Java tutorial
/* * 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. */ /* * 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 * 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; 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; use of identity-sensitive operations (including reference equality * ({@code ==}), identity hash code, or synchronization) on instances of * {@code Year} 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 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. */ private static final long serialVersionUID = -23038383694477807L; /** * Parser. */ private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder() .appendValue(YEAR, 4, 10, SignStyle.EXCEEDS_PAD).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. * Years outside the range 0000 to 9999 must be prefixed by the plus or minus symbol. * * @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) { switch ((ChronoField) field) { 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 f = (ChronoField) field; f.checkValidValue(newValue); switch (f) { 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) { switch ((ChronoUnit) unit) { 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) { long yearsUntil = ((long) end.year) - year; // no overflow switch ((ChronoUnit) unit) { 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 */ private Object writeReplace() { return new Ser(Ser.YEAR_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); } static Year readExternal(DataInput in) throws IOException { return Year.of(in.readInt()); } }