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	/*
	* Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
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	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file:
	*
	* 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.
	*
	* * 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
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	*/
	package java.time;

	import static java.time.temporal.ChronoField.ERA;
	import static java.time.temporal.ChronoField.YEAR;
	import static java.time.temporal.ChronoField.YEAR_OF_ERA;
	import static java.time.temporal.ChronoUnit.CENTURIES;
	import static java.time.temporal.ChronoUnit.DECADES;
	import static java.time.temporal.ChronoUnit.ERAS;
	import static java.time.temporal.ChronoUnit.MILLENNIA;
	import static java.time.temporal.ChronoUnit.YEARS;

	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.Chronology;
	import java.time.chrono.IsoChronology;
	import java.time.format.DateTimeFormatter;
	import java.time.format.DateTimeFormatterBuilder;
	import java.time.format.DateTimeParseException;
	import java.time.format.SignStyle;
	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.util.Objects;

	/**
	* A year in the ISO-8601 calendar system, such as {@code 2007}.
	* <p>
	* {@code Year} is an immutable date-time object that represents a year.
	* Any field that can be derived from a year can be obtained.
	* <p>
	* <b>Note that years in the ISO chronology only align with years in the
	* Gregorian-Julian system for modern years. Parts of Russia did not switch to the
	* modern Gregorian/ISO rules until 1920.
	* As such, historical years must be treated with caution.</b>
	* <p>
	* This class does not store or represent a month, day, time or time-zone.
	* For example, the value "2007" can be stored in a {@code Year}.
	* <p>
	* Years represented by this class follow the ISO-8601 standard and use
	* the proleptic numbering system. Year 1 is preceded by year 0, then by year -1.
	* <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.base/java/lang/doc-files/ValueBased.html">value-based</a>
	* class; programmers should treat instances that are
	* {@linkplain #equals(Object) equal} as interchangeable and should not
	* use instances for synchronization, or unpredictable behavior may
	* occur. For example, in a future release, synchronization may fail.
	* The {@code equals} method should be used for comparisons.
	*
	* @implSpec
	* This class is immutable and thread-safe.
	*
	* @since 1.8
	*/
	@jdk.internal.ValueBased
	public final class Year
	implements Temporal, TemporalAdjuster, Comparable<Year>, Serializable {

	/**
	* The minimum supported year, '-999,999,999'.
	*/
	public static final int MIN_VALUE = -999_999_999;
	/**
	* The maximum supported year, '+999,999,999'.
	*/
	public static final int MAX_VALUE = 999_999_999;

	/**
	* Serialization version.
	*/
	@java.io.Serial
	private static final long serialVersionUID = -23038383694477807L;
	/**
	* Parser.
	*/
	private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder()
	.parseLenient()
	.appendValue(YEAR, 1, 10, SignStyle.NORMAL)
	.toFormatter();

	/**
	* The year being represented.
	*/
	private final int year;

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

	/**
	* Obtains the current year from the system clock in the specified time-zone.
	* <p>
	* This will query the {@link Clock#system(ZoneId) system clock} to obtain the current year.
	* 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 year using the system clock, not null
	*/
	public static Year now(ZoneId zone) {
	return now(Clock.system(zone));
	}

	/**
	* Obtains the current year from the specified clock.
	* <p>
	* This will query the specified clock to obtain the current year.
	* 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 year, not null
	*/
	public static Year now(Clock clock) {
	final LocalDate now = LocalDate.now(clock); // called once
	return Year.of(now.getYear());
	}

	//-----------------------------------------------------------------------
	/**
	* Obtains an instance of {@code Year}.
	* <p>
	* This method accepts a year value from the proleptic ISO calendar system.
	* <p>
	* The year 2AD/CE is represented by 2.<br>
	* The year 1AD/CE is represented by 1.<br>
	* The year 1BC/BCE is represented by 0.<br>
	* The year 2BC/BCE is represented by -1.<br>
	*
	* @param isoYear the ISO proleptic year to represent, from {@code MIN_VALUE} to {@code MAX_VALUE}
	* @return the year, not null
	* @throws DateTimeException if the field is invalid
	*/
	public static Year of(int isoYear) {
	YEAR.checkValidValue(isoYear);
	return new Year(isoYear);
	}

	//-----------------------------------------------------------------------
	/**
	* Obtains an instance of {@code Year} from a temporal object.
	* <p>
	* This obtains a year 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 Year}.
	* <p>
	* The conversion extracts the {@link ChronoField#YEAR year} field.
	* The extraction is only permitted if the temporal object has an ISO
	* chronology, or can be converted to a {@code LocalDate}.
	* <p>
	* This method matches the signature of the functional interface {@link TemporalQuery}
	* allowing it to be used as a query via method reference, {@code Year::from}.
	*
	* @param temporal the temporal object to convert, not null
	* @return the year, not null
	* @throws DateTimeException if unable to convert to a {@code Year}
	*/
	public static Year from(TemporalAccessor temporal) {
	if (temporal instanceof Year) {
	return (Year) temporal;
	}
	Objects.requireNonNull(temporal, "temporal");
	try {
	if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
	temporal = LocalDate.from(temporal);
	}
	return of(temporal.get(YEAR));
	} catch (DateTimeException ex) {
	throw new DateTimeException("Unable to obtain Year from TemporalAccessor: " +
	temporal + " of type " + temporal.getClass().getName(), ex);
	}
	}

	//-----------------------------------------------------------------------
	/**
	* Obtains an instance of {@code Year} from a text string such as {@code 2007}.
	* <p>
	* The string must represent a valid year.
	*
	* @param text the text to parse such as "2007", not null
	* @return the parsed year, not null
	* @throws DateTimeParseException if the text cannot be parsed
	*/
	public static Year parse(CharSequence text) {
	return parse(text, PARSER);
	}

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

	//-------------------------------------------------------------------------
	/**
	* 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.
	*
	* @param year the year to check
	* @return true if the year is leap, false otherwise
	*/
	public static boolean isLeap(long year) {
	return ((year & 3) == 0) && ((year % 100) != 0 \|\| (year % 400) == 0);
	}

	//-----------------------------------------------------------------------
	/**
	* Constructor.
	*
	* @param year the year to represent
	*/
	private Year(int year) {
	this.year = year;
	}

	//-----------------------------------------------------------------------
	/**
	* Gets the year value.
	* <p>
	* The year returned by this method is proleptic as per {@code get(YEAR)}.
	*
	* @return the year, {@code MIN_VALUE} to {@code MAX_VALUE}
	*/
	public int getValue() {
	return year;
	}

	//-----------------------------------------------------------------------
	/**
	* Checks if the specified field is supported.
	* <p>
	* This checks if this year 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 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 year, false if not
	*/
	@Override
	public boolean isSupported(TemporalField field) {
	if (field instanceof ChronoField) {
	return field == YEAR \|\| field == YEAR_OF_ERA \|\| field == ERA;
	}
	return field != null && field.isSupportedBy(this);
	}

	/**
	* Checks if the specified unit is supported.
	* <p>
	* This checks if the specified unit can be added to, or subtracted from, this year.
	* 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 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
	public boolean isSupported(TemporalUnit unit) {
	if (unit instanceof ChronoUnit) {
	return unit == YEARS \|\| unit == DECADES \|\| unit == CENTURIES \|\| unit == MILLENNIA \|\| unit == ERAS;
	}
	return unit != null && unit.isSupportedBy(this);
	}

	//-----------------------------------------------------------------------
	/**
	* 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 year 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 == YEAR_OF_ERA) {
	return (year <= 0 ? ValueRange.of(1, MAX_VALUE + 1) : ValueRange.of(1, MAX_VALUE));
	}
	return Temporal.super.range(field);
	}

	/**
	* Gets the value of the specified field from this year as an {@code int}.
	* <p>
	* This queries this year 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 year.
	* 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
	public int get(TemporalField field) {
	return range(field).checkValidIntValue(getLong(field), field);
	}

	/**
	* Gets the value of the specified field from this year as a {@code long}.
	* <p>
	* This queries this year 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 year.
	* 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 chronoField) {
	switch (chronoField) {
	case YEAR_OF_ERA: return (year < 1 ? 1 - year : year);
	case YEAR: return year;
	case ERA: return (year < 1 ? 0 : 1);
	}
	throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
	}
	return field.getFrom(this);
	}

	//-----------------------------------------------------------------------
	/**
	* 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
	*/
	public boolean isLeap() {
	return Year.isLeap(year);
	}

	/**
	* Checks if the month-day is valid for this year.
	* <p>
	* This method checks whether this year and the input month and day form
	* a valid date.
	*
	* @param monthDay the month-day to validate, null returns false
	* @return true if the month and day are valid for this year
	*/
	public boolean isValidMonthDay(MonthDay monthDay) {
	return monthDay != null && monthDay.isValidYear(year);
	}

	/**
	* Gets the length of this year in days.
	*
	* @return the length of this year in days, 365 or 366
	*/
	public int length() {
	return isLeap() ? 366 : 365;
	}

	//-----------------------------------------------------------------------
	/**
	* Returns an adjusted copy of this year.
	* <p>
	* This returns a {@code Year}, based on this one, with the year 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>
	* 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 Year} 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 Year with(TemporalAdjuster adjuster) {
	return (Year) adjuster.adjustInto(this);
	}

	/**
	* Returns a copy of this year with the specified field set to a new value.
	* <p>
	* This returns a {@code Year}, based on this one, with the value
	* for the specified field changed.
	* 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>
	* If the field is a {@link ChronoField} then the adjustment is implemented here.
	* The supported fields behave as follows:
	* <ul>
	* <li>{@code YEAR_OF_ERA} -
	* Returns a {@code Year} with the specified year-of-era
	* The era will be unchanged.
	* <li>{@code YEAR} -
	* Returns a {@code Year} with the specified year.
	* This completely replaces the date and is equivalent to {@link #of(int)}.
	* <li>{@code ERA} -
	* Returns a {@code Year} with the specified era.
	* The year-of-era will be unchanged.
	* </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 Year} 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 Year with(TemporalField field, long newValue) {
	if (field instanceof ChronoField chronoField) {
	chronoField.checkValidValue(newValue);
	switch (chronoField) {
	case YEAR_OF_ERA: return Year.of((int) (year < 1 ? 1 - newValue : newValue));
	case YEAR: return Year.of((int) newValue);
	case ERA: return (getLong(ERA) == newValue ? this : Year.of(1 - year));
	}
	throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
	}
	return field.adjustInto(this, newValue);
	}

	//-----------------------------------------------------------------------
	/**
	* Returns a copy of this year with the specified amount added.
	* <p>
	* This returns a {@code Year}, 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 Year} based on this year with the addition made, not null
	* @throws DateTimeException if the addition cannot be made
	* @throws ArithmeticException if numeric overflow occurs
	*/
	@Override
	public Year plus(TemporalAmount amountToAdd) {
	return (Year) amountToAdd.addTo(this);
	}

	/**
	* Returns a copy of this year with the specified amount added.
	* <p>
	* This returns a {@code Year}, 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>
	* If the field is a {@link ChronoUnit} then the addition is implemented here.
	* The supported fields behave as follows:
	* <ul>
	* <li>{@code YEARS} -
	* Returns a {@code Year} with the specified number of years added.
	* This is equivalent to {@link #plusYears(long)}.
	* <li>{@code DECADES} -
	* Returns a {@code Year} with the specified number of decades added.
	* This is equivalent to calling {@link #plusYears(long)} with the amount
	* multiplied by 10.
	* <li>{@code CENTURIES} -
	* Returns a {@code Year} with the specified number of centuries added.
	* This is equivalent to calling {@link #plusYears(long)} with the amount
	* multiplied by 100.
	* <li>{@code MILLENNIA} -
	* Returns a {@code Year} with the specified number of millennia added.
	* This is equivalent to calling {@link #plusYears(long)} with the amount
	* multiplied by 1,000.
	* <li>{@code ERAS} -
	* Returns a {@code Year} 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.
	* </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 Year} based on this year 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 Year plus(long amountToAdd, TemporalUnit unit) {
	if (unit instanceof ChronoUnit chronoUnit) {
	switch (chronoUnit) {
	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 Year} with the specified number of years added.
	* <p>
	* This instance is immutable and unaffected by this method call.
	*
	* @param yearsToAdd the years to add, may be negative
	* @return a {@code Year} based on this year with the years added, not null
	* @throws DateTimeException if the result exceeds the supported range
	*/
	public Year plusYears(long yearsToAdd) {
	if (yearsToAdd == 0) {
	return this;
	}
	return of(YEAR.checkValidIntValue(year + yearsToAdd)); // overflow safe
	}

	//-----------------------------------------------------------------------
	/**
	* Returns a copy of this year with the specified amount subtracted.
	* <p>
	* This returns a {@code Year}, 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 Year} based on this year with the subtraction made, not null
	* @throws DateTimeException if the subtraction cannot be made
	* @throws ArithmeticException if numeric overflow occurs
	*/
	@Override
	public Year minus(TemporalAmount amountToSubtract) {
	return (Year) amountToSubtract.subtractFrom(this);
	}

	/**
	* Returns a copy of this year with the specified amount subtracted.
	* <p>
	* This returns a {@code Year}, 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 Year} based on this year 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 Year 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 Year} with the specified number of years subtracted.
	* <p>
	* This instance is immutable and unaffected by this method call.
	*
	* @param yearsToSubtract the years to subtract, may be negative
	* @return a {@code Year} based on this year with the year subtracted, not null
	* @throws DateTimeException if the result exceeds the supported range
	*/
	public Year minusYears(long yearsToSubtract) {
	return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract));
	}

	//-----------------------------------------------------------------------
	/**
	* Queries this year using the specified query.
	* <p>
	* This queries this year 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.chronology()) {
	return (R) IsoChronology.INSTANCE;
	} else if (query == TemporalQueries.precision()) {
	return (R) YEARS;
	}
	return Temporal.super.query(query);
	}

	/**
	* Adjusts the specified temporal object to have this year.
	* <p>
	* This returns a temporal object of the same observable type as the input
	* with the year changed to be the same as this.
	* <p>
	* The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
	* passing {@link ChronoField#YEAR} as the field.
	* If the specified temporal object does not use the ISO calendar system then
	* a {@code DateTimeException} is thrown.
	* <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 = thisYear.adjustInto(temporal);
	* temporal = temporal.with(thisYear);
	* </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
	public Temporal adjustInto(Temporal temporal) {
	if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
	throw new DateTimeException("Adjustment only supported on ISO date-time");
	}
	return temporal.with(YEAR, year);
	}

	/**
	* Calculates the amount of time until another year in terms of the specified unit.
	* <p>
	* This calculates the amount of time between two {@code Year}
	* objects in terms of a single {@code TemporalUnit}.
	* The start and end points are {@code this} and the specified year.
	* The result will be negative if the end is before the start.
	* The {@code Temporal} passed to this method is converted to a
	* {@code Year} using {@link #from(TemporalAccessor)}.
	* For example, the amount in decades between two year can be calculated
	* using {@code startYear.until(endYear, DECADES)}.
	* <p>
	* The calculation returns a whole number, representing the number of
	* complete units between the two years.
	* For example, the amount in decades between 2012 and 2031
	* will only be one decade as it is one year short of two decades.
	* <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, YEARS);
	* amount = YEARS.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 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 Year}, not null
	* @param unit the unit to measure the amount in, not null
	* @return the amount of time between this year and the end year
	* @throws DateTimeException if the amount cannot be calculated, or the end
	* temporal cannot be converted to a {@code Year}
	* @throws UnsupportedTemporalTypeException if the unit is not supported
	* @throws ArithmeticException if numeric overflow occurs
	*/
	@Override
	public long until(Temporal endExclusive, TemporalUnit unit) {
	Year end = Year.from(endExclusive);
	if (unit instanceof ChronoUnit chronoUnit) {
	long yearsUntil = ((long) end.year) - year; // no overflow
	switch (chronoUnit) {
	case YEARS: return yearsUntil;
	case DECADES: return yearsUntil / 10;
	case CENTURIES: return yearsUntil / 100;
	case MILLENNIA: return yearsUntil / 1000;
	case ERAS: return end.getLong(ERA) - getLong(ERA);
	}
	throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
	}
	return unit.between(this, end);
	}

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

	//-----------------------------------------------------------------------
	/**
	* Combines this year with a day-of-year to create a {@code LocalDate}.
	* <p>
	* This returns a {@code LocalDate} formed from this year and the specified day-of-year.
	* <p>
	* The day-of-year value 366 is only valid in a leap year.
	*
	* @param dayOfYear the day-of-year to use, from 1 to 365-366
	* @return the local date formed from this year and the specified date of year, not null
	* @throws DateTimeException if the day of year is zero or less, 366 or greater or equal
	* to 366 and this is not a leap year
	*/
	public LocalDate atDay(int dayOfYear) {
	return LocalDate.ofYearDay(year, dayOfYear);
	}

	/**
	* Combines this year with a month to create a {@code YearMonth}.
	* <p>
	* This returns a {@code YearMonth} formed from this year and the specified month.
	* All possible combinations of year and month are valid.
	* <p>
	* This method can be used as part of a chain to produce a date:
	* <pre>
	* LocalDate date = year.atMonth(month).atDay(day);
	* </pre>
	*
	* @param month the month-of-year to use, not null
	* @return the year-month formed from this year and the specified month, not null
	*/
	public YearMonth atMonth(Month month) {
	return YearMonth.of(year, month);
	}

	/**
	* Combines this year with a month to create a {@code YearMonth}.
	* <p>
	* This returns a {@code YearMonth} formed from this year and the specified month.
	* All possible combinations of year and month are valid.
	* <p>
	* This method can be used as part of a chain to produce a date:
	* <pre>
	* LocalDate date = year.atMonth(month).atDay(day);
	* </pre>
	*
	* @param month the month-of-year to use, from 1 (January) to 12 (December)
	* @return the year-month formed from this year and the specified month, not null
	* @throws DateTimeException if the month is invalid
	*/
	public YearMonth atMonth(int month) {
	return YearMonth.of(year, month);
	}

	/**
	* Combines this year with a month-day to create a {@code LocalDate}.
	* <p>
	* This returns a {@code LocalDate} formed from this year and the specified month-day.
	* <p>
	* A month-day of February 29th will be adjusted to February 28th in the resulting
	* date if the year is not a leap year.
	*
	* @param monthDay the month-day to use, not null
	* @return the local date formed from this year and the specified month-day, not null
	*/
	public LocalDate atMonthDay(MonthDay monthDay) {
	return monthDay.atYear(year);
	}

	//-----------------------------------------------------------------------
	/**
	* Compares this year to another year.
	* <p>
	* The comparison is based on the value of the year.
	* It is "consistent with equals", as defined by {@link Comparable}.
	*
	* @param other the other year to compare to, not null
	* @return the comparator value, negative if less, positive if greater
	*/
	@Override
	public int compareTo(Year other) {
	return year - other.year;
	}

	/**
	* Checks if this year is after the specified year.
	*
	* @param other the other year to compare to, not null
	* @return true if this is after the specified year
	*/
	public boolean isAfter(Year other) {
	return year > other.year;
	}

	/**
	* Checks if this year is before the specified year.
	*
	* @param other the other year to compare to, not null
	* @return true if this point is before the specified year
	*/
	public boolean isBefore(Year other) {
	return year < other.year;
	}

	//-----------------------------------------------------------------------
	/**
	* Checks if this year is equal to another year.
	* <p>
	* The comparison is based on the time-line position of the years.
	*
	* @param obj the object to check, null returns false
	* @return true if this is equal to the other year
	*/
	@Override
	public boolean equals(Object obj) {
	if (this == obj) {
	return true;
	}
	if (obj instanceof Year) {
	return year == ((Year) obj).year;
	}
	return false;
	}

	/**
	* A hash code for this year.
	*
	* @return a suitable hash code
	*/
	@Override
	public int hashCode() {
	return year;
	}

	//-----------------------------------------------------------------------
	/**
	* Outputs this year as a {@code String}.
	*
	* @return a string representation of this year, not null
	*/
	@Override
	public String toString() {
	return Integer.toString(year);
	}

	//-----------------------------------------------------------------------
	/**
	* Writes the object using a
	* <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
	* @serialData
	* <pre>
	* out.writeByte(11); // identifies a Year
	* out.writeInt(year);
	* </pre>
	*
	* @return the instance of {@code Ser}, not null
	*/
	@java.io.Serial
	private Object writeReplace() {
	return new Ser(Ser.YEAR_TYPE, this);
	}

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

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

	static Year readExternal(DataInput in) throws IOException {
	return Year.of(in.readInt());
	}

	}

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