p><a id="date_resolution">For the date fields</a>:
 170  * <blockquote>
 171  * <pre>
 172  * YEAR + MONTH + DAY_OF_MONTH
 173  * YEAR + MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
 174  * YEAR + MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
 175  * YEAR + DAY_OF_YEAR
 176  * YEAR + DAY_OF_WEEK + WEEK_OF_YEAR
 177  * </pre></blockquote>
 178  *
 179  * <a id="time_resolution">For the time of day fields</a>:
 180  * <blockquote>
 181  * <pre>
 182  * HOUR_OF_DAY
 183  * AM_PM + HOUR
 184  * </pre></blockquote>
 185  *
 186  * <p>If there are any calendar fields whose values haven't been set in the selected
 187  * field combination, <code>Calendar</code> uses their default values. The default
 188  * value of each field may vary by concrete calendar systems. For example, in
 189  * <code>GregorianCalendar</code>, the default of a field is the same as that
 190  * of the start of the Epoch: i.e., <code>YEAR = 1970</code>, <code>MONTH =
 191  * JANUARY</code>, <code>DAY_OF_MONTH = 1</code>, etc.
 192  *
 193  * <p>
 194  * <strong>Note:</strong> There are certain possible ambiguities in
 195  * interpretation of certain singular times, which are resolved in the
 196  * following ways:
 197  * <ol>
 198  *     <li> 23:59 is the last minute of the day and 00:00 is the first
 199  *          minute of the next day. Thus, 23:59 on Dec 31, 1999 &lt; 00:00 on
 200  *          Jan 1, 2000 &lt; 00:01 on Jan 1, 2000.
 201  *
 202  *     <li> Although historically not precise, midnight also belongs to "am",
 203  *          and noon belongs to "pm", so on the same day,
 204  *          12:00 am (midnight) &lt; 12:01 am, and 12:00 pm (noon) &lt; 12:01 pm
 205  * </ol>
 206  *
 207  * <p>
 208  * The date or time format strings are not part of the definition of a
 209  * calendar, as those must be modifiable or overridable by the user at
 210  * runtime. Use {@link DateFormat}
 211  * to format dates.
 212  *
 213  * <h4>Field Manipulation</h4>
 214  *
 215  * The calendar fields can be changed using three methods:
 216  * <code>set()</code>, <code>add()</code>, and <code>roll()</code>.
 217  *
 218  * <p><strong><code>set(f, value)</code></strong> changes calendar field
 219  * <code>f</code> to <code>value</code>.  In addition, it sets an
 220  * internal member variable to indicate that calendar field <code>f</code> has
 221  * been changed. Although calendar field <code>f</code> is changed immediately,
 222  * the calendar's time value in milliseconds is not recomputed until the next call to
 223  * <code>get()</code>, <code>getTime()</code>, <code>getTimeInMillis()</code>,
 224  * <code>add()</code>, or <code>roll()</code> is made. Thus, multiple calls to
 225  * <code>set()</code> do not trigger multiple, unnecessary
 226  * computations. As a result of changing a calendar field using
 227  * <code>set()</code>, other calendar fields may also change, depending on the
 228  * calendar field, the calendar field value, and the calendar system. In addition,
 229  * <code>get(f)</code> will not necessarily return <code>value</code> set by
 230  * the call to the <code>set</code> method
 231  * after the calendar fields have been recomputed. The specifics are determined by
 232  * the concrete calendar class.</p>
 233  *
 234  * <p><em>Example</em>: Consider a <code>GregorianCalendar</code>
 235  * originally set to August 31, 1999. Calling <code>set(Calendar.MONTH,
 236  * Calendar.SEPTEMBER)</code> sets the date to September 31,
 237  * 1999. This is a temporary internal representation that resolves to
 238  * October 1, 1999 if <code>getTime()</code>is then called. However, a
 239  * call to <code>set(Calendar.DAY_OF_MONTH, 30)</code> before the call to
 240  * <code>getTime()</code> sets the date to September 30, 1999, since
 241  * no recomputation occurs after <code>set()</code> itself.</p>
 242  *
 243  * <p><strong><code>add(f, delta)</code></strong> adds <code>delta</code>
 244  * to field <code>f</code>.  This is equivalent to calling <code>set(f,
 245  * get(f) + delta)</code> with two adjustments:</p>
 246  *
 247  * <blockquote>
 248  *   <p><strong>Add rule 1</strong>. The value of field <code>f</code>
 249  *   after the call minus the value of field <code>f</code> before the
 250  *   call is <code>delta</code>, modulo any overflow that has occurred in
 251  *   field <code>f</code>. Overflow occurs when a field value exceeds its
 252  *   range and, as a result, the next larger field is incremented or
 253  *   decremented and the field value is adjusted back into its range.</p>
 254  *
 255  *   <p><strong>Add rule 2</strong>. If a smaller field is expected to be
 256  *   invariant, but it is impossible for it to be equal to its
 257  *   prior value because of changes in its minimum or maximum after field
 258  *   <code>f</code> is changed or other constraints, such as time zone
 259  *   offset changes, then its value is adjusted to be as close
 260  *   as possible to its expected value. A smaller field represents a
 261  *   smaller unit of time. <code>HOUR</code> is a smaller field than
 262  *   <code>DAY_OF_MONTH</code>. No adjustment is made to smaller fields
 263  *   that are not expected to be invariant. The calendar system
 264  *   determines what fields are expected to be invariant.</p>
 265  * </blockquote>
 266  *
 267  * <p>In addition, unlike <code>set()</code>, <code>add()</code> forces
 268  * an immediate recomputation of the calendar's milliseconds and all
 269  * fields.</p>
 270  *
 271  * <p><em>Example</em>: Consider a <code>GregorianCalendar</code>
 272  * originally set to August 31, 1999. Calling <code>add(Calendar.MONTH,
 273  * 13)</code> sets the calendar to September 30, 2000. <strong>Add rule
 274  * 1</strong> sets the <code>MONTH</code> field to September, since
 275  * adding 13 months to August gives September of the next year. Since
 276  * <code>DAY_OF_MONTH</code> cannot be 31 in September in a
 277  * <code>GregorianCalendar</code>, <strong>add rule 2</strong> sets the
 278  * <code>DAY_OF_MONTH</code> to 30, the closest possible value. Although
 279  * it is a smaller field, <code>DAY_OF_WEEK</code> is not adjusted by
 280  * rule 2, since it is expected to change when the month changes in a
 281  * <code>GregorianCalendar</code>.</p>
 282  *
 283  * <p><strong><code>roll(f, delta)</code></strong> adds
 284  * <code>delta</code> to field <code>f</code> without changing larger
 285  * fields. This is equivalent to calling <code>add(f, delta)</code> with
 286  * the following adjustment:</p>
 287  *
 288  * <blockquote>
 289  *   <p><strong>Roll rule</strong>. Larger fields are unchanged after the
 290  *   call. A larger field represents a larger unit of
 291  *   time. <code>DAY_OF_MONTH</code> is a larger field than
 292  *   <code>HOUR</code>.</p>
 293  * </blockquote>
 294  *
 295  * <p><em>Example</em>: See {@link java.util.GregorianCalendar#roll(int, int)}.
 296  *
 297  * <p><strong>Usage model</strong>. To motivate the behavior of
 298  * <code>add()</code> and <code>roll()</code>, consider a user interface
 299  * component with increment and decrement buttons for the month, day, and
 300  * year, and an underlying <code>GregorianCalendar</code>. If the
 301  * interface reads January 31, 1999 and the user presses the month
 302  * increment button, what should it read? If the underlying
 303  * implementation uses <code>set()</code>, it might read March 3, 1999. A
 304  * better result would be February 28, 1999. Furthermore, if the user
 305  * presses the month increment button again, it should read March 31,
 306  * 1999, not March 28, 1999. By saving the original date and using either
 307  * <code>add()</code> or <code>roll()</code>, depending on whether larger
 308  * fields should be affected, the user interface can behave as most users
 309  * will intuitively expect.</p>
 310  *
 311  * @see          java.lang.System#currentTimeMillis()
 312  * @see          Date
 313  * @see          GregorianCalendar
 314  * @see          TimeZone
 315  * @see          java.text.DateFormat
 316  * @author Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu
 317  * @since 1.1
 318  */
 319 public abstract class Calendar implements Serializable, Cloneable, Comparable<Calendar> {
 320 
 321     // Data flow in Calendar
 322     // ---------------------
 323 
 324     // The current time is represented in two ways by Calendar: as UTC
 325     // milliseconds from the epoch (1 January 1970 0:00 UTC), and as local
 326     // fields such as MONTH, HOUR, AM_PM, etc.  It is possible to compute the
 327     // millis from the fields, and vice versa.  The data needed to do this
 328     // conversion is encapsulated by a TimeZone object owned by the Calendar.
 329     // The data provided by the TimeZone object may also be overridden if the
 330     // user sets the ZONE_OFFSET and/or DST_OFFSET fields directly. The class
 331     // keeps track of what information was most recently set by the caller, and
 332     // uses that to compute any other information as needed.
 333 
 334     // If the user sets the fields using set(), the data flow is as follows.
 335     // This is implemented by the Calendar subclass's computeTime() method.
 336     // During this process, certain fields may be ignored.  The disambiguation
 337     // algorithm for resolving which fields to pay attention to is described
 338     // in the class documentation.
 339 
 340     //   local fields (YEAR, MONTH, DATE, HOUR, MINUTE, etc.)
 341     //           |
 342     //           | Using Calendar-specific algorithm
 343     //           V
 344     //   local standard millis
 345     //           |
 346     //           | Using TimeZone or user-set ZONE_OFFSET / DST_OFFSET
 347     //           V
 348     //   UTC millis (in time data member)
 349 
 350     // If the user sets the UTC millis using setTime() or setTimeInMillis(),
 351     // the data flow is as follows.  This is implemented by the Calendar
 352     // subclass's computeFields() method.
 353 
 354     //   UTC millis (in time data member)
 355     //           |
 356     //           | Using TimeZone getOffset()
 357     //           V
 358     //   local standard millis
 359     //           |
 360     //           | Using Calendar-specific algorithm
 361     //           V
 362     //   local fields (YEAR, MONTH, DATE, HOUR, MINUTE, etc.)
 363 
 364     // In general, a round trip from fields, through local and UTC millis, and
 365     // back out to fields is made when necessary.  This is implemented by the
 366     // complete() method.  Resolving a partial set of fields into a UTC millis
 367     // value allows all remaining fields to be generated from that value.  If
 368     // the Calendar is lenient, the fields are also renormalized to standard
 369     // ranges when they are regenerated.
 370 
 371     /**
 372      * Field number for <code>get</code> and <code>set</code> indicating the
 373      * era, e.g., AD or BC in the Julian calendar. This is a calendar-specific
 374      * value; see subclass documentation.
 375      *
 376      * @see GregorianCalendar#AD
 377      * @see GregorianCalendar#BC
 378      */
 379     public static final int ERA = 0;
 380 
 381     /**
 382      * Field number for <code>get</code> and <code>set</code> indicating the
 383      * year. This is a calendar-specific value; see subclass documentation.
 384      */
 385     public static final int YEAR = 1;
 386 
 387     /**
 388      * Field number for <code>get</code> and <code>set</code> indicating the
 389      * month. This is a calendar-specific value. The first month of
 390      * the year in the Gregorian and Julian calendars is
 391      * <code>JANUARY</code> which is 0; the last depends on the number
 392      * of months in a year.
 393      *
 394      * @see #JANUARY
 395      * @see #FEBRUARY
 396      * @see #MARCH
 397      * @see #APRIL
 398      * @see #MAY
 399      * @see #JUNE
 400      * @see #JULY
 401      * @see #AUGUST
 402      * @see #SEPTEMBER
 403      * @see #OCTOBER
 404      * @see #NOVEMBER
 405      * @see #DECEMBER
 406      * @see #UNDECIMBER
 407      */
 408     public static final int MONTH = 2;
 409 
 410     /**
 411      * Field number for <code>get</code> and <code>set</code> indicating the
 412      * week number within the current year.  The first week of the year, as
 413      * defined by <code>getFirstDayOfWeek()</code> and
 414      * <code>getMinimalDaysInFirstWeek()</code>, has value 1.  Subclasses define
 415      * the value of <code>WEEK_OF_YEAR</code> for days before the first week of
 416      * the year.
 417      *
 418      * @see #getFirstDayOfWeek
 419      * @see #getMinimalDaysInFirstWeek
 420      */
 421     public static final int WEEK_OF_YEAR = 3;
 422 
 423     /**
 424      * Field number for <code>get</code> and <code>set</code> indicating the
 425      * week number within the current month.  The first week of the month, as
 426      * defined by <code>getFirstDayOfWeek()</code> and
 427      * <code>getMinimalDaysInFirstWeek()</code>, has value 1.  Subclasses define
 428      * the value of <code>WEEK_OF_MONTH</code> for days before the first week of
 429      * the month.
 430      *
 431      * @see #getFirstDayOfWeek
 432      * @see #getMinimalDaysInFirstWeek
 433      */
 434     public static final int WEEK_OF_MONTH = 4;
 435 
 436     /**
 437      * Field number for <code>get</code> and <code>set</code> indicating the
 438      * day of the month. This is a synonym for <code>DAY_OF_MONTH</code>.
 439      * The first day of the month has value 1.
 440      *
 441      * @see #DAY_OF_MONTH
 442      */
 443     public static final int DATE = 5;
 444 
 445     /**
 446      * Field number for <code>get</code> and <code>set</code> indicating the
 447      * day of the month. This is a synonym for <code>DATE</code>.
 448      * The first day of the month has value 1.
 449      *
 450      * @see #DATE
 451      */
 452     public static final int DAY_OF_MONTH = 5;
 453 
 454     /**
 455      * Field number for <code>get</code> and <code>set</code> indicating the day
 456      * number within the current year.  The first day of the year has value 1.
 457      */
 458     public static final int DAY_OF_YEAR = 6;
 459 
 460     /**
 461      * Field number for <code>get</code> and <code>set</code> indicating the day
 462      * of the week.  This field takes values <code>SUNDAY</code>,
 463      * <code>MONDAY</code>, <code>TUESDAY</code>, <code>WEDNESDAY</code>,
 464      * <code>THURSDAY</code>, <code>FRIDAY</code>, and <code>SATURDAY</code>.
 465      *
 466      * @see #SUNDAY
 467      * @see #MONDAY
 468      * @see #TUESDAY
 469      * @see #WEDNESDAY
 470      * @see #THURSDAY
 471      * @see #FRIDAY
 472      * @see #SATURDAY
 473      */
 474     public static final int DAY_OF_WEEK = 7;
 475 
 476     /**
 477      * Field number for <code>get</code> and <code>set</code> indicating the
 478      * ordinal number of the day of the week within the current month. Together
 479      * with the <code>DAY_OF_WEEK</code> field, this uniquely specifies a day
 480      * within a month.  Unlike <code>WEEK_OF_MONTH</code> and
 481      * <code>WEEK_OF_YEAR</code>, this field's value does <em>not</em> depend on
 482      * <code>getFirstDayOfWeek()</code> or
 483      * <code>getMinimalDaysInFirstWeek()</code>.  <code>DAY_OF_MONTH 1</code>
 484      * through <code>7</code> always correspond to <code>DAY_OF_WEEK_IN_MONTH
 485      * 1</code>; <code>8</code> through <code>14</code> correspond to
 486      * <code>DAY_OF_WEEK_IN_MONTH 2</code>, and so on.
 487      * <code>DAY_OF_WEEK_IN_MONTH 0</code> indicates the week before
 488      * <code>DAY_OF_WEEK_IN_MONTH 1</code>.  Negative values count back from the
 489      * end of the month, so the last Sunday of a month is specified as
 490      * <code>DAY_OF_WEEK = SUNDAY, DAY_OF_WEEK_IN_MONTH = -1</code>.  Because
 491      * negative values count backward they will usually be aligned differently
 492      * within the month than positive values.  For example, if a month has 31
 493      * days, <code>DAY_OF_WEEK_IN_MONTH -1</code> will overlap
 494      * <code>DAY_OF_WEEK_IN_MONTH 5</code> and the end of <code>4</code>.
 495      *
 496      * @see #DAY_OF_WEEK
 497      * @see #WEEK_OF_MONTH
 498      */
 499     public static final int DAY_OF_WEEK_IN_MONTH = 8;
 500 
 501     /**
 502      * Field number for <code>get</code> and <code>set</code> indicating
 503      * whether the <code>HOUR</code> is before or after noon.
 504      * E.g., at 10:04:15.250 PM the <code>AM_PM</code> is <code>PM</code>.
 505      *
 506      * @see #AM
 507      * @see #PM
 508      * @see #HOUR
 509      */
 510     public static final int AM_PM = 9;
 511 
 512     /**
 513      * Field number for <code>get</code> and <code>set</code> indicating the
 514      * hour of the morning or afternoon. <code>HOUR</code> is used for the
 515      * 12-hour clock (0 - 11). Noon and midnight are represented by 0, not by 12.
 516      * E.g., at 10:04:15.250 PM the <code>HOUR</code> is 10.
 517      *
 518      * @see #AM_PM
 519      * @see #HOUR_OF_DAY
 520      */
 521     public static final int HOUR = 10;
 522 
 523     /**
 524      * Field number for <code>get</code> and <code>set</code> indicating the
 525      * hour of the day. <code>HOUR_OF_DAY</code> is used for the 24-hour clock.
 526      * E.g., at 10:04:15.250 PM the <code>HOUR_OF_DAY</code> is 22.
 527      *
 528      * @see #HOUR
 529      */
 530     public static final int HOUR_OF_DAY = 11;
 531 
 532     /**
 533      * Field number for <code>get</code> and <code>set</code> indicating the
 534      * minute within the hour.
 535      * E.g., at 10:04:15.250 PM the <code>MINUTE</code> is 4.
 536      */
 537     public static final int MINUTE = 12;
 538 
 539     /**
 540      * Field number for <code>get</code> and <code>set</code> indicating the
 541      * second within the minute.
 542      * E.g., at 10:04:15.250 PM the <code>SECOND</code> is 15.
 543      */
 544     public static final int SECOND = 13;
 545 
 546     /**
 547      * Field number for <code>get</code> and <code>set</code> indicating the
 548      * millisecond within the second.
 549      * E.g., at 10:04:15.250 PM the <code>MILLISECOND</code> is 250.
 550      */
 551     public static final int MILLISECOND = 14;
 552 
 553     /**
 554      * Field number for <code>get</code> and <code>set</code>
 555      * indicating the raw offset from GMT in milliseconds.
 556      * <p>
 557      * This field reflects the correct GMT offset value of the time
 558      * zone of this <code>Calendar</code> if the
 559      * <code>TimeZone</code> implementation subclass supports
 560      * historical GMT offset changes.
 561      */
 562     public static final int ZONE_OFFSET = 15;
 563 
 564     /**
 565      * Field number for <code>get</code> and <code>set</code> indicating the
 566      * daylight saving offset in milliseconds.
 567      * <p>
 568      * This field reflects the correct daylight saving offset value of
 569      * the time zone of this <code>Calendar</code> if the
 570      * <code>TimeZone</code> implementation subclass supports
 571      * historical Daylight Saving Time schedule changes.
 572      */
 573     public static final int DST_OFFSET = 16;
 574 
 575     /**
 576      * The number of distinct fields recognized by <code>get</code> and <code>set</code>.
 577      * Field numbers range from <code>0..FIELD_COUNT-1</code>.
 578      */
 579     public static final int FIELD_COUNT = 17;
 580 
 581     /**
 582      * Value of the {@link #DAY_OF_WEEK} field indicating
 583      * Sunday.
 584      */
 585     public static final int SUNDAY = 1;
 586 
 587     /**
 588      * Value of the {@link #DAY_OF_WEEK} field indicating
 589      * Monday.
 590      */
 591     public static final int MONDAY = 2;
 592 
 593     /**
 594      * Value of the {@link #DAY_OF_WEEK} field indicating
 595      * Tuesday.
 596      */
 597     public static final int TUESDAY = 3;
 598 
 599     /**
 600      * Value of the {@link #DAY_OF_WEEK} field indicating
 601      * Wednesday.
 602      */
 603     public static final int WEDNESDAY = 4;
 604 
 605     /**
 606      * Value of the {@link #DAY_OF_WEEK} field indicating
 607      * Thursday.
 608      */
 609     public static final int THURSDAY = 5;
 610 
 611     /**
 612      * Value of the {@link #DAY_OF_WEEK} field indicating
 613      * Friday.
 614      */
 615     public static final int FRIDAY = 6;
 616 
 617     /**
 618      * Value of the {@link #DAY_OF_WEEK} field indicating
 619      * Saturday.
 620      */
 621     public static final int SATURDAY = 7;
 622 
 623     /**
 624      * Value of the {@link #MONTH} field indicating the
 625      * first month of the year in the Gregorian and Julian calendars.
 626      */
 627     public static final int JANUARY = 0;
 628 
 629     /**
 630      * Value of the {@link #MONTH} field indicating the
 631      * second month of the year in the Gregorian and Julian calendars.
 632      */
 633     public static final int FEBRUARY = 1;
 634 
 635     /**
 636      * Value of the {@link #MONTH} field indicating the
 637      * third month of the year in the Gregorian and Julian calendars.
 638      */
 639     public static final int MARCH = 2;
 640 
 641     /**
 642      * Value of the {@link #MONTH} field indicating the
 643      * fourth month of the year in the Gregorian and Julian calendars.
 644      */
 645     public static final int APRIL = 3;
 646 
 647     /**
 648      * Value of the {@link #MONTH} field indicating the
 649      * fifth month of the year in the Gregorian and Julian calendars.
 650      */
 651     public static final int MAY = 4;
 652 
 653     /**
 654      * Value of the {@link #MONTH} field indicating the
 655      * sixth month of the year in the Gregorian and Julian calendars.
 656      */
 657     public static final int JUNE = 5;
 658 
 659     /**
 660      * Value of the {@link #MONTH} field indicating the
 661      * seventh month of the year in the Gregorian and Julian calendars.
 662      */
 663     public static final int JULY = 6;
 664 
 665     /**
 666      * Value of the {@link #MONTH} field indicating the
 667      * eighth month of the year in the Gregorian and Julian calendars.
 668      */
 669     public static final int AUGUST = 7;
 670 
 671     /**
 672      * Value of the {@link #MONTH} field indicating the
 673      * ninth month of the year in the Gregorian and Julian calendars.
 674      */
 675     public static final int SEPTEMBER = 8;
 676 
 677     /**
 678      * Value of the {@link #MONTH} field indicating the
 679      * tenth month of the year in the Gregorian and Julian calendars.
 680      */
 681     public static final int OCTOBER = 9;
 682 
 683     /**
 684      * Value of the {@link #MONTH} field indicating the
 685      * eleventh month of the year in the Gregorian and Julian calendars.
 686      */
 687     public static final int NOVEMBER = 10;
 688 
 689     /**
 690      * Value of the {@link #MONTH} field indicating the
 691      * twelfth month of the year in the Gregorian and Julian calendars.
 692      */
 693     public static final int DECEMBER = 11;
 694 
 695     /**
 696      * Value of the {@link #MONTH} field indicating the
 697      * thirteenth month of the year. Although <code>GregorianCalendar</code>
 698      * does not use this value, lunar calendars do.
 699      */
 700     public static final int UNDECIMBER = 12;
 701 
 702     /**
 703      * Value of the {@link #AM_PM} field indicating the
 704      * period of the day from midnight to just before noon.
 705      */
 706     public static final int AM = 0;
 707 
 708     /**
 709      * Value of the {@link #AM_PM} field indicating the
 710      * period of the day from noon to just before midnight.
 711      */
 712     public static final int PM = 1;
 713 
 714     /**
 715      * A style specifier for {@link #getDisplayNames(int, int, Locale)
 716      * getDisplayNames} indicating names in all styles, such as
 717      * "January" and "Jan".
 718      *
 719      * @see #SHORT_FORMAT
 720      * @see #LONG_FORMAT
 721      * @see #SHORT_STANDALONE
 722      * @see #LONG_STANDALONE
 723      * @see #SHORT
 724      * @see #LONG
 725      * @since 1.6
 726      */
 727     public static final int ALL_STYLES = 0;
 728 
 729     static final int STANDALONE_MASK = 0x8000;
 730 
 731     /**
 732      * A style specifier for {@link #getDisplayName(int, int, Locale)
 733      * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
 734      * getDisplayNames} equivalent to {@link #SHORT_FORMAT}.
 735      *
 736      * @see #SHORT_STANDALONE
 737      * @see #LONG
 738      * @since 1.6
 739      */
 740     public static final int SHORT = 1;
 741 
 742     /**
 743      * A style specifier for {@link #getDisplayName(int, int, Locale)
 744      * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
 745      * getDisplayNames} equivalent to {@link #LONG_FORMAT}.
 746      *
 747      * @see #LONG_STANDALONE
 748      * @see #SHORT
 749      * @since 1.6
 750      */
 751     public static final int LONG = 2;
 752 
 753     /**
 754      * A style specifier for {@link #getDisplayName(int, int, Locale)
 755      * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
 756      * getDisplayNames} indicating a narrow name used for format. Narrow names
 757      * are typically single character strings, such as "M" for Monday.
 758      *
 759      * @see #NARROW_STANDALONE
 760      * @see #SHORT_FORMAT
 761      * @see #LONG_FORMAT
 762      * @since 1.8
 763      */
 764     public static final int NARROW_FORMAT = 4;
 765 
 766     /**
 767      * A style specifier for {@link #getDisplayName(int, int, Locale)
 768      * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
 769      * getDisplayNames} indicating a narrow name independently. Narrow names
 770      * are typically single character strings, such as "M" for Monday.
 771      *
 772      * @see #NARROW_FORMAT
 773      * @see #SHORT_STANDALONE
 774      * @see #LONG_STANDALONE
 775      * @since 1.8
 776      */
 777     public static final int NARROW_STANDALONE = NARROW_FORMAT | STANDALONE_MASK;
 778 
 779     /**
 780      * A style specifier for {@link #getDisplayName(int, int, Locale)
 781      * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
 782      * getDisplayNames} indicating a short name used for format.
 783      *
 784      * @see #SHORT_STANDALONE
 785      * @see #LONG_FORMAT
 786      * @see #LONG_STANDALONE
 787      * @since 1.8
 788      */
 789     public static final int SHORT_FORMAT = 1;
 790 
 791     /**
 792      * A style specifier for {@link #getDisplayName(int, int, Locale)
 793      * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
 794      * getDisplayNames} indicating a long name used for format.
 795      *
 796      * @see #LONG_STANDALONE
 797      * @see #SHORT_FORMAT
 798      * @see #SHORT_STANDALONE
 799      * @since 1.8
 800      */
 801     public static final int LONG_FORMAT = 2;
 802 
 803     /**
 804      * A style specifier for {@link #getDisplayName(int, int, Locale)
 805      * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
 806      * getDisplayNames} indicating a short name used independently,
 807      * such as a month abbreviation as calendar headers.
 808      *
 809      * @see #SHORT_FORMAT
 810      * @see #LONG_FORMAT
 811      * @see #LONG_STANDALONE
 812      * @since 1.8
 813      */
 814     public static final int SHORT_STANDALONE = SHORT | STANDALONE_MASK;
 815 
 816     /**
 817      * A style specifier for {@link #getDisplayName(int, int, Locale)
 818      * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
 819      * getDisplayNames} indicating a long name used independently,
 820      * such as a month name as calendar headers.
 821      *
 822      * @see #LONG_FORMAT
 823      * @see #SHORT_FORMAT
 824      * @see #SHORT_STANDALONE
 825      * @since 1.8
 826      */
 827     public static final int LONG_STANDALONE = LONG | STANDALONE_MASK;
 828 
 829     // Internal notes:
 830     // Calendar contains two kinds of time representations: current "time" in
 831     // milliseconds, and a set of calendar "fields" representing the current time.
 832     // The two representations are usually in sync, but can get out of sync
 833     // as follows.
 834     // 1. Initially, no fields are set, and the time is invalid.
 835     // 2. If the time is set, all fields are computed and in sync.
 836     // 3. If a single field is set, the time is invalid.
 837     // Recomputation of the time and fields happens when the object needs
 838     // to return a result to the user, or use a result for a computation.
 839 
 840     /**
 841      * The calendar field values for the currently set time for this calendar.
 842      * This is an array of <code>FIELD_COUNT</code> integers, with index values
 843      * <code>ERA</code> through <code>DST_OFFSET</code>.
 844      * @serial
 845      */
 846     @SuppressWarnings("ProtectedField")
 847     protected int           fields[];
 848 
 849     /**
 850      * The flags which tell if a specified calendar field for the calendar is set.
 851      * A new object has no fields set.  After the first call to a method
 852      * which generates the fields, they all remain set after that.
 853      * This is an array of <code>FIELD_COUNT</code> booleans, with index values
 854      * <code>ERA</code> through <code>DST_OFFSET</code>.
 855      * @serial
 856      */
 857     @SuppressWarnings("ProtectedField")
 858     protected boolean       isSet[];
 859 
 860     /**
 861      * Pseudo-time-stamps which specify when each field was set. There
 862      * are two special values, UNSET and COMPUTED. Values from
 863      * MINIMUM_USER_SET to Integer.MAX_VALUE are legal user set values.
 864      */
 865     private transient int   stamp[];
 866 
 867     /**
 868      * The currently set time for this calendar, expressed in milliseconds after
 869      * January 1, 1970, 0:00:00 GMT.
 870      * @see #isTimeSet
 871      * @serial
 872      */
 873     @SuppressWarnings("ProtectedField")
 874     protected long          time;
 875 
 876     /**
 877      * True if then the value of <code>time</code> is valid.
 878      * The time is made invalid by a change to an item of <code>field[]</code>.
 879      * @see #time
 880      * @serial
 881      */
 882     @SuppressWarnings("ProtectedField")
 883     protected boolean       isTimeSet;
 884 
 885     /**
 886      * True if <code>fields[]</code> are in sync with the currently set time.
 887      * If false, then the next attempt to get the value of a field will
 888      * force a recomputation of all fields from the current value of
 889      * <code>time</code>.
 890      * @serial
 891      */
 892     @SuppressWarnings("ProtectedField")
 893     protected boolean       areFieldsSet;
 894 
 895     /**
 896      * True if all fields have been set.
 897      * @serial
 898      */
 899     transient boolean       areAllFieldsSet;
 900 
 901     /**
 902      * <code>True</code> if this calendar allows out-of-range field values during computation
 903      * of <code>time</code> from <code>fields[]</code>.
 904      * @see #setLenient
 905      * @see #isLenient
 906      * @serial
 907      */
 908     private boolean         lenient = true;
 909 
 910     /**
 911      * The <code>TimeZone</code> used by this calendar. <code>Calendar</code>
 912      * uses the time zone data to translate between locale and GMT time.
 913      * @serial
 914      */
 915     private TimeZone        zone;
 916 
 917     /**
 918      * <code>True</code> if zone references to a shared TimeZone object.
 919      */
 920     private transient boolean sharedZone = false;
 921 
 922     /**
 923      * The first day of the week, with possible values <code>SUNDAY</code>,
 924      * <code>MONDAY</code>, etc.  This is a locale-dependent value.
 925      * @serial
 926      */
 927     private int             firstDayOfWeek;
 928 
 929     /**
 930      * The number of days required for the first week in a month or year,
 931      * with possible values from 1 to 7.  This is a locale-dependent value.
 932      * @serial
 933      */
 934     private int             minimalDaysInFirstWeek;
 935 
 936     /**
 937      * Cache to hold the firstDayOfWeek and minimalDaysInFirstWeek
 938      * of a Locale.
 939      */
 940     private static final ConcurrentMap<Locale, int[]> cachedLocaleData
 941         = new ConcurrentHashMap<>(3);
 942 
 943     // Special values of stamp[]
 944     /**
 945      * The corresponding fields[] has no value.
 946      */
 947     private static final int        UNSET = 0;
 948 
 949     /**
 950      * The value of the corresponding fields[] has been calculated internally.
 951      */
 952     private static final int        COMPUTED = 1;
 953 
 954     /**
 955      * The value of the corresponding fields[] has been set externally. Stamp
 956      * values which are greater than 1 represents the (pseudo) time when the
 957      * corresponding fields[] value was set.
 958      */
 959     private static final int        MINIMUM_USER_STAMP = 2;
 960 
 961     /**
 962      * The mask value that represents all of the fields.
 963      */
 964     static final int ALL_FIELDS = (1 << FIELD_COUNT) - 1;
 965 
 966     /**
 967      * The next available value for <code>stamp[]</code>, an internal array.
 968      * This actually should not be written out to the stream, and will probably
 969      * be removed from the stream in the near future.  In the meantime,
 970      * a value of <code>MINIMUM_USER_STAMP</code> should be used.
 971      * @serial
 972      */
 973     private int             nextStamp = MINIMUM_USER_STAMP;
 974 
 975     // the internal serial version which says which version was written
 976     // - 0 (default) for version up to JDK 1.1.5
 977     // - 1 for version from JDK 1.1.6, which writes a correct 'time' value
 978     //     as well as compatible values for other fields.  This is a
 979     //     transitional format.
 980     // - 2 (not implemented yet) a future version, in which fields[],
 981     //     areFieldsSet, and isTimeSet become transient, and isSet[] is
 982     //     removed. In JDK 1.1.6 we write a format compatible with version 2.
 983     static final int        currentSerialVersion = 1;
 984 
 985     /**
 986      * The version of the serialized data on the stream.  Possible values:
 987      * <dl>
 988      * <dt><b>0</b> or not present on stream</dt>
 989      * <dd>
 990      * JDK 1.1.5 or earlier.
 991      * </dd>
 992      * <dt><b>1</b></dt>
 993      * <dd>
 994      * JDK 1.1.6 or later.  Writes a correct 'time' value
 995      * as well as compatible values for other fields.  This is a
 996      * transitional format.
 997      * </dd>
 998      * </dl>
 999      * When streaming out this class, the most recent format
1000      * and the highest allowable <code>serialVersionOnStream</code>
1001      * is written.
1002      * @serial
1003      * @since 1.1.6
1004      */
1005     private int             serialVersionOnStream = currentSerialVersion;
1006 
1007     // Proclaim serialization compatibility with JDK 1.1
1008     static final long       serialVersionUID = -1807547505821590642L;
1009 
1010     // Mask values for calendar fields
1011     @SuppressWarnings("PointlessBitwiseExpression")
1012     static final int ERA_MASK           = (1 << ERA);
1013     static final int YEAR_MASK          = (1 << YEAR);
1014     static final int MONTH_MASK         = (1 << MONTH);
1015     static final int WEEK_OF_YEAR_MASK  = (1 << WEEK_OF_YEAR);
1016     static final int WEEK_OF_MONTH_MASK = (1 << WEEK_OF_MONTH);
1017     static final int DAY_OF_MONTH_MASK  = (1 << DAY_OF_MONTH);
1018     static final int DATE_MASK          = DAY_OF_MONTH_MASK;
1019     static final int DAY_OF_YEAR_MASK   = (1 << DAY_OF_YEAR);
1020     static final int DAY_OF_WEEK_MASK   = (1 << DAY_OF_WEEK);
1021     static final int DAY_OF_WEEK_IN_MONTH_MASK  = (1 << DAY_OF_WEEK_IN_MONTH);
1022     static final int AM_PM_MASK         = (1 << AM_PM);
1023     static final int HOUR_MASK          = (1 << HOUR);
1024     static final int HOUR_OF_DAY_MASK   = (1 << HOUR_OF_DAY);
1025     static final int MINUTE_MASK        = (1 << MINUTE);
1026     static final int SECOND_MASK        = (1 << SECOND);
1027     static final int MILLISECOND_MASK   = (1 << MILLISECOND);
1028     static final int ZONE_OFFSET_MASK   = (1 << ZONE_OFFSET);
1029     static final int DST_OFFSET_MASK    = (1 << DST_OFFSET);
1030 
1031     /**
1032      * {@code Calendar.Builder} is used for creating a {@code Calendar} from
1033      * various date-time parameters.
1034      *
1035      * <p>There are two ways to set a {@code Calendar} to a date-time value. One
1036      * is to set the instant parameter to a millisecond offset from the <a
1037      * href="Calendar.html#Epoch">Epoch</a>. The other is to set individual
1038      * field parameters, such as {@link Calendar#YEAR YEAR}, to their desired
1039      * values. These two ways can't be mixed. Trying to set both the instant and
1040      * individual fields will cause an {@link IllegalStateException} to be
1041      * thrown. However, it is permitted to override previous values of the
1042      * instant or field parameters.
1043      *
1044      * <p>If no enough field parameters are given for determining date and/or
1045      * time, calendar specific default values are used when building a
1046      * {@code Calendar}. For example, if the {@link Calendar#YEAR YEAR} value
1047      * isn't given for the Gregorian calendar, 1970 will be used. If there are
1048      * any conflicts among field parameters, the <a
1049      * href="Calendar.html#resolution"> resolution rules</a> are applied.
1050      * Therefore, the order of field setting matters.
1051      *
1052      * <p>In addition to the date-time parameters,
1053      * the {@linkplain #setLocale(Locale) locale},
1054      * {@linkplain #setTimeZone(TimeZone) time zone},
1055      * {@linkplain #setWeekDefinition(int, int) week definition}, and
1056      * {@linkplain #setLenient(boolean) leniency mode} parameters can be set.
1057      *
1058      * <p><b>Examples</b>
1059      * <p>The following are sample usages. Sample code assumes that the
1060      * {@code Calendar} constants are statically imported.
1061      *
1062      * <p>The following code produces a {@code Calendar} with date 2012-12-31
1063      * (Gregorian) because Monday is the first day of a week with the <a
1064      * href="GregorianCalendar.html#iso8601_compatible_setting"> ISO 8601
1065      * compatible week parameters</a>.
1066      * <pre>
1067      *   Calendar cal = new Calendar.Builder().setCalendarType("iso8601")
1068      *                        .setWeekDate(2013, 1, MONDAY).build();</pre>
1069      * <p>The following code produces a Japanese {@code Calendar} with date
1070      * 1989-01-08 (Gregorian), assuming that the default {@link Calendar#ERA ERA}
1071      * is <em>Heisei</em> that started on that day.
1072      * <pre>
1073      *   Calendar cal = new Calendar.Builder().setCalendarType("japanese")
1074      *                        .setFields(YEAR, 1, DAY_OF_YEAR, 1).build();</pre>
1075      *
1076      * @since 1.8
1077      * @see Calendar#getInstance(TimeZone, Locale)
1078      * @see Calendar#fields
1079      */
1080     public static class Builder {
1081         private static final int NFIELDS = FIELD_COUNT + 1; // +1 for WEEK_YEAR
1082         private static final int WEEK_YEAR = FIELD_COUNT;
1083 
1084         private long instant;
1085         // Calendar.stamp[] (lower half) and Calendar.fields[] (upper half) combined
1086         private int[] fields;
1087         // Pseudo timestamp starting from MINIMUM_USER_STAMP.
1088         // (COMPUTED is used to indicate that the instant has been set.)
1089         private int nextStamp;
1090         // maxFieldIndex keeps the max index of fields which have been set.
1091         // (WEEK_YEAR is never included.)
1092         private int maxFieldIndex;
1093         private String type;
1094         private TimeZone zone;
1095         private boolean lenient = true;
1096         private Locale locale;
1097         private int firstDayOfWeek, minimalDaysInFirstWeek;
1098 
1099         /**
1100          * Constructs a {@code Calendar.Builder}.
1101          */
1102         public Builder() {
1103         }
1104 
1105         /**
1106          * Sets the instant parameter to the given {@code instant} value that is
1107          * a millisecond offset from <a href="Calendar.html#Epoch">the
1108          * Epoch</a>.
1109          *
1110          * @param instant a millisecond offset from the Epoch
1111          * @return this {@code Calendar.Builder}
1112          * @throws IllegalStateException if any of the field parameters have
1113          *                               already been set
1114          * @see Calendar#setTime(Date)
1115          * @see Calendar#setTimeInMillis(long)
1116          * @see Calendar#time
1117          */
1118         public Builder setInstant(long instant) {
1119             if (fields != null) {
1120                 throw new IllegalStateException();
1121             }
1122             this.instant = instant;
1123             nextStamp = COMPUTED;
1124             return this;
1125         }
1126 
1127         /**
1128          * Sets the instant parameter to the {@code instant} value given by a
1129          * {@link Date}. This method is equivalent to a call to
1130          * {@link #setInstant(long) setInstant(instant.getTime())}.
1131          *
1132          * @param instant a {@code Date} representing a millisecond offset from
1133          *                the Epoch
1134          * @return this {@code Calendar.Builder}
1135          * @throws NullPointerException  if {@code instant} is {@code null}
1136          * @throws IllegalStateException if any of the field parameters have
1137          *                               already been set
1138          * @see Calendar#setTime(Date)
1139          * @see Calendar#setTimeInMillis(long)
1140          * @see Calendar#time
1141          */
1142         public Builder setInstant(Date instant) {
1143             return setInstant(instant.getTime()); // NPE if instant == null
1144         }
1145 
1146         /**
1147          * Sets the {@code field} parameter to the given {@code value}.
1148          * {@code field} is an index to the {@link Calendar#fields}, such as
1149          * {@link Calendar#DAY_OF_MONTH DAY_OF_MONTH}. Field value validation is
1150          * not performed in this method. Any out of range values are either
1151          * normalized in lenient mode or detected as an invalid value in
1152          * non-lenient mode when building a {@code Calendar}.
1153          *
1154          * @param field an index to the {@code Calendar} fields
1155          * @param value the field value
1156          * @return this {@code Calendar.Builder}
1157          * @throws IllegalArgumentException if {@code field} is invalid
1158          * @throws IllegalStateException if the instant value has already been set,
1159          *                      or if fields have been set too many
1160          *                      (approximately {@link Integer#MAX_VALUE}) times.
1161          * @see Calendar#set(int, int)
1162          */
1163         public Builder set(int field, int value) {
1164             // Note: WEEK_YEAR can't be set with this method.
1165             if (field < 0 || field >= FIELD_COUNT) {
1166                 throw new IllegalArgumentException("field is invalid");
1167             }
1168             if (isInstantSet()) {
1169                 throw new IllegalStateException("instant has been set");
1170             }
1171             allocateFields();
1172             internalSet(field, value);
1173             return this;
1174         }
1175 
1176         /**
1177          * Sets field parameters to their values given by
1178          * {@code fieldValuePairs} that are pairs of a field and its value.
1179          * For example,
1180          * <pre>
1181          *   setFields(Calendar.YEAR, 2013,
1182          *             Calendar.MONTH, Calendar.DECEMBER,
1183          *             Calendar.DAY_OF_MONTH, 23);</pre>
1184          * is equivalent to the sequence of the following
1185          * {@link #set(int, int) set} calls:
1186          * <pre>
1187          *   set(Calendar.YEAR, 2013)
1188          *   .set(Calendar.MONTH, Calendar.DECEMBER)
1189          *   .set(Calendar.DAY_OF_MONTH, 23);</pre>
1190          *
1191          * @param fieldValuePairs field-value pairs
1192          * @return this {@code Calendar.Builder}
1193          * @throws NullPointerException if {@code fieldValuePairs} is {@code null}
1194          * @throws IllegalArgumentException if any of fields are invalid,
1195          *             or if {@code fieldValuePairs.length} is an odd number.
1196          * @throws IllegalStateException    if the instant value has been set,
1197          *             or if fields have been set too many (approximately
1198          *             {@link Integer#MAX_VALUE}) times.
1199          */
1200         public Builder setFields(int... fieldValuePairs) {
1201             int len = fieldValuePairs.length;
1202             if ((len % 2) != 0) {
1203                 throw new IllegalArgumentException();
1204             }
1205             if (isInstantSet()) {
1206                 throw new IllegalStateException("instant has been set");
1207             }
1208             if ((nextStamp + len / 2) < 0) {
1209                 throw new IllegalStateException("stamp counter overflow");
1210             }
1211             allocateFields();
1212             for (int i = 0; i < len; ) {
1213                 int field = fieldValuePairs[i++];
1214                 // Note: WEEK_YEAR can't be set with this method.
1215                 if (field < 0 || field >= FIELD_COUNT) {
1216                     throw new IllegalArgumentException("field is invalid");
1217                 }
1218                 internalSet(field, fieldValuePairs[i++]);
1219             }
1220             return this;
1221         }
1222 
1223         /**
1224          * Sets the date field parameters to the values given by {@code year},
1225          * {@code month}, and {@code dayOfMonth}. This method is equivalent to
1226          * a call to:
1227          * <pre>
1228          *   setFields(Calendar.YEAR, year,
1229          *             Calendar.MONTH, month,
1230          *             Calendar.DAY_OF_MONTH, dayOfMonth);</pre>
1231          *
1232          * @param year       the {@link Calendar#YEAR YEAR} value
1233          * @param month      the {@link Calendar#MONTH MONTH} value
1234          *                   (the month numbering is <em>0-based</em>).
1235          * @param dayOfMonth the {@link Calendar#DAY_OF_MONTH DAY_OF_MONTH} value
1236          * @return this {@code Calendar.Builder}
1237          */
1238         public Builder setDate(int year, int month, int dayOfMonth) {
1239             return setFields(YEAR, year, MONTH, month, DAY_OF_MONTH, dayOfMonth);
1240         }
1241 
1242         /**
1243          * Sets the time of day field parameters to the values given by
1244          * {@code hourOfDay}, {@code minute}, and {@code second}. This method is
1245          * equivalent to a call to:
1246          * <pre>
1247          *   setTimeOfDay(hourOfDay, minute, second, 0);</pre>
1248          *
1249          * @param hourOfDay the {@link Calendar#HOUR_OF_DAY HOUR_OF_DAY} value
1250          *                  (24-hour clock)
1251          * @param minute    the {@link Calendar#MINUTE MINUTE} value
1252          * @param second    the {@link Calendar#SECOND SECOND} value
1253          * @return this {@code Calendar.Builder}
1254          */
1255         public Builder setTimeOfDay(int hourOfDay, int minute, int second) {
1256             return setTimeOfDay(hourOfDay, minute, second, 0);
1257         }
1258 
1259         /**
1260          * Sets the time of day field parameters to the values given by
1261          * {@code hourOfDay}, {@code minute}, {@code second}, and
1262          * {@code millis}. This method is equivalent to a call to:
1263          * <pre>
1264          *   setFields(Calendar.HOUR_OF_DAY, hourOfDay,
1265          *             Calendar.MINUTE, minute,
1266          *             Calendar.SECOND, second,
1267          *             Calendar.MILLISECOND, millis);</pre>
1268          *
1269          * @param hourOfDay the {@link Calendar#HOUR_OF_DAY HOUR_OF_DAY} value
1270          *                  (24-hour clock)
1271          * @param minute    the {@link Calendar#MINUTE MINUTE} value
1272          * @param second    the {@link Calendar#SECOND SECOND} value
1273          * @param millis    the {@link Calendar#MILLISECOND MILLISECOND} value
1274          * @return this {@code Calendar.Builder}
1275          */
1276         public Builder setTimeOfDay(int hourOfDay, int minute, int second, int millis) {
1277             return setFields(HOUR_OF_DAY, hourOfDay, MINUTE, minute,
1278                              SECOND, second, MILLISECOND, millis);
1279         }
1280 
1281         /**
1282          * Sets the week-based date parameters to the values with the given
1283          * date specifiers - week year, week of year, and day of week.
1284          *
1285          * <p>If the specified calendar doesn't support week dates, the
1286          * {@link #build() build} method will throw an {@link IllegalArgumentException}.
1287          *
1288          * @param weekYear   the week year
1289          * @param weekOfYear the week number based on {@code weekYear}
1290          * @param dayOfWeek  the day of week value: one of the constants
1291          *     for the {@link Calendar#DAY_OF_WEEK DAY_OF_WEEK} field:
1292          *     {@link Calendar#SUNDAY SUNDAY}, ..., {@link Calendar#SATURDAY SATURDAY}.
1293          * @return this {@code Calendar.Builder}
1294          * @see Calendar#setWeekDate(int, int, int)
1295          * @see Calendar#isWeekDateSupported()
1296          */
1297         public Builder setWeekDate(int weekYear, int weekOfYear, int dayOfWeek) {
1298             allocateFields();
1299             internalSet(WEEK_YEAR, weekYear);
1300             internalSet(WEEK_OF_YEAR, weekOfYear);
1301             internalSet(DAY_OF_WEEK, dayOfWeek);
1302             return this;
1303         }
1304 
1305         /**
1306          * Sets the time zone parameter to the given {@code zone}. If no time
1307          * zone parameter is given to this {@code Calendar.Builder}, the
1308          * {@linkplain TimeZone#getDefault() default
1309          * <code>TimeZone</code>} will be used in the {@link #build() build}
1310          * method.
1311          *
1312          * @param zone the {@link TimeZone}
1313          * @return this {@code Calendar.Builder}
1314          * @throws NullPointerException if {@code zone} is {@code null}
1315          * @see Calendar#setTimeZone(TimeZone)
1316          */
1317         public Builder setTimeZone(TimeZone zone) {
1318             if (zone == null) {
1319                 throw new NullPointerException();
1320             }
1321             this.zone = zone;
1322             return this;
1323         }
1324 
1325         /**
1326          * Sets the lenient mode parameter to the value given by {@code lenient}.
1327          * If no lenient parameter is given to this {@code Calendar.Builder},
1328          * lenient mode will be used in the {@link #build() build} method.
1329          *
1330          * @param lenient {@code true} for lenient mode;
1331          *                {@code false} for non-lenient mode
1332          * @return this {@code Calendar.Builder}
1333          * @see Calendar#setLenient(boolean)
1334          */
1335         public Builder setLenient(boolean lenient) {
1336             this.lenient = lenient;
1337             return this;
1338         }
1339 
1340         /**
1341          * Sets the calendar type parameter to the given {@code type}. The
1342          * calendar type given by this method has precedence over any explicit
1343          * or implicit calendar type given by the
1344          * {@linkplain #setLocale(Locale) locale}.
1345          *
1346          * <p>In addition to the available calendar types returned by the
1347          * {@link Calendar#getAvailableCalendarTypes() Calendar.getAvailableCalendarTypes}
1348          * method, {@code "gregorian"} and {@code "iso8601"} as aliases of
1349          * {@code "gregory"} can be used with this method.
1350          *
1351          * @param type the calendar type
1352          * @return this {@code Calendar.Builder}
1353          * @throws NullPointerException if {@code type} is {@code null}
1354          * @throws IllegalArgumentException if {@code type} is unknown
1355          * @throws IllegalStateException if another calendar type has already been set
1356          * @see Calendar#getCalendarType()
1357          * @see Calendar#getAvailableCalendarTypes()
1358          */
1359         public Builder setCalendarType(String type) {
1360             if (type.equals("gregorian")) { // NPE if type == null
1361                 type = "gregory";
1362             }
1363             if (!Calendar.getAvailableCalendarTypes().contains(type)
1364                     && !type.equals("iso8601")) {
1365                 throw new IllegalArgumentException("unknown calendar type: " + type);
1366             }
1367             if (this.type == null) {
1368                 this.type = type;
1369             } else {
1370                 if (!this.type.equals(type)) {
1371                     throw new IllegalStateException("calendar type override");
1372                 }
1373             }
1374             return this;
1375         }
1376 
1377         /**
1378          * Sets the locale parameter to the given {@code locale}. If no locale
1379          * is given to this {@code Calendar.Builder}, the {@linkplain
1380          * Locale#getDefault(Locale.Category) default <code>Locale</code>}
1381          * for {@link Locale.Category#FORMAT} will be used.
1382          *
1383          * <p>If no calendar type is explicitly given by a call to the
1384          * {@link #setCalendarType(String) setCalendarType} method,
1385          * the {@code Locale} value is used to determine what type of
1386          * {@code Calendar} to be built.
1387          *
1388          * <p>If no week definition parameters are explicitly given by a call to
1389          * the {@link #setWeekDefinition(int,int) setWeekDefinition} method, the
1390          * {@code Locale}'s default values are used.
1391          *
1392          * @param locale the {@link Locale}
1393          * @throws NullPointerException if {@code locale} is {@code null}
1394          * @return this {@code Calendar.Builder}
1395          * @see Calendar#getInstance(Locale)
1396          */
1397         public Builder setLocale(Locale locale) {
1398             if (locale == null) {
1399                 throw new NullPointerException();
1400             }
1401             this.locale = locale;
1402             return this;
1403         }
1404 
1405         /**
1406          * Sets the week definition parameters to the values given by
1407          * {@code firstDayOfWeek} and {@code minimalDaysInFirstWeek} that are
1408          * used to determine the <a href="Calendar.html#first_week">first
1409          * week</a> of a year. The parameters given by this method have
1410          * precedence over the default values given by the
1411          * {@linkplain #setLocale(Locale) locale}.
1412          *
1413          * @param firstDayOfWeek the first day of a week; one of
1414          *                       {@link Calendar#SUNDAY} to {@link Calendar#SATURDAY}
1415          * @param minimalDaysInFirstWeek the minimal number of days in the first
1416          *                               week (1..7)
1417          * @return this {@code Calendar.Builder}
1418          * @throws IllegalArgumentException if {@code firstDayOfWeek} or
1419          *                                  {@code minimalDaysInFirstWeek} is invalid
1420          * @see Calendar#getFirstDayOfWeek()
1421          * @see Calendar#getMinimalDaysInFirstWeek()
1422          */
1423         public Builder setWeekDefinition(int firstDayOfWeek, int minimalDaysInFirstWeek) {
1424             if (!isValidWeekParameter(firstDayOfWeek)
1425                     || !isValidWeekParameter(minimalDaysInFirstWeek)) {
1426                 throw new IllegalArgumentException();
1427             }
1428             this.firstDayOfWeek = firstDayOfWeek;
1429             this.minimalDaysInFirstWeek = minimalDaysInFirstWeek;
1430             return this;
1431         }
1432 
1433         /**
1434          * Returns a {@code Calendar} built from the parameters set by the
1435          * setter methods. The calendar type given by the {@link #setCalendarType(String)
1436          * setCalendarType} method or the {@linkplain #setLocale(Locale) locale} is
1437          * used to determine what {@code Calendar} to be created. If no explicit
1438          * calendar type is given, the locale's default calendar is created.
1439          *
1440          * <p>If the calendar type is {@code "iso8601"}, the
1441          * {@linkplain GregorianCalendar#setGregorianChange(Date) Gregorian change date}
1442          * of a {@link GregorianCalendar} is set to {@code Date(Long.MIN_VALUE)}
1443          * to be the <em>proleptic</em> Gregorian calendar. Its week definition
1444          * parameters are also set to be <a
1445          * href="GregorianCalendar.html#iso8601_compatible_setting">compatible
1446          * with the ISO 8601 standard</a>. Note that the
1447          * {@link GregorianCalendar#getCalendarType() getCalendarType} method of
1448          * a {@code GregorianCalendar} created with {@code "iso8601"} returns
1449          * {@code "gregory"}.
1450          *
1451          * <p>The default values are used for locale and time zone if these
1452          * parameters haven't been given explicitly.
1453          *
1454          * <p>Any out of range field values are either normalized in lenient
1455          * mode or detected as an invalid value in non-lenient mode.
1456          *
1457          * @return a {@code Calendar} built with parameters of this {@code
1458          *         Calendar.Builder}
1459          * @throws IllegalArgumentException if the calendar type is unknown, or
1460          *             if any invalid field values are given in non-lenient mode, or
1461          *             if a week date is given for the calendar type that doesn't
1462          *             support week dates.
1463          * @see Calendar#getInstance(TimeZone, Locale)
1464          * @see Locale#getDefault(Locale.Category)
1465          * @see TimeZone#getDefault()
1466          */
1467         public Calendar build() {
1468             if (locale == null) {
1469                 locale = Locale.getDefault();
1470             }
1471             if (zone == null) {
1472                 zone = defaultTimeZone(locale);
1473             }
1474             Calendar cal;
1475             if (type == null) {
1476                 type = locale.getUnicodeLocaleType("ca");
1477             }
1478             if (type == null) {
1479                 if (locale.getCountry() == "TH"
1480                     && locale.getLanguage() == "th") {
1481                     type = "buddhist";
1482                 } else {
1483                     type = "gregory";
1484                 }
1485             }
1486             switch (type) {
1487             case "gregory":
1488                 cal = new GregorianCalendar(zone, locale, true);
1489                 break;
1490             case "iso8601":
1491                 GregorianCalendar gcal = new GregorianCalendar(zone, locale, true);
1492                 // make gcal a proleptic Gregorian
1493                 gcal.setGregorianChange(new Date(Long.MIN_VALUE));
1494                 // and week definition to be compatible with ISO 8601
1495                 setWeekDefinition(MONDAY, 4);
1496                 cal = gcal;
1497                 break;
1498             case "buddhist":
1499                 cal = new BuddhistCalendar(zone, locale);
1500                 cal.clear();
1501                 break;
1502             case "japanese":
1503                 cal = new JapaneseImperialCalendar(zone, locale, true);
1504                 break;
1505             default:
1506                 throw new IllegalArgumentException("unknown calendar type: " + type);
1507             }
1508             cal.setLenient(lenient);
1509             if (firstDayOfWeek != 0) {
1510                 cal.setFirstDayOfWeek(firstDayOfWeek);
1511                 cal.setMinimalDaysInFirstWeek(minimalDaysInFirstWeek);
1512             }
1513             if (isInstantSet()) {
1514                 cal.setTimeInMillis(instant);
1515                 cal.complete();
1516                 return cal;
1517             }
1518 
1519             if (fields != null) {
1520                 boolean weekDate = isSet(WEEK_YEAR)
1521                                        && fields[WEEK_YEAR] > fields[YEAR];
1522                 if (weekDate && !cal.isWeekDateSupported()) {
1523                     throw new IllegalArgumentException("week date is unsupported by " + type);
1524                 }
1525 
1526                 // Set the fields from the min stamp to the max stamp so that
1527                 // the fields resolution works in the Calendar.
1528                 for (int stamp = MINIMUM_USER_STAMP; stamp < nextStamp; stamp++) {
1529                     for (int index = 0; index <= maxFieldIndex; index++) {
1530                         if (fields[index] == stamp) {
1531                             cal.set(index, fields[NFIELDS + index]);
1532                             break;
1533                         }
1534                     }
1535                 }
1536 
1537                 if (weekDate) {
1538                     int weekOfYear = isSet(WEEK_OF_YEAR) ? fields[NFIELDS + WEEK_OF_YEAR] : 1;
1539                     int dayOfWeek = isSet(DAY_OF_WEEK)
1540                                     ? fields[NFIELDS + DAY_OF_WEEK] : cal.getFirstDayOfWeek();
1541                     cal.setWeekDate(fields[NFIELDS + WEEK_YEAR], weekOfYear, dayOfWeek);
1542                 }
1543                 cal.complete();
1544             }
1545 
1546             return cal;
1547         }
1548 
1549         private void allocateFields() {
1550             if (fields == null) {
1551                 fields = new int[NFIELDS * 2];
1552                 nextStamp = MINIMUM_USER_STAMP;
1553                 maxFieldIndex = -1;
1554             }
1555         }
1556 
1557         private void internalSet(int field, int value) {
1558             fields[field] = nextStamp++;
1559             if (nextStamp < 0) {
1560                 throw new IllegalStateException("stamp counter overflow");
1561             }
1562             fields[NFIELDS + field] = value;
1563             if (field > maxFieldIndex && field < WEEK_YEAR) {
1564                 maxFieldIndex = field;
1565             }
1566         }
1567 
1568         private boolean isInstantSet() {
1569             return nextStamp == COMPUTED;
1570         }
1571 
1572         private boolean isSet(int index) {
1573             return fields != null && fields[index] > UNSET;
1574         }
1575 
1576         private boolean isValidWeekParameter(int value) {
1577             return value > 0 && value <= 7;
1578         }
1579     }
1580 
1581     /**
1582      * Constructs a Calendar with the default time zone
1583      * and the default {@link java.util.Locale.Category#FORMAT FORMAT}
1584      * locale.
1585      * @see     TimeZone#getDefault
1586      */
1587     protected Calendar()
1588     {
1589         this(TimeZone.getDefaultRef(), Locale.getDefault(Locale.Category.FORMAT));
1590         sharedZone = true;
1591     }
1592 
1593     /**
1594      * Constructs a calendar with the specified time zone and locale.
1595      *
1596      * @param zone the time zone to use
1597      * @param aLocale the locale for the week data
1598      */
1599     protected Calendar(TimeZone zone, Locale aLocale)
1600     {
1601         fields = new int[FIELD_COUNT];
1602         isSet = new boolean[FIELD_COUNT];
1603         stamp = new int[FIELD_COUNT];
1604 
1605         this.zone = zone;
1606         setWeekCountData(aLocale);
1607     }
1608 
1609     /**
1610      * Gets a calendar using the default time zone and locale. The
1611      * <code>Calendar</code> returned is based on the current time
1612      * in the default time zone with the default
1613      * {@link Locale.Category#FORMAT FORMAT} locale.
1614      *
1615      * @return a Calendar.
1616      */
1617     public static Calendar getInstance()
1618     {
1619         Locale aLocale = Locale.getDefault(Locale.Category.FORMAT);
1620         return createCalendar(defaultTimeZone(aLocale), aLocale);
1621     }
1622 
1623     /**
1624      * Gets a calendar using the specified time zone and default locale.
1625      * The <code>Calendar</code> returned is based on the current time
1626      * in the given time zone with the default
1627      * {@link Locale.Category#FORMAT FORMAT} locale.
1628      *
1629      * @param zone the time zone to use
1630      * @return a Calendar.
1631      */
1632     public static Calendar getInstance(TimeZone zone)
1633     {
1634         return createCalendar(zone, Locale.getDefault(Locale.Category.FORMAT));
1635     }
1636 
1637     /**
1638      * Gets a calendar using the default time zone and specified locale.
1639      * The <code>Calendar</code> returned is based on the current time
1640      * in the default time zone with the given locale.
1641      *
1642      * @param aLocale the locale for the week data
1643      * @return a Calendar.
1644      */
1645     public static Calendar getInstance(Locale aLocale)
1646     {
1647         return createCalendar(defaultTimeZone(aLocale), aLocale);
1648     }
1649 
1650     /**
1651      * Gets a calendar with the specified time zone and locale.
1652      * The <code>Calendar</code> returned is based on the current time
1653      * in the given time zone with the given locale.
1654      *
1655      * @param zone the time zone to use
1656      * @param aLocale the locale for the week data
1657      * @return a Calendar.
1658      */
1659     public static Calendar getInstance(TimeZone zone,
1660                                        Locale aLocale)
1661     {
1662         return createCalendar(zone, aLocale);
1663     }
1664 
1665     private static TimeZone defaultTimeZone(Locale l) {
1666         TimeZone defaultTZ = TimeZone.getDefault();
1667         String shortTZID = l.getUnicodeLocaleType("tz");
1668         return shortTZID != null ? 
1669             TimeZoneNameUtility.convertLDMLShortID(shortTZID)
1670                 .map(TimeZone::getTimeZone)
1671                 .orElse(defaultTZ) :
1672             defaultTZ;
1673     }
1674 
1675     private static Calendar createCalendar(TimeZone zone,
1676                                            Locale aLocale)
1677     {
1678         CalendarProvider provider =
1679             LocaleProviderAdapter.getAdapter(CalendarProvider.class, aLocale)
1680                                  .getCalendarProvider();
1681         if (provider != null) {
1682             try {
1683                 return provider.getInstance(zone, aLocale);
1684             } catch (IllegalArgumentException iae) {
1685                 // fall back to the default instantiation
1686             }
1687         }
1688 
1689         Calendar cal = null;
1690 
1691         if (aLocale.hasExtensions()) {
1692             String caltype = aLocale.getUnicodeLocaleType("ca");
1693             if (caltype != null) {
1694                 switch (caltype) {
1695                 case "buddhist":
1696                 cal = new BuddhistCalendar(zone, aLocale);
1697                     break;
1698                 case "japanese":
1699                     cal = new JapaneseImperialCalendar(zone, aLocale);
1700                     break;
1701                 case "gregory":
1702                     cal = new GregorianCalendar(zone, aLocale);
1703                     break;
1704                 }
1705             }
1706         }
1707         if (cal == null) {
1708             // If no known calendar type is explicitly specified,
1709             // perform the traditional way to create a Calendar:
1710             // create a BuddhistCalendar for th_TH locale,
1711             // a JapaneseImperialCalendar for ja_JP_JP locale, or
1712             // a GregorianCalendar for any other locales.
1713             // NOTE: The language, country and variant strings are interned.
1714             if (aLocale.getLanguage() == "th" && aLocale.getCountry() == "TH") {
1715                 cal = new BuddhistCalendar(zone, aLocale);
1716             } else if (aLocale.getVariant() == "JP" && aLocale.getLanguage() == "ja"
1717                        && aLocale.getCountry() == "JP") {
1718                 cal = new JapaneseImperialCalendar(zone, aLocale);
1719             } else {
1720                 cal = new GregorianCalendar(zone, aLocale);
1721             }
1722         }
1723         return cal;
1724     }
1725 
1726     /**
1727      * Returns an array of all locales for which the <code>getInstance</code>
1728      * methods of this class can return localized instances.
1729      * The array returned must contain at least a <code>Locale</code>
1730      * instance equal to {@link java.util.Locale#US Locale.US}.
1731      *
1732      * @return An array of locales for which localized
1733      *         <code>Calendar</code> instances are available.
1734      */
1735     public static synchronized Locale[] getAvailableLocales()
1736     {
1737         return DateFormat.getAvailableLocales();
1738     }
1739 
1740     /**
1741      * Converts the current calendar field values in {@link #fields fields[]}
1742      * to the millisecond time value
1743      * {@link #time}.
1744      *
1745      * @see #complete()
1746      * @see #computeFields()
1747      */
1748     protected abstract void computeTime();
1749 
1750     /**
1751      * Converts the current millisecond time value {@link #time}
1752      * to calendar field values in {@link #fields fields[]}.
1753      * This allows you to sync up the calendar field values with
1754      * a new time that is set for the calendar.  The time is <em>not</em>
1755      * recomputed first; to recompute the time, then the fields, call the
1756      * {@link #complete()} method.
1757      *
1758      * @see #computeTime()
1759      */
1760     protected abstract void computeFields();
1761 
1762     /**
1763      * Returns a <code>Date</code> object representing this
1764      * <code>Calendar</code>'s time value (millisecond offset from the <a
1765      * href="#Epoch">Epoch</a>").
1766      *
1767      * @return a <code>Date</code> representing the time value.
1768      * @see #setTime(Date)
1769      * @see #getTimeInMillis()
1770      */
1771     public final Date getTime() {
1772         return new Date(getTimeInMillis());
1773     }
1774 
1775     /**
1776      * Sets this Calendar's time with the given <code>Date</code>.
1777      * <p>
1778      * Note: Calling <code>setTime()</code> with
1779      * <code>Date(Long.MAX_VALUE)</code> or <code>Date(Long.MIN_VALUE)</code>
1780      * may yield incorrect field values from <code>get()</code>.
1781      *
1782      * @param date the given Date.
1783      * @see #getTime()
1784      * @see #setTimeInMillis(long)
1785      */
1786     public final void setTime(Date date) {
1787         setTimeInMillis(date.getTime());
1788     }
1789 
1790     /**
1791      * Returns this Calendar's time value in milliseconds.
1792      *
1793      * @return the current time as UTC milliseconds from the epoch.
1794      * @see #getTime()
1795      * @see #setTimeInMillis(long)
1796      */
1797     public long getTimeInMillis() {
1798         if (!isTimeSet) {
1799             updateTime();
1800         }
1801         return time;
1802     }
1803 
1804     /**
1805      * Sets this Calendar's current time from the given long value.
1806      *
1807      * @param millis the new time in UTC milliseconds from the epoch.
1808      * @see #setTime(Date)
1809      * @see #getTimeInMillis()
1810      */
1811     public void setTimeInMillis(long millis) {
1812         // If we don't need to recalculate the calendar field values,
1813         // do nothing.
1814         if (time == millis && isTimeSet && areFieldsSet && areAllFieldsSet
1815             && (zone instanceof ZoneInfo) && !((ZoneInfo)zone).isDirty()) {
1816             return;
1817         }
1818         time = millis;
1819         isTimeSet = true;
1820         areFieldsSet = false;
1821         computeFields();
1822         areAllFieldsSet = areFieldsSet = true;
1823     }
1824 
1825     /**
1826      * Returns the value of the given calendar field. In lenient mode,
1827      * all calendar fields are normalized. In non-lenient mode, all
1828      * calendar fields are validated and this method throws an
1829      * exception if any calendar fields have out-of-range values. The
1830      * normalization and validation are handled by the
1831      * {@link #complete()} method, which process is calendar
1832      * system dependent.
1833      *
1834      * @param field the given calendar field.
1835      * @return the value for the given calendar field.
1836      * @throws ArrayIndexOutOfBoundsException if the specified field is out of range
1837      *             (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
1838      * @see #set(int,int)
1839      * @see #complete()
1840      */
1841     public int get(int field)
1842     {
1843         complete();
1844         return internalGet(field);
1845     }
1846 
1847     /**
1848      * Returns the value of the given calendar field. This method does
1849      * not involve normalization or validation of the field value.
1850      *
1851      * @param field the given calendar field.
1852      * @return the value for the given calendar field.
1853      * @see #get(int)
1854      */
1855     protected final int internalGet(int field)
1856     {
1857         return fields[field];
1858     }
1859 
1860     /**
1861      * Sets the value of the given calendar field. This method does
1862      * not affect any setting state of the field in this
1863      * <code>Calendar</code> instance.
1864      *
1865      * @throws IndexOutOfBoundsException if the specified field is out of range
1866      *             (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
1867      * @see #areFieldsSet
1868      * @see #isTimeSet
1869      * @see #areAllFieldsSet
1870      * @see #set(int,int)
1871      */
1872     final void internalSet(int field, int value)
1873     {
1874         fields[field] = value;
1875     }
1876 
1877     /**
1878      * Sets the given calendar field to the given value. The value is not
1879      * interpreted by this method regardless of the leniency mode.
1880      *
1881      * @param field the given calendar field.
1882      * @param value the value to be set for the given calendar field.
1883      * @throws ArrayIndexOutOfBoundsException if the specified field is out of range
1884      *             (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
1885      * in non-lenient mode.
1886      * @see #set(int,int,int)
1887      * @see #set(int,int,int,int,int)
1888      * @see #set(int,int,int,int,int,int)
1889      * @see #get(int)
1890      */
1891     public void set(int field, int value)
1892     {
1893         // If the fields are partially normalized, calculate all the
1894         // fields before changing any fields.
1895         if (areFieldsSet && !areAllFieldsSet) {
1896             computeFields();
1897         }
1898         internalSet(field, value);
1899         isTimeSet = false;
1900         areFieldsSet = false;
1901         isSet[field] = true;
1902         stamp[field] = nextStamp++;
1903         if (nextStamp == Integer.MAX_VALUE) {
1904             adjustStamp();
1905         }
1906     }
1907 
1908     /**
1909      * Sets the values for the calendar fields <code>YEAR</code>,
1910      * <code>MONTH</code>, and <code>DAY_OF_MONTH</code>.
1911      * Previous values of other calendar fields are retained.  If this is not desired,
1912      * call {@link #clear()} first.
1913      *
1914      * @param year the value used to set the <code>YEAR</code> calendar field.
1915      * @param month the value used to set the <code>MONTH</code> calendar field.
1916      * Month value is 0-based. e.g., 0 for January.
1917      * @param date the value used to set the <code>DAY_OF_MONTH</code> calendar field.
1918      * @see #set(int,int)
1919      * @see #set(int,int,int,int,int)
1920      * @see #set(int,int,int,int,int,int)
1921      */
1922     public final void set(int year, int month, int date)
1923     {
1924         set(YEAR, year);
1925         set(MONTH, month);
1926         set(DATE, date);
1927     }
1928 
1929     /**
1930      * Sets the values for the calendar fields <code>YEAR</code>,
1931      * <code>MONTH</code>, <code>DAY_OF_MONTH</code>,
1932      * <code>HOUR_OF_DAY</code>, and <code>MINUTE</code>.
1933      * Previous values of other fields are retained.  If this is not desired,
1934      * call {@link #clear()} first.
1935      *
1936      * @param year the value used to set the <code>YEAR</code> calendar field.
1937      * @param month the value used to set the <code>MONTH</code> calendar field.
1938      * Month value is 0-based. e.g., 0 for January.
1939      * @param date the value used to set the <code>DAY_OF_MONTH</code> calendar field.
1940      * @param hourOfDay the value used to set the <code>HOUR_OF_DAY</code> calendar field.
1941      * @param minute the value used to set the <code>MINUTE</code> calendar field.
1942      * @see #set(int,int)
1943      * @see #set(int,int,int)
1944      * @see #set(int,int,int,int,int,int)
1945      */
1946     public final void set(int year, int month, int date, int hourOfDay, int minute)
1947     {
1948         set(YEAR, year);
1949         set(MONTH, month);
1950         set(DATE, date);
1951         set(HOUR_OF_DAY, hourOfDay);
1952         set(MINUTE, minute);
1953     }
1954 
1955     /**
1956      * Sets the values for the fields <code>YEAR</code>, <code>MONTH</code>,
1957      * <code>DAY_OF_MONTH</code>, <code>HOUR_OF_DAY</code>, <code>MINUTE</code>, and
1958      * <code>SECOND</code>.
1959      * Previous values of other fields are retained.  If this is not desired,
1960      * call {@link #clear()} first.
1961      *
1962      * @param year the value used to set the <code>YEAR</code> calendar field.
1963      * @param month the value used to set the <code>MONTH</code> calendar field.
1964      * Month value is 0-based. e.g., 0 for January.
1965      * @param date the value used to set the <code>DAY_OF_MONTH</code> calendar field.
1966      * @param hourOfDay the value used to set the <code>HOUR_OF_DAY</code> calendar field.
1967      * @param minute the value used to set the <code>MINUTE</code> calendar field.
1968      * @param second the value used to set the <code>SECOND</code> calendar field.
1969      * @see #set(int,int)
1970      * @see #set(int,int,int)
1971      * @see #set(int,int,int,int,int)
1972      */
1973     public final void set(int year, int month, int date, int hourOfDay, int minute,
1974                           int second)
1975     {
1976         set(YEAR, year);
1977         set(MONTH, month);
1978         set(DATE, date);
1979         set(HOUR_OF_DAY, hourOfDay);
1980         set(MINUTE, minute);
1981         set(SECOND, second);
1982     }
1983 
1984     /**
1985      * Sets all the calendar field values and the time value
1986      * (millisecond offset from the <a href="#Epoch">Epoch</a>) of
1987      * this <code>Calendar</code> undefined. This means that {@link
1988      * #isSet(int) isSet()} will return <code>false</code> for all the
1989      * calendar fields, and the date and time calculations will treat
1990      * the fields as if they had never been set. A
1991      * <code>Calendar</code> implementation class may use its specific
1992      * default field values for date/time calculations. For example,
1993      * <code>GregorianCalendar</code> uses 1970 if the
1994      * <code>YEAR</code> field value is undefined.
1995      *
1996      * @see #clear(int)
1997      */
1998     public final void clear()
1999     {
2000         for (int i = 0; i < fields.length; ) {
2001             stamp[i] = fields[i] = 0; // UNSET == 0
2002             isSet[i++] = false;
2003         }
2004         areAllFieldsSet = areFieldsSet = false;
2005         isTimeSet = false;
2006     }
2007 
2008     /**
2009      * Sets the given calendar field value and the time value
2010      * (millisecond offset from the <a href="#Epoch">Epoch</a>) of
2011      * this <code>Calendar</code> undefined. This means that {@link
2012      * #isSet(int) isSet(field)} will return <code>false</code>, and
2013      * the date and time calculations will treat the field as if it
2014      * had never been set. A <code>Calendar</code> implementation
2015      * class may use the field's specific default value for date and
2016      * time calculations.
2017      *
2018      * <p>The {@link #HOUR_OF_DAY}, {@link #HOUR} and {@link #AM_PM}
2019      * fields are handled independently and the <a
2020      * href="#time_resolution">the resolution rule for the time of
2021      * day</a> is applied. Clearing one of the fields doesn't reset
2022      * the hour of day value of this <code>Calendar</code>. Use {@link
2023      * #set(int,int) set(Calendar.HOUR_OF_DAY, 0)} to reset the hour
2024      * value.
2025      *
2026      * @param field the calendar field to be cleared.
2027      * @see #clear()
2028      */
2029     public final void clear(int field)
2030     {
2031         fields[field] = 0;
2032         stamp[field] = UNSET;
2033         isSet[field] = false;
2034 
2035         areAllFieldsSet = areFieldsSet = false;
2036         isTimeSet = false;
2037     }
2038 
2039     /**
2040      * Determines if the given calendar field has a value set,
2041      * including cases that the value has been set by internal fields
2042      * calculations triggered by a <code>get</code> method call.
2043      *
2044      * @param field the calendar field to test
2045      * @return <code>true</code> if the given calendar field has a value set;
2046      * <code>false</code> otherwise.
2047      */
2048     public final boolean isSet(int field)
2049     {
2050         return stamp[field] != UNSET;
2051     }
2052 
2053     /**
2054      * Returns the string representation of the calendar
2055      * <code>field</code> value in the given <code>style</code> and
2056      * <code>locale</code>.  If no string representation is
2057      * applicable, <code>null</code> is returned. This method calls
2058      * {@link Calendar#get(int) get(field)} to get the calendar
2059      * <code>field</code> value if the string representation is
2060      * applicable to the given calendar <code>field</code>.
2061      *
2062      * <p>For example, if this <code>Calendar</code> is a
2063      * <code>GregorianCalendar</code> and its date is 2005-01-01, then
2064      * the string representation of the {@link #MONTH} field would be
2065      * "January" in the long style in an English locale or "Jan" in
2066      * the short style. However, no string representation would be
2067      * available for the {@link #DAY_OF_MONTH} field, and this method
2068      * would return <code>null</code>.
2069      *
2070      * <p>The default implementation supports the calendar fields for
2071      * which a {@link DateFormatSymbols} has names in the given
2072      * <code>locale</code>.
2073      *
2074      * @param field
2075      *        the calendar field for which the string representation
2076      *        is returned
2077      * @param style
2078      *        the style applied to the string representation; one of {@link
2079      *        #SHORT_FORMAT} ({@link #SHORT}), {@link #SHORT_STANDALONE},
2080      *        {@link #LONG_FORMAT} ({@link #LONG}), {@link #LONG_STANDALONE},
2081      *        {@link #NARROW_FORMAT}, or {@link #NARROW_STANDALONE}.
2082      * @param locale
2083      *        the locale for the string representation
2084      *        (any calendar types specified by {@code locale} are ignored)
2085      * @return the string representation of the given
2086      *        {@code field} in the given {@code style}, or
2087      *        {@code null} if no string representation is
2088      *        applicable.
2089      * @exception IllegalArgumentException
2090      *        if {@code field} or {@code style} is invalid,
2091      *        or if this {@code Calendar} is non-lenient and any
2092      *        of the calendar fields have invalid values
2093      * @exception NullPointerException
2094      *        if {@code locale} is null
2095      * @since 1.6
2096      */
2097     public String getDisplayName(int field, int style, Locale locale) {
2098         if (!checkDisplayNameParams(field, style, SHORT, NARROW_FORMAT, locale,
2099                             ERA_MASK|MONTH_MASK|DAY_OF_WEEK_MASK|AM_PM_MASK)) {
2100             return null;
2101         }
2102 
2103         String calendarType = getCalendarType();
2104         int fieldValue = get(field);
2105         // the standalone/narrow styles and short era are supported only through
2106         // CalendarNameProviders.
2107         if (isStandaloneStyle(style) || isNarrowFormatStyle(style) ||
2108             field == ERA && (style & SHORT) == SHORT) {
2109             String val = CalendarDataUtility.retrieveFieldValueName(calendarType,
2110                                                                     field, fieldValue,
2111                                                                     style, locale);
2112             // Perform fallback here to follow the CLDR rules
2113             if (val == null) {
2114                 if (isNarrowFormatStyle(style)) {
2115                     val = CalendarDataUtility.retrieveFieldValueName(calendarType,
2116                                                                      field, fieldValue,
2117                                                                      toStandaloneStyle(style),
2118                                                                      locale);
2119                 } else if (isStandaloneStyle(style)) {
2120                     val = CalendarDataUtility.retrieveFieldValueName(calendarType,
2121                                                                      field, fieldValue,
2122                                                                      getBaseStyle(style),
2123                                                                      locale);
2124                 }
2125             }
2126             return val;
2127         }
2128 
2129         DateFormatSymbols symbols = DateFormatSymbols.getInstance(locale);
2130         String[] strings = getFieldStrings(field, style, symbols);
2131         if (strings != null) {
2132             if (fieldValue < strings.length) {
2133                 return strings[fieldValue];
2134             }
2135         }
2136         return null;
2137     }
2138 
2139     /**
2140      * Returns a {@code Map} containing all names of the calendar
2141      * {@code field} in the given {@code style} and
2142      * {@code locale} and their corresponding field values. For
2143      * example, if this {@code Calendar} is a {@link
2144      * GregorianCalendar}, the returned map would contain "Jan" to
2145      * {@link #JANUARY}, "Feb" to {@link #FEBRUARY}, and so on, in the
2146      * {@linkplain #SHORT short} style in an English locale.
2147      *
2148      * <p>Narrow names may not be unique due to use of single characters,
2149      * such as "S" for Sunday and Saturday. In that case narrow names are not
2150      * included in the returned {@code Map}.
2151      *
2152      * <p>The values of other calendar fields may be taken into
2153      * account to determine a set of display names. For example, if
2154      * this {@code Calendar} is a lunisolar calendar system and
2155      * the year value given by the {@link #YEAR} field has a leap
2156      * month, this method would return month names containing the leap
2157      * month name, and month names are mapped to their values specific
2158      * for the year.
2159      *
2160      * <p>The default implementation supports display names contained in
2161      * a {@link DateFormatSymbols}. For example, if {@code field}
2162      * is {@link #MONTH} and {@code style} is {@link
2163      * #ALL_STYLES}, this method returns a {@code Map} containing
2164      * all strings returned by {@link DateFormatSymbols#getShortMonths()}
2165      * and {@link DateFormatSymbols#getMonths()}.
2166      *
2167      * @param field
2168      *        the calendar field for which the display names are returned
2169      * @param style
2170      *        the style applied to the string representation; one of {@link
2171      *        #SHORT_FORMAT} ({@link #SHORT}), {@link #SHORT_STANDALONE},
2172      *        {@link #LONG_FORMAT} ({@link #LONG}), {@link #LONG_STANDALONE},
2173      *        {@link #NARROW_FORMAT}, or {@link #NARROW_STANDALONE}
2174      * @param locale
2175      *        the locale for the display names
2176      * @return a {@code Map} containing all display names in
2177      *        {@code style} and {@code locale} and their
2178      *        field values, or {@code null} if no display names
2179      *        are defined for {@code field}
2180      * @exception IllegalArgumentException
2181      *        if {@code field} or {@code style} is invalid,
2182      *        or if this {@code Calendar} is non-lenient and any
2183      *        of the calendar fields have invalid values
2184      * @exception NullPointerException
2185      *        if {@code locale} is null
2186      * @since 1.6
2187      */
2188     public Map<String, Integer> getDisplayNames(int field, int style, Locale locale) {
2189         if (!checkDisplayNameParams(field, style, ALL_STYLES, NARROW_FORMAT, locale,
2190                                     ERA_MASK|MONTH_MASK|DAY_OF_WEEK_MASK|AM_PM_MASK)) {
2191             return null;
2192         }
2193 
2194         String calendarType = getCalendarType();
2195         if (style == ALL_STYLES || isStandaloneStyle(style) || isNarrowFormatStyle(style)) {
2196             Map<String, Integer> map;
2197             map = CalendarDataUtility.retrieveFieldValueNames(calendarType, field, style, locale);
2198 
2199             // Perform fallback here to follow the CLDR rules
2200             if (map == null) {
2201                 if (isNarrowFormatStyle(style)) {
2202                     map = CalendarDataUtility.retrieveFieldValueNames(calendarType, field,
2203                                                                       toStandaloneStyle(style), locale);
2204                 } else if (style != ALL_STYLES) {
2205                     map = CalendarDataUtility.retrieveFieldValueNames(calendarType, field,
2206                                                                       getBaseStyle(style), locale);
2207                 }
2208             }
2209             return map;
2210         }
2211 
2212         // SHORT or LONG
2213         return getDisplayNamesImpl(field, style, locale);
2214     }
2215 
2216     private Map<String,Integer> getDisplayNamesImpl(int field, int style, Locale locale) {
2217         DateFormatSymbols symbols = DateFormatSymbols.getInstance(locale);
2218         String[] strings = getFieldStrings(field, style, symbols);
2219         if (strings != null) {
2220             Map<String,Integer> names = new HashMap<>();
2221             for (int i = 0; i < strings.length; i++) {
2222                 if (strings[i].length() == 0) {
2223                     continue;
2224                 }
2225                 names.put(strings[i], i);
2226             }
2227             return names;
2228         }
2229         return null;
2230     }
2231 
2232     boolean checkDisplayNameParams(int field, int style, int minStyle, int maxStyle,
2233                                    Locale locale, int fieldMask) {
2234         int baseStyle = getBaseStyle(style); // Ignore the standalone mask
2235         if (field < 0 || field >= fields.length ||
2236             baseStyle < minStyle || baseStyle > maxStyle || baseStyle == 3) {
2237             throw new IllegalArgumentException();
2238         }
2239         if (locale == null) {
2240             throw new NullPointerException();
2241         }
2242         return isFieldSet(fieldMask, field);
2243     }
2244 
2245     private String[] getFieldStrings(int field, int style, DateFormatSymbols symbols) {
2246         int baseStyle = getBaseStyle(style); // ignore the standalone mask
2247 
2248         // DateFormatSymbols doesn't support any narrow names.
2249         if (baseStyle == NARROW_FORMAT) {
2250             return null;
2251         }
2252 
2253         String[] strings = null;
2254         switch (field) {
2255         case ERA:
2256             strings = symbols.getEras();
2257             break;
2258 
2259         case MONTH:
2260             strings = (baseStyle == LONG) ? symbols.getMonths() : symbols.getShortMonths();
2261             break;
2262 
2263         case DAY_OF_WEEK:
2264             strings = (baseStyle == LONG) ? symbols.getWeekdays() : symbols.getShortWeekdays();
2265             break;
2266 
2267         case AM_PM:
2268             strings = symbols.getAmPmStrings();
2269             break;
2270         }
2271         return strings;
2272     }
2273 
2274     /**
2275      * Fills in any unset fields in the calendar fields. First, the {@link
2276      * #computeTime()} method is called if the time value (millisecond offset
2277      * from the <a href="#Epoch">Epoch</a>) has not been calculated from
2278      * calendar field values. Then, the {@link #computeFields()} method is
2279      * called to calculate all calendar field values.
2280      */
2281     protected void complete()
2282     {
2283         if (!isTimeSet) {
2284             updateTime();
2285         }
2286         if (!areFieldsSet || !areAllFieldsSet) {
2287             computeFields(); // fills in unset fields
2288             areAllFieldsSet = areFieldsSet = true;
2289         }
2290     }
2291 
2292     /**
2293      * Returns whether the value of the specified calendar field has been set
2294      * externally by calling one of the setter methods rather than by the
2295      * internal time calculation.
2296      *
2297      * @return <code>true</code> if the field has been set externally,
2298      * <code>false</code> otherwise.
2299      * @exception IndexOutOfBoundsException if the specified
2300      *                <code>field</code> is out of range
2301      *               (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
2302      * @see #selectFields()
2303      * @see #setFieldsComputed(int)
2304      */
2305     final boolean isExternallySet(int field) {
2306         return stamp[field] >= MINIMUM_USER_STAMP;
2307     }
2308 
2309     /**
2310      * Returns a field mask (bit mask) indicating all calendar fields that
2311      * have the state of externally or internally set.
2312      *
2313      * @return a bit mask indicating set state fields
2314      */
2315     final int getSetStateFields() {
2316         int mask = 0;
2317         for (int i = 0; i < fields.length; i++) {
2318             if (stamp[i] != UNSET) {
2319                 mask |= 1 << i;
2320             }
2321         }
2322         return mask;
2323     }
2324 
2325     /**
2326      * Sets the state of the specified calendar fields to
2327      * <em>computed</em>. This state means that the specified calendar fields
2328      * have valid values that have been set by internal time calculation
2329      * rather than by calling one of the setter methods.
2330      *
2331      * @param fieldMask the field to be marked as computed.
2332      * @exception IndexOutOfBoundsException if the specified
2333      *                <code>field</code> is out of range
2334      *               (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
2335      * @see #isExternallySet(int)
2336      * @see #selectFields()
2337      */
2338     final void setFieldsComputed(int fieldMask) {
2339         if (fieldMask == ALL_FIELDS) {
2340             for (int i = 0; i < fields.length; i++) {
2341                 stamp[i] = COMPUTED;
2342                 isSet[i] = true;
2343             }
2344             areFieldsSet = areAllFieldsSet = true;
2345         } else {
2346             for (int i = 0; i < fields.length; i++) {
2347                 if ((fieldMask & 1) == 1) {
2348                     stamp[i] = COMPUTED;
2349                     isSet[i] = true;
2350                 } else {
2351                     if (areAllFieldsSet && !isSet[i]) {
2352                         areAllFieldsSet = false;
2353                     }
2354                 }
2355                 fieldMask >>>= 1;
2356             }
2357         }
2358     }
2359 
2360     /**
2361      * Sets the state of the calendar fields that are <em>not</em> specified
2362      * by <code>fieldMask</code> to <em>unset</em>. If <code>fieldMask</code>
2363      * specifies all the calendar fields, then the state of this
2364      * <code>Calendar</code> becomes that all the calendar fields are in sync
2365      * with the time value (millisecond offset from the Epoch).
2366      *
2367      * @param fieldMask the field mask indicating which calendar fields are in
2368      * sync with the time value.
2369      * @exception IndexOutOfBoundsException if the specified
2370      *                <code>field</code> is out of range
2371      *               (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
2372      * @see #isExternallySet(int)
2373      * @see #selectFields()
2374      */
2375     final void setFieldsNormalized(int fieldMask) {
2376         if (fieldMask != ALL_FIELDS) {
2377             for (int i = 0; i < fields.length; i++) {
2378                 if ((fieldMask & 1) == 0) {
2379                     stamp[i] = fields[i] = 0; // UNSET == 0
2380                     isSet[i] = false;
2381                 }
2382                 fieldMask >>= 1;
2383             }
2384         }
2385 
2386         // Some or all of the fields are in sync with the
2387         // milliseconds, but the stamp values are not normalized yet.
2388         areFieldsSet = true;
2389         areAllFieldsSet = false;
2390     }
2391 
2392     /**
2393      * Returns whether the calendar fields are partially in sync with the time
2394      * value or fully in sync but not stamp values are not normalized yet.
2395      */
2396     final boolean isPartiallyNormalized() {
2397         return areFieldsSet && !areAllFieldsSet;
2398     }
2399 
2400     /**
2401      * Returns whether the calendar fields are fully in sync with the time
2402      * value.
2403      */
2404     final boolean isFullyNormalized() {
2405         return areFieldsSet && areAllFieldsSet;
2406     }
2407 
2408     /**
2409      * Marks this Calendar as not sync'd.
2410      */
2411     final void setUnnormalized() {
2412         areFieldsSet = areAllFieldsSet = false;
2413     }
2414 
2415     /**
2416      * Returns whether the specified <code>field</code> is on in the
2417      * <code>fieldMask</code>.
2418      */
2419     static boolean isFieldSet(int fieldMask, int field) {
2420         return (fieldMask & (1 << field)) != 0;
2421     }
2422 
2423     /**
2424      * Returns a field mask indicating which calendar field values
2425      * to be used to calculate the time value. The calendar fields are
2426      * returned as a bit mask, each bit of which corresponds to a field, i.e.,
2427      * the mask value of <code>field</code> is <code>(1 &lt;&lt;
2428      * field)</code>. For example, 0x26 represents the <code>YEAR</code>,
2429      * <code>MONTH</code>, and <code>DAY_OF_MONTH</code> fields (i.e., 0x26 is
2430      * equal to
2431      * <code>(1&lt;&lt;YEAR)|(1&lt;&lt;MONTH)|(1&lt;&lt;DAY_OF_MONTH))</code>.
2432      *
2433      * <p>This method supports the calendar fields resolution as described in
2434      * the class description. If the bit mask for a given field is on and its
2435      * field has not been set (i.e., <code>isSet(field)</code> is
2436      * <code>false</code>), then the default value of the field has to be
2437      * used, which case means that the field has been selected because the
2438      * selected combination involves the field.
2439      *
2440      * @return a bit mask of selected fields
2441      * @see #isExternallySet(int)
2442      */
2443     final int selectFields() {
2444         // This implementation has been taken from the GregorianCalendar class.
2445 
2446         // The YEAR field must always be used regardless of its SET
2447         // state because YEAR is a mandatory field to determine the date
2448         // and the default value (EPOCH_YEAR) may change through the
2449         // normalization process.
2450         int fieldMask = YEAR_MASK;
2451 
2452         if (stamp[ERA] != UNSET) {
2453             fieldMask |= ERA_MASK;
2454         }
2455         // Find the most recent group of fields specifying the day within
2456         // the year.  These may be any of the following combinations:
2457         //   MONTH + DAY_OF_MONTH
2458         //   MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
2459         //   MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
2460         //   DAY_OF_YEAR
2461         //   WEEK_OF_YEAR + DAY_OF_WEEK
2462         // We look for the most recent of the fields in each group to determine
2463         // the age of the group.  For groups involving a week-related field such
2464         // as WEEK_OF_MONTH, DAY_OF_WEEK_IN_MONTH, or WEEK_OF_YEAR, both the
2465         // week-related field and the DAY_OF_WEEK must be set for the group as a
2466         // whole to be considered.  (See bug 4153860 - liu 7/24/98.)
2467         int dowStamp = stamp[DAY_OF_WEEK];
2468         int monthStamp = stamp[MONTH];
2469         int domStamp = stamp[DAY_OF_MONTH];
2470         int womStamp = aggregateStamp(stamp[WEEK_OF_MONTH], dowStamp);
2471         int dowimStamp = aggregateStamp(stamp[DAY_OF_WEEK_IN_MONTH], dowStamp);
2472         int doyStamp = stamp[DAY_OF_YEAR];
2473         int woyStamp = aggregateStamp(stamp[WEEK_OF_YEAR], dowStamp);
2474 
2475         int bestStamp = domStamp;
2476         if (womStamp > bestStamp) {
2477             bestStamp = womStamp;
2478         }
2479         if (dowimStamp > bestStamp) {
2480             bestStamp = dowimStamp;
2481         }
2482         if (doyStamp > bestStamp) {
2483             bestStamp = doyStamp;
2484         }
2485         if (woyStamp > bestStamp) {
2486             bestStamp = woyStamp;
2487         }
2488 
2489         /* No complete combination exists.  Look for WEEK_OF_MONTH,
2490          * DAY_OF_WEEK_IN_MONTH, or WEEK_OF_YEAR alone.  Treat DAY_OF_WEEK alone
2491          * as DAY_OF_WEEK_IN_MONTH.
2492          */
2493         if (bestStamp == UNSET) {
2494             womStamp = stamp[WEEK_OF_MONTH];
2495             dowimStamp = Math.max(stamp[DAY_OF_WEEK_IN_MONTH], dowStamp);
2496             woyStamp = stamp[WEEK_OF_YEAR];
2497             bestStamp = Math.max(Math.max(womStamp, dowimStamp), woyStamp);
2498 
2499             /* Treat MONTH alone or no fields at all as DAY_OF_MONTH.  This may
2500              * result in bestStamp = domStamp = UNSET if no fields are set,
2501              * which indicates DAY_OF_MONTH.
2502              */
2503             if (bestStamp == UNSET) {
2504                 bestStamp = domStamp = monthStamp;
2505             }
2506         }
2507 
2508         if (bestStamp == domStamp ||
2509            (bestStamp == womStamp && stamp[WEEK_OF_MONTH] >= stamp[WEEK_OF_YEAR]) ||
2510            (bestStamp == dowimStamp && stamp[DAY_OF_WEEK_IN_MONTH] >= stamp[WEEK_OF_YEAR])) {
2511             fieldMask |= MONTH_MASK;
2512             if (bestStamp == domStamp) {
2513                 fieldMask |= DAY_OF_MONTH_MASK;
2514             } else {
2515                 assert (bestStamp == womStamp || bestStamp == dowimStamp);
2516                 if (dowStamp != UNSET) {
2517                     fieldMask |= DAY_OF_WEEK_MASK;
2518                 }
2519                 if (womStamp == dowimStamp) {
2520                     // When they are equal, give the priority to
2521                     // WEEK_OF_MONTH for compatibility.
2522                     if (stamp[WEEK_OF_MONTH] >= stamp[DAY_OF_WEEK_IN_MONTH]) {
2523                         fieldMask |= WEEK_OF_MONTH_MASK;
2524                     } else {
2525                         fieldMask |= DAY_OF_WEEK_IN_MONTH_MASK;
2526                     }
2527                 } else {
2528                     if (bestStamp == womStamp) {
2529                         fieldMask |= WEEK_OF_MONTH_MASK;
2530                     } else {
2531                         assert (bestStamp == dowimStamp);
2532                         if (stamp[DAY_OF_WEEK_IN_MONTH] != UNSET) {
2533                             fieldMask |= DAY_OF_WEEK_IN_MONTH_MASK;
2534                         }
2535                     }
2536                 }
2537             }
2538         } else {
2539             assert (bestStamp == doyStamp || bestStamp == woyStamp ||
2540                     bestStamp == UNSET);
2541             if (bestStamp == doyStamp) {
2542                 fieldMask |= DAY_OF_YEAR_MASK;
2543             } else {
2544                 assert (bestStamp == woyStamp);
2545                 if (dowStamp != UNSET) {
2546                     fieldMask |= DAY_OF_WEEK_MASK;
2547                 }
2548                 fieldMask |= WEEK_OF_YEAR_MASK;
2549             }
2550         }
2551 
2552         // Find the best set of fields specifying the time of day.  There
2553         // are only two possibilities here; the HOUR_OF_DAY or the
2554         // AM_PM and the HOUR.
2555         int hourOfDayStamp = stamp[HOUR_OF_DAY];
2556         int hourStamp = aggregateStamp(stamp[HOUR], stamp[AM_PM]);
2557         bestStamp = (hourStamp > hourOfDayStamp) ? hourStamp : hourOfDayStamp;
2558 
2559         // if bestStamp is still UNSET, then take HOUR or AM_PM. (See 4846659)
2560         if (bestStamp == UNSET) {
2561             bestStamp = Math.max(stamp[HOUR], stamp[AM_PM]);
2562         }
2563 
2564         // Hours
2565         if (bestStamp != UNSET) {
2566             if (bestStamp == hourOfDayStamp) {
2567                 fieldMask |= HOUR_OF_DAY_MASK;
2568             } else {
2569                 fieldMask |= HOUR_MASK;
2570                 if (stamp[AM_PM] != UNSET) {
2571                     fieldMask |= AM_PM_MASK;
2572                 }
2573             }
2574         }
2575         if (stamp[MINUTE] != UNSET) {
2576             fieldMask |= MINUTE_MASK;
2577         }
2578         if (stamp[SECOND] != UNSET) {
2579             fieldMask |= SECOND_MASK;
2580         }
2581         if (stamp[MILLISECOND] != UNSET) {
2582             fieldMask |= MILLISECOND_MASK;
2583         }
2584         if (stamp[ZONE_OFFSET] >= MINIMUM_USER_STAMP) {
2585                 fieldMask |= ZONE_OFFSET_MASK;
2586         }
2587         if (stamp[DST_OFFSET] >= MINIMUM_USER_STAMP) {
2588             fieldMask |= DST_OFFSET_MASK;
2589         }
2590 
2591         return fieldMask;
2592     }
2593 
2594     int getBaseStyle(int style) {
2595         return style & ~STANDALONE_MASK;
2596     }
2597 
2598     private int toStandaloneStyle(int style) {
2599         return style | STANDALONE_MASK;
2600     }
2601 
2602     private boolean isStandaloneStyle(int style) {
2603         return (style & STANDALONE_MASK) != 0;
2604     }
2605 
2606     private boolean isNarrowStyle(int style) {
2607         return style == NARROW_FORMAT || style == NARROW_STANDALONE;
2608     }
2609 
2610     private boolean isNarrowFormatStyle(int style) {
2611         return style == NARROW_FORMAT;
2612     }
2613 
2614     /**
2615      * Returns the pseudo-time-stamp for two fields, given their
2616      * individual pseudo-time-stamps.  If either of the fields
2617      * is unset, then the aggregate is unset.  Otherwise, the
2618      * aggregate is the later of the two stamps.
2619      */
2620     private static int aggregateStamp(int stamp_a, int stamp_b) {
2621         if (stamp_a == UNSET || stamp_b == UNSET) {
2622             return UNSET;
2623         }
2624         return (stamp_a > stamp_b) ? stamp_a : stamp_b;
2625     }
2626 
2627     /**
2628      * Returns an unmodifiable {@code Set} containing all calendar types
2629      * supported by {@code Calendar} in the runtime environment. The available
2630      * calendar types can be used for the <a
2631      * href="Locale.html#def_locale_extension">Unicode locale extensions</a>.
2632      * The {@code Set} returned contains at least {@code "gregory"}. The
2633      * calendar types don't include aliases, such as {@code "gregorian"} for
2634      * {@code "gregory"}.
2635      *
2636      * @return an unmodifiable {@code Set} containing all available calendar types
2637      * @since 1.8
2638      * @see #getCalendarType()
2639      * @see Calendar.Builder#setCalendarType(String)
2640      * @see Locale#getUnicodeLocaleType(String)
2641      */
2642     public static Set<String> getAvailableCalendarTypes() {
2643         return AvailableCalendarTypes.SET;
2644     }
2645 
2646     private static class AvailableCalendarTypes {
2647         private static final Set<String> SET;
2648         static {
2649             Set<String> set = new HashSet<>(3);
2650             set.add("gregory");
2651             set.add("buddhist");
2652             set.add("japanese");
2653             SET = Collections.unmodifiableSet(set);
2654         }
2655         private AvailableCalendarTypes() {
2656         }
2657     }
2658 
2659     /**
2660      * Returns the calendar type of this {@code Calendar}. Calendar types are
2661      * defined by the <em>Unicode Locale Data Markup Language (LDML)</em>
2662      * specification.
2663      *
2664      * <p>The default implementation of this method returns the class name of
2665      * this {@code Calendar} instance. Any subclasses that implement
2666      * LDML-defined calendar systems should override this method to return
2667      * appropriate calendar types.
2668      *
2669      * @return the LDML-defined calendar type or the class name of this
2670      *         {@code Calendar} instance
2671      * @since 1.8
2672      * @see <a href="Locale.html#def_extensions">Locale extensions</a>
2673      * @see Locale.Builder#setLocale(Locale)
2674      * @see Locale.Builder#setUnicodeLocaleKeyword(String, String)
2675      */
2676     public String getCalendarType() {
2677         return this.getClass().getName();
2678     }
2679 
2680     /**
2681      * Compares this <code>Calendar</code> to the specified
2682      * <code>Object</code>.  The result is <code>true</code> if and only if
2683      * the argument is a <code>Calendar</code> object of the same calendar
2684      * system that represents the same time value (millisecond offset from the
2685      * <a href="#Epoch">Epoch</a>) under the same
2686      * <code>Calendar</code> parameters as this object.
2687      *
2688      * <p>The <code>Calendar</code> parameters are the values represented
2689      * by the <code>isLenient</code>, <code>getFirstDayOfWeek</code>,
2690      * <code>getMinimalDaysInFirstWeek</code> and <code>getTimeZone</code>
2691      * methods. If there is any difference in those parameters
2692      * between the two <code>Calendar</code>s, this method returns
2693      * <code>false</code>.
2694      *
2695      * <p>Use the {@link #compareTo(Calendar) compareTo} method to
2696      * compare only the time values.
2697      *
2698      * @param obj the object to compare with.
2699      * @return <code>true</code> if this object is equal to <code>obj</code>;
2700      * <code>false</code> otherwise.
2701      */
2702     @SuppressWarnings("EqualsWhichDoesntCheckParameterClass")
2703     @Override
2704     public boolean equals(Object obj) {
2705         if (this == obj) {
2706             return true;
2707         }
2708         try {
2709             Calendar that = (Calendar)obj;
2710             return compareTo(getMillisOf(that)) == 0 &&
2711                 lenient == that.lenient &&
2712                 firstDayOfWeek == that.firstDayOfWeek &&
2713                 minimalDaysInFirstWeek == that.minimalDaysInFirstWeek &&
2714                 zone.equals(that.zone);
2715         } catch (Exception e) {
2716             // Note: GregorianCalendar.computeTime throws
2717             // IllegalArgumentException if the ERA value is invalid
2718             // even it's in lenient mode.
2719         }
2720         return false;
2721     }
2722 
2723     /**
2724      * Returns a hash code for this calendar.
2725      *
2726      * @return a hash code value for this object.
2727      * @since 1.2
2728      */
2729     @Override
2730     public int hashCode() {
2731         // 'otheritems' represents the hash code for the previous versions.
2732         int otheritems = (lenient ? 1 : 0)
2733             | (firstDayOfWeek << 1)
2734             | (minimalDaysInFirstWeek << 4)
2735             | (zone.hashCode() << 7);
2736         long t = getMillisOf(this);
2737         return (int) t ^ (int)(t >> 32) ^ otheritems;
2738     }
2739 
2740     /**
2741      * Returns whether this <code>Calendar</code> represents a time
2742      * before the time represented by the specified
2743      * <code>Object</code>. This method is equivalent to:
2744      * <pre>{@code
2745      *         compareTo(when) < 0
2746      * }</pre>
2747      * if and only if <code>when</code> is a <code>Calendar</code>
2748      * instance. Otherwise, the method returns <code>false</code>.
2749      *
2750      * @param when the <code>Object</code> to be compared
2751      * @return <code>true</code> if the time of this
2752      * <code>Calendar</code> is before the time represented by
2753      * <code>when</code>; <code>false</code> otherwise.
2754      * @see     #compareTo(Calendar)
2755      */
2756     public boolean before(Object when) {
2757         return when instanceof Calendar
2758             && compareTo((Calendar)when) < 0;
2759     }
2760 
2761     /**
2762      * Returns whether this <code>Calendar</code> represents a time
2763      * after the time represented by the specified
2764      * <code>Object</code>. This method is equivalent to:
2765      * <pre>{@code
2766      *         compareTo(when) > 0
2767      * }</pre>
2768      * if and only if <code>when</code> is a <code>Calendar</code>
2769      * instance. Otherwise, the method returns <code>false</code>.
2770      *
2771      * @param when the <code>Object</code> to be compared
2772      * @return <code>true</code> if the time of this <code>Calendar</code> is
2773      * after the time represented by <code>when</code>; <code>false</code>
2774      * otherwise.
2775      * @see     #compareTo(Calendar)
2776      */
2777     public boolean after(Object when) {
2778         return when instanceof Calendar
2779             && compareTo((Calendar)when) > 0;
2780     }
2781 
2782     /**
2783      * Compares the time values (millisecond offsets from the <a
2784      * href="#Epoch">Epoch</a>) represented by two
2785      * <code>Calendar</code> objects.
2786      *
2787      * @param anotherCalendar the <code>Calendar</code> to be compared.
2788      * @return the value <code>0</code> if the time represented by the argument
2789      * is equal to the time represented by this <code>Calendar</code>; a value
2790      * less than <code>0</code> if the time of this <code>Calendar</code> is
2791      * before the time represented by the argument; and a value greater than
2792      * <code>0</code> if the time of this <code>Calendar</code> is after the
2793      * time represented by the argument.
2794      * @exception NullPointerException if the specified <code>Calendar</code> is
2795      *            <code>null</code>.
2796      * @exception IllegalArgumentException if the time value of the
2797      * specified <code>Calendar</code> object can't be obtained due to
2798      * any invalid calendar values.
2799      * @since   1.5
2800      */
2801     @Override
2802     public int compareTo(Calendar anotherCalendar) {
2803         return compareTo(getMillisOf(anotherCalendar));
2804     }
2805 
2806     /**
2807      * Adds or subtracts the specified amount of time to the given calendar field,
2808      * based on the calendar's rules. For example, to subtract 5 days from
2809      * the current time of the calendar, you can achieve it by calling:
2810      * <p><code>add(Calendar.DAY_OF_MONTH, -5)</code>.
2811      *
2812      * @param field the calendar field.
2813      * @param amount the amount of date or time to be added to the field.
2814      * @see #roll(int,int)
2815      * @see #set(int,int)
2816      */
2817     public abstract void add(int field, int amount);
2818 
2819     /**
2820      * Adds or subtracts (up/down) a single unit of time on the given time
2821      * field without changing larger fields. For example, to roll the current
2822      * date up by one day, you can achieve it by calling:
2823      * <p>roll(Calendar.DATE, true).
2824      * When rolling on the year or Calendar.YEAR field, it will roll the year
2825      * value in the range between 1 and the value returned by calling
2826      * <code>getMaximum(Calendar.YEAR)</code>.
2827      * When rolling on the month or Calendar.MONTH field, other fields like
2828      * date might conflict and, need to be changed. For instance,
2829      * rolling the month on the date 01/31/96 will result in 02/29/96.
2830      * When rolling on the hour-in-day or Calendar.HOUR_OF_DAY field, it will
2831      * roll the hour value in the range between 0 and 23, which is zero-based.
2832      *
2833      * @param field the time field.
2834      * @param up indicates if the value of the specified time field is to be
2835      * rolled up or rolled down. Use true if rolling up, false otherwise.
2836      * @see Calendar#add(int,int)
2837      * @see Calendar#set(int,int)
2838      */
2839     public abstract void roll(int field, boolean up);
2840 
2841     /**
2842      * Adds the specified (signed) amount to the specified calendar field
2843      * without changing larger fields.  A negative amount means to roll
2844      * down.
2845      *
2846      * <p>NOTE:  This default implementation on <code>Calendar</code> just repeatedly calls the
2847      * version of {@link #roll(int,boolean) roll()} that rolls by one unit.  This may not
2848      * always do the right thing.  For example, if the <code>DAY_OF_MONTH</code> field is 31,
2849      * rolling through February will leave it set to 28.  The <code>GregorianCalendar</code>
2850      * version of this function takes care of this problem.  Other subclasses
2851      * should also provide overrides of this function that do the right thing.
2852      *
2853      * @param field the calendar field.
2854      * @param amount the signed amount to add to the calendar <code>field</code>.
2855      * @since 1.2
2856      * @see #roll(int,boolean)
2857      * @see #add(int,int)
2858      * @see #set(int,int)
2859      */
2860     public void roll(int field, int amount)
2861     {
2862         while (amount > 0) {
2863             roll(field, true);
2864             amount--;
2865         }
2866         while (amount < 0) {
2867             roll(field, false);
2868             amount++;
2869         }
2870     }
2871 
2872     /**
2873      * Sets the time zone with the given time zone value.
2874      *
2875      * @param value the given time zone.
2876      */
2877     public void setTimeZone(TimeZone value)
2878     {
2879         zone = value;
2880         sharedZone = false;
2881         /* Recompute the fields from the time using the new zone.  This also
2882          * works if isTimeSet is false (after a call to set()).  In that case
2883          * the time will be computed from the fields using the new zone, then
2884          * the fields will get recomputed from that.  Consider the sequence of
2885          * calls: cal.setTimeZone(EST); cal.set(HOUR, 1); cal.setTimeZone(PST).
2886          * Is cal set to 1 o'clock EST or 1 o'clock PST?  Answer: PST.  More
2887          * generally, a call to setTimeZone() affects calls to set() BEFORE AND
2888          * AFTER it up to the next call to complete().
2889          */
2890         areAllFieldsSet = areFieldsSet = false;
2891     }
2892 
2893     /**
2894      * Gets the time zone.
2895      *
2896      * @return the time zone object associated with this calendar.
2897      */
2898     public TimeZone getTimeZone()
2899     {
2900         // If the TimeZone object is shared by other Calendar instances, then
2901         // create a clone.
2902         if (sharedZone) {
2903             zone = (TimeZone) zone.clone();
2904             sharedZone = false;
2905         }
2906         return zone;
2907     }
2908 
2909     /**
2910      * Returns the time zone (without cloning).
2911      */
2912     TimeZone getZone() {
2913         return zone;
2914     }
2915 
2916     /**
2917      * Sets the sharedZone flag to <code>shared</code>.
2918      */
2919     void setZoneShared(boolean shared) {
2920         sharedZone = shared;
2921     }
2922 
2923     /**
2924      * Specifies whether or not date/time interpretation is to be lenient.  With
2925      * lenient interpretation, a date such as "February 942, 1996" will be
2926      * treated as being equivalent to the 941st day after February 1, 1996.
2927      * With strict (non-lenient) interpretation, such dates will cause an exception to be
2928      * thrown. The default is lenient.
2929      *
2930      * @param lenient <code>true</code> if the lenient mode is to be turned
2931      * on; <code>false</code> if it is to be turned off.
2932      * @see #isLenient()
2933      * @see java.text.DateFormat#setLenient
2934      */
2935     public void setLenient(boolean lenient)
2936     {
2937         this.lenient = lenient;
2938     }
2939 
2940     /**
2941      * Tells whether date/time interpretation is to be lenient.
2942      *
2943      * @return <code>true</code> if the interpretation mode of this calendar is lenient;
2944      * <code>false</code> otherwise.
2945      * @see #setLenient(boolean)
2946      */
2947     public boolean isLenient()
2948     {
2949         return lenient;
2950     }
2951 
2952     /**
2953      * Sets what the first day of the week is; e.g., <code>SUNDAY</code> in the U.S.,
2954      * <code>MONDAY</code> in France.
2955      *
2956      * @param value the given first day of the week.
2957      * @see #getFirstDayOfWeek()
2958      * @see #getMinimalDaysInFirstWeek()
2959      */
2960     public void setFirstDayOfWeek(int value)
2961     {
2962         if (firstDayOfWeek == value) {
2963             return;
2964         }
2965         firstDayOfWeek = value;
2966         invalidateWeekFields();
2967     }
2968 
2969     /**
2970      * Gets what the first day of the week is; e.g., <code>SUNDAY</code> in the U.S.,
2971      * <code>MONDAY</code> in France.
2972      *
2973      * @return the first day of the week.
2974      * @see #setFirstDayOfWeek(int)
2975      * @see #getMinimalDaysInFirstWeek()
2976      */
2977     public int getFirstDayOfWeek()
2978     {
2979         return firstDayOfWeek;
2980     }
2981 
2982     /**
2983      * Sets what the minimal days required in the first week of the year are;
2984      * For example, if the first week is defined as one that contains the first
2985      * day of the first month of a year, call this method with value 1. If it
2986      * must be a full week, use value 7.
2987      *
2988      * @param value the given minimal days required in the first week
2989      * of the year.
2990      * @see #getMinimalDaysInFirstWeek()
2991      */
2992     public void setMinimalDaysInFirstWeek(int value)
2993     {
2994         if (minimalDaysInFirstWeek == value) {
2995             return;
2996         }
2997         minimalDaysInFirstWeek = value;
2998         invalidateWeekFields();
2999     }
3000 
3001     /**
3002      * Gets what the minimal days required in the first week of the year are;
3003      * e.g., if the first week is defined as one that contains the first day
3004      * of the first month of a year, this method returns 1. If
3005      * the minimal days required must be a full week, this method
3006      * returns 7.
3007      *
3008      * @return the minimal days required in the first week of the year.
3009      * @see #setMinimalDaysInFirstWeek(int)
3010      */
3011     public int getMinimalDaysInFirstWeek()
3012     {
3013         return minimalDaysInFirstWeek;
3014     }
3015 
3016     /**
3017      * Returns whether this {@code Calendar} supports week dates.
3018      *
3019      * <p>The default implementation of this method returns {@code false}.
3020      *
3021      * @return {@code true} if this {@code Calendar} supports week dates;
3022      *         {@code false} otherwise.
3023      * @see #getWeekYear()
3024      * @see #setWeekDate(int,int,int)
3025      * @see #getWeeksInWeekYear()
3026      * @since 1.7
3027      */
3028     public boolean isWeekDateSupported() {
3029         return false;
3030     }
3031 
3032     /**
3033      * Returns the week year represented by this {@code Calendar}. The
3034      * week year is in sync with the week cycle. The {@linkplain
3035      * #getFirstDayOfWeek() first day of the first week} is the first
3036      * day of the week year.
3037      *
3038      * <p>The default implementation of this method throws an
3039      * {@link UnsupportedOperationException}.
3040      *
3041      * @return the week year of this {@code Calendar}
3042      * @exception UnsupportedOperationException
3043      *            if any week year numbering isn't supported
3044      *            in this {@code Calendar}.
3045      * @see #isWeekDateSupported()
3046      * @see #getFirstDayOfWeek()
3047      * @see #getMinimalDaysInFirstWeek()
3048      * @since 1.7
3049      */
3050     public int getWeekYear() {
3051         throw new UnsupportedOperationException();
3052     }
3053 
3054     /**
3055      * Sets the date of this {@code Calendar} with the given date
3056      * specifiers - week year, week of year, and day of week.
3057      *
3058      * <p>Unlike the {@code set} method, all of the calendar fields
3059      * and {@code time} values are calculated upon return.
3060      *
3061      * <p>If {@code weekOfYear} is out of the valid week-of-year range
3062      * in {@code weekYear}, the {@code weekYear} and {@code
3063      * weekOfYear} values are adjusted in lenient mode, or an {@code
3064      * IllegalArgumentException} is thrown in non-lenient mode.
3065      *
3066      * <p>The default implementation of this method throws an
3067      * {@code UnsupportedOperationException}.
3068      *
3069      * @param weekYear   the week year
3070      * @param weekOfYear the week number based on {@code weekYear}
3071      * @param dayOfWeek  the day of week value: one of the constants
3072      *                   for the {@link #DAY_OF_WEEK} field: {@link
3073      *                   #SUNDAY}, ..., {@link #SATURDAY}.
3074      * @exception IllegalArgumentException
3075      *            if any of the given date specifiers is invalid
3076      *            or any of the calendar fields are inconsistent
3077      *            with the given date specifiers in non-lenient mode
3078      * @exception UnsupportedOperationException
3079      *            if any week year numbering isn't supported in this
3080      *            {@code Calendar}.
3081      * @see #isWeekDateSupported()
3082      * @see #getFirstDayOfWeek()
3083      * @see #getMinimalDaysInFirstWeek()
3084      * @since 1.7
3085      */
3086     public void setWeekDate(int weekYear, int weekOfYear, int dayOfWeek) {
3087         throw new UnsupportedOperationException();
3088     }
3089 
3090     /**
3091      * Returns the number of weeks in the week year represented by this
3092      * {@code Calendar}.
3093      *
3094      * <p>The default implementation of this method throws an
3095      * {@code UnsupportedOperationException}.
3096      *
3097      * @return the number of weeks in the week year.
3098      * @exception UnsupportedOperationException
3099      *            if any week year numbering isn't supported in this
3100      *            {@code Calendar}.
3101      * @see #WEEK_OF_YEAR
3102      * @see #isWeekDateSupported()
3103      * @see #getWeekYear()
3104      * @see #getActualMaximum(int)
3105      * @since 1.7
3106      */
3107     public int getWeeksInWeekYear() {
3108         throw new UnsupportedOperationException();
3109     }
3110 
3111     /**
3112      * Returns the minimum value for the given calendar field of this
3113      * <code>Calendar</code> instance. The minimum value is defined as
3114      * the smallest value returned by the {@link #get(int) get} method
3115      * for any possible time value.  The minimum value depends on
3116      * calendar system specific parameters of the instance.
3117      *
3118      * @param field the calendar field.
3119      * @return the minimum value for the given calendar field.
3120      * @see #getMaximum(int)
3121      * @see #getGreatestMinimum(int)
3122      * @see #getLeastMaximum(int)
3123      * @see #getActualMinimum(int)
3124      * @see #getActualMaximum(int)
3125      */
3126     public abstract int getMinimum(int field);
3127 
3128     /**
3129      * Returns the maximum value for the given calendar field of this
3130      * <code>Calendar</code> instance. The maximum value is defined as
3131      * the largest value returned by the {@link #get(int) get} method
3132      * for any possible time value. The maximum value depends on
3133      * calendar system specific parameters of the instance.
3134      *
3135      * @param field the calendar field.
3136      * @return the maximum value for the given calendar field.
3137      * @see #getMinimum(int)
3138      * @see #getGreatestMinimum(int)
3139      * @see #getLeastMaximum(int)
3140      * @see #getActualMinimum(int)
3141      * @see #getActualMaximum(int)
3142      */
3143     public abstract int getMaximum(int field);
3144 
3145     /**
3146      * Returns the highest minimum value for the given calendar field
3147      * of this <code>Calendar</code> instance. The highest minimum
3148      * value is defined as the largest value returned by {@link
3149      * #getActualMinimum(int)} for any possible time value. The
3150      * greatest minimum value depends on calendar system specific
3151      * parameters of the instance.
3152      *
3153      * @param field the calendar field.
3154      * @return the highest minimum value for the given calendar field.
3155      * @see #getMinimum(int)
3156      * @see #getMaximum(int)
3157      * @see #getLeastMaximum(int)
3158      * @see #getActualMinimum(int)
3159      * @see #getActualMaximum(int)
3160      */
3161     public abstract int getGreatestMinimum(int field);
3162 
3163     /**
3164      * Returns the lowest maximum value for the given calendar field
3165      * of this <code>Calendar</code> instance. The lowest maximum
3166      * value is defined as the smallest value returned by {@link
3167      * #getActualMaximum(int)} for any possible time value. The least
3168      * maximum value depends on calendar system specific parameters of
3169      * the instance. For example, a <code>Calendar</code> for the
3170      * Gregorian calendar system returns 28 for the
3171      * <code>DAY_OF_MONTH</code> field, because the 28th is the last
3172      * day of the shortest month of this calendar, February in a
3173      * common year.
3174      *
3175      * @param field the calendar field.
3176      * @return the lowest maximum value for the given calendar field.
3177      * @see #getMinimum(int)
3178      * @see #getMaximum(int)
3179      * @see #getGreatestMinimum(int)
3180      * @see #getActualMinimum(int)
3181      * @see #getActualMaximum(int)
3182      */
3183     public abstract int getLeastMaximum(int field);
3184 
3185     /**
3186      * Returns the minimum value that the specified calendar field
3187      * could have, given the time value of this <code>Calendar</code>.
3188      *
3189      * <p>The default implementation of this method uses an iterative
3190      * algorithm to determine the actual minimum value for the
3191      * calendar field. Subclasses should, if possible, override this
3192      * with a more efficient implementation - in many cases, they can
3193      * simply return <code>getMinimum()</code>.
3194      *
3195      * @param field the calendar field
3196      * @return the minimum of the given calendar field for the time
3197      * value of this <code>Calendar</code>
3198      * @see #getMinimum(int)
3199      * @see #getMaximum(int)
3200      * @see #getGreatestMinimum(int)
3201      * @see #getLeastMaximum(int)
3202      * @see #getActualMaximum(int)
3203      * @since 1.2
3204      */
3205     public int getActualMinimum(int field) {
3206         int fieldValue = getGreatestMinimum(field);
3207         int endValue = getMinimum(field);
3208 
3209         // if we know that the minimum value is always the same, just return it
3210         if (fieldValue == endValue) {
3211             return fieldValue;
3212         }
3213 
3214         // clone the calendar so we don't mess with the real one, and set it to
3215         // accept anything for the field values
3216         Calendar work = (Calendar)this.clone();
3217         work.setLenient(true);
3218 
3219         // now try each value from getLeastMaximum() to getMaximum() one by one until
3220         // we get a value that normalizes to another value.  The last value that
3221         // normalizes to itself is the actual minimum for the current date
3222         int result = fieldValue;
3223 
3224         do {
3225             work.set(field, fieldValue);
3226             if (work.get(field) != fieldValue) {
3227                 break;
3228             } else {
3229                 result = fieldValue;
3230                 fieldValue--;
3231             }
3232         } while (fieldValue >= endValue);
3233 
3234         return result;
3235     }
3236 
3237     /**
3238      * Returns the maximum value that the specified calendar field
3239      * could have, given the time value of this
3240      * <code>Calendar</code>. For example, the actual maximum value of
3241      * the <code>MONTH</code> field is 12 in some years, and 13 in
3242      * other years in the Hebrew calendar system.
3243      *
3244      * <p>The default implementation of this method uses an iterative
3245      * algorithm to determine the actual maximum value for the
3246      * calendar field. Subclasses should, if possible, override this
3247      * with a more efficient implementation.
3248      *
3249      * @param field the calendar field
3250      * @return the maximum of the given calendar field for the time
3251      * value of this <code>Calendar</code>
3252      * @see #getMinimum(int)
3253      * @see #getMaximum(int)
3254      * @see #getGreatestMinimum(int)
3255      * @see #getLeastMaximum(int)
3256      * @see #getActualMinimum(int)
3257      * @since 1.2
3258      */
3259     public int getActualMaximum(int field) {
3260         int fieldValue = getLeastMaximum(field);
3261         int endValue = getMaximum(field);
3262 
3263         // if we know that the maximum value is always the same, just return it.
3264         if (fieldValue == endValue) {
3265             return fieldValue;
3266         }
3267 
3268         // clone the calendar so we don't mess with the real one, and set it to
3269         // accept anything for the field values.
3270         Calendar work = (Calendar)this.clone();
3271         work.setLenient(true);
3272 
3273         // if we're counting weeks, set the day of the week to Sunday.  We know the
3274         // last week of a month or year will contain the first day of the week.
3275         if (field == WEEK_OF_YEAR || field == WEEK_OF_MONTH) {
3276             work.set(DAY_OF_WEEK, firstDayOfWeek);
3277         }
3278 
3279         // now try each value from getLeastMaximum() to getMaximum() one by one until
3280         // we get a value that normalizes to another value.  The last value that
3281         // normalizes to itself is the actual maximum for the current date
3282         int result = fieldValue;
3283 
3284         do {
3285             work.set(field, fieldValue);
3286             if (work.get(field) != fieldValue) {
3287                 break;
3288             } else {
3289                 result = fieldValue;
3290                 fieldValue++;
3291             }
3292         } while (fieldValue <= endValue);
3293 
3294         return result;
3295     }
3296 
3297     /**
3298      * Creates and returns a copy of this object.
3299      *
3300      * @return a copy of this object.
3301      */
3302     @Override
3303     public Object clone()
3304     {
3305         try {
3306             Calendar other = (Calendar) super.clone();
3307 
3308             other.fields = new int[FIELD_COUNT];
3309             other.isSet = new boolean[FIELD_COUNT];
3310             other.stamp = new int[FIELD_COUNT];
3311             for (int i = 0; i < FIELD_COUNT; i++) {
3312                 other.fields[i] = fields[i];
3313                 other.stamp[i] = stamp[i];
3314                 other.isSet[i] = isSet[i];
3315             }
3316             other.zone = (TimeZone) zone.clone();
3317             return other;
3318         }
3319         catch (CloneNotSupportedException e) {
3320             // this shouldn't happen, since we are Cloneable
3321             throw new InternalError(e);
3322         }
3323     }
3324 
3325     private static final String[] FIELD_NAME = {
3326         "ERA", "YEAR", "MONTH", "WEEK_OF_YEAR", "WEEK_OF_MONTH", "DAY_OF_MONTH",
3327         "DAY_OF_YEAR", "DAY_OF_WEEK", "DAY_OF_WEEK_IN_MONTH", "AM_PM", "HOUR",
3328         "HOUR_OF_DAY", "MINUTE", "SECOND", "MILLISECOND", "ZONE_OFFSET",
3329         "DST_OFFSET"
3330     };
3331 
3332     /**
3333      * Returns the name of the specified calendar field.
3334      *
3335      * @param field the calendar field
3336      * @return the calendar field name
3337      * @exception IndexOutOfBoundsException if <code>field</code> is negative,
3338      * equal to or greater than {@code FIELD_COUNT}.
3339      */
3340     static String getFieldName(int field) {
3341         return FIELD_NAME[field];
3342     }
3343 
3344     /**
3345      * Return a string representation of this calendar. This method
3346      * is intended to be used only for debugging purposes, and the
3347      * format of the returned string may vary between implementations.
3348      * The returned string may be empty but may not be <code>null</code>.
3349      *
3350      * @return  a string representation of this calendar.
3351      */
3352     @Override
3353     public String toString() {
3354         // NOTE: BuddhistCalendar.toString() interprets the string
3355         // produced by this method so that the Gregorian year number
3356         // is substituted by its B.E. year value. It relies on
3357         // "...,YEAR=<year>,..." or "...,YEAR=?,...".
3358         StringBuilder buffer = new StringBuilder(800);
3359         buffer.append(getClass().getName()).append('[');
3360         appendValue(buffer, "time", isTimeSet, time);
3361         buffer.append(",areFieldsSet=").append(areFieldsSet);
3362         buffer.append(",areAllFieldsSet=").append(areAllFieldsSet);
3363         buffer.append(",lenient=").append(lenient);
3364         buffer.append(",zone=").append(zone);
3365         appendValue(buffer, ",firstDayOfWeek", true, (long) firstDayOfWeek);
3366         appendValue(buffer, ",minimalDaysInFirstWeek", true, (long) minimalDaysInFirstWeek);
3367         for (int i = 0; i < FIELD_COUNT; ++i) {
3368             buffer.append(',');
3369             appendValue(buffer, FIELD_NAME[i], isSet(i), (long) fields[i]);
3370         }
3371         buffer.append(']');
3372         return buffer.toString();
3373     }
3374 
3375     // =======================privates===============================
3376 
3377     private static void appendValue(StringBuilder sb, String item, boolean valid, long value) {
3378         sb.append(item).append('=');
3379         if (valid) {
3380             sb.append(value);
3381         } else {
3382             sb.append('?');
3383         }
3384     }
3385 
3386     /**
3387      * Both firstDayOfWeek and minimalDaysInFirstWeek are locale-dependent.
3388      * They are used to figure out the week count for a specific date for
3389      * a given locale. These must be set when a Calendar is constructed.
3390      * @param desiredLocale the given locale.
3391      */
3392     private void setWeekCountData(Locale desiredLocale)
3393     {
3394         /* try to get the Locale data from the cache */
3395         int[] data = cachedLocaleData.get(desiredLocale);
3396         if (data == null) {  /* cache miss */
3397             data = new int[2];
3398             data[0] = CalendarDataUtility.retrieveFirstDayOfWeek(desiredLocale);
3399             data[1] = CalendarDataUtility.retrieveMinimalDaysInFirstWeek(desiredLocale);
3400             cachedLocaleData.putIfAbsent(desiredLocale, data);
3401         }
3402         firstDayOfWeek = data[0];
3403         minimalDaysInFirstWeek = data[1];
3404     }
3405 
3406     /**
3407      * Recomputes the time and updates the status fields isTimeSet
3408      * and areFieldsSet.  Callers should check isTimeSet and only
3409      * call this method if isTimeSet is false.
3410      */
3411     private void updateTime() {
3412         computeTime();
3413         // The areFieldsSet and areAllFieldsSet values are no longer
3414         // controlled here (as of 1.5).
3415         isTimeSet = true;
3416     }
3417 
3418     private int compareTo(long t) {
3419         long thisTime = getMillisOf(this);
3420         return (thisTime > t) ? 1 : (thisTime == t) ? 0 : -1;
3421     }
3422 
3423     private static long getMillisOf(Calendar calendar) {
3424         if (calendar.isTimeSet) {
3425             return calendar.time;
3426         }
3427         Calendar cal = (Calendar) calendar.clone();
3428         cal.setLenient(true);
3429         return cal.getTimeInMillis();
3430     }
3431 
3432     /**
3433      * Adjusts the stamp[] values before nextStamp overflow. nextStamp
3434      * is set to the next stamp value upon the return.
3435      */
3436     private void adjustStamp() {
3437         int max = MINIMUM_USER_STAMP;
3438         int newStamp = MINIMUM_USER_STAMP;
3439 
3440         for (;;) {
3441             int min = Integer.MAX_VALUE;
3442             for (int v : stamp) {
3443                 if (v >= newStamp && min > v) {
3444                     min = v;
3445                 }
3446                 if (max < v) {
3447                     max = v;
3448                 }
3449             }
3450             if (max != min && min == Integer.MAX_VALUE) {
3451                 break;
3452             }
3453             for (int i = 0; i < stamp.length; i++) {
3454                 if (stamp[i] == min) {
3455                     stamp[i] = newStamp;
3456                 }
3457             }
3458             newStamp++;
3459             if (min == max) {
3460                 break;
3461             }
3462         }
3463         nextStamp = newStamp;
3464     }
3465 
3466     /**
3467      * Sets the WEEK_OF_MONTH and WEEK_OF_YEAR fields to new values with the
3468      * new parameter value if they have been calculated internally.
3469      */
3470     private void invalidateWeekFields()
3471     {
3472         if (stamp[WEEK_OF_MONTH] != COMPUTED &&
3473             stamp[WEEK_OF_YEAR] != COMPUTED) {
3474             return;
3475         }
3476 
3477         // We have to check the new values of these fields after changing
3478         // firstDayOfWeek and/or minimalDaysInFirstWeek. If the field values
3479         // have been changed, then set the new values. (4822110)
3480         Calendar cal = (Calendar) clone();
3481         cal.setLenient(true);
3482         cal.clear(WEEK_OF_MONTH);
3483         cal.clear(WEEK_OF_YEAR);
3484 
3485         if (stamp[WEEK_OF_MONTH] == COMPUTED) {
3486             int weekOfMonth = cal.get(WEEK_OF_MONTH);
3487             if (fields[WEEK_OF_MONTH] != weekOfMonth) {
3488                 fields[WEEK_OF_MONTH] = weekOfMonth;
3489             }
3490         }
3491 
3492         if (stamp[WEEK_OF_YEAR] == COMPUTED) {
3493             int weekOfYear = cal.get(WEEK_OF_YEAR);
3494             if (fields[WEEK_OF_YEAR] != weekOfYear) {
3495                 fields[WEEK_OF_YEAR] = weekOfYear;
3496             }
3497         }
3498     }
3499 
3500     /**
3501      * Save the state of this object to a stream (i.e., serialize it).
3502      *
3503      * Ideally, <code>Calendar</code> would only write out its state data and
3504      * the current time, and not write any field data out, such as
3505      * <code>fields[]</code>, <code>isTimeSet</code>, <code>areFieldsSet</code>,
3506      * and <code>isSet[]</code>.  <code>nextStamp</code> also should not be part
3507      * of the persistent state. Unfortunately, this didn't happen before JDK 1.1
3508      * shipped. To be compatible with JDK 1.1, we will always have to write out
3509      * the field values and state flags.  However, <code>nextStamp</code> can be
3510      * removed from the serialization stream; this will probably happen in the
3511      * near future.
3512      */
3513     private synchronized void writeObject(ObjectOutputStream stream)
3514          throws IOException
3515     {
3516         // Try to compute the time correctly, for the future (stream
3517         // version 2) in which we don't write out fields[] or isSet[].
3518         if (!isTimeSet) {
3519             try {
3520                 updateTime();
3521             }
3522             catch (IllegalArgumentException e) {}
3523         }
3524 
3525         // If this Calendar has a ZoneInfo, save it and set a
3526         // SimpleTimeZone equivalent (as a single DST schedule) for
3527         // backward compatibility.
3528         TimeZone savedZone = null;
3529         if (zone instanceof ZoneInfo) {
3530             SimpleTimeZone stz = ((ZoneInfo)zone).getLastRuleInstance();
3531             if (stz == null) {
3532                 stz = new SimpleTimeZone(zone.getRawOffset(), zone.getID());
3533             }
3534             savedZone = zone;
3535             zone = stz;
3536         }
3537 
3538         // Write out the 1.1 FCS object.
3539         stream.defaultWriteObject();
3540 
3541         // Write out the ZoneInfo object
3542         // 4802409: we write out even if it is null, a temporary workaround
3543         // the real fix for bug 4844924 in corba-iiop
3544         stream.writeObject(savedZone);
3545         if (savedZone != null) {
3546             zone = savedZone;
3547         }
3548     }
3549 
3550     private static class CalendarAccessControlContext {
3551         private static final AccessControlContext INSTANCE;
3552         static {
3553             RuntimePermission perm = new RuntimePermission("accessClassInPackage.sun.util.calendar");
3554             PermissionCollection perms = perm.newPermissionCollection();
3555             perms.add(perm);
3556             INSTANCE = new AccessControlContext(new ProtectionDomain[] {
3557                                                     new ProtectionDomain(null, perms)
3558                                                 });
3559         }
3560         private CalendarAccessControlContext() {
3561         }
3562     }
3563 
3564     /**
3565      * Reconstitutes this object from a stream (i.e., deserialize it).
3566      */
3567     private void readObject(ObjectInputStream stream)
3568          throws IOException, ClassNotFoundException
3569     {
3570         final ObjectInputStream input = stream;
3571         input.defaultReadObject();
3572 
3573         stamp = new int[FIELD_COUNT];
3574 
3575         // Starting with version 2 (not implemented yet), we expect that
3576         // fields[], isSet[], isTimeSet, and areFieldsSet may not be
3577         // streamed out anymore.  We expect 'time' to be correct.
3578         if (serialVersionOnStream >= 2)
3579         {
3580             isTimeSet = true;
3581             if (fields == null) {
3582                 fields = new int[FIELD_COUNT];
3583             }
3584             if (isSet == null) {
3585                 isSet = new boolean[FIELD_COUNT];
3586             }
3587         }
3588         else if (serialVersionOnStream >= 0)
3589         {
3590             for (int i=0; i<FIELD_COUNT; ++i) {
3591                 stamp[i] = isSet[i] ? COMPUTED : UNSET;
3592             }
3593         }
3594 
3595         serialVersionOnStream = currentSerialVersion;
3596 
3597         // If there's a ZoneInfo object, use it for zone.
3598         ZoneInfo zi = null;
3599         try {
3600             zi = AccessController.doPrivileged(
3601                     new PrivilegedExceptionAction<>() {
3602                         @Override
3603                         public ZoneInfo run() throws Exception {
3604                             return (ZoneInfo) input.readObject();
3605                         }
3606                     },
3607                     CalendarAccessControlContext.INSTANCE);
3608         } catch (PrivilegedActionException pae) {
3609             Exception e = pae.getException();
3610             if (!(e instanceof OptionalDataException)) {
3611                 if (e instanceof RuntimeException) {
3612                     throw (RuntimeException) e;
3613                 } else if (e instanceof IOException) {
3614                     throw (IOException) e;
3615                 } else if (e instanceof ClassNotFoundException) {
3616                     throw (ClassNotFoundException) e;
3617                 }
3618                 throw new RuntimeException(e);
3619             }
3620         }
3621         if (zi != null) {
3622             zone = zi;
3623         }
3624 
3625         // If the deserialized object has a SimpleTimeZone, try to
3626         // replace it with a ZoneInfo equivalent (as of 1.4) in order
3627         // to be compatible with the SimpleTimeZone-based
3628         // implementation as much as possible.
3629         if (zone instanceof SimpleTimeZone) {
3630             String id = zone.getID();
3631             TimeZone tz = TimeZone.getTimeZone(id);
3632             if (tz != null && tz.hasSameRules(zone) && tz.getID().equals(id)) {
3633                 zone = tz;
3634             }
3635         }
3636     }
3637 
3638     /**
3639      * Converts this object to an {@link Instant}.
3640      * <p>
3641      * The conversion creates an {@code Instant} that represents the
3642      * same point on the time-line as this {@code Calendar}.
3643      *
3644      * @return the instant representing the same point on the time-line
3645      * @since 1.8
3646      */
3647     public final Instant toInstant() {
3648         return Instant.ofEpochMilli(getTimeInMillis());
3649     }
3650 }