1 /*
   2  * Copyright (c) 2012, 2015, 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
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   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  * This file is available under and governed by the GNU General Public
  28  * License version 2 only, as published by the Free Software Foundation.
  29  * However, the following notice accompanied the original version of this
  30  * file:
  31  *
  32  * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
  33  *
  34  * All rights reserved.
  35  *
  36  * Redistribution and use in source and binary forms, with or without
  37  * modification, are permitted provided that the following conditions are met:
  38  *
  39  *  * Redistributions of source code must retain the above copyright notice,
  40  *    this list of conditions and the following disclaimer.
  41  *
  42  *  * Redistributions in binary form must reproduce the above copyright notice,
  43  *    this list of conditions and the following disclaimer in the documentation
  44  *    and/or other materials provided with the distribution.
  45  *
  46  *  * Neither the name of JSR-310 nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  51  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  52  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  53  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  54  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  55  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  56  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  57  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  58  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  59  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  60  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  61  */
  62 package java.time;
  63 
  64 import static java.time.LocalTime.SECONDS_PER_DAY;
  65 import static java.time.temporal.ChronoField.ALIGNED_DAY_OF_WEEK_IN_MONTH;
  66 import static java.time.temporal.ChronoField.ALIGNED_DAY_OF_WEEK_IN_YEAR;
  67 import static java.time.temporal.ChronoField.ALIGNED_WEEK_OF_MONTH;
  68 import static java.time.temporal.ChronoField.ALIGNED_WEEK_OF_YEAR;
  69 import static java.time.temporal.ChronoField.DAY_OF_MONTH;
  70 import static java.time.temporal.ChronoField.DAY_OF_YEAR;
  71 import static java.time.temporal.ChronoField.EPOCH_DAY;
  72 import static java.time.temporal.ChronoField.ERA;
  73 import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
  74 import static java.time.temporal.ChronoField.PROLEPTIC_MONTH;
  75 import static java.time.temporal.ChronoField.YEAR;
  76 
  77 import java.io.DataInput;
  78 import java.io.DataOutput;
  79 import java.io.IOException;
  80 import java.io.InvalidObjectException;
  81 import java.io.ObjectInputStream;
  82 import java.io.Serializable;
  83 import java.time.chrono.ChronoLocalDate;
  84 import java.time.chrono.IsoEra;
  85 import java.time.chrono.IsoChronology;
  86 import java.time.format.DateTimeFormatter;
  87 import java.time.format.DateTimeParseException;
  88 import java.time.temporal.ChronoField;
  89 import java.time.temporal.ChronoUnit;
  90 import java.time.temporal.Temporal;
  91 import java.time.temporal.TemporalAccessor;
  92 import java.time.temporal.TemporalAdjuster;
  93 import java.time.temporal.TemporalAmount;
  94 import java.time.temporal.TemporalField;
  95 import java.time.temporal.TemporalQueries;
  96 import java.time.temporal.TemporalQuery;
  97 import java.time.temporal.TemporalUnit;
  98 import java.time.temporal.UnsupportedTemporalTypeException;
  99 import java.time.temporal.ValueRange;
 100 import java.time.zone.ZoneOffsetTransition;
 101 import java.time.zone.ZoneRules;
 102 import java.util.Objects;
 103 
 104 /**
 105  * A date without a time-zone in the ISO-8601 calendar system,
 106  * such as {@code 2007-12-03}.
 107  * <p>
 108  * {@code LocalDate} is an immutable date-time object that represents a date,
 109  * often viewed as year-month-day. Other date fields, such as day-of-year,
 110  * day-of-week and week-of-year, can also be accessed.
 111  * For example, the value "2nd October 2007" can be stored in a {@code LocalDate}.
 112  * <p>
 113  * This class does not store or represent a time or time-zone.
 114  * Instead, it is a description of the date, as used for birthdays.
 115  * It cannot represent an instant on the time-line without additional information
 116  * such as an offset or time-zone.
 117  * <p>
 118  * The ISO-8601 calendar system is the modern civil calendar system used today
 119  * in most of the world. It is equivalent to the proleptic Gregorian calendar
 120  * system, in which today's rules for leap years are applied for all time.
 121  * For most applications written today, the ISO-8601 rules are entirely suitable.
 122  * However, any application that makes use of historical dates, and requires them
 123  * to be accurate will find the ISO-8601 approach unsuitable.
 124  *
 125  * <p>
 126  * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
 127  * class; use of identity-sensitive operations (including reference equality
 128  * ({@code ==}), identity hash code, or synchronization) on instances of
 129  * {@code LocalDate} may have unpredictable results and should be avoided.
 130  * The {@code equals} method should be used for comparisons.
 131  *
 132  * @implSpec
 133  * This class is immutable and thread-safe.
 134  *
 135  * @since 1.8
 136  */
 137 public final class LocalDate
 138         implements Temporal, TemporalAdjuster, ChronoLocalDate, Serializable {
 139 
 140     /**
 141      * The minimum supported {@code LocalDate}, '-999999999-01-01'.
 142      * This could be used by an application as a "far past" date.
 143      */
 144     public static final LocalDate MIN = LocalDate.of(Year.MIN_VALUE, 1, 1);
 145     /**
 146      * The maximum supported {@code LocalDate}, '+999999999-12-31'.
 147      * This could be used by an application as a "far future" date.
 148      */
 149     public static final LocalDate MAX = LocalDate.of(Year.MAX_VALUE, 12, 31);
 150 
 151     /**
 152      * Serialization version.
 153      */
 154     private static final long serialVersionUID = 2942565459149668126L;
 155     /**
 156      * The number of days in a 400 year cycle.
 157      */
 158     private static final int DAYS_PER_CYCLE = 146097;
 159     /**
 160      * The number of days from year zero to year 1970.
 161      * There are five 400 year cycles from year zero to 2000.
 162      * There are 7 leap years from 1970 to 2000.
 163      */
 164     static final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
 165 
 166     /**
 167      * The year.
 168      */
 169     private final int year;
 170     /**
 171      * The month-of-year.
 172      */
 173     private final short month;
 174     /**
 175      * The day-of-month.
 176      */
 177     private final short day;
 178 
 179     //-----------------------------------------------------------------------
 180     /**
 181      * Obtains the current date from the system clock in the default time-zone.
 182      * <p>
 183      * This will query the {@link Clock#systemDefaultZone() system clock} in the default
 184      * time-zone to obtain the current date.
 185      * <p>
 186      * Using this method will prevent the ability to use an alternate clock for testing
 187      * because the clock is hard-coded.
 188      *
 189      * @return the current date using the system clock and default time-zone, not null
 190      */
 191     public static LocalDate now() {
 192         return now(Clock.systemDefaultZone());
 193     }
 194 
 195     /**
 196      * Obtains the current date from the system clock in the specified time-zone.
 197      * <p>
 198      * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current date.
 199      * Specifying the time-zone avoids dependence on the default time-zone.
 200      * <p>
 201      * Using this method will prevent the ability to use an alternate clock for testing
 202      * because the clock is hard-coded.
 203      *
 204      * @param zone  the zone ID to use, not null
 205      * @return the current date using the system clock, not null
 206      */
 207     public static LocalDate now(ZoneId zone) {
 208         return now(Clock.system(zone));
 209     }
 210 
 211     /**
 212      * Obtains the current date from the specified clock.
 213      * <p>
 214      * This will query the specified clock to obtain the current date - today.
 215      * Using this method allows the use of an alternate clock for testing.
 216      * The alternate clock may be introduced using {@link Clock dependency injection}.
 217      *
 218      * @param clock  the clock to use, not null
 219      * @return the current date, not null
 220      */
 221     public static LocalDate now(Clock clock) {
 222         Objects.requireNonNull(clock, "clock");
 223         final Instant now = clock.instant();  // called once
 224         return ofInstant(now, clock.getZone());
 225     }
 226 
 227     //-----------------------------------------------------------------------
 228     /**
 229      * Obtains an instance of {@code LocalDate} from a year, month and day.
 230      * <p>
 231      * This returns a {@code LocalDate} with the specified year, month and day-of-month.
 232      * The day must be valid for the year and month, otherwise an exception will be thrown.
 233      *
 234      * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
 235      * @param month  the month-of-year to represent, not null
 236      * @param dayOfMonth  the day-of-month to represent, from 1 to 31
 237      * @return the local date, not null
 238      * @throws DateTimeException if the value of any field is out of range,
 239      *  or if the day-of-month is invalid for the month-year
 240      */
 241     public static LocalDate of(int year, Month month, int dayOfMonth) {
 242         YEAR.checkValidValue(year);
 243         Objects.requireNonNull(month, "month");
 244         DAY_OF_MONTH.checkValidValue(dayOfMonth);
 245         return create(year, month.getValue(), dayOfMonth);
 246     }
 247 
 248     /**
 249      * Obtains an instance of {@code LocalDate} from a year, month and day.
 250      * <p>
 251      * This returns a {@code LocalDate} with the specified year, month and day-of-month.
 252      * The day must be valid for the year and month, otherwise an exception will be thrown.
 253      *
 254      * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
 255      * @param month  the month-of-year to represent, from 1 (January) to 12 (December)
 256      * @param dayOfMonth  the day-of-month to represent, from 1 to 31
 257      * @return the local date, not null
 258      * @throws DateTimeException if the value of any field is out of range,
 259      *  or if the day-of-month is invalid for the month-year
 260      */
 261     public static LocalDate of(int year, int month, int dayOfMonth) {
 262         YEAR.checkValidValue(year);
 263         MONTH_OF_YEAR.checkValidValue(month);
 264         DAY_OF_MONTH.checkValidValue(dayOfMonth);
 265         return create(year, month, dayOfMonth);
 266     }
 267 
 268     //-----------------------------------------------------------------------
 269     /**
 270      * Obtains an instance of {@code LocalDate} from a year and day-of-year.
 271      * <p>
 272      * This returns a {@code LocalDate} with the specified year and day-of-year.
 273      * The day-of-year must be valid for the year, otherwise an exception will be thrown.
 274      *
 275      * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
 276      * @param dayOfYear  the day-of-year to represent, from 1 to 366
 277      * @return the local date, not null
 278      * @throws DateTimeException if the value of any field is out of range,
 279      *  or if the day-of-year is invalid for the year
 280      */
 281     public static LocalDate ofYearDay(int year, int dayOfYear) {
 282         YEAR.checkValidValue(year);
 283         DAY_OF_YEAR.checkValidValue(dayOfYear);
 284         boolean leap = IsoChronology.INSTANCE.isLeapYear(year);
 285         if (dayOfYear == 366 && leap == false) {
 286             throw new DateTimeException("Invalid date 'DayOfYear 366' as '" + year + "' is not a leap year");
 287         }
 288         Month moy = Month.of((dayOfYear - 1) / 31 + 1);
 289         int monthEnd = moy.firstDayOfYear(leap) + moy.length(leap) - 1;
 290         if (dayOfYear > monthEnd) {
 291             moy = moy.plus(1);
 292         }
 293         int dom = dayOfYear - moy.firstDayOfYear(leap) + 1;
 294         return new LocalDate(year, moy.getValue(), dom);
 295     }
 296 
 297     //-----------------------------------------------------------------------
 298     /**
 299      * Obtains an instance of {@code LocalDate} from an {@code Instant} and zone ID.
 300      * <p>
 301      * This creates a local date based on the specified instant.
 302      * First, the offset from UTC/Greenwich is obtained using the zone ID and instant,
 303      * which is simple as there is only one valid offset for each instant.
 304      * Then, the instant and offset are used to calculate the local date.
 305      *
 306      * @param instant  the instant to create the date from, not null
 307      * @param zone  the time-zone, which may be an offset, not null
 308      * @return the local date, not null
 309      * @throws DateTimeException if the result exceeds the supported range
 310      */
 311     public static LocalDate ofInstant(Instant instant, ZoneId zone) {
 312         Objects.requireNonNull(instant, "instant");
 313         Objects.requireNonNull(zone, "zone");
 314         ZoneRules rules = zone.getRules();
 315         ZoneOffset offset = rules.getOffset(instant);
 316         long localSecond = instant.getEpochSecond() + offset.getTotalSeconds();
 317         long localEpochDay = Math.floorDiv(localSecond, SECONDS_PER_DAY);
 318         return ofEpochDay(localEpochDay);
 319     }
 320 
 321     //-----------------------------------------------------------------------
 322     /**
 323      * Obtains an instance of {@code LocalDate} from the epoch day count.
 324      * <p>
 325      * This returns a {@code LocalDate} with the specified epoch-day.
 326      * The {@link ChronoField#EPOCH_DAY EPOCH_DAY} is a simple incrementing count
 327      * of days where day 0 is 1970-01-01. Negative numbers represent earlier days.
 328      *
 329      * @param epochDay  the Epoch Day to convert, based on the epoch 1970-01-01
 330      * @return the local date, not null
 331      * @throws DateTimeException if the epoch day exceeds the supported date range
 332      */
 333     public static LocalDate ofEpochDay(long epochDay) {
 334         long zeroDay = epochDay + DAYS_0000_TO_1970;
 335         // find the march-based year
 336         zeroDay -= 60;  // adjust to 0000-03-01 so leap day is at end of four year cycle
 337         long adjust = 0;
 338         if (zeroDay < 0) {
 339             // adjust negative years to positive for calculation
 340             long adjustCycles = (zeroDay + 1) / DAYS_PER_CYCLE - 1;
 341             adjust = adjustCycles * 400;
 342             zeroDay += -adjustCycles * DAYS_PER_CYCLE;
 343         }
 344         long yearEst = (400 * zeroDay + 591) / DAYS_PER_CYCLE;
 345         long doyEst = zeroDay - (365 * yearEst + yearEst / 4 - yearEst / 100 + yearEst / 400);
 346         if (doyEst < 0) {
 347             // fix estimate
 348             yearEst--;
 349             doyEst = zeroDay - (365 * yearEst + yearEst / 4 - yearEst / 100 + yearEst / 400);
 350         }
 351         yearEst += adjust;  // reset any negative year
 352         int marchDoy0 = (int) doyEst;
 353 
 354         // convert march-based values back to january-based
 355         int marchMonth0 = (marchDoy0 * 5 + 2) / 153;
 356         int month = (marchMonth0 + 2) % 12 + 1;
 357         int dom = marchDoy0 - (marchMonth0 * 306 + 5) / 10 + 1;
 358         yearEst += marchMonth0 / 10;
 359 
 360         // check year now we are certain it is correct
 361         int year = YEAR.checkValidIntValue(yearEst);
 362         return new LocalDate(year, month, dom);
 363     }
 364 
 365     //-----------------------------------------------------------------------
 366     /**
 367      * Obtains an instance of {@code LocalDate} from a temporal object.
 368      * <p>
 369      * This obtains a local date based on the specified temporal.
 370      * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
 371      * which this factory converts to an instance of {@code LocalDate}.
 372      * <p>
 373      * The conversion uses the {@link TemporalQueries#localDate()} query, which relies
 374      * on extracting the {@link ChronoField#EPOCH_DAY EPOCH_DAY} field.
 375      * <p>
 376      * This method matches the signature of the functional interface {@link TemporalQuery}
 377      * allowing it to be used as a query via method reference, {@code LocalDate::from}.
 378      *
 379      * @param temporal  the temporal object to convert, not null
 380      * @return the local date, not null
 381      * @throws DateTimeException if unable to convert to a {@code LocalDate}
 382      */
 383     public static LocalDate from(TemporalAccessor temporal) {
 384         Objects.requireNonNull(temporal, "temporal");
 385         LocalDate date = temporal.query(TemporalQueries.localDate());
 386         if (date == null) {
 387             throw new DateTimeException("Unable to obtain LocalDate from TemporalAccessor: " +
 388                     temporal + " of type " + temporal.getClass().getName());
 389         }
 390         return date;
 391     }
 392 
 393     //-----------------------------------------------------------------------
 394     /**
 395      * Obtains an instance of {@code LocalDate} from a text string such as {@code 2007-12-03}.
 396      * <p>
 397      * The string must represent a valid date and is parsed using
 398      * {@link java.time.format.DateTimeFormatter#ISO_LOCAL_DATE}.
 399      *
 400      * @param text  the text to parse such as "2007-12-03", not null
 401      * @return the parsed local date, not null
 402      * @throws DateTimeParseException if the text cannot be parsed
 403      */
 404     public static LocalDate parse(CharSequence text) {
 405         return parse(text, DateTimeFormatter.ISO_LOCAL_DATE);
 406     }
 407 
 408     /**
 409      * Obtains an instance of {@code LocalDate} from a text string using a specific formatter.
 410      * <p>
 411      * The text is parsed using the formatter, returning a date.
 412      *
 413      * @param text  the text to parse, not null
 414      * @param formatter  the formatter to use, not null
 415      * @return the parsed local date, not null
 416      * @throws DateTimeParseException if the text cannot be parsed
 417      */
 418     public static LocalDate parse(CharSequence text, DateTimeFormatter formatter) {
 419         Objects.requireNonNull(formatter, "formatter");
 420         return formatter.parse(text, LocalDate::from);
 421     }
 422 
 423     //-----------------------------------------------------------------------
 424     /**
 425      * Creates a local date from the year, month and day fields.
 426      *
 427      * @param year  the year to represent, validated from MIN_YEAR to MAX_YEAR
 428      * @param month  the month-of-year to represent, from 1 to 12, validated
 429      * @param dayOfMonth  the day-of-month to represent, validated from 1 to 31
 430      * @return the local date, not null
 431      * @throws DateTimeException if the day-of-month is invalid for the month-year
 432      */
 433     private static LocalDate create(int year, int month, int dayOfMonth) {
 434         if (dayOfMonth > 28) {
 435             int dom = 31;
 436             switch (month) {
 437                 case 2:
 438                     dom = (IsoChronology.INSTANCE.isLeapYear(year) ? 29 : 28);
 439                     break;
 440                 case 4:
 441                 case 6:
 442                 case 9:
 443                 case 11:
 444                     dom = 30;
 445                     break;
 446             }
 447             if (dayOfMonth > dom) {
 448                 if (dayOfMonth == 29) {
 449                     throw new DateTimeException("Invalid date 'February 29' as '" + year + "' is not a leap year");
 450                 } else {
 451                     throw new DateTimeException("Invalid date '" + Month.of(month).name() + " " + dayOfMonth + "'");
 452                 }
 453             }
 454         }
 455         return new LocalDate(year, month, dayOfMonth);
 456     }
 457 
 458     /**
 459      * Resolves the date, resolving days past the end of month.
 460      *
 461      * @param year  the year to represent, validated from MIN_YEAR to MAX_YEAR
 462      * @param month  the month-of-year to represent, validated from 1 to 12
 463      * @param day  the day-of-month to represent, validated from 1 to 31
 464      * @return the resolved date, not null
 465      */
 466     private static LocalDate resolvePreviousValid(int year, int month, int day) {
 467         switch (month) {
 468             case 2:
 469                 day = Math.min(day, IsoChronology.INSTANCE.isLeapYear(year) ? 29 : 28);
 470                 break;
 471             case 4:
 472             case 6:
 473             case 9:
 474             case 11:
 475                 day = Math.min(day, 30);
 476                 break;
 477         }
 478         return new LocalDate(year, month, day);
 479     }
 480 
 481     /**
 482      * Constructor, previously validated.
 483      *
 484      * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
 485      * @param month  the month-of-year to represent, not null
 486      * @param dayOfMonth  the day-of-month to represent, valid for year-month, from 1 to 31
 487      */
 488     private LocalDate(int year, int month, int dayOfMonth) {
 489         this.year = year;
 490         this.month = (short) month;
 491         this.day = (short) dayOfMonth;
 492     }
 493 
 494     //-----------------------------------------------------------------------
 495     /**
 496      * Checks if the specified field is supported.
 497      * <p>
 498      * This checks if this date can be queried for the specified field.
 499      * If false, then calling the {@link #range(TemporalField) range},
 500      * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
 501      * methods will throw an exception.
 502      * <p>
 503      * If the field is a {@link ChronoField} then the query is implemented here.
 504      * The supported fields are:
 505      * <ul>
 506      * <li>{@code DAY_OF_WEEK}
 507      * <li>{@code ALIGNED_DAY_OF_WEEK_IN_MONTH}
 508      * <li>{@code ALIGNED_DAY_OF_WEEK_IN_YEAR}
 509      * <li>{@code DAY_OF_MONTH}
 510      * <li>{@code DAY_OF_YEAR}
 511      * <li>{@code EPOCH_DAY}
 512      * <li>{@code ALIGNED_WEEK_OF_MONTH}
 513      * <li>{@code ALIGNED_WEEK_OF_YEAR}
 514      * <li>{@code MONTH_OF_YEAR}
 515      * <li>{@code PROLEPTIC_MONTH}
 516      * <li>{@code YEAR_OF_ERA}
 517      * <li>{@code YEAR}
 518      * <li>{@code ERA}
 519      * </ul>
 520      * All other {@code ChronoField} instances will return false.
 521      * <p>
 522      * If the field is not a {@code ChronoField}, then the result of this method
 523      * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
 524      * passing {@code this} as the argument.
 525      * Whether the field is supported is determined by the field.
 526      *
 527      * @param field  the field to check, null returns false
 528      * @return true if the field is supported on this date, false if not
 529      */
 530     @Override  // override for Javadoc
 531     public boolean isSupported(TemporalField field) {
 532         return ChronoLocalDate.super.isSupported(field);
 533     }
 534 
 535     /**
 536      * Checks if the specified unit is supported.
 537      * <p>
 538      * This checks if the specified unit can be added to, or subtracted from, this date.
 539      * If false, then calling the {@link #plus(long, TemporalUnit)} and
 540      * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
 541      * <p>
 542      * If the unit is a {@link ChronoUnit} then the query is implemented here.
 543      * The supported units are:
 544      * <ul>
 545      * <li>{@code DAYS}
 546      * <li>{@code WEEKS}
 547      * <li>{@code MONTHS}
 548      * <li>{@code YEARS}
 549      * <li>{@code DECADES}
 550      * <li>{@code CENTURIES}
 551      * <li>{@code MILLENNIA}
 552      * <li>{@code ERAS}
 553      * </ul>
 554      * All other {@code ChronoUnit} instances will return false.
 555      * <p>
 556      * If the unit is not a {@code ChronoUnit}, then the result of this method
 557      * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
 558      * passing {@code this} as the argument.
 559      * Whether the unit is supported is determined by the unit.
 560      *
 561      * @param unit  the unit to check, null returns false
 562      * @return true if the unit can be added/subtracted, false if not
 563      */
 564     @Override  // override for Javadoc
 565     public boolean isSupported(TemporalUnit unit) {
 566         return ChronoLocalDate.super.isSupported(unit);
 567     }
 568 
 569     //-----------------------------------------------------------------------
 570     /**
 571      * Gets the range of valid values for the specified field.
 572      * <p>
 573      * The range object expresses the minimum and maximum valid values for a field.
 574      * This date is used to enhance the accuracy of the returned range.
 575      * If it is not possible to return the range, because the field is not supported
 576      * or for some other reason, an exception is thrown.
 577      * <p>
 578      * If the field is a {@link ChronoField} then the query is implemented here.
 579      * The {@link #isSupported(TemporalField) supported fields} will return
 580      * appropriate range instances.
 581      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 582      * <p>
 583      * If the field is not a {@code ChronoField}, then the result of this method
 584      * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
 585      * passing {@code this} as the argument.
 586      * Whether the range can be obtained is determined by the field.
 587      *
 588      * @param field  the field to query the range for, not null
 589      * @return the range of valid values for the field, not null
 590      * @throws DateTimeException if the range for the field cannot be obtained
 591      * @throws UnsupportedTemporalTypeException if the field is not supported
 592      */
 593     @Override
 594     public ValueRange range(TemporalField field) {
 595         if (field instanceof ChronoField) {
 596             ChronoField f = (ChronoField) field;
 597             if (f.isDateBased()) {
 598                 switch (f) {
 599                     case DAY_OF_MONTH: return ValueRange.of(1, lengthOfMonth());
 600                     case DAY_OF_YEAR: return ValueRange.of(1, lengthOfYear());
 601                     case ALIGNED_WEEK_OF_MONTH: return ValueRange.of(1, getMonth() == Month.FEBRUARY && isLeapYear() == false ? 4 : 5);
 602                     case YEAR_OF_ERA:
 603                         return (getYear() <= 0 ? ValueRange.of(1, Year.MAX_VALUE + 1) : ValueRange.of(1, Year.MAX_VALUE));
 604                 }
 605                 return field.range();
 606             }
 607             throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 608         }
 609         return field.rangeRefinedBy(this);
 610     }
 611 
 612     /**
 613      * Gets the value of the specified field from this date as an {@code int}.
 614      * <p>
 615      * This queries this date for the value of the specified field.
 616      * The returned value will always be within the valid range of values for the field.
 617      * If it is not possible to return the value, because the field is not supported
 618      * or for some other reason, an exception is thrown.
 619      * <p>
 620      * If the field is a {@link ChronoField} then the query is implemented here.
 621      * The {@link #isSupported(TemporalField) supported fields} will return valid
 622      * values based on this date, except {@code EPOCH_DAY} and {@code PROLEPTIC_MONTH}
 623      * which are too large to fit in an {@code int} and throw an {@code UnsupportedTemporalTypeException}.
 624      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 625      * <p>
 626      * If the field is not a {@code ChronoField}, then the result of this method
 627      * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
 628      * passing {@code this} as the argument. Whether the value can be obtained,
 629      * and what the value represents, is determined by the field.
 630      *
 631      * @param field  the field to get, not null
 632      * @return the value for the field
 633      * @throws DateTimeException if a value for the field cannot be obtained or
 634      *         the value is outside the range of valid values for the field
 635      * @throws UnsupportedTemporalTypeException if the field is not supported or
 636      *         the range of values exceeds an {@code int}
 637      * @throws ArithmeticException if numeric overflow occurs
 638      */
 639     @Override  // override for Javadoc and performance
 640     public int get(TemporalField field) {
 641         if (field instanceof ChronoField) {
 642             return get0(field);
 643         }
 644         return ChronoLocalDate.super.get(field);
 645     }
 646 
 647     /**
 648      * Gets the value of the specified field from this date as a {@code long}.
 649      * <p>
 650      * This queries this date for the value of the specified field.
 651      * If it is not possible to return the value, because the field is not supported
 652      * or for some other reason, an exception is thrown.
 653      * <p>
 654      * If the field is a {@link ChronoField} then the query is implemented here.
 655      * The {@link #isSupported(TemporalField) supported fields} will return valid
 656      * values based on this date.
 657      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 658      * <p>
 659      * If the field is not a {@code ChronoField}, then the result of this method
 660      * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
 661      * passing {@code this} as the argument. Whether the value can be obtained,
 662      * and what the value represents, is determined by the field.
 663      *
 664      * @param field  the field to get, not null
 665      * @return the value for the field
 666      * @throws DateTimeException if a value for the field cannot be obtained
 667      * @throws UnsupportedTemporalTypeException if the field is not supported
 668      * @throws ArithmeticException if numeric overflow occurs
 669      */
 670     @Override
 671     public long getLong(TemporalField field) {
 672         if (field instanceof ChronoField) {
 673             if (field == EPOCH_DAY) {
 674                 return toEpochDay();
 675             }
 676             if (field == PROLEPTIC_MONTH) {
 677                 return getProlepticMonth();
 678             }
 679             return get0(field);
 680         }
 681         return field.getFrom(this);
 682     }
 683 
 684     private int get0(TemporalField field) {
 685         switch ((ChronoField) field) {
 686             case DAY_OF_WEEK: return getDayOfWeek().getValue();
 687             case ALIGNED_DAY_OF_WEEK_IN_MONTH: return ((day - 1) % 7) + 1;
 688             case ALIGNED_DAY_OF_WEEK_IN_YEAR: return ((getDayOfYear() - 1) % 7) + 1;
 689             case DAY_OF_MONTH: return day;
 690             case DAY_OF_YEAR: return getDayOfYear();
 691             case EPOCH_DAY: throw new UnsupportedTemporalTypeException("Invalid field 'EpochDay' for get() method, use getLong() instead");
 692             case ALIGNED_WEEK_OF_MONTH: return ((day - 1) / 7) + 1;
 693             case ALIGNED_WEEK_OF_YEAR: return ((getDayOfYear() - 1) / 7) + 1;
 694             case MONTH_OF_YEAR: return month;
 695             case PROLEPTIC_MONTH: throw new UnsupportedTemporalTypeException("Invalid field 'ProlepticMonth' for get() method, use getLong() instead");
 696             case YEAR_OF_ERA: return (year >= 1 ? year : 1 - year);
 697             case YEAR: return year;
 698             case ERA: return (year >= 1 ? 1 : 0);
 699         }
 700         throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 701     }
 702 
 703     private long getProlepticMonth() {
 704         return (year * 12L + month - 1);
 705     }
 706 
 707     //-----------------------------------------------------------------------
 708     /**
 709      * Gets the chronology of this date, which is the ISO calendar system.
 710      * <p>
 711      * The {@code Chronology} represents the calendar system in use.
 712      * The ISO-8601 calendar system is the modern civil calendar system used today
 713      * in most of the world. It is equivalent to the proleptic Gregorian calendar
 714      * system, in which today's rules for leap years are applied for all time.
 715      *
 716      * @return the ISO chronology, not null
 717      */
 718     @Override
 719     public IsoChronology getChronology() {
 720         return IsoChronology.INSTANCE;
 721     }
 722 
 723     /**
 724      * Gets the era applicable at this date.
 725      * <p>
 726      * The official ISO-8601 standard does not define eras, however {@code IsoChronology} does.
 727      * It defines two eras, 'CE' from year one onwards and 'BCE' from year zero backwards.
 728      * Since dates before the Julian-Gregorian cutover are not in line with history,
 729      * the cutover between 'BCE' and 'CE' is also not aligned with the commonly used
 730      * eras, often referred to using 'BC' and 'AD'.
 731      * <p>
 732      * Users of this class should typically ignore this method as it exists primarily
 733      * to fulfill the {@link ChronoLocalDate} contract where it is necessary to support
 734      * the Japanese calendar system.
 735      *
 736      * @return the IsoEra applicable at this date, not null
 737      */
 738     @Override // override for Javadoc
 739     public IsoEra getEra() {
 740         return (getYear() >= 1 ? IsoEra.CE : IsoEra.BCE);
 741     }
 742 
 743     /**
 744      * Gets the year field.
 745      * <p>
 746      * This method returns the primitive {@code int} value for the year.
 747      * <p>
 748      * The year returned by this method is proleptic as per {@code get(YEAR)}.
 749      * To obtain the year-of-era, use {@code get(YEAR_OF_ERA)}.
 750      *
 751      * @return the year, from MIN_YEAR to MAX_YEAR
 752      */
 753     public int getYear() {
 754         return year;
 755     }
 756 
 757     /**
 758      * Gets the month-of-year field from 1 to 12.
 759      * <p>
 760      * This method returns the month as an {@code int} from 1 to 12.
 761      * Application code is frequently clearer if the enum {@link Month}
 762      * is used by calling {@link #getMonth()}.
 763      *
 764      * @return the month-of-year, from 1 to 12
 765      * @see #getMonth()
 766      */
 767     public int getMonthValue() {
 768         return month;
 769     }
 770 
 771     /**
 772      * Gets the month-of-year field using the {@code Month} enum.
 773      * <p>
 774      * This method returns the enum {@link Month} for the month.
 775      * This avoids confusion as to what {@code int} values mean.
 776      * If you need access to the primitive {@code int} value then the enum
 777      * provides the {@link Month#getValue() int value}.
 778      *
 779      * @return the month-of-year, not null
 780      * @see #getMonthValue()
 781      */
 782     public Month getMonth() {
 783         return Month.of(month);
 784     }
 785 
 786     /**
 787      * Gets the day-of-month field.
 788      * <p>
 789      * This method returns the primitive {@code int} value for the day-of-month.
 790      *
 791      * @return the day-of-month, from 1 to 31
 792      */
 793     public int getDayOfMonth() {
 794         return day;
 795     }
 796 
 797     /**
 798      * Gets the day-of-year field.
 799      * <p>
 800      * This method returns the primitive {@code int} value for the day-of-year.
 801      *
 802      * @return the day-of-year, from 1 to 365, or 366 in a leap year
 803      */
 804     public int getDayOfYear() {
 805         return getMonth().firstDayOfYear(isLeapYear()) + day - 1;
 806     }
 807 
 808     /**
 809      * Gets the day-of-week field, which is an enum {@code DayOfWeek}.
 810      * <p>
 811      * This method returns the enum {@link DayOfWeek} for the day-of-week.
 812      * This avoids confusion as to what {@code int} values mean.
 813      * If you need access to the primitive {@code int} value then the enum
 814      * provides the {@link DayOfWeek#getValue() int value}.
 815      * <p>
 816      * Additional information can be obtained from the {@code DayOfWeek}.
 817      * This includes textual names of the values.
 818      *
 819      * @return the day-of-week, not null
 820      */
 821     public DayOfWeek getDayOfWeek() {
 822         int dow0 = (int)Math.floorMod(toEpochDay() + 3, 7);
 823         return DayOfWeek.of(dow0 + 1);
 824     }
 825 
 826     //-----------------------------------------------------------------------
 827     /**
 828      * Checks if the year is a leap year, according to the ISO proleptic
 829      * calendar system rules.
 830      * <p>
 831      * This method applies the current rules for leap years across the whole time-line.
 832      * In general, a year is a leap year if it is divisible by four without
 833      * remainder. However, years divisible by 100, are not leap years, with
 834      * the exception of years divisible by 400 which are.
 835      * <p>
 836      * For example, 1904 is a leap year it is divisible by 4.
 837      * 1900 was not a leap year as it is divisible by 100, however 2000 was a
 838      * leap year as it is divisible by 400.
 839      * <p>
 840      * The calculation is proleptic - applying the same rules into the far future and far past.
 841      * This is historically inaccurate, but is correct for the ISO-8601 standard.
 842      *
 843      * @return true if the year is leap, false otherwise
 844      */
 845     @Override // override for Javadoc and performance
 846     public boolean isLeapYear() {
 847         return IsoChronology.INSTANCE.isLeapYear(year);
 848     }
 849 
 850     /**
 851      * Returns the length of the month represented by this date.
 852      * <p>
 853      * This returns the length of the month in days.
 854      * For example, a date in January would return 31.
 855      *
 856      * @return the length of the month in days
 857      */
 858     @Override
 859     public int lengthOfMonth() {
 860         switch (month) {
 861             case 2:
 862                 return (isLeapYear() ? 29 : 28);
 863             case 4:
 864             case 6:
 865             case 9:
 866             case 11:
 867                 return 30;
 868             default:
 869                 return 31;
 870         }
 871     }
 872 
 873     /**
 874      * Returns the length of the year represented by this date.
 875      * <p>
 876      * This returns the length of the year in days, either 365 or 366.
 877      *
 878      * @return 366 if the year is leap, 365 otherwise
 879      */
 880     @Override // override for Javadoc and performance
 881     public int lengthOfYear() {
 882         return (isLeapYear() ? 366 : 365);
 883     }
 884 
 885     //-----------------------------------------------------------------------
 886     /**
 887      * Returns an adjusted copy of this date.
 888      * <p>
 889      * This returns a {@code LocalDate}, based on this one, with the date adjusted.
 890      * The adjustment takes place using the specified adjuster strategy object.
 891      * Read the documentation of the adjuster to understand what adjustment will be made.
 892      * <p>
 893      * A simple adjuster might simply set the one of the fields, such as the year field.
 894      * A more complex adjuster might set the date to the last day of the month.
 895      * <p>
 896      * A selection of common adjustments is provided in
 897      * {@link java.time.temporal.TemporalAdjusters TemporalAdjusters}.
 898      * These include finding the "last day of the month" and "next Wednesday".
 899      * Key date-time classes also implement the {@code TemporalAdjuster} interface,
 900      * such as {@link Month} and {@link java.time.MonthDay MonthDay}.
 901      * The adjuster is responsible for handling special cases, such as the varying
 902      * lengths of month and leap years.
 903      * <p>
 904      * For example this code returns a date on the last day of July:
 905      * <pre>
 906      *  import static java.time.Month.*;
 907      *  import static java.time.temporal.TemporalAdjusters.*;
 908      *
 909      *  result = localDate.with(JULY).with(lastDayOfMonth());
 910      * </pre>
 911      * <p>
 912      * The result of this method is obtained by invoking the
 913      * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
 914      * specified adjuster passing {@code this} as the argument.
 915      * <p>
 916      * This instance is immutable and unaffected by this method call.
 917      *
 918      * @param adjuster the adjuster to use, not null
 919      * @return a {@code LocalDate} based on {@code this} with the adjustment made, not null
 920      * @throws DateTimeException if the adjustment cannot be made
 921      * @throws ArithmeticException if numeric overflow occurs
 922      */
 923     @Override
 924     public LocalDate with(TemporalAdjuster adjuster) {
 925         // optimizations
 926         if (adjuster instanceof LocalDate) {
 927             return (LocalDate) adjuster;
 928         }
 929         return (LocalDate) adjuster.adjustInto(this);
 930     }
 931 
 932     /**
 933      * Returns a copy of this date with the specified field set to a new value.
 934      * <p>
 935      * This returns a {@code LocalDate}, based on this one, with the value
 936      * for the specified field changed.
 937      * This can be used to change any supported field, such as the year, month or day-of-month.
 938      * If it is not possible to set the value, because the field is not supported or for
 939      * some other reason, an exception is thrown.
 940      * <p>
 941      * In some cases, changing the specified field can cause the resulting date to become invalid,
 942      * such as changing the month from 31st January to February would make the day-of-month invalid.
 943      * In cases like this, the field is responsible for resolving the date. Typically it will choose
 944      * the previous valid date, which would be the last valid day of February in this example.
 945      * <p>
 946      * If the field is a {@link ChronoField} then the adjustment is implemented here.
 947      * The supported fields behave as follows:
 948      * <ul>
 949      * <li>{@code DAY_OF_WEEK} -
 950      *  Returns a {@code LocalDate} with the specified day-of-week.
 951      *  The date is adjusted up to 6 days forward or backward within the boundary
 952      *  of a Monday to Sunday week.
 953      * <li>{@code ALIGNED_DAY_OF_WEEK_IN_MONTH} -
 954      *  Returns a {@code LocalDate} with the specified aligned-day-of-week.
 955      *  The date is adjusted to the specified month-based aligned-day-of-week.
 956      *  Aligned weeks are counted such that the first week of a given month starts
 957      *  on the first day of that month.
 958      *  This may cause the date to be moved up to 6 days into the following month.
 959      * <li>{@code ALIGNED_DAY_OF_WEEK_IN_YEAR} -
 960      *  Returns a {@code LocalDate} with the specified aligned-day-of-week.
 961      *  The date is adjusted to the specified year-based aligned-day-of-week.
 962      *  Aligned weeks are counted such that the first week of a given year starts
 963      *  on the first day of that year.
 964      *  This may cause the date to be moved up to 6 days into the following year.
 965      * <li>{@code DAY_OF_MONTH} -
 966      *  Returns a {@code LocalDate} with the specified day-of-month.
 967      *  The month and year will be unchanged. If the day-of-month is invalid for the
 968      *  year and month, then a {@code DateTimeException} is thrown.
 969      * <li>{@code DAY_OF_YEAR} -
 970      *  Returns a {@code LocalDate} with the specified day-of-year.
 971      *  The year will be unchanged. If the day-of-year is invalid for the
 972      *  year, then a {@code DateTimeException} is thrown.
 973      * <li>{@code EPOCH_DAY} -
 974      *  Returns a {@code LocalDate} with the specified epoch-day.
 975      *  This completely replaces the date and is equivalent to {@link #ofEpochDay(long)}.
 976      * <li>{@code ALIGNED_WEEK_OF_MONTH} -
 977      *  Returns a {@code LocalDate} with the specified aligned-week-of-month.
 978      *  Aligned weeks are counted such that the first week of a given month starts
 979      *  on the first day of that month.
 980      *  This adjustment moves the date in whole week chunks to match the specified week.
 981      *  The result will have the same day-of-week as this date.
 982      *  This may cause the date to be moved into the following month.
 983      * <li>{@code ALIGNED_WEEK_OF_YEAR} -
 984      *  Returns a {@code LocalDate} with the specified aligned-week-of-year.
 985      *  Aligned weeks are counted such that the first week of a given year starts
 986      *  on the first day of that year.
 987      *  This adjustment moves the date in whole week chunks to match the specified week.
 988      *  The result will have the same day-of-week as this date.
 989      *  This may cause the date to be moved into the following year.
 990      * <li>{@code MONTH_OF_YEAR} -
 991      *  Returns a {@code LocalDate} with the specified month-of-year.
 992      *  The year will be unchanged. The day-of-month will also be unchanged,
 993      *  unless it would be invalid for the new month and year. In that case, the
 994      *  day-of-month is adjusted to the maximum valid value for the new month and year.
 995      * <li>{@code PROLEPTIC_MONTH} -
 996      *  Returns a {@code LocalDate} with the specified proleptic-month.
 997      *  The day-of-month will be unchanged, unless it would be invalid for the new month
 998      *  and year. In that case, the day-of-month is adjusted to the maximum valid value
 999      *  for the new month and year.
1000      * <li>{@code YEAR_OF_ERA} -
1001      *  Returns a {@code LocalDate} with the specified year-of-era.
1002      *  The era and month will be unchanged. The day-of-month will also be unchanged,
1003      *  unless it would be invalid for the new month and year. In that case, the
1004      *  day-of-month is adjusted to the maximum valid value for the new month and year.
1005      * <li>{@code YEAR} -
1006      *  Returns a {@code LocalDate} with the specified year.
1007      *  The month will be unchanged. The day-of-month will also be unchanged,
1008      *  unless it would be invalid for the new month and year. In that case, the
1009      *  day-of-month is adjusted to the maximum valid value for the new month and year.
1010      * <li>{@code ERA} -
1011      *  Returns a {@code LocalDate} with the specified era.
1012      *  The year-of-era and month will be unchanged. The day-of-month will also be unchanged,
1013      *  unless it would be invalid for the new month and year. In that case, the
1014      *  day-of-month is adjusted to the maximum valid value for the new month and year.
1015      * </ul>
1016      * <p>
1017      * In all cases, if the new value is outside the valid range of values for the field
1018      * then a {@code DateTimeException} will be thrown.
1019      * <p>
1020      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
1021      * <p>
1022      * If the field is not a {@code ChronoField}, then the result of this method
1023      * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
1024      * passing {@code this} as the argument. In this case, the field determines
1025      * whether and how to adjust the instant.
1026      * <p>
1027      * This instance is immutable and unaffected by this method call.
1028      *
1029      * @param field  the field to set in the result, not null
1030      * @param newValue  the new value of the field in the result
1031      * @return a {@code LocalDate} based on {@code this} with the specified field set, not null
1032      * @throws DateTimeException if the field cannot be set
1033      * @throws UnsupportedTemporalTypeException if the field is not supported
1034      * @throws ArithmeticException if numeric overflow occurs
1035      */
1036     @Override
1037     public LocalDate with(TemporalField field, long newValue) {
1038         if (field instanceof ChronoField) {
1039             ChronoField f = (ChronoField) field;
1040             f.checkValidValue(newValue);
1041             switch (f) {
1042                 case DAY_OF_WEEK: return plusDays(newValue - getDayOfWeek().getValue());
1043                 case ALIGNED_DAY_OF_WEEK_IN_MONTH: return plusDays(newValue - getLong(ALIGNED_DAY_OF_WEEK_IN_MONTH));
1044                 case ALIGNED_DAY_OF_WEEK_IN_YEAR: return plusDays(newValue - getLong(ALIGNED_DAY_OF_WEEK_IN_YEAR));
1045                 case DAY_OF_MONTH: return withDayOfMonth((int) newValue);
1046                 case DAY_OF_YEAR: return withDayOfYear((int) newValue);
1047                 case EPOCH_DAY: return LocalDate.ofEpochDay(newValue);
1048                 case ALIGNED_WEEK_OF_MONTH: return plusWeeks(newValue - getLong(ALIGNED_WEEK_OF_MONTH));
1049                 case ALIGNED_WEEK_OF_YEAR: return plusWeeks(newValue - getLong(ALIGNED_WEEK_OF_YEAR));
1050                 case MONTH_OF_YEAR: return withMonth((int) newValue);
1051                 case PROLEPTIC_MONTH: return plusMonths(newValue - getProlepticMonth());
1052                 case YEAR_OF_ERA: return withYear((int) (year >= 1 ? newValue : 1 - newValue));
1053                 case YEAR: return withYear((int) newValue);
1054                 case ERA: return (getLong(ERA) == newValue ? this : withYear(1 - year));
1055             }
1056             throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
1057         }
1058         return field.adjustInto(this, newValue);
1059     }
1060 
1061     //-----------------------------------------------------------------------
1062     /**
1063      * Returns a copy of this {@code LocalDate} with the year altered.
1064      * <p>
1065      * If the day-of-month is invalid for the year, it will be changed to the last valid day of the month.
1066      * <p>
1067      * This instance is immutable and unaffected by this method call.
1068      *
1069      * @param year  the year to set in the result, from MIN_YEAR to MAX_YEAR
1070      * @return a {@code LocalDate} based on this date with the requested year, not null
1071      * @throws DateTimeException if the year value is invalid
1072      */
1073     public LocalDate withYear(int year) {
1074         if (this.year == year) {
1075             return this;
1076         }
1077         YEAR.checkValidValue(year);
1078         return resolvePreviousValid(year, month, day);
1079     }
1080 
1081     /**
1082      * Returns a copy of this {@code LocalDate} with the month-of-year altered.
1083      * <p>
1084      * If the day-of-month is invalid for the year, it will be changed to the last valid day of the month.
1085      * <p>
1086      * This instance is immutable and unaffected by this method call.
1087      *
1088      * @param month  the month-of-year to set in the result, from 1 (January) to 12 (December)
1089      * @return a {@code LocalDate} based on this date with the requested month, not null
1090      * @throws DateTimeException if the month-of-year value is invalid
1091      */
1092     public LocalDate withMonth(int month) {
1093         if (this.month == month) {
1094             return this;
1095         }
1096         MONTH_OF_YEAR.checkValidValue(month);
1097         return resolvePreviousValid(year, month, day);
1098     }
1099 
1100     /**
1101      * Returns a copy of this {@code LocalDate} with the day-of-month altered.
1102      * <p>
1103      * If the resulting date is invalid, an exception is thrown.
1104      * <p>
1105      * This instance is immutable and unaffected by this method call.
1106      *
1107      * @param dayOfMonth  the day-of-month to set in the result, from 1 to 28-31
1108      * @return a {@code LocalDate} based on this date with the requested day, not null
1109      * @throws DateTimeException if the day-of-month value is invalid,
1110      *  or if the day-of-month is invalid for the month-year
1111      */
1112     public LocalDate withDayOfMonth(int dayOfMonth) {
1113         if (this.day == dayOfMonth) {
1114             return this;
1115         }
1116         return of(year, month, dayOfMonth);
1117     }
1118 
1119     /**
1120      * Returns a copy of this {@code LocalDate} with the day-of-year altered.
1121      * <p>
1122      * If the resulting date is invalid, an exception is thrown.
1123      * <p>
1124      * This instance is immutable and unaffected by this method call.
1125      *
1126      * @param dayOfYear  the day-of-year to set in the result, from 1 to 365-366
1127      * @return a {@code LocalDate} based on this date with the requested day, not null
1128      * @throws DateTimeException if the day-of-year value is invalid,
1129      *  or if the day-of-year is invalid for the year
1130      */
1131     public LocalDate withDayOfYear(int dayOfYear) {
1132         if (this.getDayOfYear() == dayOfYear) {
1133             return this;
1134         }
1135         return ofYearDay(year, dayOfYear);
1136     }
1137 
1138     //-----------------------------------------------------------------------
1139     /**
1140      * Returns a copy of this date with the specified amount added.
1141      * <p>
1142      * This returns a {@code LocalDate}, based on this one, with the specified amount added.
1143      * The amount is typically {@link Period} but may be any other type implementing
1144      * the {@link TemporalAmount} interface.
1145      * <p>
1146      * The calculation is delegated to the amount object by calling
1147      * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
1148      * to implement the addition in any way it wishes, however it typically
1149      * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
1150      * of the amount implementation to determine if it can be successfully added.
1151      * <p>
1152      * This instance is immutable and unaffected by this method call.
1153      *
1154      * @param amountToAdd  the amount to add, not null
1155      * @return a {@code LocalDate} based on this date with the addition made, not null
1156      * @throws DateTimeException if the addition cannot be made
1157      * @throws ArithmeticException if numeric overflow occurs
1158      */
1159     @Override
1160     public LocalDate plus(TemporalAmount amountToAdd) {
1161         if (amountToAdd instanceof Period) {
1162             Period periodToAdd = (Period) amountToAdd;
1163             return plusMonths(periodToAdd.toTotalMonths()).plusDays(periodToAdd.getDays());
1164         }
1165         Objects.requireNonNull(amountToAdd, "amountToAdd");
1166         return (LocalDate) amountToAdd.addTo(this);
1167     }
1168 
1169     /**
1170      * Returns a copy of this date with the specified amount added.
1171      * <p>
1172      * This returns a {@code LocalDate}, based on this one, with the amount
1173      * in terms of the unit added. If it is not possible to add the amount, because the
1174      * unit is not supported or for some other reason, an exception is thrown.
1175      * <p>
1176      * In some cases, adding the amount can cause the resulting date to become invalid.
1177      * For example, adding one month to 31st January would result in 31st February.
1178      * In cases like this, the unit is responsible for resolving the date.
1179      * Typically it will choose the previous valid date, which would be the last valid
1180      * day of February in this example.
1181      * <p>
1182      * If the field is a {@link ChronoUnit} then the addition is implemented here.
1183      * The supported fields behave as follows:
1184      * <ul>
1185      * <li>{@code DAYS} -
1186      *  Returns a {@code LocalDate} with the specified number of days added.
1187      *  This is equivalent to {@link #plusDays(long)}.
1188      * <li>{@code WEEKS} -
1189      *  Returns a {@code LocalDate} with the specified number of weeks added.
1190      *  This is equivalent to {@link #plusWeeks(long)} and uses a 7 day week.
1191      * <li>{@code MONTHS} -
1192      *  Returns a {@code LocalDate} with the specified number of months added.
1193      *  This is equivalent to {@link #plusMonths(long)}.
1194      *  The day-of-month will be unchanged unless it would be invalid for the new
1195      *  month and year. In that case, the day-of-month is adjusted to the maximum
1196      *  valid value for the new month and year.
1197      * <li>{@code YEARS} -
1198      *  Returns a {@code LocalDate} with the specified number of years added.
1199      *  This is equivalent to {@link #plusYears(long)}.
1200      *  The day-of-month will be unchanged unless it would be invalid for the new
1201      *  month and year. In that case, the day-of-month is adjusted to the maximum
1202      *  valid value for the new month and year.
1203      * <li>{@code DECADES} -
1204      *  Returns a {@code LocalDate} with the specified number of decades added.
1205      *  This is equivalent to calling {@link #plusYears(long)} with the amount
1206      *  multiplied by 10.
1207      *  The day-of-month will be unchanged unless it would be invalid for the new
1208      *  month and year. In that case, the day-of-month is adjusted to the maximum
1209      *  valid value for the new month and year.
1210      * <li>{@code CENTURIES} -
1211      *  Returns a {@code LocalDate} with the specified number of centuries added.
1212      *  This is equivalent to calling {@link #plusYears(long)} with the amount
1213      *  multiplied by 100.
1214      *  The day-of-month will be unchanged unless it would be invalid for the new
1215      *  month and year. In that case, the day-of-month is adjusted to the maximum
1216      *  valid value for the new month and year.
1217      * <li>{@code MILLENNIA} -
1218      *  Returns a {@code LocalDate} with the specified number of millennia added.
1219      *  This is equivalent to calling {@link #plusYears(long)} with the amount
1220      *  multiplied by 1,000.
1221      *  The day-of-month will be unchanged unless it would be invalid for the new
1222      *  month and year. In that case, the day-of-month is adjusted to the maximum
1223      *  valid value for the new month and year.
1224      * <li>{@code ERAS} -
1225      *  Returns a {@code LocalDate} with the specified number of eras added.
1226      *  Only two eras are supported so the amount must be one, zero or minus one.
1227      *  If the amount is non-zero then the year is changed such that the year-of-era
1228      *  is unchanged.
1229      *  The day-of-month will be unchanged unless it would be invalid for the new
1230      *  month and year. In that case, the day-of-month is adjusted to the maximum
1231      *  valid value for the new month and year.
1232      * </ul>
1233      * <p>
1234      * All other {@code ChronoUnit} instances will throw an {@code UnsupportedTemporalTypeException}.
1235      * <p>
1236      * If the field is not a {@code ChronoUnit}, then the result of this method
1237      * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
1238      * passing {@code this} as the argument. In this case, the unit determines
1239      * whether and how to perform the addition.
1240      * <p>
1241      * This instance is immutable and unaffected by this method call.
1242      *
1243      * @param amountToAdd  the amount of the unit to add to the result, may be negative
1244      * @param unit  the unit of the amount to add, not null
1245      * @return a {@code LocalDate} based on this date with the specified amount added, not null
1246      * @throws DateTimeException if the addition cannot be made
1247      * @throws UnsupportedTemporalTypeException if the unit is not supported
1248      * @throws ArithmeticException if numeric overflow occurs
1249      */
1250     @Override
1251     public LocalDate plus(long amountToAdd, TemporalUnit unit) {
1252         if (unit instanceof ChronoUnit) {
1253             ChronoUnit f = (ChronoUnit) unit;
1254             switch (f) {
1255                 case DAYS: return plusDays(amountToAdd);
1256                 case WEEKS: return plusWeeks(amountToAdd);
1257                 case MONTHS: return plusMonths(amountToAdd);
1258                 case YEARS: return plusYears(amountToAdd);
1259                 case DECADES: return plusYears(Math.multiplyExact(amountToAdd, 10));
1260                 case CENTURIES: return plusYears(Math.multiplyExact(amountToAdd, 100));
1261                 case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000));
1262                 case ERAS: return with(ERA, Math.addExact(getLong(ERA), amountToAdd));
1263             }
1264             throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
1265         }
1266         return unit.addTo(this, amountToAdd);
1267     }
1268 
1269     //-----------------------------------------------------------------------
1270     /**
1271      * Returns a copy of this {@code LocalDate} with the specified number of years added.
1272      * <p>
1273      * This method adds the specified amount to the years field in three steps:
1274      * <ol>
1275      * <li>Add the input years to the year field</li>
1276      * <li>Check if the resulting date would be invalid</li>
1277      * <li>Adjust the day-of-month to the last valid day if necessary</li>
1278      * </ol>
1279      * <p>
1280      * For example, 2008-02-29 (leap year) plus one year would result in the
1281      * invalid date 2009-02-29 (standard year). Instead of returning an invalid
1282      * result, the last valid day of the month, 2009-02-28, is selected instead.
1283      * <p>
1284      * This instance is immutable and unaffected by this method call.
1285      *
1286      * @param yearsToAdd  the years to add, may be negative
1287      * @return a {@code LocalDate} based on this date with the years added, not null
1288      * @throws DateTimeException if the result exceeds the supported date range
1289      */
1290     public LocalDate plusYears(long yearsToAdd) {
1291         if (yearsToAdd == 0) {
1292             return this;
1293         }
1294         int newYear = YEAR.checkValidIntValue(year + yearsToAdd);  // safe overflow
1295         return resolvePreviousValid(newYear, month, day);
1296     }
1297 
1298     /**
1299      * Returns a copy of this {@code LocalDate} with the specified number of months added.
1300      * <p>
1301      * This method adds the specified amount to the months field in three steps:
1302      * <ol>
1303      * <li>Add the input months to the month-of-year field</li>
1304      * <li>Check if the resulting date would be invalid</li>
1305      * <li>Adjust the day-of-month to the last valid day if necessary</li>
1306      * </ol>
1307      * <p>
1308      * For example, 2007-03-31 plus one month would result in the invalid date
1309      * 2007-04-31. Instead of returning an invalid result, the last valid day
1310      * of the month, 2007-04-30, is selected instead.
1311      * <p>
1312      * This instance is immutable and unaffected by this method call.
1313      *
1314      * @param monthsToAdd  the months to add, may be negative
1315      * @return a {@code LocalDate} based on this date with the months added, not null
1316      * @throws DateTimeException if the result exceeds the supported date range
1317      */
1318     public LocalDate plusMonths(long monthsToAdd) {
1319         if (monthsToAdd == 0) {
1320             return this;
1321         }
1322         long monthCount = year * 12L + (month - 1);
1323         long calcMonths = monthCount + monthsToAdd;  // safe overflow
1324         int newYear = YEAR.checkValidIntValue(Math.floorDiv(calcMonths, 12));
1325         int newMonth = (int)Math.floorMod(calcMonths, 12) + 1;
1326         return resolvePreviousValid(newYear, newMonth, day);
1327     }
1328 
1329     /**
1330      * Returns a copy of this {@code LocalDate} with the specified number of weeks added.
1331      * <p>
1332      * This method adds the specified amount in weeks to the days field incrementing
1333      * the month and year fields as necessary to ensure the result remains valid.
1334      * The result is only invalid if the maximum/minimum year is exceeded.
1335      * <p>
1336      * For example, 2008-12-31 plus one week would result in 2009-01-07.
1337      * <p>
1338      * This instance is immutable and unaffected by this method call.
1339      *
1340      * @param weeksToAdd  the weeks to add, may be negative
1341      * @return a {@code LocalDate} based on this date with the weeks added, not null
1342      * @throws DateTimeException if the result exceeds the supported date range
1343      */
1344     public LocalDate plusWeeks(long weeksToAdd) {
1345         return plusDays(Math.multiplyExact(weeksToAdd, 7));
1346     }
1347 
1348     /**
1349      * Returns a copy of this {@code LocalDate} with the specified number of days added.
1350      * <p>
1351      * This method adds the specified amount to the days field incrementing the
1352      * month and year fields as necessary to ensure the result remains valid.
1353      * The result is only invalid if the maximum/minimum year is exceeded.
1354      * <p>
1355      * For example, 2008-12-31 plus one day would result in 2009-01-01.
1356      * <p>
1357      * This instance is immutable and unaffected by this method call.
1358      *
1359      * @param daysToAdd  the days to add, may be negative
1360      * @return a {@code LocalDate} based on this date with the days added, not null
1361      * @throws DateTimeException if the result exceeds the supported date range
1362      */
1363     public LocalDate plusDays(long daysToAdd) {
1364         if (daysToAdd == 0) {
1365             return this;
1366         }
1367         long mjDay = Math.addExact(toEpochDay(), daysToAdd);
1368         return LocalDate.ofEpochDay(mjDay);
1369     }
1370 
1371     //-----------------------------------------------------------------------
1372     /**
1373      * Returns a copy of this date with the specified amount subtracted.
1374      * <p>
1375      * This returns a {@code LocalDate}, based on this one, with the specified amount subtracted.
1376      * The amount is typically {@link Period} but may be any other type implementing
1377      * the {@link TemporalAmount} interface.
1378      * <p>
1379      * The calculation is delegated to the amount object by calling
1380      * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
1381      * to implement the subtraction in any way it wishes, however it typically
1382      * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
1383      * of the amount implementation to determine if it can be successfully subtracted.
1384      * <p>
1385      * This instance is immutable and unaffected by this method call.
1386      *
1387      * @param amountToSubtract  the amount to subtract, not null
1388      * @return a {@code LocalDate} based on this date with the subtraction made, not null
1389      * @throws DateTimeException if the subtraction cannot be made
1390      * @throws ArithmeticException if numeric overflow occurs
1391      */
1392     @Override
1393     public LocalDate minus(TemporalAmount amountToSubtract) {
1394         if (amountToSubtract instanceof Period) {
1395             Period periodToSubtract = (Period) amountToSubtract;
1396             return minusMonths(periodToSubtract.toTotalMonths()).minusDays(periodToSubtract.getDays());
1397         }
1398         Objects.requireNonNull(amountToSubtract, "amountToSubtract");
1399         return (LocalDate) amountToSubtract.subtractFrom(this);
1400     }
1401 
1402     /**
1403      * Returns a copy of this date with the specified amount subtracted.
1404      * <p>
1405      * This returns a {@code LocalDate}, based on this one, with the amount
1406      * in terms of the unit subtracted. If it is not possible to subtract the amount,
1407      * because the unit is not supported or for some other reason, an exception is thrown.
1408      * <p>
1409      * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
1410      * See that method for a full description of how addition, and thus subtraction, works.
1411      * <p>
1412      * This instance is immutable and unaffected by this method call.
1413      *
1414      * @param amountToSubtract  the amount of the unit to subtract from the result, may be negative
1415      * @param unit  the unit of the amount to subtract, not null
1416      * @return a {@code LocalDate} based on this date with the specified amount subtracted, not null
1417      * @throws DateTimeException if the subtraction cannot be made
1418      * @throws UnsupportedTemporalTypeException if the unit is not supported
1419      * @throws ArithmeticException if numeric overflow occurs
1420      */
1421     @Override
1422     public LocalDate minus(long amountToSubtract, TemporalUnit unit) {
1423         return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
1424     }
1425 
1426     //-----------------------------------------------------------------------
1427     /**
1428      * Returns a copy of this {@code LocalDate} with the specified number of years subtracted.
1429      * <p>
1430      * This method subtracts the specified amount from the years field in three steps:
1431      * <ol>
1432      * <li>Subtract the input years from the year field</li>
1433      * <li>Check if the resulting date would be invalid</li>
1434      * <li>Adjust the day-of-month to the last valid day if necessary</li>
1435      * </ol>
1436      * <p>
1437      * For example, 2008-02-29 (leap year) minus one year would result in the
1438      * invalid date 2007-02-29 (standard year). Instead of returning an invalid
1439      * result, the last valid day of the month, 2007-02-28, is selected instead.
1440      * <p>
1441      * This instance is immutable and unaffected by this method call.
1442      *
1443      * @param yearsToSubtract  the years to subtract, may be negative
1444      * @return a {@code LocalDate} based on this date with the years subtracted, not null
1445      * @throws DateTimeException if the result exceeds the supported date range
1446      */
1447     public LocalDate minusYears(long yearsToSubtract) {
1448         return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
1449     }
1450 
1451     /**
1452      * Returns a copy of this {@code LocalDate} with the specified number of months subtracted.
1453      * <p>
1454      * This method subtracts the specified amount from the months field in three steps:
1455      * <ol>
1456      * <li>Subtract the input months from the month-of-year field</li>
1457      * <li>Check if the resulting date would be invalid</li>
1458      * <li>Adjust the day-of-month to the last valid day if necessary</li>
1459      * </ol>
1460      * <p>
1461      * For example, 2007-03-31 minus one month would result in the invalid date
1462      * 2007-02-31. Instead of returning an invalid result, the last valid day
1463      * of the month, 2007-02-28, is selected instead.
1464      * <p>
1465      * This instance is immutable and unaffected by this method call.
1466      *
1467      * @param monthsToSubtract  the months to subtract, may be negative
1468      * @return a {@code LocalDate} based on this date with the months subtracted, not null
1469      * @throws DateTimeException if the result exceeds the supported date range
1470      */
1471     public LocalDate minusMonths(long monthsToSubtract) {
1472         return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
1473     }
1474 
1475     /**
1476      * Returns a copy of this {@code LocalDate} with the specified number of weeks subtracted.
1477      * <p>
1478      * This method subtracts the specified amount in weeks from the days field decrementing
1479      * the month and year fields as necessary to ensure the result remains valid.
1480      * The result is only invalid if the maximum/minimum year is exceeded.
1481      * <p>
1482      * For example, 2009-01-07 minus one week would result in 2008-12-31.
1483      * <p>
1484      * This instance is immutable and unaffected by this method call.
1485      *
1486      * @param weeksToSubtract  the weeks to subtract, may be negative
1487      * @return a {@code LocalDate} based on this date with the weeks subtracted, not null
1488      * @throws DateTimeException if the result exceeds the supported date range
1489      */
1490     public LocalDate minusWeeks(long weeksToSubtract) {
1491         return (weeksToSubtract == Long.MIN_VALUE ? plusWeeks(Long.MAX_VALUE).plusWeeks(1) : plusWeeks(-weeksToSubtract));
1492     }
1493 
1494     /**
1495      * Returns a copy of this {@code LocalDate} with the specified number of days subtracted.
1496      * <p>
1497      * This method subtracts the specified amount from the days field decrementing the
1498      * month and year fields as necessary to ensure the result remains valid.
1499      * The result is only invalid if the maximum/minimum year is exceeded.
1500      * <p>
1501      * For example, 2009-01-01 minus one day would result in 2008-12-31.
1502      * <p>
1503      * This instance is immutable and unaffected by this method call.
1504      *
1505      * @param daysToSubtract  the days to subtract, may be negative
1506      * @return a {@code LocalDate} based on this date with the days subtracted, not null
1507      * @throws DateTimeException if the result exceeds the supported date range
1508      */
1509     public LocalDate minusDays(long daysToSubtract) {
1510         return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
1511     }
1512 
1513     //-----------------------------------------------------------------------
1514     /**
1515      * Queries this date using the specified query.
1516      * <p>
1517      * This queries this date using the specified query strategy object.
1518      * The {@code TemporalQuery} object defines the logic to be used to
1519      * obtain the result. Read the documentation of the query to understand
1520      * what the result of this method will be.
1521      * <p>
1522      * The result of this method is obtained by invoking the
1523      * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
1524      * specified query passing {@code this} as the argument.
1525      *
1526      * @param <R> the type of the result
1527      * @param query  the query to invoke, not null
1528      * @return the query result, null may be returned (defined by the query)
1529      * @throws DateTimeException if unable to query (defined by the query)
1530      * @throws ArithmeticException if numeric overflow occurs (defined by the query)
1531      */
1532     @SuppressWarnings("unchecked")
1533     @Override
1534     public <R> R query(TemporalQuery<R> query) {
1535         if (query == TemporalQueries.localDate()) {
1536             return (R) this;
1537         }
1538         return ChronoLocalDate.super.query(query);
1539     }
1540 
1541     /**
1542      * Adjusts the specified temporal object to have the same date as this object.
1543      * <p>
1544      * This returns a temporal object of the same observable type as the input
1545      * with the date changed to be the same as this.
1546      * <p>
1547      * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
1548      * passing {@link ChronoField#EPOCH_DAY} as the field.
1549      * <p>
1550      * In most cases, it is clearer to reverse the calling pattern by using
1551      * {@link Temporal#with(TemporalAdjuster)}:
1552      * <pre>
1553      *   // these two lines are equivalent, but the second approach is recommended
1554      *   temporal = thisLocalDate.adjustInto(temporal);
1555      *   temporal = temporal.with(thisLocalDate);
1556      * </pre>
1557      * <p>
1558      * This instance is immutable and unaffected by this method call.
1559      *
1560      * @param temporal  the target object to be adjusted, not null
1561      * @return the adjusted object, not null
1562      * @throws DateTimeException if unable to make the adjustment
1563      * @throws ArithmeticException if numeric overflow occurs
1564      */
1565     @Override  // override for Javadoc
1566     public Temporal adjustInto(Temporal temporal) {
1567         return ChronoLocalDate.super.adjustInto(temporal);
1568     }
1569 
1570     /**
1571      * Calculates the amount of time until another date in terms of the specified unit.
1572      * <p>
1573      * This calculates the amount of time between two {@code LocalDate}
1574      * objects in terms of a single {@code TemporalUnit}.
1575      * The start and end points are {@code this} and the specified date.
1576      * The result will be negative if the end is before the start.
1577      * The {@code Temporal} passed to this method is converted to a
1578      * {@code LocalDate} using {@link #from(TemporalAccessor)}.
1579      * For example, the amount in days between two dates can be calculated
1580      * using {@code startDate.until(endDate, DAYS)}.
1581      * <p>
1582      * The calculation returns a whole number, representing the number of
1583      * complete units between the two dates.
1584      * For example, the amount in months between 2012-06-15 and 2012-08-14
1585      * will only be one month as it is one day short of two months.
1586      * <p>
1587      * There are two equivalent ways of using this method.
1588      * The first is to invoke this method.
1589      * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
1590      * <pre>
1591      *   // these two lines are equivalent
1592      *   amount = start.until(end, MONTHS);
1593      *   amount = MONTHS.between(start, end);
1594      * </pre>
1595      * The choice should be made based on which makes the code more readable.
1596      * <p>
1597      * The calculation is implemented in this method for {@link ChronoUnit}.
1598      * The units {@code DAYS}, {@code WEEKS}, {@code MONTHS}, {@code YEARS},
1599      * {@code DECADES}, {@code CENTURIES}, {@code MILLENNIA} and {@code ERAS}
1600      * are supported. Other {@code ChronoUnit} values will throw an exception.
1601      * <p>
1602      * If the unit is not a {@code ChronoUnit}, then the result of this method
1603      * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
1604      * passing {@code this} as the first argument and the converted input temporal
1605      * as the second argument.
1606      * <p>
1607      * This instance is immutable and unaffected by this method call.
1608      *
1609      * @param endExclusive  the end date, exclusive, which is converted to a {@code LocalDate}, not null
1610      * @param unit  the unit to measure the amount in, not null
1611      * @return the amount of time between this date and the end date
1612      * @throws DateTimeException if the amount cannot be calculated, or the end
1613      *  temporal cannot be converted to a {@code LocalDate}
1614      * @throws UnsupportedTemporalTypeException if the unit is not supported
1615      * @throws ArithmeticException if numeric overflow occurs
1616      */
1617     @Override
1618     public long until(Temporal endExclusive, TemporalUnit unit) {
1619         LocalDate end = LocalDate.from(endExclusive);
1620         if (unit instanceof ChronoUnit) {
1621             switch ((ChronoUnit) unit) {
1622                 case DAYS: return daysUntil(end);
1623                 case WEEKS: return daysUntil(end) / 7;
1624                 case MONTHS: return monthsUntil(end);
1625                 case YEARS: return monthsUntil(end) / 12;
1626                 case DECADES: return monthsUntil(end) / 120;
1627                 case CENTURIES: return monthsUntil(end) / 1200;
1628                 case MILLENNIA: return monthsUntil(end) / 12000;
1629                 case ERAS: return end.getLong(ERA) - getLong(ERA);
1630             }
1631             throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
1632         }
1633         return unit.between(this, end);
1634     }
1635 
1636     long daysUntil(LocalDate end) {
1637         return end.toEpochDay() - toEpochDay();  // no overflow
1638     }
1639 
1640     private long monthsUntil(LocalDate end) {
1641         long packed1 = getProlepticMonth() * 32L + getDayOfMonth();  // no overflow
1642         long packed2 = end.getProlepticMonth() * 32L + end.getDayOfMonth();  // no overflow
1643         return (packed2 - packed1) / 32;
1644     }
1645 
1646     /**
1647      * Calculates the period between this date and another date as a {@code Period}.
1648      * <p>
1649      * This calculates the period between two dates in terms of years, months and days.
1650      * The start and end points are {@code this} and the specified date.
1651      * The result will be negative if the end is before the start.
1652      * The negative sign will be the same in each of year, month and day.
1653      * <p>
1654      * The calculation is performed using the ISO calendar system.
1655      * If necessary, the input date will be converted to ISO.
1656      * <p>
1657      * The start date is included, but the end date is not.
1658      * The period is calculated by removing complete months, then calculating
1659      * the remaining number of days, adjusting to ensure that both have the same sign.
1660      * The number of months is then normalized into years and months based on a 12 month year.
1661      * A month is considered to be complete if the end day-of-month is greater
1662      * than or equal to the start day-of-month.
1663      * For example, from {@code 2010-01-15} to {@code 2011-03-18} is "1 year, 2 months and 3 days".
1664      * <p>
1665      * There are two equivalent ways of using this method.
1666      * The first is to invoke this method.
1667      * The second is to use {@link Period#between(LocalDate, LocalDate)}:
1668      * <pre>
1669      *   // these two lines are equivalent
1670      *   period = start.until(end);
1671      *   period = Period.between(start, end);
1672      * </pre>
1673      * The choice should be made based on which makes the code more readable.
1674      *
1675      * @param endDateExclusive  the end date, exclusive, which may be in any chronology, not null
1676      * @return the period between this date and the end date, not null
1677      */
1678     @Override
1679     public Period until(ChronoLocalDate endDateExclusive) {
1680         LocalDate end = LocalDate.from(endDateExclusive);
1681         long totalMonths = end.getProlepticMonth() - this.getProlepticMonth();  // safe
1682         int days = end.day - this.day;
1683         if (totalMonths > 0 && days < 0) {
1684             totalMonths--;
1685             LocalDate calcDate = this.plusMonths(totalMonths);
1686             days = (int) (end.toEpochDay() - calcDate.toEpochDay());  // safe
1687         } else if (totalMonths < 0 && days > 0) {
1688             totalMonths++;
1689             days -= end.lengthOfMonth();
1690         }
1691         long years = totalMonths / 12;  // safe
1692         int months = (int) (totalMonths % 12);  // safe
1693         return Period.of(Math.toIntExact(years), months, days);
1694     }
1695 
1696     /**
1697      * Formats this date using the specified formatter.
1698      * <p>
1699      * This date will be passed to the formatter to produce a string.
1700      *
1701      * @param formatter  the formatter to use, not null
1702      * @return the formatted date string, not null
1703      * @throws DateTimeException if an error occurs during printing
1704      */
1705     @Override  // override for Javadoc and performance
1706     public String format(DateTimeFormatter formatter) {
1707         Objects.requireNonNull(formatter, "formatter");
1708         return formatter.format(this);
1709     }
1710 
1711     //-----------------------------------------------------------------------
1712     /**
1713      * Combines this date with a time to create a {@code LocalDateTime}.
1714      * <p>
1715      * This returns a {@code LocalDateTime} formed from this date at the specified time.
1716      * All possible combinations of date and time are valid.
1717      *
1718      * @param time  the time to combine with, not null
1719      * @return the local date-time formed from this date and the specified time, not null
1720      */
1721     @Override
1722     public LocalDateTime atTime(LocalTime time) {
1723         return LocalDateTime.of(this, time);
1724     }
1725 
1726     /**
1727      * Combines this date with a time to create a {@code LocalDateTime}.
1728      * <p>
1729      * This returns a {@code LocalDateTime} formed from this date at the
1730      * specified hour and minute.
1731      * The seconds and nanosecond fields will be set to zero.
1732      * The individual time fields must be within their valid range.
1733      * All possible combinations of date and time are valid.
1734      *
1735      * @param hour  the hour-of-day to use, from 0 to 23
1736      * @param minute  the minute-of-hour to use, from 0 to 59
1737      * @return the local date-time formed from this date and the specified time, not null
1738      * @throws DateTimeException if the value of any field is out of range
1739      */
1740     public LocalDateTime atTime(int hour, int minute) {
1741         return atTime(LocalTime.of(hour, minute));
1742     }
1743 
1744     /**
1745      * Combines this date with a time to create a {@code LocalDateTime}.
1746      * <p>
1747      * This returns a {@code LocalDateTime} formed from this date at the
1748      * specified hour, minute and second.
1749      * The nanosecond field will be set to zero.
1750      * The individual time fields must be within their valid range.
1751      * All possible combinations of date and time are valid.
1752      *
1753      * @param hour  the hour-of-day to use, from 0 to 23
1754      * @param minute  the minute-of-hour to use, from 0 to 59
1755      * @param second  the second-of-minute to represent, from 0 to 59
1756      * @return the local date-time formed from this date and the specified time, not null
1757      * @throws DateTimeException if the value of any field is out of range
1758      */
1759     public LocalDateTime atTime(int hour, int minute, int second) {
1760         return atTime(LocalTime.of(hour, minute, second));
1761     }
1762 
1763     /**
1764      * Combines this date with a time to create a {@code LocalDateTime}.
1765      * <p>
1766      * This returns a {@code LocalDateTime} formed from this date at the
1767      * specified hour, minute, second and nanosecond.
1768      * The individual time fields must be within their valid range.
1769      * All possible combinations of date and time are valid.
1770      *
1771      * @param hour  the hour-of-day to use, from 0 to 23
1772      * @param minute  the minute-of-hour to use, from 0 to 59
1773      * @param second  the second-of-minute to represent, from 0 to 59
1774      * @param nanoOfSecond  the nano-of-second to represent, from 0 to 999,999,999
1775      * @return the local date-time formed from this date and the specified time, not null
1776      * @throws DateTimeException if the value of any field is out of range
1777      */
1778     public LocalDateTime atTime(int hour, int minute, int second, int nanoOfSecond) {
1779         return atTime(LocalTime.of(hour, minute, second, nanoOfSecond));
1780     }
1781 
1782     /**
1783      * Combines this date with an offset time to create an {@code OffsetDateTime}.
1784      * <p>
1785      * This returns an {@code OffsetDateTime} formed from this date at the specified time.
1786      * All possible combinations of date and time are valid.
1787      *
1788      * @param time  the time to combine with, not null
1789      * @return the offset date-time formed from this date and the specified time, not null
1790      */
1791     public OffsetDateTime atTime(OffsetTime time) {
1792         return OffsetDateTime.of(LocalDateTime.of(this, time.toLocalTime()), time.getOffset());
1793     }
1794 
1795     /**
1796      * Combines this date with the time of midnight to create a {@code LocalDateTime}
1797      * at the start of this date.
1798      * <p>
1799      * This returns a {@code LocalDateTime} formed from this date at the time of
1800      * midnight, 00:00, at the start of this date.
1801      *
1802      * @return the local date-time of midnight at the start of this date, not null
1803      */
1804     public LocalDateTime atStartOfDay() {
1805         return LocalDateTime.of(this, LocalTime.MIDNIGHT);
1806     }
1807 
1808     /**
1809      * Returns a zoned date-time from this date at the earliest valid time according
1810      * to the rules in the time-zone.
1811      * <p>
1812      * Time-zone rules, such as daylight savings, mean that not every local date-time
1813      * is valid for the specified zone, thus the local date-time may not be midnight.
1814      * <p>
1815      * In most cases, there is only one valid offset for a local date-time.
1816      * In the case of an overlap, there are two valid offsets, and the earlier one is used,
1817      * corresponding to the first occurrence of midnight on the date.
1818      * In the case of a gap, the zoned date-time will represent the instant just after the gap.
1819      * <p>
1820      * If the zone ID is a {@link ZoneOffset}, then the result always has a time of midnight.
1821      * <p>
1822      * To convert to a specific time in a given time-zone call {@link #atTime(LocalTime)}
1823      * followed by {@link LocalDateTime#atZone(ZoneId)}.
1824      *
1825      * @param zone  the zone ID to use, not null
1826      * @return the zoned date-time formed from this date and the earliest valid time for the zone, not null
1827      */
1828     public ZonedDateTime atStartOfDay(ZoneId zone) {
1829         Objects.requireNonNull(zone, "zone");
1830         // need to handle case where there is a gap from 11:30 to 00:30
1831         // standard ZDT factory would result in 01:00 rather than 00:30
1832         LocalDateTime ldt = atTime(LocalTime.MIDNIGHT);
1833         if (zone instanceof ZoneOffset == false) {
1834             ZoneRules rules = zone.getRules();
1835             ZoneOffsetTransition trans = rules.getTransition(ldt);
1836             if (trans != null && trans.isGap()) {
1837                 ldt = trans.getDateTimeAfter();
1838             }
1839         }
1840         return ZonedDateTime.of(ldt, zone);
1841     }
1842 
1843     //-----------------------------------------------------------------------
1844     @Override
1845     public long toEpochDay() {
1846         long y = year;
1847         long m = month;
1848         long total = 0;
1849         total += 365 * y;
1850         if (y >= 0) {
1851             total += (y + 3) / 4 - (y + 99) / 100 + (y + 399) / 400;
1852         } else {
1853             total -= y / -4 - y / -100 + y / -400;
1854         }
1855         total += ((367 * m - 362) / 12);
1856         total += day - 1;
1857         if (m > 2) {
1858             total--;
1859             if (isLeapYear() == false) {
1860                 total--;
1861             }
1862         }
1863         return total - DAYS_0000_TO_1970;
1864     }
1865 
1866     /**
1867      * Converts this {@code LocalDate} to the number of seconds since the epoch
1868      * of 1970-01-01T00:00:00Z.
1869      * <p>
1870      * This returns the number of seconds from the epoch for this {@link LocalDate}.
1871      *
1872      * @param offset the zone offset, not null
1873      * @return the number of seconds since the epoch of 1970-01-01T00:00:00Z, may be negative
1874      */
1875     public long toEpochSecond(ZoneOffset offset) {
1876         Objects.requireNonNull(offset, "offset");
1877         long secs = toEpochDay() * SECONDS_PER_DAY;
1878         secs -= offset.getTotalSeconds();
1879         return secs;
1880     }
1881 
1882     //-----------------------------------------------------------------------
1883     /**
1884      * Compares this date to another date.
1885      * <p>
1886      * The comparison is primarily based on the date, from earliest to latest.
1887      * It is "consistent with equals", as defined by {@link Comparable}.
1888      * <p>
1889      * If all the dates being compared are instances of {@code LocalDate},
1890      * then the comparison will be entirely based on the date.
1891      * If some dates being compared are in different chronologies, then the
1892      * chronology is also considered, see {@link java.time.chrono.ChronoLocalDate#compareTo}.
1893      *
1894      * @param other  the other date to compare to, not null
1895      * @return the comparator value, negative if less, positive if greater
1896      */
1897     @Override  // override for Javadoc and performance
1898     public int compareTo(ChronoLocalDate other) {
1899         if (other instanceof LocalDate) {
1900             return compareTo0((LocalDate) other);
1901         }
1902         return ChronoLocalDate.super.compareTo(other);
1903     }
1904 
1905     int compareTo0(LocalDate otherDate) {
1906         int cmp = (year - otherDate.year);
1907         if (cmp == 0) {
1908             cmp = (month - otherDate.month);
1909             if (cmp == 0) {
1910                 cmp = (day - otherDate.day);
1911             }
1912         }
1913         return cmp;
1914     }
1915 
1916     /**
1917      * Checks if this date is after the specified date.
1918      * <p>
1919      * This checks to see if this date represents a point on the
1920      * local time-line after the other date.
1921      * <pre>
1922      *   LocalDate a = LocalDate.of(2012, 6, 30);
1923      *   LocalDate b = LocalDate.of(2012, 7, 1);
1924      *   a.isAfter(b) == false
1925      *   a.isAfter(a) == false
1926      *   b.isAfter(a) == true
1927      * </pre>
1928      * <p>
1929      * This method only considers the position of the two dates on the local time-line.
1930      * It does not take into account the chronology, or calendar system.
1931      * This is different from the comparison in {@link #compareTo(ChronoLocalDate)},
1932      * but is the same approach as {@link ChronoLocalDate#timeLineOrder()}.
1933      *
1934      * @param other  the other date to compare to, not null
1935      * @return true if this date is after the specified date
1936      */
1937     @Override  // override for Javadoc and performance
1938     public boolean isAfter(ChronoLocalDate other) {
1939         if (other instanceof LocalDate) {
1940             return compareTo0((LocalDate) other) > 0;
1941         }
1942         return ChronoLocalDate.super.isAfter(other);
1943     }
1944 
1945     /**
1946      * Checks if this date is before the specified date.
1947      * <p>
1948      * This checks to see if this date represents a point on the
1949      * local time-line before the other date.
1950      * <pre>
1951      *   LocalDate a = LocalDate.of(2012, 6, 30);
1952      *   LocalDate b = LocalDate.of(2012, 7, 1);
1953      *   a.isBefore(b) == true
1954      *   a.isBefore(a) == false
1955      *   b.isBefore(a) == false
1956      * </pre>
1957      * <p>
1958      * This method only considers the position of the two dates on the local time-line.
1959      * It does not take into account the chronology, or calendar system.
1960      * This is different from the comparison in {@link #compareTo(ChronoLocalDate)},
1961      * but is the same approach as {@link ChronoLocalDate#timeLineOrder()}.
1962      *
1963      * @param other  the other date to compare to, not null
1964      * @return true if this date is before the specified date
1965      */
1966     @Override  // override for Javadoc and performance
1967     public boolean isBefore(ChronoLocalDate other) {
1968         if (other instanceof LocalDate) {
1969             return compareTo0((LocalDate) other) < 0;
1970         }
1971         return ChronoLocalDate.super.isBefore(other);
1972     }
1973 
1974     /**
1975      * Checks if this date is equal to the specified date.
1976      * <p>
1977      * This checks to see if this date represents the same point on the
1978      * local time-line as the other date.
1979      * <pre>
1980      *   LocalDate a = LocalDate.of(2012, 6, 30);
1981      *   LocalDate b = LocalDate.of(2012, 7, 1);
1982      *   a.isEqual(b) == false
1983      *   a.isEqual(a) == true
1984      *   b.isEqual(a) == false
1985      * </pre>
1986      * <p>
1987      * This method only considers the position of the two dates on the local time-line.
1988      * It does not take into account the chronology, or calendar system.
1989      * This is different from the comparison in {@link #compareTo(ChronoLocalDate)}
1990      * but is the same approach as {@link ChronoLocalDate#timeLineOrder()}.
1991      *
1992      * @param other  the other date to compare to, not null
1993      * @return true if this date is equal to the specified date
1994      */
1995     @Override  // override for Javadoc and performance
1996     public boolean isEqual(ChronoLocalDate other) {
1997         if (other instanceof LocalDate) {
1998             return compareTo0((LocalDate) other) == 0;
1999         }
2000         return ChronoLocalDate.super.isEqual(other);
2001     }
2002 
2003     //-----------------------------------------------------------------------
2004     /**
2005      * Checks if this date is equal to another date.
2006      * <p>
2007      * Compares this {@code LocalDate} with another ensuring that the date is the same.
2008      * <p>
2009      * Only objects of type {@code LocalDate} are compared, other types return false.
2010      * To compare the dates of two {@code TemporalAccessor} instances, including dates
2011      * in two different chronologies, use {@link ChronoField#EPOCH_DAY} as a comparator.
2012      *
2013      * @param obj  the object to check, null returns false
2014      * @return true if this is equal to the other date
2015      */
2016     @Override
2017     public boolean equals(Object obj) {
2018         if (this == obj) {
2019             return true;
2020         }
2021         if (obj instanceof LocalDate) {
2022             return compareTo0((LocalDate) obj) == 0;
2023         }
2024         return false;
2025     }
2026 
2027     /**
2028      * A hash code for this date.
2029      *
2030      * @return a suitable hash code
2031      */
2032     @Override
2033     public int hashCode() {
2034         int yearValue = year;
2035         int monthValue = month;
2036         int dayValue = day;
2037         return (yearValue & 0xFFFFF800) ^ ((yearValue << 11) + (monthValue << 6) + (dayValue));
2038     }
2039 
2040     //-----------------------------------------------------------------------
2041     /**
2042      * Outputs this date as a {@code String}, such as {@code 2007-12-03}.
2043      * <p>
2044      * The output will be in the ISO-8601 format {@code uuuu-MM-dd}.
2045      *
2046      * @return a string representation of this date, not null
2047      */
2048     @Override
2049     public String toString() {
2050         int yearValue = year;
2051         int monthValue = month;
2052         int dayValue = day;
2053         int absYear = Math.abs(yearValue);
2054         StringBuilder buf = new StringBuilder(10);
2055         if (absYear < 1000) {
2056             if (yearValue < 0) {
2057                 buf.append(yearValue - 10000).deleteCharAt(1);
2058             } else {
2059                 buf.append(yearValue + 10000).deleteCharAt(0);
2060             }
2061         } else {
2062             if (yearValue > 9999) {
2063                 buf.append('+');
2064             }
2065             buf.append(yearValue);
2066         }
2067         return buf.append(monthValue < 10 ? "-0" : "-")
2068             .append(monthValue)
2069             .append(dayValue < 10 ? "-0" : "-")
2070             .append(dayValue)
2071             .toString();
2072     }
2073 
2074     //-----------------------------------------------------------------------
2075     /**
2076      * Writes the object using a
2077      * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
2078      * @serialData
2079      * <pre>
2080      *  out.writeByte(3);  // identifies a LocalDate
2081      *  out.writeInt(year);
2082      *  out.writeByte(month);
2083      *  out.writeByte(day);
2084      * </pre>
2085      *
2086      * @return the instance of {@code Ser}, not null
2087      */
2088     private Object writeReplace() {
2089         return new Ser(Ser.LOCAL_DATE_TYPE, this);
2090     }
2091 
2092     /**
2093      * Defend against malicious streams.
2094      *
2095      * @param s the stream to read
2096      * @throws InvalidObjectException always
2097      */
2098     private void readObject(ObjectInputStream s) throws InvalidObjectException {
2099         throw new InvalidObjectException("Deserialization via serialization delegate");
2100     }
2101 
2102     void writeExternal(DataOutput out) throws IOException {
2103         out.writeInt(year);
2104         out.writeByte(month);
2105         out.writeByte(day);
2106     }
2107 
2108     static LocalDate readExternal(DataInput in) throws IOException {
2109         int year = in.readInt();
2110         int month = in.readByte();
2111         int dayOfMonth = in.readByte();
2112         return LocalDate.of(year, month, dayOfMonth);
2113     }
2114 
2115 }