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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
*
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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/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 java.time.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(java.time.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 in queries 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 date-time.
* 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 for 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 for 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 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 period added, not null
* @throws DateTimeException if the result exceeds the supported year 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 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 period subtracted, not null
* @throws DateTimeException if the result exceeds the supported year 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 period 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 period 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, not null
* @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>
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