https://openjdk.java.net/ 
/*
 * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * Copyright (c) 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
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * 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
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package java.time.chrono;

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.MONTH_OF_YEAR;
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.Clock;
import java.time.DateTimeException;
import java.time.LocalDate;
import java.time.LocalTime;
import java.time.Period;
import java.time.ZoneId;
import java.time.temporal.ChronoField;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalAmount;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQuery;
import java.time.temporal.TemporalUnit;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.util.Calendar;
import java.util.Objects;

import sun.util.calendar.CalendarDate;
import sun.util.calendar.LocalGregorianCalendar;


A date in the Japanese Imperial calendar system.

 This date operates using the Japanese Imperial calendar. This calendar system is primarily used in Japan. 

The Japanese Imperial calendar system is the same as the ISO calendar system
apart from the era-based year numbering. The proleptic-year is defined to be
equal to the ISO proleptic-year.


Japan introduced the Gregorian calendar starting with Meiji 6.
Only Meiji and later eras are supported;
dates before Meiji 6, January 1 are not supported.


For example, the Japanese year "Heisei 24" corresponds to ISO year "2012".
 Calling japaneseDate.get(YEAR_OF_ERA) will return 24.
 Calling japaneseDate.get(YEAR) will return 2012.
 Calling japaneseDate.get(ERA) will return 2, corresponding to JapaneseChronology.ERA_HEISEI.



This is a value-based class; use of identity-sensitive operations (including reference equality (==), identity hash code, or synchronization) on instances of JapaneseDate may have unpredictable results and should be avoided. The equals method should be used for comparisons. 
Implementation Requirements:
This class is immutable and thread-safe.
Since:1.8
/**
 * A date in the Japanese Imperial calendar system.
 * <p>
 * This date operates using the {@linkplain JapaneseChronology Japanese Imperial calendar}.
 * This calendar system is primarily used in Japan.
 * <p>
 * The Japanese Imperial calendar system is the same as the ISO calendar system
 * apart from the era-based year numbering. The proleptic-year is defined to be
 * equal to the ISO proleptic-year.
 * <p>
 * Japan introduced the Gregorian calendar starting with Meiji 6.
 * Only Meiji and later eras are supported;
 * dates before Meiji 6, January 1 are not supported.
 * <p>
 * For example, the Japanese year "Heisei 24" corresponds to ISO year "2012".<br>
 * Calling {@code japaneseDate.get(YEAR_OF_ERA)} will return 24.<br>
 * Calling {@code japaneseDate.get(YEAR)} will return 2012.<br>
 * Calling {@code japaneseDate.get(ERA)} will return 2, corresponding to
 * {@code JapaneseChronology.ERA_HEISEI}.<br>
 *
 * <p>
 * This is a <a href="{@docRoot}/java.base/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 JapaneseDate} 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 JapaneseDate
        extends ChronoLocalDateImpl<JapaneseDate>
        implements ChronoLocalDate, Serializable {

    
Serialization version.

/**
     * Serialization version.
     */
    private static final long serialVersionUID = -305327627230580483L;

    
The underlying ISO local date.

/**
     * The underlying ISO local date.
     */
    private final transient LocalDate isoDate;
    
The JapaneseEra of this date.

/**
     * The JapaneseEra of this date.
     */
    private transient JapaneseEra era;
    
The Japanese imperial calendar year of this date.

/**
     * The Japanese imperial calendar year of this date.
     */
    private transient int yearOfEra;

    
The first day supported by the JapaneseChronology is Meiji 6, January 1st.

/**
     * The first day supported by the JapaneseChronology is Meiji 6, January 1st.
     */
    static final LocalDate MEIJI_6_ISODATE = LocalDate.of(1873, 1, 1);

    //-----------------------------------------------------------------------
    
Obtains the current JapaneseDate from the system clock in the default time-zone. 
 This will query the system clock in the default time-zone to obtain the current date. 

Using this method will prevent the ability to use an alternate clock for testing
because the clock is hard-coded.

Returns:the current date using the system clock and default time-zone, not null
/**
     * Obtains the current {@code JapaneseDate} 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 JapaneseDate now() {
        return now(Clock.systemDefaultZone());
    }

    
Obtains the current JapaneseDate from the system clock in the specified time-zone. 
 This will query the system clock to obtain the current date. Specifying the time-zone avoids dependence on the default time-zone. 

Using this method will prevent the ability to use an alternate clock for testing
because the clock is hard-coded.

Params:
  • zone –  the zone ID to use, not null
Returns:the current date using the system clock, not null
/**
     * Obtains the current {@code JapaneseDate} 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 JapaneseDate now(ZoneId zone) {
        return now(Clock.system(zone));
    }

    
Obtains the current JapaneseDate from the specified clock. 
 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 dependency injection. 
Params:
  • clock –  the clock to use, not null
Throws:
Returns:the current date, not null
/**
     * Obtains the current {@code JapaneseDate} 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 {@linkplain Clock dependency injection}.
     *
     * @param clock  the clock to use, not null
     * @return the current date, not null
     * @throws DateTimeException if the current date cannot be obtained
     */
    public static JapaneseDate now(Clock clock) {
        return new JapaneseDate(LocalDate.now(clock));
    }

    
Obtains a JapaneseDate representing a date in the Japanese calendar system from the era, year-of-era, month-of-year and day-of-month fields. 
 This returns a JapaneseDate with the specified fields. The day must be valid for the year and month, otherwise an exception will be thrown. 

The Japanese month and day-of-month are the same as those in the
ISO calendar system. They are not reset when the era changes.
For example:

 6th Jan Showa 64 = ISO 1989-01-06
 7th Jan Showa 64 = ISO 1989-01-07
 8th Jan Heisei 1 = ISO 1989-01-08
 9th Jan Heisei 1 = ISO 1989-01-09



Params:
  • era –  the Japanese era, not null
  • yearOfEra –  the Japanese year-of-era
  • month –  the Japanese month-of-year, from 1 to 12
  • dayOfMonth –  the Japanese day-of-month, from 1 to 31
Throws:
  • DateTimeException – if the value of any field is out of range,
 or if the day-of-month is invalid for the month-year,
 or if the date is not a Japanese era
Returns:the date in Japanese calendar system, not null
/**
     * Obtains a {@code JapaneseDate} representing a date in the Japanese calendar
     * system from the era, year-of-era, month-of-year and day-of-month fields.
     * <p>
     * This returns a {@code JapaneseDate} with the specified fields.
     * The day must be valid for the year and month, otherwise an exception will be thrown.
     * <p>
     * The Japanese month and day-of-month are the same as those in the
     * ISO calendar system. They are not reset when the era changes.
     * For example:
     * <pre>
     *  6th Jan Showa 64 = ISO 1989-01-06
     *  7th Jan Showa 64 = ISO 1989-01-07
     *  8th Jan Heisei 1 = ISO 1989-01-08
     *  9th Jan Heisei 1 = ISO 1989-01-09
     * </pre>
     *
     * @param era  the Japanese era, not null
     * @param yearOfEra  the Japanese year-of-era
     * @param month  the Japanese month-of-year, from 1 to 12
     * @param dayOfMonth  the Japanese day-of-month, from 1 to 31
     * @return the date in Japanese calendar system, 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,
     *  or if the date is not a Japanese era
     */
    public static JapaneseDate of(JapaneseEra era, int yearOfEra, int month, int dayOfMonth) {
        Objects.requireNonNull(era, "era");
        LocalGregorianCalendar.Date jdate = JapaneseChronology.JCAL.newCalendarDate(null);
        jdate.setEra(era.getPrivateEra()).setDate(yearOfEra, month, dayOfMonth);
        if (!JapaneseChronology.JCAL.validate(jdate)) {
            throw new DateTimeException("year, month, and day not valid for Era");
        }
        LocalDate date = LocalDate.of(jdate.getNormalizedYear(), month, dayOfMonth);
        return new JapaneseDate(era, yearOfEra, date);
    }

    
Obtains a JapaneseDate representing a date in the Japanese calendar system from the proleptic-year, month-of-year and day-of-month fields. 
 This returns a JapaneseDate with the specified fields. The day must be valid for the year and month, otherwise an exception will be thrown. 

The Japanese proleptic year, month and day-of-month are the same as those
in the ISO calendar system. They are not reset when the era changes.

Params:
  • prolepticYear –  the Japanese proleptic-year
  • month –  the Japanese month-of-year, from 1 to 12
  • dayOfMonth –  the Japanese day-of-month, from 1 to 31
Throws:
  • DateTimeException – if the value of any field is out of range,
 or if the day-of-month is invalid for the month-year
Returns:the date in Japanese calendar system, not null
/**
     * Obtains a {@code JapaneseDate} representing a date in the Japanese calendar
     * system from the proleptic-year, month-of-year and day-of-month fields.
     * <p>
     * This returns a {@code JapaneseDate} with the specified fields.
     * The day must be valid for the year and month, otherwise an exception will be thrown.
     * <p>
     * The Japanese proleptic year, month and day-of-month are the same as those
     * in the ISO calendar system. They are not reset when the era changes.
     *
     * @param prolepticYear  the Japanese proleptic-year
     * @param month  the Japanese month-of-year, from 1 to 12
     * @param dayOfMonth  the Japanese day-of-month, from 1 to 31
     * @return the date in Japanese calendar system, 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 JapaneseDate of(int prolepticYear, int month, int dayOfMonth) {
        return new JapaneseDate(LocalDate.of(prolepticYear, month, dayOfMonth));
    }

    
Obtains a JapaneseDate representing a date in the Japanese calendar system from the era, year-of-era and day-of-year fields. 
 This returns a JapaneseDate with the specified fields. The day must be valid for the year, otherwise an exception will be thrown. 

The day-of-year in this factory is expressed relative to the start of the year-of-era.
This definition changes the normal meaning of day-of-year only in those years
where the year-of-era is reset to one due to a change in the era.
For example:

 6th Jan Showa 64 = day-of-year 6
 7th Jan Showa 64 = day-of-year 7
 8th Jan Heisei 1 = day-of-year 1
 9th Jan Heisei 1 = day-of-year 2



Params:
  • era –  the Japanese era, not null
  • yearOfEra –  the Japanese year-of-era
  • dayOfYear –  the chronology day-of-year, from 1 to 366
Throws:
  • DateTimeException – if the value of any field is out of range,
 or if the day-of-year is invalid for the year
Returns:the date in Japanese calendar system, not null
/**
     * Obtains a {@code JapaneseDate} representing a date in the Japanese calendar
     * system from the era, year-of-era and day-of-year fields.
     * <p>
     * This returns a {@code JapaneseDate} with the specified fields.
     * The day must be valid for the year, otherwise an exception will be thrown.
     * <p>
     * The day-of-year in this factory is expressed relative to the start of the year-of-era.
     * This definition changes the normal meaning of day-of-year only in those years
     * where the year-of-era is reset to one due to a change in the era.
     * For example:
     * <pre>
     *  6th Jan Showa 64 = day-of-year 6
     *  7th Jan Showa 64 = day-of-year 7
     *  8th Jan Heisei 1 = day-of-year 1
     *  9th Jan Heisei 1 = day-of-year 2
     * </pre>
     *
     * @param era  the Japanese era, not null
     * @param yearOfEra  the Japanese year-of-era
     * @param dayOfYear  the chronology day-of-year, from 1 to 366
     * @return the date in Japanese calendar system, 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
     */
    static JapaneseDate ofYearDay(JapaneseEra era, int yearOfEra, int dayOfYear) {
        Objects.requireNonNull(era, "era");
        CalendarDate firstDay = era.getPrivateEra().getSinceDate();
        LocalGregorianCalendar.Date jdate = JapaneseChronology.JCAL.newCalendarDate(null);
        jdate.setEra(era.getPrivateEra());
        if (yearOfEra == 1) {
            jdate.setDate(yearOfEra, firstDay.getMonth(), firstDay.getDayOfMonth() + dayOfYear - 1);
        } else {
            jdate.setDate(yearOfEra, 1, dayOfYear);
        }
        JapaneseChronology.JCAL.normalize(jdate);
        if (era.getPrivateEra() != jdate.getEra() || yearOfEra != jdate.getYear()) {
            throw new DateTimeException("Invalid parameters");
        }
        LocalDate localdate = LocalDate.of(jdate.getNormalizedYear(),
                                      jdate.getMonth(), jdate.getDayOfMonth());
        return new JapaneseDate(era, yearOfEra, localdate);
    }

    
Obtains a JapaneseDate from a temporal object. 
 This obtains a date in the Japanese calendar system based on the specified temporal. A TemporalAccessor represents an arbitrary set of date and time information, which this factory converts to an instance of JapaneseDate. 
 The conversion typically uses the EPOCH_DAY field, which is standardized across calendar systems. 
 This method matches the signature of the functional interface TemporalQuery allowing it to be used as a query via method reference, JapaneseDate::from. 
Params:
  • temporal –  the temporal object to convert, not null
Throws:
Returns:the date in Japanese calendar system, not null
/**
     * Obtains a {@code JapaneseDate} from a temporal object.
     * <p>
     * This obtains a date in the Japanese calendar system 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 JapaneseDate}.
     * <p>
     * The conversion typically uses the {@link ChronoField#EPOCH_DAY EPOCH_DAY}
     * field, which is standardized across calendar systems.
     * <p>
     * This method matches the signature of the functional interface {@link TemporalQuery}
     * allowing it to be used as a query via method reference, {@code JapaneseDate::from}.
     *
     * @param temporal  the temporal object to convert, not null
     * @return the date in Japanese calendar system, not null
     * @throws DateTimeException if unable to convert to a {@code JapaneseDate}
     */
    public static JapaneseDate from(TemporalAccessor temporal) {
        return JapaneseChronology.INSTANCE.date(temporal);
    }

    //-----------------------------------------------------------------------
    
Creates an instance from an ISO date.

Params:
  • isoDate –  the standard local date, validated not null
/**
     * Creates an instance from an ISO date.
     *
     * @param isoDate  the standard local date, validated not null
     */
    JapaneseDate(LocalDate isoDate) {
        if (isoDate.isBefore(MEIJI_6_ISODATE)) {
            throw new DateTimeException("JapaneseDate before Meiji 6 is not supported");
        }
        LocalGregorianCalendar.Date jdate = toPrivateJapaneseDate(isoDate);
        this.era = JapaneseEra.toJapaneseEra(jdate.getEra());
        this.yearOfEra = jdate.getYear();
        this.isoDate = isoDate;
    }

    
Constructs a JapaneseDate. This constructor does NOT validate the given parameters, and era and year must agree with isoDate. 
Params:
  • era –  the era, validated not null
  • year –  the year-of-era, validated
  • isoDate –  the standard local date, validated not null
/**
     * Constructs a {@code JapaneseDate}. This constructor does NOT validate the given parameters,
     * and {@code era} and {@code year} must agree with {@code isoDate}.
     *
     * @param era  the era, validated not null
     * @param year  the year-of-era, validated
     * @param isoDate  the standard local date, validated not null
     */
    JapaneseDate(JapaneseEra era, int year, LocalDate isoDate) {
        if (isoDate.isBefore(MEIJI_6_ISODATE)) {
            throw new DateTimeException("JapaneseDate before Meiji 6 is not supported");
        }
        this.era = era;
        this.yearOfEra = year;
        this.isoDate = isoDate;
    }

    //-----------------------------------------------------------------------
    
Gets the chronology of this date, which is the Japanese calendar system.

 The Chronology represents the calendar system in use. The era and other fields in ChronoField are defined by the chronology. 
Returns:the Japanese chronology, not null
/**
     * Gets the chronology of this date, which is the Japanese calendar system.
     * <p>
     * The {@code Chronology} represents the calendar system in use.
     * The era and other fields in {@link ChronoField} are defined by the chronology.
     *
     * @return the Japanese chronology, not null
     */
    @Override
    public JapaneseChronology getChronology() {
        return JapaneseChronology.INSTANCE;
    }

    
Gets the era applicable at this date.

 The Japanese calendar system has multiple eras defined by JapaneseEra. 
Returns:the era applicable at this date, not null
/**
     * Gets the era applicable at this date.
     * <p>
     * The Japanese calendar system has multiple eras defined by {@link JapaneseEra}.
     *
     * @return the era applicable at this date, not null
     */
    @Override
    public JapaneseEra getEra() {
        return era;
    }

    
Returns the length of the month represented by this date.


This returns the length of the month in days.
Month lengths match those of the ISO calendar system.

Returns:the length of the month in days
/**
     * Returns the length of the month represented by this date.
     * <p>
     * This returns the length of the month in days.
     * Month lengths match those of the ISO calendar system.
     *
     * @return the length of the month in days
     */
    @Override
    public int lengthOfMonth() {
        return isoDate.lengthOfMonth();
    }

    @Override
    public int lengthOfYear() {
        Calendar jcal = Calendar.getInstance(JapaneseChronology.LOCALE);
        jcal.set(Calendar.ERA, era.getValue() + JapaneseEra.ERA_OFFSET);
        jcal.set(yearOfEra, isoDate.getMonthValue() - 1, isoDate.getDayOfMonth());
        return  jcal.getActualMaximum(Calendar.DAY_OF_YEAR);
    }

    //-----------------------------------------------------------------------
    
Checks if the specified field is supported.

 This checks if this date can be queried for the specified field. If false, then calling the range and get methods will throw an exception. 
 If the field is a ChronoField then the query is implemented here. The supported fields are: 
    

  • DAY_OF_WEEK 
  • DAY_OF_MONTH 
  • DAY_OF_YEAR 
  • EPOCH_DAY 
  • MONTH_OF_YEAR 
  • PROLEPTIC_MONTH 
  • YEAR_OF_ERA 
  • YEAR 
  • ERA 
 All other ChronoField instances will return false. 
 If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.isSupportedBy(TemporalAccessor) passing this as the argument. Whether the field is supported is determined by the field. 
Params:
  • field –  the field to check, null returns false
Returns:true if the field is supported on this date, false if not
/**
     * 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} and
     * {@link #get(TemporalField) get} 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 DAY_OF_MONTH}
     * <li>{@code DAY_OF_YEAR}
     * <li>{@code EPOCH_DAY}
     * <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
    public boolean isSupported(TemporalField field) {
        if (field == ALIGNED_DAY_OF_WEEK_IN_MONTH || field == ALIGNED_DAY_OF_WEEK_IN_YEAR ||
                field == ALIGNED_WEEK_OF_MONTH || field == ALIGNED_WEEK_OF_YEAR) {
            return false;
        }
        return super.isSupported(field);
    }

    @Override
    public ValueRange range(TemporalField field) {
        if (field instanceof ChronoField) {
            if (isSupported(field)) {
                ChronoField f = (ChronoField) field;
                switch (f) {
                    case DAY_OF_MONTH: return ValueRange.of(1, lengthOfMonth());
                    case DAY_OF_YEAR: return ValueRange.of(1, lengthOfYear());
                    case YEAR_OF_ERA: {
                        Calendar jcal = Calendar.getInstance(JapaneseChronology.LOCALE);
                        jcal.set(Calendar.ERA, era.getValue() + JapaneseEra.ERA_OFFSET);
                        jcal.set(yearOfEra, isoDate.getMonthValue() - 1, isoDate.getDayOfMonth());
                        return ValueRange.of(1, jcal.getActualMaximum(Calendar.YEAR));
                    }
                }
                return getChronology().range(f);
            }
            throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        }
        return field.rangeRefinedBy(this);
    }

    @Override
    public long getLong(TemporalField field) {
        if (field instanceof ChronoField) {
            // same as ISO:
            // DAY_OF_WEEK, DAY_OF_MONTH, EPOCH_DAY, MONTH_OF_YEAR, PROLEPTIC_MONTH, YEAR
            //
            // calendar specific fields
            // DAY_OF_YEAR, YEAR_OF_ERA, ERA
            switch ((ChronoField) field) {
                case ALIGNED_DAY_OF_WEEK_IN_MONTH:
                case ALIGNED_DAY_OF_WEEK_IN_YEAR:
                case ALIGNED_WEEK_OF_MONTH:
                case ALIGNED_WEEK_OF_YEAR:
                    throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
                case YEAR_OF_ERA:
                    return yearOfEra;
                case ERA:
                    return era.getValue();
                case DAY_OF_YEAR:
                    Calendar jcal = Calendar.getInstance(JapaneseChronology.LOCALE);
                    jcal.set(Calendar.ERA, era.getValue() + JapaneseEra.ERA_OFFSET);
                    jcal.set(yearOfEra, isoDate.getMonthValue() - 1, isoDate.getDayOfMonth());
                    return jcal.get(Calendar.DAY_OF_YEAR);
            }
            return isoDate.getLong(field);
        }
        return field.getFrom(this);
    }

    
Returns a LocalGregorianCalendar.Date converted from the given isoDate. 
Params:
  • isoDate –  the local date, not null
Returns:a LocalGregorianCalendar.Date, not null
/**
     * Returns a {@code LocalGregorianCalendar.Date} converted from the given {@code isoDate}.
     *
     * @param isoDate  the local date, not null
     * @return a {@code LocalGregorianCalendar.Date}, not null
     */
    private static LocalGregorianCalendar.Date toPrivateJapaneseDate(LocalDate isoDate) {
        LocalGregorianCalendar.Date jdate = JapaneseChronology.JCAL.newCalendarDate(null);
        sun.util.calendar.Era sunEra = JapaneseEra.privateEraFrom(isoDate);
        int year = isoDate.getYear();
        if (sunEra != null) {
            year -= sunEra.getSinceDate().getYear() - 1;
        }
        jdate.setEra(sunEra).setYear(year).setMonth(isoDate.getMonthValue()).setDayOfMonth(isoDate.getDayOfMonth());
        JapaneseChronology.JCAL.normalize(jdate);
        return jdate;
    }

    //-----------------------------------------------------------------------
    @Override
    public JapaneseDate with(TemporalField field, long newValue) {
        if (field instanceof ChronoField) {
            ChronoField f = (ChronoField) field;
            if (getLong(f) == newValue) {  // getLong() validates for supported fields
                return this;
            }
            switch (f) {
                case YEAR_OF_ERA:
                case YEAR:
                case ERA: {
                    int nvalue = getChronology().range(f).checkValidIntValue(newValue, f);
                    switch (f) {
                        case YEAR_OF_ERA:
                            return this.withYear(nvalue);
                        case YEAR:
                            return with(isoDate.withYear(nvalue));
                        case ERA: {
                            return this.withYear(JapaneseEra.of(nvalue), yearOfEra);
                        }
                    }
                }
            }
            // YEAR, PROLEPTIC_MONTH and others are same as ISO
            return with(isoDate.with(field, newValue));
        }
        return super.with(field, newValue);
    }

    
{@inheritDoc}

Throws:
/**
     * {@inheritDoc}
     * @throws DateTimeException {@inheritDoc}
     * @throws ArithmeticException {@inheritDoc}
     */
    @Override
    public  JapaneseDate with(TemporalAdjuster adjuster) {
        return super.with(adjuster);
    }

    
{@inheritDoc}

Throws:
/**
     * {@inheritDoc}
     * @throws DateTimeException {@inheritDoc}
     * @throws ArithmeticException {@inheritDoc}
     */
    @Override
    public JapaneseDate plus(TemporalAmount amount) {
        return super.plus(amount);
    }

    
{@inheritDoc}

Throws:
/**
     * {@inheritDoc}
     * @throws DateTimeException {@inheritDoc}
     * @throws ArithmeticException {@inheritDoc}
     */
    @Override
    public JapaneseDate minus(TemporalAmount amount) {
        return super.minus(amount);
    }
    //-----------------------------------------------------------------------
    
Returns a copy of this date with the year altered.


This method changes the year of the date.
If the month-day is invalid for the year, then the previous valid day
will be selected instead.


This instance is immutable and unaffected by this method call.

Params:
  • era –  the era to set in the result, not null
  • yearOfEra –  the year-of-era to set in the returned date
Throws:
Returns:a JapaneseDate based on this date with the requested year, never null
/**
     * Returns a copy of this date with the year altered.
     * <p>
     * This method changes the year of the date.
     * If the month-day is invalid for the year, then the previous valid day
     * will be selected instead.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param era  the era to set in the result, not null
     * @param yearOfEra  the year-of-era to set in the returned date
     * @return a {@code JapaneseDate} based on this date with the requested year, never null
     * @throws DateTimeException if {@code year} is invalid
     */
    private JapaneseDate withYear(JapaneseEra era, int yearOfEra) {
        int year = JapaneseChronology.INSTANCE.prolepticYear(era, yearOfEra);
        return with(isoDate.withYear(year));
    }

    
Returns a copy of this date with the year-of-era altered.


This method changes the year-of-era of the date.
If the month-day is invalid for the year, then the previous valid day
will be selected instead.


This instance is immutable and unaffected by this method call.

Params:
  • year –  the year to set in the returned date
Throws:
Returns:a JapaneseDate based on this date with the requested year-of-era, never null
/**
     * Returns a copy of this date with the year-of-era altered.
     * <p>
     * This method changes the year-of-era of the date.
     * If the month-day is invalid for the year, then the previous valid day
     * will be selected instead.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param year  the year to set in the returned date
     * @return a {@code JapaneseDate} based on this date with the requested year-of-era, never null
     * @throws DateTimeException if {@code year} is invalid
     */
    private JapaneseDate withYear(int year) {
        return withYear(getEra(), year);
    }

    //-----------------------------------------------------------------------
    @Override
    JapaneseDate plusYears(long years) {
        return with(isoDate.plusYears(years));
    }

    @Override
    JapaneseDate plusMonths(long months) {
        return with(isoDate.plusMonths(months));
    }

    @Override
    JapaneseDate plusWeeks(long weeksToAdd) {
        return with(isoDate.plusWeeks(weeksToAdd));
    }

    @Override
    JapaneseDate plusDays(long days) {
        return with(isoDate.plusDays(days));
    }

    @Override
    public JapaneseDate plus(long amountToAdd, TemporalUnit unit) {
        return super.plus(amountToAdd, unit);
    }

    @Override
    public JapaneseDate minus(long amountToAdd, TemporalUnit unit) {
        return super.minus(amountToAdd, unit);
    }

    @Override
    JapaneseDate minusYears(long yearsToSubtract) {
        return super.minusYears(yearsToSubtract);
    }

    @Override
    JapaneseDate minusMonths(long monthsToSubtract) {
        return super.minusMonths(monthsToSubtract);
    }

    @Override
    JapaneseDate minusWeeks(long weeksToSubtract) {
        return super.minusWeeks(weeksToSubtract);
    }

    @Override
    JapaneseDate minusDays(long daysToSubtract) {
        return super.minusDays(daysToSubtract);
    }

    private JapaneseDate with(LocalDate newDate) {
        return (newDate.equals(isoDate) ? this : new JapaneseDate(newDate));
    }

    @Override        // for javadoc and covariant return type
    @SuppressWarnings("unchecked")
    public final ChronoLocalDateTime<JapaneseDate> atTime(LocalTime localTime) {
        return (ChronoLocalDateTime<JapaneseDate>)super.atTime(localTime);
    }

    @Override
    public ChronoPeriod until(ChronoLocalDate endDate) {
        Period period = isoDate.until(endDate);
        return getChronology().period(period.getYears(), period.getMonths(), period.getDays());
    }

    @Override  // override for performance
    public long toEpochDay() {
        return isoDate.toEpochDay();
    }

    //-------------------------------------------------------------------------
    
Compares this date to another date, including the chronology.

 Compares this JapaneseDate with another ensuring that the date is the same. 
 Only objects of type JapaneseDate are compared, other types return false. To compare the dates of two TemporalAccessor instances, including dates in two different chronologies, use ChronoField.EPOCH_DAY as a comparator. 
Params:
  • obj –  the object to check, null returns false
Returns:true if this is equal to the other date
/**
     * Compares this date to another date, including the chronology.
     * <p>
     * Compares this {@code JapaneseDate} with another ensuring that the date is the same.
     * <p>
     * Only objects of type {@code JapaneseDate} 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  // override for performance
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof JapaneseDate) {
            JapaneseDate otherDate = (JapaneseDate) obj;
            return this.isoDate.equals(otherDate.isoDate);
        }
        return false;
    }

    
A hash code for this date.

Returns:a suitable hash code based only on the Chronology and the date
/**
     * A hash code for this date.
     *
     * @return a suitable hash code based only on the Chronology and the date
     */
    @Override  // override for performance
    public int hashCode() {
        return getChronology().getId().hashCode() ^ isoDate.hashCode();
    }

    //-----------------------------------------------------------------------
    
Defend against malicious streams.

Params:
  • s – the stream to read
Throws:
/**
     * 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");
    }

    
Writes the object using a
dedicated serialized form.

@serialData

 out.writeByte(4);                 // identifies a JapaneseDate
 out.writeInt(get(YEAR));
 out.writeByte(get(MONTH_OF_YEAR));
 out.writeByte(get(DAY_OF_MONTH));

Returns:the instance of Ser, not null
/**
     * Writes the object using a
     * <a href="../../../serialized-form.html#java.time.chrono.Ser">dedicated serialized form</a>.
     * @serialData
     * <pre>
     *  out.writeByte(4);                 // identifies a JapaneseDate
     *  out.writeInt(get(YEAR));
     *  out.writeByte(get(MONTH_OF_YEAR));
     *  out.writeByte(get(DAY_OF_MONTH));
     * </pre>
     *
     * @return the instance of {@code Ser}, not null
     */
    private Object writeReplace() {
        return new Ser(Ser.JAPANESE_DATE_TYPE, this);
    }

    void writeExternal(DataOutput out) throws IOException {
        // JapaneseChronology is implicit in the JAPANESE_DATE_TYPE
        out.writeInt(get(YEAR));
        out.writeByte(get(MONTH_OF_YEAR));
        out.writeByte(get(DAY_OF_MONTH));
    }

    static JapaneseDate readExternal(DataInput in) throws IOException {
        int year = in.readInt();
        int month = in.readByte();
        int dayOfMonth = in.readByte();
        return JapaneseChronology.INSTANCE.date(year, month, dayOfMonth);
    }

}