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/*
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 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
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 * * Neither the name of JSR-310 nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package java.time;

import static java.time.LocalTime.SECONDS_PER_DAY;
import static java.time.temporal.ChronoField.ALIGNED_DAY_OF_WEEK_IN_MONTH;
import static java.time.temporal.ChronoField.ALIGNED_DAY_OF_WEEK_IN_YEAR;
import static java.time.temporal.ChronoField.ALIGNED_WEEK_OF_MONTH;
import static java.time.temporal.ChronoField.ALIGNED_WEEK_OF_YEAR;
import static java.time.temporal.ChronoField.DAY_OF_MONTH;
import static java.time.temporal.ChronoField.DAY_OF_YEAR;
import static java.time.temporal.ChronoField.EPOCH_DAY;
import static java.time.temporal.ChronoField.ERA;
import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static java.time.temporal.ChronoField.PROLEPTIC_MONTH;
import static java.time.temporal.ChronoField.YEAR;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.time.chrono.ChronoLocalDate;
import java.time.chrono.Era;
import java.time.chrono.IsoChronology;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.time.temporal.ChronoField;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalAmount;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalQuery;
import java.time.temporal.TemporalUnit;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.time.zone.ZoneOffsetTransition;
import java.time.zone.ZoneRules;
import java.util.Objects;

/**
 * A date without a time-zone in the ISO-8601 calendar system,
 * such as {@code 2007年12月03日}.
 * <p>
 * {@code LocalDate} is an immutable date-time object that represents a date,
 * often viewed as year-month-day. Other date fields, such as day-of-year,
 * day-of-week and week-of-year, can also be accessed.
 * For example, the value "2nd October 2007" can be stored in a {@code LocalDate}.
 * <p>
 * This class does not store or represent a time or time-zone.
 * Instead, it is a description of the date, as used for birthdays.
 * It cannot represent an instant on the time-line without additional information
 * such as an offset or time-zone.
 * <p>
 * The ISO-8601 calendar system is the modern civil calendar system used today
 * in most of the world. It is equivalent to the proleptic Gregorian calendar
 * system, in which today's rules for leap years are applied for all time.
 * For most applications written today, the ISO-8601 rules are entirely suitable.
 * However, any application that makes use of historical dates, and requires them
 * to be accurate will find the ISO-8601 approach unsuitable.
 *
 * <p>
 * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
 * class; use of identity-sensitive operations (including reference equality
 * ({@code ==}), identity hash code, or synchronization) on instances of
 * {@code LocalDate} may have unpredictable results and should be avoided.
 * The {@code equals} method should be used for comparisons.
 *
 * @implSpec
 * This class is immutable and thread-safe.
 *
 * @since 1.8
 */
public final class LocalDate
 implements Temporal, TemporalAdjuster, ChronoLocalDate, Serializable {

 /**
 * The minimum supported {@code LocalDate}, '-999999999-01-01'.
 * This could be used by an application as a "far past" date.
 */
 public static final LocalDate MIN = LocalDate.of(Year.MIN_VALUE, 1, 1);
 /**
 * The maximum supported {@code LocalDate}, '+999999999-12-31'.
 * This could be used by an application as a "far future" date.
 */
 public static final LocalDate MAX = LocalDate.of(Year.MAX_VALUE, 12, 31);

 /**
 * Serialization version.
 */
 private static final long serialVersionUID = 2942565459149668126L;
 /**
 * The number of days in a 400 year cycle.
 */
 private static final int DAYS_PER_CYCLE = 146097;
 /**
 * The number of days from year zero to year 1970.
 * There are five 400 year cycles from year zero to 2000.
 * There are 7 leap years from 1970 to 2000.
 */
 static final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);

 /**
 * The year.
 */
 private final int year;
 /**
 * The month-of-year.
 */
 private final short month;
 /**
 * The day-of-month.
 */
 private final short day;

 //-----------------------------------------------------------------------
 /**
 * Obtains the current date from the system clock in the default time-zone.
 * <p>
 * This will query the {@link Clock#systemDefaultZone() system clock} in the default
 * time-zone to obtain the current date.
 * <p>
 * Using this method will prevent the ability to use an alternate clock for testing
 * because the clock is hard-coded.
 *
 * @return the current date using the system clock and default time-zone, not null
 */
 public static LocalDate now() {
 return now(Clock.systemDefaultZone());
 }

 /**
 * Obtains the current date from the system clock in the specified time-zone.
 * <p>
 * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current date.
 * Specifying the time-zone avoids dependence on the default time-zone.
 * <p>
 * Using this method will prevent the ability to use an alternate clock for testing
 * because the clock is hard-coded.
 *
 * @param zone the zone ID to use, not null
 * @return the current date using the system clock, not null
 */
 public static LocalDate now(ZoneId zone) {
 return now(Clock.system(zone));
 }

 /**
 * Obtains the current date from the specified clock.
 * <p>
 * This will query the specified clock to obtain the current date - today.
 * Using this method allows the use of an alternate clock for testing.
 * The alternate clock may be introduced using {@link Clock dependency injection}.
 *
 * @param clock the clock to use, not null
 * @return the current date, not null
 */
 public static LocalDate now(Clock clock) {
 Objects.requireNonNull(clock, "clock");
 // inline to avoid creating object and Instant checks
 final Instant now = clock.instant(); // called once
 ZoneOffset offset = clock.getZone().getRules().getOffset(now);
 long epochSec = now.getEpochSecond() + offset.getTotalSeconds(); // overflow caught later
 long epochDay = Math.floorDiv(epochSec, SECONDS_PER_DAY);
 return LocalDate.ofEpochDay(epochDay);
 }

 //-----------------------------------------------------------------------
 /**
 * Obtains an instance of {@code LocalDate} from a year, month and day.
 * <p>
 * This returns a {@code LocalDate} with the specified year, month and day-of-month.
 * The day must be valid for the year and month, otherwise an exception will be thrown.
 *
 * @param year the year to represent, from MIN_YEAR to MAX_YEAR
 * @param month the month-of-year to represent, not null
 * @param dayOfMonth the day-of-month to represent, from 1 to 31
 * @return the local date, not null
 * @throws DateTimeException if the value of any field is out of range,
 * or if the day-of-month is invalid for the month-year
 */
 public static LocalDate of(int year, Month month, int dayOfMonth) {
 YEAR.checkValidValue(year);
 Objects.requireNonNull(month, "month");
 DAY_OF_MONTH.checkValidValue(dayOfMonth);
 return create(year, month.getValue(), dayOfMonth);
 }

 /**
 * Obtains an instance of {@code LocalDate} from a year, month and day.
 * <p>
 * This returns a {@code LocalDate} with the specified year, month and day-of-month.
 * The day must be valid for the year and month, otherwise an exception will be thrown.
 *
 * @param year the year to represent, from MIN_YEAR to MAX_YEAR
 * @param month the month-of-year to represent, from 1 (January) to 12 (December)
 * @param dayOfMonth the day-of-month to represent, from 1 to 31
 * @return the local date, not null
 * @throws DateTimeException if the value of any field is out of range,
 * or if the day-of-month is invalid for the month-year
 */
 public static LocalDate of(int year, int month, int dayOfMonth) {
 YEAR.checkValidValue(year);
 MONTH_OF_YEAR.checkValidValue(month);
 DAY_OF_MONTH.checkValidValue(dayOfMonth);
 return create(year, month, dayOfMonth);
 }

 //-----------------------------------------------------------------------
 /**
 * Obtains an instance of {@code LocalDate} from a year and day-of-year.
 * <p>
 * This returns a {@code LocalDate} with the specified year and day-of-year.
 * The day-of-year must be valid for the year, otherwise an exception will be thrown.
 *
 * @param year the year to represent, from MIN_YEAR to MAX_YEAR
 * @param dayOfYear the day-of-year to represent, from 1 to 366
 * @return the local date, not null
 * @throws DateTimeException if the value of any field is out of range,
 * or if the day-of-year is invalid for the year
 */
 public static LocalDate ofYearDay(int year, int dayOfYear) {
 YEAR.checkValidValue(year);
 DAY_OF_YEAR.checkValidValue(dayOfYear);
 boolean leap = IsoChronology.INSTANCE.isLeapYear(year);
 if (dayOfYear == 366 && leap == false) {
 throw new DateTimeException("Invalid date 'DayOfYear 366' as '" + year + "' is not a leap year");
 }
 Month moy = Month.of((dayOfYear - 1) / 31 + 1);
 int monthEnd = moy.firstDayOfYear(leap) + moy.length(leap) - 1;
 if (dayOfYear > monthEnd) {
 moy = moy.plus(1);
 }
 int dom = dayOfYear - moy.firstDayOfYear(leap) + 1;
 return new LocalDate(year, moy.getValue(), dom);
 }

 //-----------------------------------------------------------------------
 /**
 * Obtains an instance of {@code LocalDate} from the epoch day count.
 * <p>
 * This returns a {@code LocalDate} with the specified epoch-day.
 * The {@link ChronoField#EPOCH_DAY EPOCH_DAY} is a simple incrementing count
 * of days where day 0 is 1970年01月01日. Negative numbers represent earlier days.
 *
 * @param epochDay the Epoch Day to convert, based on the epoch 1970年01月01日
 * @return the local date, not null
 * @throws DateTimeException if the epoch day exceeds the supported date range
 */
 public static LocalDate ofEpochDay(long epochDay) {
 long zeroDay = epochDay + DAYS_0000_TO_1970;
 // find the march-based year
 zeroDay -= 60; // adjust to 0000年03月01日 so leap day is at end of four year cycle
 long adjust = 0;
 if (zeroDay < 0) {
 // adjust negative years to positive for calculation
 long adjustCycles = (zeroDay + 1) / DAYS_PER_CYCLE - 1;
 adjust = adjustCycles * 400;
 zeroDay += -adjustCycles * DAYS_PER_CYCLE;
 }
 long yearEst = (400 * zeroDay + 591) / DAYS_PER_CYCLE;
 long doyEst = zeroDay - (365 * yearEst + yearEst / 4 - yearEst / 100 + yearEst / 400);
 if (doyEst < 0) {
 // fix estimate
 yearEst--;
 doyEst = zeroDay - (365 * yearEst + yearEst / 4 - yearEst / 100 + yearEst / 400);
 }
 yearEst += adjust; // reset any negative year
 int marchDoy0 = (int) doyEst;

 // convert march-based values back to january-based
 int marchMonth0 = (marchDoy0 * 5 + 2) / 153;
 int month = (marchMonth0 + 2) % 12 + 1;
 int dom = marchDoy0 - (marchMonth0 * 306 + 5) / 10 + 1;
 yearEst += marchMonth0 / 10;

 // check year now we are certain it is correct
 int year = YEAR.checkValidIntValue(yearEst);
 return new LocalDate(year, month, dom);
 }

 //-----------------------------------------------------------------------
 /**
 * Obtains an instance of {@code LocalDate} from a temporal object.
 * <p>
 * This obtains a local date based on the specified temporal.
 * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
 * which this factory converts to an instance of {@code LocalDate}.
 * <p>
 * The conversion uses the {@link TemporalQueries#localDate()} query, which relies
 * on extracting the {@link ChronoField#EPOCH_DAY EPOCH_DAY} field.
 * <p>
 * This method matches the signature of the functional interface {@link TemporalQuery}
 * allowing it to be used as a query via method reference, {@code LocalDate::from}.
 *
 * @param temporal the temporal object to convert, not null
 * @return the local date, not null
 * @throws DateTimeException if unable to convert to a {@code LocalDate}
 */
 public static LocalDate from(TemporalAccessor temporal) {
 Objects.requireNonNull(temporal, "temporal");
 LocalDate date = temporal.query(TemporalQueries.localDate());
 if (date == null) {
 throw new DateTimeException("Unable to obtain LocalDate from TemporalAccessor: " +
 temporal + " of type " + temporal.getClass().getName());
 }
 return date;
 }

 //-----------------------------------------------------------------------
 /**
 * Obtains an instance of {@code LocalDate} from a text string such as {@code 2007年12月03日}.
 * <p>
 * The string must represent a valid date and is parsed using
 * {@link java.time.format.DateTimeFormatter#ISO_LOCAL_DATE}.
 *
 * @param text the text to parse such as "2007-12-03", not null
 * @return the parsed local date, not null
 * @throws DateTimeParseException if the text cannot be parsed
 */
 public static LocalDate parse(CharSequence text) {
 return parse(text, DateTimeFormatter.ISO_LOCAL_DATE);
 }

 /**
 * Obtains an instance of {@code LocalDate} from a text string using a specific formatter.
 * <p>
 * The text is parsed using the formatter, returning a date.
 *
 * @param text the text to parse, not null
 * @param formatter the formatter to use, not null
 * @return the parsed local date, not null
 * @throws DateTimeParseException if the text cannot be parsed
 */
 public static LocalDate parse(CharSequence text, DateTimeFormatter formatter) {
 Objects.requireNonNull(formatter, "formatter");
 return formatter.parse(text, LocalDate::from);
 }

 //-----------------------------------------------------------------------
 /**
 * Creates a local date from the year, month and day fields.
 *
 * @param year the year to represent, validated from MIN_YEAR to MAX_YEAR
 * @param month the month-of-year to represent, from 1 to 12, validated
 * @param dayOfMonth the day-of-month to represent, validated from 1 to 31
 * @return the local date, not null
 * @throws DateTimeException if the day-of-month is invalid for the month-year
 */
 private static LocalDate create(int year, int month, int dayOfMonth) {
 if (dayOfMonth > 28) {
 int dom = 31;
 switch (month) {
 case 2:
 dom = (IsoChronology.INSTANCE.isLeapYear(year) ? 29 : 28);
 break;
 case 4:
 case 6:
 case 9:
 case 11:
 dom = 30;
 break;
 }
 if (dayOfMonth > dom) {
 if (dayOfMonth == 29) {
 throw new DateTimeException("Invalid date 'February 29' as '" + year + "' is not a leap year");
 } else {
 throw new DateTimeException("Invalid date '" + Month.of(month).name() + " " + dayOfMonth + "'");
 }
 }
 }
 return new LocalDate(year, month, dayOfMonth);
 }

 /**
 * Resolves the date, resolving days past the end of month.
 *
 * @param year the year to represent, validated from MIN_YEAR to MAX_YEAR
 * @param month the month-of-year to represent, validated from 1 to 12
 * @param day the day-of-month to represent, validated from 1 to 31
 * @return the resolved date, not null
 */
 private static LocalDate resolvePreviousValid(int year, int month, int day) {
 switch (month) {
 case 2:
 day = Math.min(day, IsoChronology.INSTANCE.isLeapYear(year) ? 29 : 28);
 break;
 case 4:
 case 6:
 case 9:
 case 11:
 day = Math.min(day, 30);
 break;
 }
 return new LocalDate(year, month, day);
 }

 /**
 * Constructor, previously validated.
 *
 * @param year the year to represent, from MIN_YEAR to MAX_YEAR
 * @param month the month-of-year to represent, not null
 * @param dayOfMonth the day-of-month to represent, valid for year-month, from 1 to 31
 */
 private LocalDate(int year, int month, int dayOfMonth) {
 this.year = year;
 this.month = (short) month;
 this.day = (short) dayOfMonth;
 }

 //-----------------------------------------------------------------------
 /**
 * Checks if the specified field is supported.
 * <p>
 * This checks if this date can be queried for the specified field.
 * If false, then calling the {@link #range(TemporalField) range},
 * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
 * methods will throw an exception.
 * <p>
 * If the field is a {@link ChronoField} then the query is implemented here.
 * The supported fields are:
 * <ul>
 * <li>{@code DAY_OF_WEEK}
 * <li>{@code ALIGNED_DAY_OF_WEEK_IN_MONTH}
 * <li>{@code ALIGNED_DAY_OF_WEEK_IN_YEAR}
 * <li>{@code DAY_OF_MONTH}
 * <li>{@code DAY_OF_YEAR}
 * <li>{@code EPOCH_DAY}
 * <li>{@code ALIGNED_WEEK_OF_MONTH}
 * <li>{@code ALIGNED_WEEK_OF_YEAR}
 * <li>{@code MONTH_OF_YEAR}
 * <li>{@code PROLEPTIC_MONTH}
 * <li>{@code YEAR_OF_ERA}
 * <li>{@code YEAR}
 * <li>{@code ERA}
 * </ul>
 * All other {@code ChronoField} instances will return false.
 * <p>
 * If the field is not a {@code ChronoField}, then the result of this method
 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
 * passing {@code this} as the argument.
 * Whether the field is supported is determined by the field.
 *
 * @param field the field to check, null returns false
 * @return true if the field is supported on this date, false if not
 */
 @Override // override for Javadoc
 public boolean isSupported(TemporalField field) {
 return ChronoLocalDate.super.isSupported(field);
 }

 /**
 * Checks if the specified unit is supported.
 * <p>
 * This checks if the specified unit can be added to, or subtracted from, this date.
 * If false, then calling the {@link #plus(long, TemporalUnit)} and
 * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
 * <p>
 * If the unit is a {@link ChronoUnit} then the query is implemented here.
 * The supported units are:
 * <ul>
 * <li>{@code DAYS}
 * <li>{@code WEEKS}
 * <li>{@code MONTHS}
 * <li>{@code YEARS}
 * <li>{@code DECADES}
 * <li>{@code CENTURIES}
 * <li>{@code MILLENNIA}
 * <li>{@code ERAS}
 * </ul>
 * All other {@code ChronoUnit} instances will return false.
 * <p>
 * If the unit is not a {@code ChronoUnit}, then the result of this method
 * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
 * passing {@code this} as the argument.
 * Whether the unit is supported is determined by the unit.
 *
 * @param unit the unit to check, null returns false
 * @return true if the unit can be added/subtracted, false if not
 */
 @Override // override for Javadoc
 public boolean isSupported(TemporalUnit unit) {
 return ChronoLocalDate.super.isSupported(unit);
 }

 //-----------------------------------------------------------------------
 /**
 * Gets the range of valid values for the specified field.
 * <p>
 * The range object expresses the minimum and maximum valid values for a field.
 * This date is used to enhance the accuracy of the returned range.
 * If it is not possible to return the range, because the field is not supported
 * or for some other reason, an exception is thrown.
 * <p>
 * If the field is a {@link ChronoField} then the query is implemented here.
 * The {@link #isSupported(TemporalField) supported fields} will return
 * appropriate range instances.
 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 * <p>
 * If the field is not a {@code ChronoField}, then the result of this method
 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
 * passing {@code this} as the argument.
 * Whether the range can be obtained is determined by the field.
 *
 * @param field the field to query the range for, not null
 * @return the range of valid values for the field, not null
 * @throws DateTimeException if the range for the field cannot be obtained
 * @throws UnsupportedTemporalTypeException if the field is not supported
 */
 @Override
 public ValueRange range(TemporalField field) {
 if (field instanceof ChronoField) {
 ChronoField f = (ChronoField) field;
 if (f.isDateBased()) {
 switch (f) {
 case DAY_OF_MONTH: return ValueRange.of(1, lengthOfMonth());
 case DAY_OF_YEAR: return ValueRange.of(1, lengthOfYear());
 case ALIGNED_WEEK_OF_MONTH: return ValueRange.of(1, getMonth() == Month.FEBRUARY && isLeapYear() == false ? 4 : 5);
 case YEAR_OF_ERA:
 return (getYear() <= 0 ? ValueRange.of(1, Year.MAX_VALUE + 1) : ValueRange.of(1, Year.MAX_VALUE));
 }
 return field.range();
 }
 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 }
 return field.rangeRefinedBy(this);
 }

 /**
 * Gets the value of the specified field from this date as an {@code int}.
 * <p>
 * This queries this date for the value of the specified field.
 * The returned value will always be within the valid range of values for the field.
 * If it is not possible to return the value, because the field is not supported
 * or for some other reason, an exception is thrown.
 * <p>
 * If the field is a {@link ChronoField} then the query is implemented here.
 * The {@link #isSupported(TemporalField) supported fields} will return valid
 * values based on this date, except {@code EPOCH_DAY} and {@code PROLEPTIC_MONTH}
 * which are too large to fit in an {@code int} and throw a {@code DateTimeException}.
 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 * <p>
 * If the field is not a {@code ChronoField}, then the result of this method
 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
 * passing {@code this} as the argument. Whether the value can be obtained,
 * and what the value represents, is determined by the field.
 *
 * @param field the field to get, not null
 * @return the value for the field
 * @throws DateTimeException if a value for the field cannot be obtained or
 * the value is outside the range of valid values for the field
 * @throws UnsupportedTemporalTypeException if the field is not supported or
 * the range of values exceeds an {@code int}
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override // override for Javadoc and performance
 public int get(TemporalField field) {
 if (field instanceof ChronoField) {
 return get0(field);
 }
 return ChronoLocalDate.super.get(field);
 }

 /**
 * Gets the value of the specified field from this date as a {@code long}.
 * <p>
 * This queries this date for the value of the specified field.
 * If it is not possible to return the value, because the field is not supported
 * or for some other reason, an exception is thrown.
 * <p>
 * If the field is a {@link ChronoField} then the query is implemented here.
 * The {@link #isSupported(TemporalField) supported fields} will return valid
 * values based on this date.
 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 * <p>
 * If the field is not a {@code ChronoField}, then the result of this method
 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
 * passing {@code this} as the argument. Whether the value can be obtained,
 * and what the value represents, is determined by the field.
 *
 * @param field the field to get, not null
 * @return the value for the field
 * @throws DateTimeException if a value for the field cannot be obtained
 * @throws UnsupportedTemporalTypeException if the field is not supported
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override
 public long getLong(TemporalField field) {
 if (field instanceof ChronoField) {
 if (field == EPOCH_DAY) {
 return toEpochDay();
 }
 if (field == PROLEPTIC_MONTH) {
 return getProlepticMonth();
 }
 return get0(field);
 }
 return field.getFrom(this);
 }

 private int get0(TemporalField field) {
 switch ((ChronoField) field) {
 case DAY_OF_WEEK: return getDayOfWeek().getValue();
 case ALIGNED_DAY_OF_WEEK_IN_MONTH: return ((day - 1) % 7) + 1;
 case ALIGNED_DAY_OF_WEEK_IN_YEAR: return ((getDayOfYear() - 1) % 7) + 1;
 case DAY_OF_MONTH: return day;
 case DAY_OF_YEAR: return getDayOfYear();
 case EPOCH_DAY: throw new UnsupportedTemporalTypeException("Invalid field 'EpochDay' for get() method, use getLong() instead");
 case ALIGNED_WEEK_OF_MONTH: return ((day - 1) / 7) + 1;
 case ALIGNED_WEEK_OF_YEAR: return ((getDayOfYear() - 1) / 7) + 1;
 case MONTH_OF_YEAR: return month;
 case PROLEPTIC_MONTH: throw new UnsupportedTemporalTypeException("Invalid field 'ProlepticMonth' for get() method, use getLong() instead");
 case YEAR_OF_ERA: return (year >= 1 ? year : 1 - year);
 case YEAR: return year;
 case ERA: return (year >= 1 ? 1 : 0);
 }
 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 }

 private long getProlepticMonth() {
 return (year * 12L + month - 1);
 }

 //-----------------------------------------------------------------------
 /**
 * Gets the chronology of this date, which is the ISO calendar system.
 * <p>
 * The {@code Chronology} represents the calendar system in use.
 * The ISO-8601 calendar system is the modern civil calendar system used today
 * in most of the world. It is equivalent to the proleptic Gregorian calendar
 * system, in which today's rules for leap years are applied for all time.
 *
 * @return the ISO chronology, not null
 */
 @Override
 public IsoChronology getChronology() {
 return IsoChronology.INSTANCE;
 }

 /**
 * Gets the era applicable at this date.
 * <p>
 * The official ISO-8601 standard does not define eras, however {@code IsoChronology} does.
 * It defines two eras, 'CE' from year one onwards and 'BCE' from year zero backwards.
 * Since dates before the Julian-Gregorian cutover are not in line with history,
 * the cutover between 'BCE' and 'CE' is also not aligned with the commonly used
 * eras, often referred to using 'BC' and 'AD'.
 * <p>
 * Users of this class should typically ignore this method as it exists primarily
 * to fulfill the {@link ChronoLocalDate} contract where it is necessary to support
 * the Japanese calendar system.
 * <p>
 * The returned era will be a singleton capable of being compared with the constants
 * in {@link IsoChronology} using the {@code ==} operator.
 *
 * @return the {@code IsoChronology} era constant applicable at this date, not null
 */
 @Override // override for Javadoc
 public Era getEra() {
 return ChronoLocalDate.super.getEra();
 }

 /**
 * Gets the year field.
 * <p>
 * This method returns the primitive {@code int} value for the year.
 * <p>
 * The year returned by this method is proleptic as per {@code get(YEAR)}.
 * To obtain the year-of-era, use {@code get(YEAR_OF_ERA)}.
 *
 * @return the year, from MIN_YEAR to MAX_YEAR
 */
 public int getYear() {
 return year;
 }

 /**
 * Gets the month-of-year field from 1 to 12.
 * <p>
 * This method returns the month as an {@code int} from 1 to 12.
 * Application code is frequently clearer if the enum {@link Month}
 * is used by calling {@link #getMonth()}.
 *
 * @return the month-of-year, from 1 to 12
 * @see #getMonth()
 */
 public int getMonthValue() {
 return month;
 }

 /**
 * Gets the month-of-year field using the {@code Month} enum.
 * <p>
 * This method returns the enum {@link Month} for the month.
 * This avoids confusion as to what {@code int} values mean.
 * If you need access to the primitive {@code int} value then the enum
 * provides the {@link Month#getValue() int value}.
 *
 * @return the month-of-year, not null
 * @see #getMonthValue()
 */
 public Month getMonth() {
 return Month.of(month);
 }

 /**
 * Gets the day-of-month field.
 * <p>
 * This method returns the primitive {@code int} value for the day-of-month.
 *
 * @return the day-of-month, from 1 to 31
 */
 public int getDayOfMonth() {
 return day;
 }

 /**
 * Gets the day-of-year field.
 * <p>
 * This method returns the primitive {@code int} value for the day-of-year.
 *
 * @return the day-of-year, from 1 to 365, or 366 in a leap year
 */
 public int getDayOfYear() {
 return getMonth().firstDayOfYear(isLeapYear()) + day - 1;
 }

 /**
 * Gets the day-of-week field, which is an enum {@code DayOfWeek}.
 * <p>
 * This method returns the enum {@link DayOfWeek} for the day-of-week.
 * This avoids confusion as to what {@code int} values mean.
 * If you need access to the primitive {@code int} value then the enum
 * provides the {@link DayOfWeek#getValue() int value}.
 * <p>
 * Additional information can be obtained from the {@code DayOfWeek}.
 * This includes textual names of the values.
 *
 * @return the day-of-week, not null
 */
 public DayOfWeek getDayOfWeek() {
 int dow0 = (int)Math.floorMod(toEpochDay() + 3, 7);
 return DayOfWeek.of(dow0 + 1);
 }

 //-----------------------------------------------------------------------
 /**
 * Checks if the year is a leap year, according to the ISO proleptic
 * calendar system rules.
 * <p>
 * This method applies the current rules for leap years across the whole time-line.
 * In general, a year is a leap year if it is divisible by four without
 * remainder. However, years divisible by 100, are not leap years, with
 * the exception of years divisible by 400 which are.
 * <p>
 * For example, 1904 is a leap year it is divisible by 4.
 * 1900 was not a leap year as it is divisible by 100, however 2000 was a
 * leap year as it is divisible by 400.
 * <p>
 * The calculation is proleptic - applying the same rules into the far future and far past.
 * This is historically inaccurate, but is correct for the ISO-8601 standard.
 *
 * @return true if the year is leap, false otherwise
 */
 @Override // override for Javadoc and performance
 public boolean isLeapYear() {
 return IsoChronology.INSTANCE.isLeapYear(year);
 }

 /**
 * Returns the length of the month represented by this date.
 * <p>
 * This returns the length of the month in days.
 * For example, a date in January would return 31.
 *
 * @return the length of the month in days
 */
 @Override
 public int lengthOfMonth() {
 switch (month) {
 case 2:
 return (isLeapYear() ? 29 : 28);
 case 4:
 case 6:
 case 9:
 case 11:
 return 30;
 default:
 return 31;
 }
 }

 /**
 * Returns the length of the year represented by this date.
 * <p>
 * This returns the length of the year in days, either 365 or 366.
 *
 * @return 366 if the year is leap, 365 otherwise
 */
 @Override // override for Javadoc and performance
 public int lengthOfYear() {
 return (isLeapYear() ? 366 : 365);
 }

 //-----------------------------------------------------------------------
 /**
 * Returns an adjusted copy of this date.
 * <p>
 * This returns a {@code LocalDate}, based on this one, with the date adjusted.
 * The adjustment takes place using the specified adjuster strategy object.
 * Read the documentation of the adjuster to understand what adjustment will be made.
 * <p>
 * A simple adjuster might simply set the one of the fields, such as the year field.
 * A more complex adjuster might set the date to the last day of the month.
 * <p>
 * A selection of common adjustments is provided in
 * {@link java.time.temporal.TemporalAdjusters TemporalAdjusters}.
 * These include finding the "last day of the month" and "next Wednesday".
 * Key date-time classes also implement the {@code TemporalAdjuster} interface,
 * such as {@link Month} and {@link java.time.MonthDay MonthDay}.
 * The adjuster is responsible for handling special cases, such as the varying
 * lengths of month and leap years.
 * <p>
 * For example this code returns a date on the last day of July:
 * <pre>
 * import static java.time.Month.*;
 * import static java.time.temporal.TemporalAdjusters.*;
 *
 * result = localDate.with(JULY).with(lastDayOfMonth());
 * </pre>
 * <p>
 * The result of this method is obtained by invoking the
 * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
 * specified adjuster passing {@code this} as the argument.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param adjuster the adjuster to use, not null
 * @return a {@code LocalDate} based on {@code this} with the adjustment made, not null
 * @throws DateTimeException if the adjustment cannot be made
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override
 public LocalDate with(TemporalAdjuster adjuster) {
 // optimizations
 if (adjuster instanceof LocalDate) {
 return (LocalDate) adjuster;
 }
 return (LocalDate) adjuster.adjustInto(this);
 }

 /**
 * Returns a copy of this date with the specified field set to a new value.
 * <p>
 * This returns a {@code LocalDate}, based on this one, with the value
 * for the specified field changed.
 * This can be used to change any supported field, such as the year, month or day-of-month.
 * If it is not possible to set the value, because the field is not supported or for
 * some other reason, an exception is thrown.
 * <p>
 * In some cases, changing the specified field can cause the resulting date to become invalid,
 * such as changing the month from 31st January to February would make the day-of-month invalid.
 * In cases like this, the field is responsible for resolving the date. Typically it will choose
 * the previous valid date, which would be the last valid day of February in this example.
 * <p>
 * If the field is a {@link ChronoField} then the adjustment is implemented here.
 * The supported fields behave as follows:
 * <ul>
 * <li>{@code DAY_OF_WEEK} -
 * Returns a {@code LocalDate} with the specified day-of-week.
 * The date is adjusted up to 6 days forward or backward within the boundary
 * of a Monday to Sunday week.
 * <li>{@code ALIGNED_DAY_OF_WEEK_IN_MONTH} -
 * Returns a {@code LocalDate} with the specified aligned-day-of-week.
 * The date is adjusted to the specified month-based aligned-day-of-week.
 * Aligned weeks are counted such that the first week of a given month starts
 * on the first day of that month.
 * This may cause the date to be moved up to 6 days into the following month.
 * <li>{@code ALIGNED_DAY_OF_WEEK_IN_YEAR} -
 * Returns a {@code LocalDate} with the specified aligned-day-of-week.
 * The date is adjusted to the specified year-based aligned-day-of-week.
 * Aligned weeks are counted such that the first week of a given year starts
 * on the first day of that year.
 * This may cause the date to be moved up to 6 days into the following year.
 * <li>{@code DAY_OF_MONTH} -
 * Returns a {@code LocalDate} with the specified day-of-month.
 * The month and year will be unchanged. If the day-of-month is invalid for the
 * year and month, then a {@code DateTimeException} is thrown.
 * <li>{@code DAY_OF_YEAR} -
 * Returns a {@code LocalDate} with the specified day-of-year.
 * The year will be unchanged. If the day-of-year is invalid for the
 * year, then a {@code DateTimeException} is thrown.
 * <li>{@code EPOCH_DAY} -
 * Returns a {@code LocalDate} with the specified epoch-day.
 * This completely replaces the date and is equivalent to {@link #ofEpochDay(long)}.
 * <li>{@code ALIGNED_WEEK_OF_MONTH} -
 * Returns a {@code LocalDate} with the specified aligned-week-of-month.
 * Aligned weeks are counted such that the first week of a given month starts
 * on the first day of that month.
 * This adjustment moves the date in whole week chunks to match the specified week.
 * The result will have the same day-of-week as this date.
 * This may cause the date to be moved into the following month.
 * <li>{@code ALIGNED_WEEK_OF_YEAR} -
 * Returns a {@code LocalDate} with the specified aligned-week-of-year.
 * Aligned weeks are counted such that the first week of a given year starts
 * on the first day of that year.
 * This adjustment moves the date in whole week chunks to match the specified week.
 * The result will have the same day-of-week as this date.
 * This may cause the date to be moved into the following year.
 * <li>{@code MONTH_OF_YEAR} -
 * Returns a {@code LocalDate} with the specified month-of-year.
 * The year will be unchanged. The day-of-month will also be unchanged,
 * unless it would be invalid for the new month and year. In that case, the
 * day-of-month is adjusted to the maximum valid value for the new month and year.
 * <li>{@code PROLEPTIC_MONTH} -
 * Returns a {@code LocalDate} with the specified proleptic-month.
 * The day-of-month will be unchanged, unless it would be invalid for the new month
 * and year. In that case, the day-of-month is adjusted to the maximum valid value
 * for the new month and year.
 * <li>{@code YEAR_OF_ERA} -
 * Returns a {@code LocalDate} with the specified year-of-era.
 * The era and month will be unchanged. The day-of-month will also be unchanged,
 * unless it would be invalid for the new month and year. In that case, the
 * day-of-month is adjusted to the maximum valid value for the new month and year.
 * <li>{@code YEAR} -
 * Returns a {@code LocalDate} with the specified year.
 * The month will be unchanged. The day-of-month will also be unchanged,
 * unless it would be invalid for the new month and year. In that case, the
 * day-of-month is adjusted to the maximum valid value for the new month and year.
 * <li>{@code ERA} -
 * Returns a {@code LocalDate} with the specified era.
 * The year-of-era and month will be unchanged. The day-of-month will also be unchanged,
 * unless it would be invalid for the new month and year. In that case, the
 * day-of-month is adjusted to the maximum valid value for the new month and year.
 * </ul>
 * <p>
 * In all cases, if the new value is outside the valid range of values for the field
 * then a {@code DateTimeException} will be thrown.
 * <p>
 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 * <p>
 * If the field is not a {@code ChronoField}, then the result of this method
 * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
 * passing {@code this} as the argument. In this case, the field determines
 * whether and how to adjust the instant.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param field the field to set in the result, not null
 * @param newValue the new value of the field in the result
 * @return a {@code LocalDate} based on {@code this} with the specified field set, not null
 * @throws DateTimeException if the field cannot be set
 * @throws UnsupportedTemporalTypeException if the field is not supported
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override
 public LocalDate with(TemporalField field, long newValue) {
 if (field instanceof ChronoField) {
 ChronoField f = (ChronoField) field;
 f.checkValidValue(newValue);
 switch (f) {
 case DAY_OF_WEEK: return plusDays(newValue - getDayOfWeek().getValue());
 case ALIGNED_DAY_OF_WEEK_IN_MONTH: return plusDays(newValue - getLong(ALIGNED_DAY_OF_WEEK_IN_MONTH));
 case ALIGNED_DAY_OF_WEEK_IN_YEAR: return plusDays(newValue - getLong(ALIGNED_DAY_OF_WEEK_IN_YEAR));
 case DAY_OF_MONTH: return withDayOfMonth((int) newValue);
 case DAY_OF_YEAR: return withDayOfYear((int) newValue);
 case EPOCH_DAY: return LocalDate.ofEpochDay(newValue);
 case ALIGNED_WEEK_OF_MONTH: return plusWeeks(newValue - getLong(ALIGNED_WEEK_OF_MONTH));
 case ALIGNED_WEEK_OF_YEAR: return plusWeeks(newValue - getLong(ALIGNED_WEEK_OF_YEAR));
 case MONTH_OF_YEAR: return withMonth((int) newValue);
 case PROLEPTIC_MONTH: return plusMonths(newValue - getProlepticMonth());
 case YEAR_OF_ERA: return withYear((int) (year >= 1 ? newValue : 1 - newValue));
 case YEAR: return withYear((int) newValue);
 case ERA: return (getLong(ERA) == newValue ? this : withYear(1 - year));
 }
 throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 }
 return field.adjustInto(this, newValue);
 }

 //-----------------------------------------------------------------------
 /**
 * Returns a copy of this {@code LocalDate} with the year altered.
 * <p>
 * If the day-of-month is invalid for the year, it will be changed to the last valid day of the month.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param year the year to set in the result, from MIN_YEAR to MAX_YEAR
 * @return a {@code LocalDate} based on this date with the requested year, not null
 * @throws DateTimeException if the year value is invalid
 */
 public LocalDate withYear(int year) {
 if (this.year == year) {
 return this;
 }
 YEAR.checkValidValue(year);
 return resolvePreviousValid(year, month, day);
 }

 /**
 * Returns a copy of this {@code LocalDate} with the month-of-year altered.
 * <p>
 * If the day-of-month is invalid for the year, it will be changed to the last valid day of the month.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param month the month-of-year to set in the result, from 1 (January) to 12 (December)
 * @return a {@code LocalDate} based on this date with the requested month, not null
 * @throws DateTimeException if the month-of-year value is invalid
 */
 public LocalDate withMonth(int month) {
 if (this.month == month) {
 return this;
 }
 MONTH_OF_YEAR.checkValidValue(month);
 return resolvePreviousValid(year, month, day);
 }

 /**
 * Returns a copy of this {@code LocalDate} with the day-of-month altered.
 * <p>
 * If the resulting date is invalid, an exception is thrown.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param dayOfMonth the day-of-month to set in the result, from 1 to 28-31
 * @return a {@code LocalDate} based on this date with the requested day, not null
 * @throws DateTimeException if the day-of-month value is invalid,
 * or if the day-of-month is invalid for the month-year
 */
 public LocalDate withDayOfMonth(int dayOfMonth) {
 if (this.day == dayOfMonth) {
 return this;
 }
 return of(year, month, dayOfMonth);
 }

 /**
 * Returns a copy of this {@code LocalDate} with the day-of-year altered.
 * <p>
 * If the resulting date is invalid, an exception is thrown.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param dayOfYear the day-of-year to set in the result, from 1 to 365-366
 * @return a {@code LocalDate} based on this date with the requested day, not null
 * @throws DateTimeException if the day-of-year value is invalid,
 * or if the day-of-year is invalid for the year
 */
 public LocalDate withDayOfYear(int dayOfYear) {
 if (this.getDayOfYear() == dayOfYear) {
 return this;
 }
 return ofYearDay(year, dayOfYear);
 }

 //-----------------------------------------------------------------------
 /**
 * Returns a copy of this date with the specified amount added.
 * <p>
 * This returns a {@code LocalDate}, based on this one, with the specified amount added.
 * The amount is typically {@link Period} but may be any other type implementing
 * the {@link TemporalAmount} interface.
 * <p>
 * The calculation is delegated to the amount object by calling
 * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
 * to implement the addition in any way it wishes, however it typically
 * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
 * of the amount implementation to determine if it can be successfully added.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param amountToAdd the amount to add, not null
 * @return a {@code LocalDate} based on this date with the addition made, not null
 * @throws DateTimeException if the addition cannot be made
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override
 public LocalDate plus(TemporalAmount amountToAdd) {
 if (amountToAdd instanceof Period) {
 Period periodToAdd = (Period) amountToAdd;
 return plusMonths(periodToAdd.toTotalMonths()).plusDays(periodToAdd.getDays());
 }
 Objects.requireNonNull(amountToAdd, "amountToAdd");
 return (LocalDate) amountToAdd.addTo(this);
 }

 /**
 * Returns a copy of this date with the specified amount added.
 * <p>
 * This returns a {@code LocalDate}, based on this one, with the amount
 * in terms of the unit added. If it is not possible to add the amount, because the
 * unit is not supported or for some other reason, an exception is thrown.
 * <p>
 * In some cases, adding the amount can cause the resulting date to become invalid.
 * For example, adding one month to 31st January would result in 31st February.
 * In cases like this, the unit is responsible for resolving the date.
 * Typically it will choose the previous valid date, which would be the last valid
 * day of February in this example.
 * <p>
 * If the field is a {@link ChronoUnit} then the addition is implemented here.
 * The supported fields behave as follows:
 * <ul>
 * <li>{@code DAYS} -
 * Returns a {@code LocalDate} with the specified number of days added.
 * This is equivalent to {@link #plusDays(long)}.
 * <li>{@code WEEKS} -
 * Returns a {@code LocalDate} with the specified number of weeks added.
 * This is equivalent to {@link #plusWeeks(long)} and uses a 7 day week.
 * <li>{@code MONTHS} -
 * Returns a {@code LocalDate} with the specified number of months added.
 * This is equivalent to {@link #plusMonths(long)}.
 * The day-of-month will be unchanged unless it would be invalid for the new
 * month and year. In that case, the day-of-month is adjusted to the maximum
 * valid value for the new month and year.
 * <li>{@code YEARS} -
 * Returns a {@code LocalDate} with the specified number of years added.
 * This is equivalent to {@link #plusYears(long)}.
 * The day-of-month will be unchanged unless it would be invalid for the new
 * month and year. In that case, the day-of-month is adjusted to the maximum
 * valid value for the new month and year.
 * <li>{@code DECADES} -
 * Returns a {@code LocalDate} with the specified number of decades added.
 * This is equivalent to calling {@link #plusYears(long)} with the amount
 * multiplied by 10.
 * The day-of-month will be unchanged unless it would be invalid for the new
 * month and year. In that case, the day-of-month is adjusted to the maximum
 * valid value for the new month and year.
 * <li>{@code CENTURIES} -
 * Returns a {@code LocalDate} with the specified number of centuries added.
 * This is equivalent to calling {@link #plusYears(long)} with the amount
 * multiplied by 100.
 * The day-of-month will be unchanged unless it would be invalid for the new
 * month and year. In that case, the day-of-month is adjusted to the maximum
 * valid value for the new month and year.
 * <li>{@code MILLENNIA} -
 * Returns a {@code LocalDate} with the specified number of millennia added.
 * This is equivalent to calling {@link #plusYears(long)} with the amount
 * multiplied by 1,000.
 * The day-of-month will be unchanged unless it would be invalid for the new
 * month and year. In that case, the day-of-month is adjusted to the maximum
 * valid value for the new month and year.
 * <li>{@code ERAS} -
 * Returns a {@code LocalDate} with the specified number of eras added.
 * Only two eras are supported so the amount must be one, zero or minus one.
 * If the amount is non-zero then the year is changed such that the year-of-era
 * is unchanged.
 * The day-of-month will be unchanged unless it would be invalid for the new
 * month and year. In that case, the day-of-month is adjusted to the maximum
 * valid value for the new month and year.
 * </ul>
 * <p>
 * All other {@code ChronoUnit} instances will throw an {@code UnsupportedTemporalTypeException}.
 * <p>
 * If the field is not a {@code ChronoUnit}, then the result of this method
 * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
 * passing {@code this} as the argument. In this case, the unit determines
 * whether and how to perform the addition.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param amountToAdd the amount of the unit to add to the result, may be negative
 * @param unit the unit of the amount to add, not null
 * @return a {@code LocalDate} based on this date with the specified amount added, not null
 * @throws DateTimeException if the addition cannot be made
 * @throws UnsupportedTemporalTypeException if the unit is not supported
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override
 public LocalDate plus(long amountToAdd, TemporalUnit unit) {
 if (unit instanceof ChronoUnit) {
 ChronoUnit f = (ChronoUnit) unit;
 switch (f) {
 case DAYS: return plusDays(amountToAdd);
 case WEEKS: return plusWeeks(amountToAdd);
 case MONTHS: return plusMonths(amountToAdd);
 case YEARS: return plusYears(amountToAdd);
 case DECADES: return plusYears(Math.multiplyExact(amountToAdd, 10));
 case CENTURIES: return plusYears(Math.multiplyExact(amountToAdd, 100));
 case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000));
 case ERAS: return with(ERA, Math.addExact(getLong(ERA), amountToAdd));
 }
 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
 }
 return unit.addTo(this, amountToAdd);
 }

 //-----------------------------------------------------------------------
 /**
 * Returns a copy of this {@code LocalDate} with the specified number of years added.
 * <p>
 * This method adds the specified amount to the years field in three steps:
 * <ol>
 * <li>Add the input years to the year field</li>
 * <li>Check if the resulting date would be invalid</li>
 * <li>Adjust the day-of-month to the last valid day if necessary</li>
 * </ol>
 * <p>
 * For example, 2008年02月29日 (leap year) plus one year would result in the
 * invalid date 2009-02-29 (standard year). Instead of returning an invalid
 * result, the last valid day of the month, 2009年02月28日, is selected instead.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param yearsToAdd the years to add, may be negative
 * @return a {@code LocalDate} based on this date with the years added, not null
 * @throws DateTimeException if the result exceeds the supported date range
 */
 public LocalDate plusYears(long yearsToAdd) {
 if (yearsToAdd == 0) {
 return this;
 }
 int newYear = YEAR.checkValidIntValue(year + yearsToAdd); // safe overflow
 return resolvePreviousValid(newYear, month, day);
 }

 /**
 * Returns a copy of this {@code LocalDate} with the specified number of months added.
 * <p>
 * This method adds the specified amount to the months field in three steps:
 * <ol>
 * <li>Add the input months to the month-of-year field</li>
 * <li>Check if the resulting date would be invalid</li>
 * <li>Adjust the day-of-month to the last valid day if necessary</li>
 * </ol>
 * <p>
 * For example, 2007年03月31日 plus one month would result in the invalid date
 * 2007-04-31. Instead of returning an invalid result, the last valid day
 * of the month, 2007年04月30日, is selected instead.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param monthsToAdd the months to add, may be negative
 * @return a {@code LocalDate} based on this date with the months added, not null
 * @throws DateTimeException if the result exceeds the supported date range
 */
 public LocalDate plusMonths(long monthsToAdd) {
 if (monthsToAdd == 0) {
 return this;
 }
 long monthCount = year * 12L + (month - 1);
 long calcMonths = monthCount + monthsToAdd; // safe overflow
 int newYear = YEAR.checkValidIntValue(Math.floorDiv(calcMonths, 12));
 int newMonth = (int)Math.floorMod(calcMonths, 12) + 1;
 return resolvePreviousValid(newYear, newMonth, day);
 }

 /**
 * Returns a copy of this {@code LocalDate} with the specified number of weeks added.
 * <p>
 * This method adds the specified amount in weeks to the days field incrementing
 * the month and year fields as necessary to ensure the result remains valid.
 * The result is only invalid if the maximum/minimum year is exceeded.
 * <p>
 * For example, 2008年12月31日 plus one week would result in 2009年01月07日.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param weeksToAdd the weeks to add, may be negative
 * @return a {@code LocalDate} based on this date with the weeks added, not null
 * @throws DateTimeException if the result exceeds the supported date range
 */
 public LocalDate plusWeeks(long weeksToAdd) {
 return plusDays(Math.multiplyExact(weeksToAdd, 7));
 }

 /**
 * Returns a copy of this {@code LocalDate} with the specified number of days added.
 * <p>
 * This method adds the specified amount to the days field incrementing the
 * month and year fields as necessary to ensure the result remains valid.
 * The result is only invalid if the maximum/minimum year is exceeded.
 * <p>
 * For example, 2008年12月31日 plus one day would result in 2009年01月01日.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param daysToAdd the days to add, may be negative
 * @return a {@code LocalDate} based on this date with the days added, not null
 * @throws DateTimeException if the result exceeds the supported date range
 */
 public LocalDate plusDays(long daysToAdd) {
 if (daysToAdd == 0) {
 return this;
 }
 long mjDay = Math.addExact(toEpochDay(), daysToAdd);
 return LocalDate.ofEpochDay(mjDay);
 }

 //-----------------------------------------------------------------------
 /**
 * Returns a copy of this date with the specified amount subtracted.
 * <p>
 * This returns a {@code LocalDate}, based on this one, with the specified amount subtracted.
 * The amount is typically {@link Period} but may be any other type implementing
 * the {@link TemporalAmount} interface.
 * <p>
 * The calculation is delegated to the amount object by calling
 * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
 * to implement the subtraction in any way it wishes, however it typically
 * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
 * of the amount implementation to determine if it can be successfully subtracted.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param amountToSubtract the amount to subtract, not null
 * @return a {@code LocalDate} based on this date with the subtraction made, not null
 * @throws DateTimeException if the subtraction cannot be made
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override
 public LocalDate minus(TemporalAmount amountToSubtract) {
 if (amountToSubtract instanceof Period) {
 Period periodToSubtract = (Period) amountToSubtract;
 return minusMonths(periodToSubtract.toTotalMonths()).minusDays(periodToSubtract.getDays());
 }
 Objects.requireNonNull(amountToSubtract, "amountToSubtract");
 return (LocalDate) amountToSubtract.subtractFrom(this);
 }

 /**
 * Returns a copy of this date with the specified amount subtracted.
 * <p>
 * This returns a {@code LocalDate}, based on this one, with the amount
 * in terms of the unit subtracted. If it is not possible to subtract the amount,
 * because the unit is not supported or for some other reason, an exception is thrown.
 * <p>
 * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
 * See that method for a full description of how addition, and thus subtraction, works.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param amountToSubtract the amount of the unit to subtract from the result, may be negative
 * @param unit the unit of the amount to subtract, not null
 * @return a {@code LocalDate} based on this date with the specified amount subtracted, not null
 * @throws DateTimeException if the subtraction cannot be made
 * @throws UnsupportedTemporalTypeException if the unit is not supported
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override
 public LocalDate minus(long amountToSubtract, TemporalUnit unit) {
 return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
 }

 //-----------------------------------------------------------------------
 /**
 * Returns a copy of this {@code LocalDate} with the specified number of years subtracted.
 * <p>
 * This method subtracts the specified amount from the years field in three steps:
 * <ol>
 * <li>Subtract the input years from the year field</li>
 * <li>Check if the resulting date would be invalid</li>
 * <li>Adjust the day-of-month to the last valid day if necessary</li>
 * </ol>
 * <p>
 * For example, 2008年02月29日 (leap year) minus one year would result in the
 * invalid date 2007-02-29 (standard year). Instead of returning an invalid
 * result, the last valid day of the month, 2007年02月28日, is selected instead.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param yearsToSubtract the years to subtract, may be negative
 * @return a {@code LocalDate} based on this date with the years subtracted, not null
 * @throws DateTimeException if the result exceeds the supported date range
 */
 public LocalDate minusYears(long yearsToSubtract) {
 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
 }

 /**
 * Returns a copy of this {@code LocalDate} with the specified number of months subtracted.
 * <p>
 * This method subtracts the specified amount from the months field in three steps:
 * <ol>
 * <li>Subtract the input months from the month-of-year field</li>
 * <li>Check if the resulting date would be invalid</li>
 * <li>Adjust the day-of-month to the last valid day if necessary</li>
 * </ol>
 * <p>
 * For example, 2007年03月31日 minus one month would result in the invalid date
 * 2007-02-31. Instead of returning an invalid result, the last valid day
 * of the month, 2007年02月28日, is selected instead.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param monthsToSubtract the months to subtract, may be negative
 * @return a {@code LocalDate} based on this date with the months subtracted, not null
 * @throws DateTimeException if the result exceeds the supported date range
 */
 public LocalDate minusMonths(long monthsToSubtract) {
 return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract));
 }

 /**
 * Returns a copy of this {@code LocalDate} with the specified number of weeks subtracted.
 * <p>
 * This method subtracts the specified amount in weeks from the days field decrementing
 * the month and year fields as necessary to ensure the result remains valid.
 * The result is only invalid if the maximum/minimum year is exceeded.
 * <p>
 * For example, 2009年01月07日 minus one week would result in 2008年12月31日.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param weeksToSubtract the weeks to subtract, may be negative
 * @return a {@code LocalDate} based on this date with the weeks subtracted, not null
 * @throws DateTimeException if the result exceeds the supported date range
 */
 public LocalDate minusWeeks(long weeksToSubtract) {
 return (weeksToSubtract == Long.MIN_VALUE ? plusWeeks(Long.MAX_VALUE).plusWeeks(1) : plusWeeks(-weeksToSubtract));
 }

 /**
 * Returns a copy of this {@code LocalDate} with the specified number of days subtracted.
 * <p>
 * This method subtracts the specified amount from the days field decrementing the
 * month and year fields as necessary to ensure the result remains valid.
 * The result is only invalid if the maximum/minimum year is exceeded.
 * <p>
 * For example, 2009年01月01日 minus one day would result in 2008年12月31日.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param daysToSubtract the days to subtract, may be negative
 * @return a {@code LocalDate} based on this date with the days subtracted, not null
 * @throws DateTimeException if the result exceeds the supported date range
 */
 public LocalDate minusDays(long daysToSubtract) {
 return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
 }

 //-----------------------------------------------------------------------
 /**
 * Queries this date using the specified query.
 * <p>
 * This queries this date using the specified query strategy object.
 * The {@code TemporalQuery} object defines the logic to be used to
 * obtain the result. Read the documentation of the query to understand
 * what the result of this method will be.
 * <p>
 * The result of this method is obtained by invoking the
 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
 * specified query passing {@code this} as the argument.
 *
 * @param <R> the type of the result
 * @param query the query to invoke, not null
 * @return the query result, null may be returned (defined by the query)
 * @throws DateTimeException if unable to query (defined by the query)
 * @throws ArithmeticException if numeric overflow occurs (defined by the query)
 */
 @SuppressWarnings("unchecked")
 @Override
 public <R> R query(TemporalQuery<R> query) {
 if (query == TemporalQueries.localDate()) {
 return (R) this;
 }
 return ChronoLocalDate.super.query(query);
 }

 /**
 * Adjusts the specified temporal object to have the same date as this object.
 * <p>
 * This returns a temporal object of the same observable type as the input
 * with the date changed to be the same as this.
 * <p>
 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
 * passing {@link ChronoField#EPOCH_DAY} as the field.
 * <p>
 * In most cases, it is clearer to reverse the calling pattern by using
 * {@link Temporal#with(TemporalAdjuster)}:
 * <pre>
 * // these two lines are equivalent, but the second approach is recommended
 * temporal = thisLocalDate.adjustInto(temporal);
 * temporal = temporal.with(thisLocalDate);
 * </pre>
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param temporal the target object to be adjusted, not null
 * @return the adjusted object, not null
 * @throws DateTimeException if unable to make the adjustment
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override // override for Javadoc
 public Temporal adjustInto(Temporal temporal) {
 return ChronoLocalDate.super.adjustInto(temporal);
 }

 /**
 * Calculates the amount of time until another date in terms of the specified unit.
 * <p>
 * This calculates the amount of time between two {@code LocalDate}
 * objects in terms of a single {@code TemporalUnit}.
 * The start and end points are {@code this} and the specified date.
 * The result will be negative if the end is before the start.
 * The {@code Temporal} passed to this method is converted to a
 * {@code LocalDate} using {@link #from(TemporalAccessor)}.
 * For example, the amount in days between two dates can be calculated
 * using {@code startDate.until(endDate, DAYS)}.
 * <p>
 * The calculation returns a whole number, representing the number of
 * complete units between the two dates.
 * For example, the amount in months between 2012年06月15日 and 2012年08月14日
 * will only be one month as it is one day short of two months.
 * <p>
 * There are two equivalent ways of using this method.
 * The first is to invoke this method.
 * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
 * <pre>
 * // these two lines are equivalent
 * amount = start.until(end, MONTHS);
 * amount = MONTHS.between(start, end);
 * </pre>
 * The choice should be made based on which makes the code more readable.
 * <p>
 * The calculation is implemented in this method for {@link ChronoUnit}.
 * The units {@code DAYS}, {@code WEEKS}, {@code MONTHS}, {@code YEARS},
 * {@code DECADES}, {@code CENTURIES}, {@code MILLENNIA} and {@code ERAS}
 * are supported. Other {@code ChronoUnit} values will throw an exception.
 * <p>
 * If the unit is not a {@code ChronoUnit}, then the result of this method
 * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
 * passing {@code this} as the first argument and the converted input temporal
 * as the second argument.
 * <p>
 * This instance is immutable and unaffected by this method call.
 *
 * @param endExclusive the end date, exclusive, which is converted to a {@code LocalDate}, not null
 * @param unit the unit to measure the amount in, not null
 * @return the amount of time between this date and the end date
 * @throws DateTimeException if the amount cannot be calculated, or the end
 * temporal cannot be converted to a {@code LocalDate}
 * @throws UnsupportedTemporalTypeException if the unit is not supported
 * @throws ArithmeticException if numeric overflow occurs
 */
 @Override
 public long until(Temporal endExclusive, TemporalUnit unit) {
 LocalDate end = LocalDate.from(endExclusive);
 if (unit instanceof ChronoUnit) {
 switch ((ChronoUnit) unit) {
 case DAYS: return daysUntil(end);
 case WEEKS: return daysUntil(end) / 7;
 case MONTHS: return monthsUntil(end);
 case YEARS: return monthsUntil(end) / 12;
 case DECADES: return monthsUntil(end) / 120;
 case CENTURIES: return monthsUntil(end) / 1200;
 case MILLENNIA: return monthsUntil(end) / 12000;
 case ERAS: return end.getLong(ERA) - getLong(ERA);
 }
 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
 }
 return unit.between(this, end);
 }

 long daysUntil(LocalDate end) {
 return end.toEpochDay() - toEpochDay(); // no overflow
 }

 private long monthsUntil(LocalDate end) {
 long packed1 = getProlepticMonth() * 32L + getDayOfMonth(); // no overflow
 long packed2 = end.getProlepticMonth() * 32L + end.getDayOfMonth(); // no overflow
 return (packed2 - packed1) / 32;
 }

 /**
 * Calculates the period between this date and another date as a {@code Period}.
 * <p>
 * This calculates the period between two dates in terms of years, months and days.
 * The start and end points are {@code this} and the specified date.
 * The result will be negative if the end is before the start.
 * The negative sign will be the same in each of year, month and day.
 * <p>
 * The calculation is performed using the ISO calendar system.
 * If necessary, the input date will be converted to ISO.
 * <p>
 * The start date is included, but the end date is not.
 * The period is calculated by removing complete months, then calculating
 * the remaining number of days, adjusting to ensure that both have the same sign.
 * The number of months is then normalized into years and months based on a 12 month year.
 * A month is considered to be complete if the end day-of-month is greater
 * than or equal to the start day-of-month.
 * For example, from {@code 2010年01月15日} to {@code 2011年03月18日} is "1 year, 2 months and 3 days".
 * <p>
 * There are two equivalent ways of using this method.
 * The first is to invoke this method.
 * The second is to use {@link Period#between(LocalDate, LocalDate)}:
 * <pre>
 * // these two lines are equivalent
 * period = start.until(end);
 * period = Period.between(start, end);
 * </pre>
 * The choice should be made based on which makes the code more readable.
 *
 * @param endDateExclusive the end date, exclusive, which may be in any chronology, not null
 * @return the period between this date and the end date, not null
 */
 @Override
 public Period until(ChronoLocalDate endDateExclusive) {
 LocalDate end = LocalDate.from(endDateExclusive);
 long totalMonths = end.getProlepticMonth() - this.getProlepticMonth(); // safe
 int days = end.day - this.day;
 if (totalMonths > 0 && days < 0) {
 totalMonths--;
 LocalDate calcDate = this.plusMonths(totalMonths);
 days = (int) (end.toEpochDay() - calcDate.toEpochDay()); // safe
 } else if (totalMonths < 0 && days > 0) {
 totalMonths++;
 days -= end.lengthOfMonth();
 }
 long years = totalMonths / 12; // safe
 int months = (int) (totalMonths % 12); // safe
 return Period.of(Math.toIntExact(years), months, days);
 }

 /**
 * Formats this date using the specified formatter.
 * <p>
 * This date will be passed to the formatter to produce a string.
 *
 * @param formatter the formatter to use, not null
 * @return the formatted date string, not null
 * @throws DateTimeException if an error occurs during printing
 */
 @Override // override for Javadoc and performance
 public String format(DateTimeFormatter formatter) {
 Objects.requireNonNull(formatter, "formatter");
 return formatter.format(this);
 }

 //-----------------------------------------------------------------------
 /**
 * Combines this date with a time to create a {@code LocalDateTime}.
 * <p>
 * This returns a {@code LocalDateTime} formed from this date at the specified time.
 * All possible combinations of date and time are valid.
 *
 * @param time the time to combine with, not null
 * @return the local date-time formed from this date and the specified time, not null
 */
 @Override
 public LocalDateTime atTime(LocalTime time) {
 return LocalDateTime.of(this, time);
 }

 /**
 * Combines this date with a time to create a {@code LocalDateTime}.
 * <p>
 * This returns a {@code LocalDateTime} formed from this date at the
 * specified hour and minute.
 * The seconds and nanosecond fields will be set to zero.
 * The individual time fields must be within their valid range.
 * All possible combinations of date and time are valid.
 *
 * @param hour the hour-of-day to use, from 0 to 23
 * @param minute the minute-of-hour to use, from 0 to 59
 * @return the local date-time formed from this date and the specified time, not null
 * @throws DateTimeException if the value of any field is out of range
 */
 public LocalDateTime atTime(int hour, int minute) {
 return atTime(LocalTime.of(hour, minute));
 }

 /**
 * Combines this date with a time to create a {@code LocalDateTime}.
 * <p>
 * This returns a {@code LocalDateTime} formed from this date at the
 * specified hour, minute and second.
 * The nanosecond field will be set to zero.
 * The individual time fields must be within their valid range.
 * All possible combinations of date and time are valid.
 *
 * @param hour the hour-of-day to use, from 0 to 23
 * @param minute the minute-of-hour to use, from 0 to 59
 * @param second the second-of-minute to represent, from 0 to 59
 * @return the local date-time formed from this date and the specified time, not null
 * @throws DateTimeException if the value of any field is out of range
 */
 public LocalDateTime atTime(int hour, int minute, int second) {
 return atTime(LocalTime.of(hour, minute, second));
 }

 /**
 * Combines this date with a time to create a {@code LocalDateTime}.
 * <p>
 * This returns a {@code LocalDateTime} formed from this date at the
 * specified hour, minute, second and nanosecond.
 * The individual time fields must be within their valid range.
 * All possible combinations of date and time are valid.
 *
 * @param hour the hour-of-day to use, from 0 to 23
 * @param minute the minute-of-hour to use, from 0 to 59
 * @param second the second-of-minute to represent, from 0 to 59
 * @param nanoOfSecond the nano-of-second to represent, from 0 to 999,999,999
 * @return the local date-time formed from this date and the specified time, not null
 * @throws DateTimeException if the value of any field is out of range
 */
 public LocalDateTime atTime(int hour, int minute, int second, int nanoOfSecond) {
 return atTime(LocalTime.of(hour, minute, second, nanoOfSecond));
 }

 /**
 * Combines this date with an offset time to create an {@code OffsetDateTime}.
 * <p>
 * This returns an {@code OffsetDateTime} formed from this date at the specified time.
 * All possible combinations of date and time are valid.
 *
 * @param time the time to combine with, not null
 * @return the offset date-time formed from this date and the specified time, not null
 */
 public OffsetDateTime atTime(OffsetTime time) {
 return OffsetDateTime.of(LocalDateTime.of(this, time.toLocalTime()), time.getOffset());
 }

 /**
 * Combines this date with the time of midnight to create a {@code LocalDateTime}
 * at the start of this date.
 * <p>
 * This returns a {@code LocalDateTime} formed from this date at the time of
 * midnight, 00:00, at the start of this date.
 *
 * @return the local date-time of midnight at the start of this date, not null
 */
 public LocalDateTime atStartOfDay() {
 return LocalDateTime.of(this, LocalTime.MIDNIGHT);
 }

 /**
 * Returns a zoned date-time from this date at the earliest valid time according
 * to the rules in the time-zone.
 * <p>
 * Time-zone rules, such as daylight savings, mean that not every local date-time
 * is valid for the specified zone, thus the local date-time may not be midnight.
 * <p>
 * In most cases, there is only one valid offset for a local date-time.
 * In the case of an overlap, there are two valid offsets, and the earlier one is used,
 * corresponding to the first occurrence of midnight on the date.
 * In the case of a gap, the zoned date-time will represent the instant just after the gap.
 * <p>
 * If the zone ID is a {@link ZoneOffset}, then the result always has a time of midnight.
 * <p>
 * To convert to a specific time in a given time-zone call {@link #atTime(LocalTime)}
 * followed by {@link LocalDateTime#atZone(ZoneId)}.
 *
 * @param zone the zone ID to use, not null
 * @return the zoned date-time formed from this date and the earliest valid time for the zone, not null
 */
 public ZonedDateTime atStartOfDay(ZoneId zone) {
 Objects.requireNonNull(zone, "zone");
 // need to handle case where there is a gap from 11:30 to 00:30
 // standard ZDT factory would result in 01:00 rather than 00:30
 LocalDateTime ldt = atTime(LocalTime.MIDNIGHT);
 if (zone instanceof ZoneOffset == false) {
 ZoneRules rules = zone.getRules();
 ZoneOffsetTransition trans = rules.getTransition(ldt);
 if (trans != null && trans.isGap()) {
 ldt = trans.getDateTimeAfter();
 }
 }
 return ZonedDateTime.of(ldt, zone);
 }

 //-----------------------------------------------------------------------
 @Override
 public long toEpochDay() {
 long y = year;
 long m = month;
 long total = 0;
 total += 365 * y;
 if (y >= 0) {
 total += (y + 3) / 4 - (y + 99) / 100 + (y + 399) / 400;
 } else {
 total -= y / -4 - y / -100 + y / -400;
 }
 total += ((367 * m - 362) / 12);
 total += day - 1;
 if (m > 2) {
 total--;
 if (isLeapYear() == false) {
 total--;
 }
 }
 return total - DAYS_0000_TO_1970;
 }

 //-----------------------------------------------------------------------
 /**
 * Compares this date to another date.
 * <p>
 * The comparison is primarily based on the date, from earliest to latest.
 * It is "consistent with equals", as defined by {@link Comparable}.
 * <p>
 * If all the dates being compared are instances of {@code LocalDate},
 * then the comparison will be entirely based on the date.
 * If some dates being compared are in different chronologies, then the
 * chronology is also considered, see {@link java.time.chrono.ChronoLocalDate#compareTo}.
 *
 * @param other the other date to compare to, not null
 * @return the comparator value, negative if less, positive if greater
 */
 @Override // override for Javadoc and performance
 public int compareTo(ChronoLocalDate other) {
 if (other instanceof LocalDate) {
 return compareTo0((LocalDate) other);
 }
 return ChronoLocalDate.super.compareTo(other);
 }

 int compareTo0(LocalDate otherDate) {
 int cmp = (year - otherDate.year);
 if (cmp == 0) {
 cmp = (month - otherDate.month);
 if (cmp == 0) {
 cmp = (day - otherDate.day);
 }
 }
 return cmp;
 }

 /**
 * Checks if this date is after the specified date.
 * <p>
 * This checks to see if this date represents a point on the
 * local time-line after the other date.
 * <pre>
 * LocalDate a = LocalDate.of(2012, 6, 30);
 * LocalDate b = LocalDate.of(2012, 7, 1);
 * a.isAfter(b) == false
 * a.isAfter(a) == false
 * b.isAfter(a) == true
 * </pre>
 * <p>
 * This method only considers the position of the two dates on the local time-line.
 * It does not take into account the chronology, or calendar system.
 * This is different from the comparison in {@link #compareTo(ChronoLocalDate)},
 * but is the same approach as {@link ChronoLocalDate#timeLineOrder()}.
 *
 * @param other the other date to compare to, not null
 * @return true if this date is after the specified date
 */
 @Override // override for Javadoc and performance
 public boolean isAfter(ChronoLocalDate other) {
 if (other instanceof LocalDate) {
 return compareTo0((LocalDate) other) > 0;
 }
 return ChronoLocalDate.super.isAfter(other);
 }

 /**
 * Checks if this date is before the specified date.
 * <p>
 * This checks to see if this date represents a point on the
 * local time-line before the other date.
 * <pre>
 * LocalDate a = LocalDate.of(2012, 6, 30);
 * LocalDate b = LocalDate.of(2012, 7, 1);
 * a.isBefore(b) == true
 * a.isBefore(a) == false
 * b.isBefore(a) == false
 * </pre>
 * <p>
 * This method only considers the position of the two dates on the local time-line.
 * It does not take into account the chronology, or calendar system.
 * This is different from the comparison in {@link #compareTo(ChronoLocalDate)},
 * but is the same approach as {@link ChronoLocalDate#timeLineOrder()}.
 *
 * @param other the other date to compare to, not null
 * @return true if this date is before the specified date
 */
 @Override // override for Javadoc and performance
 public boolean isBefore(ChronoLocalDate other) {
 if (other instanceof LocalDate) {
 return compareTo0((LocalDate) other) < 0;
 }
 return ChronoLocalDate.super.isBefore(other);
 }

 /**
 * Checks if this date is equal to the specified date.
 * <p>
 * This checks to see if this date represents the same point on the
 * local time-line as the other date.
 * <pre>
 * LocalDate a = LocalDate.of(2012, 6, 30);
 * LocalDate b = LocalDate.of(2012, 7, 1);
 * a.isEqual(b) == false
 * a.isEqual(a) == true
 * b.isEqual(a) == false
 * </pre>
 * <p>
 * This method only considers the position of the two dates on the local time-line.
 * It does not take into account the chronology, or calendar system.
 * This is different from the comparison in {@link #compareTo(ChronoLocalDate)}
 * but is the same approach as {@link ChronoLocalDate#timeLineOrder()}.
 *
 * @param other the other date to compare to, not null
 * @return true if this date is equal to the specified date
 */
 @Override // override for Javadoc and performance
 public boolean isEqual(ChronoLocalDate other) {
 if (other instanceof LocalDate) {
 return compareTo0((LocalDate) other) == 0;
 }
 return ChronoLocalDate.super.isEqual(other);
 }

 //-----------------------------------------------------------------------
 /**
 * Checks if this date is equal to another date.
 * <p>
 * Compares this {@code LocalDate} with another ensuring that the date is the same.
 * <p>
 * Only objects of type {@code LocalDate} are compared, other types return false.
 * To compare the dates of two {@code TemporalAccessor} instances, including dates
 * in two different chronologies, use {@link ChronoField#EPOCH_DAY} as a comparator.
 *
 * @param obj the object to check, null returns false
 * @return true if this is equal to the other date
 */
 @Override
 public boolean equals(Object obj) {
 if (this == obj) {
 return true;
 }
 if (obj instanceof LocalDate) {
 return compareTo0((LocalDate) obj) == 0;
 }
 return false;
 }

 /**
 * A hash code for this date.
 *
 * @return a suitable hash code
 */
 @Override
 public int hashCode() {
 int yearValue = year;
 int monthValue = month;
 int dayValue = day;
 return (yearValue & 0xFFFFF800) ^ ((yearValue << 11) + (monthValue << 6) + (dayValue));
 }

 //-----------------------------------------------------------------------
 /**
 * Outputs this date as a {@code String}, such as {@code 2007年12月03日}.
 * <p>
 * The output will be in the ISO-8601 format {@code uuuu-MM-dd}.
 *
 * @return a string representation of this date, not null
 */
 @Override
 public String toString() {
 int yearValue = year;
 int monthValue = month;
 int dayValue = day;
 int absYear = Math.abs(yearValue);
 StringBuilder buf = new StringBuilder(10);
 if (absYear < 1000) {
 if (yearValue < 0) {
 buf.append(yearValue - 10000).deleteCharAt(1);
 } else {
 buf.append(yearValue + 10000).deleteCharAt(0);
 }
 } else {
 if (yearValue > 9999) {
 buf.append('+');
 }
 buf.append(yearValue);
 }
 return buf.append(monthValue < 10 ? "-0" : "-")
 .append(monthValue)
 .append(dayValue < 10 ? "-0" : "-")
 .append(dayValue)
 .toString();
 }

 //-----------------------------------------------------------------------
 /**
 * Writes the object using a
 * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
 * @serialData
 * <pre>
 * out.writeByte(3); // identifies a LocalDate
 * out.writeInt(year);
 * out.writeByte(month);
 * out.writeByte(day);
 * </pre>
 *
 * @return the instance of {@code Ser}, not null
 */
 private Object writeReplace() {
 return new Ser(Ser.LOCAL_DATE_TYPE, this);
 }

 /**
 * Defend against malicious streams.
 *
 * @param s the stream to read
 * @throws InvalidObjectException always
 */
 private void readObject(ObjectInputStream s) throws InvalidObjectException {
 throw new InvalidObjectException("Deserialization via serialization delegate");
 }

 void writeExternal(DataOutput out) throws IOException {
 out.writeInt(year);
 out.writeByte(month);
 out.writeByte(day);
 }

 static LocalDate readExternal(DataInput in) throws IOException {
 int year = in.readInt();
 int month = in.readByte();
 int dayOfMonth = in.readByte();
 return LocalDate.of(year, month, dayOfMonth);
 }

}