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/*
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* Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright notice,
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package java.time;
import static java.time.temporal.
ChronoField.
ERA;
import static java.time.temporal.
ChronoField.
MONTH_OF_YEAR;
import static java.time.temporal.
ChronoField.
PROLEPTIC_MONTH;
import static java.time.temporal.
ChronoField.
YEAR;
import 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.
MONTHS;
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-month in the ISO-8601 calendar system, such as {@code 2007-12}.
* <p>
* {@code YearMonth} is an immutable date-time object that represents the combination
* of a year and month. Any field that can be derived from a year and month, such as
* quarter-of-year, can be obtained.
* <p>
* This class does not store or represent a day, time or time-zone.
* For example, the value "October 2007" can be stored in a {@code YearMonth}.
* <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 YearMonth} 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
YearMonth
implements
Temporal,
TemporalAdjuster,
Comparable<
YearMonth>,
Serializable {
/**
* Serialization version.
*/
private static final long
serialVersionUID = 4183400860270640070L;
/**
* Parser.
*/
private static final
DateTimeFormatter PARSER = new
DateTimeFormatterBuilder()
.
appendValue(
YEAR, 4, 10,
SignStyle.
EXCEEDS_PAD)
.
appendLiteral('-')
.
appendValue(
MONTH_OF_YEAR, 2)
.
toFormatter();
/**
* The year.
*/
private final int
year;
/**
* The month-of-year, not null.
*/
private final int
month;
//-----------------------------------------------------------------------
/**
* Obtains the current year-month 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-month.
* <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-month using the system clock and default time-zone, not null
*/
public static
YearMonth now() {
return
now(
Clock.
systemDefaultZone());
}
/**
* Obtains the current year-month 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-month.
* 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-month using the system clock, not null
*/
public static
YearMonth now(
ZoneId zone) {
return
now(
Clock.
system(
zone));
}
/**
* Obtains the current year-month from the specified clock.
* <p>
* This will query the specified clock to obtain the current year-month.
* 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-month, not null
*/
public static
YearMonth now(
Clock clock) {
final
LocalDate now =
LocalDate.
now(
clock); // called once
return
YearMonth.
of(
now.
getYear(),
now.
getMonth());
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code YearMonth} from a year and month.
*
* @param year the year to represent, from MIN_YEAR to MAX_YEAR
* @param month the month-of-year to represent, not null
* @return the year-month, not null
* @throws DateTimeException if the year value is invalid
*/
public static
YearMonth of(int
year,
Month month) {
Objects.
requireNonNull(
month, "month");
return
of(
year,
month.
getValue());
}
/**
* Obtains an instance of {@code YearMonth} from a year and month.
*
* @param year the year to represent, from MIN_YEAR to MAX_YEAR
* @param month the month-of-year to represent, from 1 (January) to 12 (December)
* @return the year-month, not null
* @throws DateTimeException if either field value is invalid
*/
public static
YearMonth of(int
year, int
month) {
YEAR.
checkValidValue(
year);
MONTH_OF_YEAR.
checkValidValue(
month);
return new
YearMonth(
year,
month);
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code YearMonth} from a temporal object.
* <p>
* This obtains a year-month 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 YearMonth}.
* <p>
* The conversion extracts the {@link ChronoField#YEAR YEAR} and
* {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} fields.
* 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 YearMonth::from}.
*
* @param temporal the temporal object to convert, not null
* @return the year-month, not null
* @throws DateTimeException if unable to convert to a {@code YearMonth}
*/
public static
YearMonth from(
TemporalAccessor temporal) {
if (
temporal instanceof
YearMonth) {
return (
YearMonth)
temporal;
}
Objects.
requireNonNull(
temporal, "temporal");
try {
if (
IsoChronology.
INSTANCE.
equals(
Chronology.
from(
temporal)) == false) {
temporal =
LocalDate.
from(
temporal);
}
return
of(
temporal.
get(
YEAR),
temporal.
get(
MONTH_OF_YEAR));
} catch (
DateTimeException ex) {
throw new
DateTimeException("Unable to obtain YearMonth from TemporalAccessor: " +
temporal + " of type " +
temporal.
getClass().
getName(),
ex);
}
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code YearMonth} from a text string such as {@code 2007-12}.
* <p>
* The string must represent a valid year-month.
* The format must be {@code uuuu-MM}.
* Years outside the range 0000 to 9999 must be prefixed by the plus or minus symbol.
*
* @param text the text to parse such as "2007-12", not null
* @return the parsed year-month, not null
* @throws DateTimeParseException if the text cannot be parsed
*/
public static
YearMonth parse(
CharSequence text) {
return
parse(
text,
PARSER);
}
/**
* Obtains an instance of {@code YearMonth} from a text string using a specific formatter.
* <p>
* The text is parsed using the formatter, returning a year-month.
*
* @param text the text to parse, not null
* @param formatter the formatter to use, not null
* @return the parsed year-month, not null
* @throws DateTimeParseException if the text cannot be parsed
*/
public static
YearMonth parse(
CharSequence text,
DateTimeFormatter formatter) {
Objects.
requireNonNull(
formatter, "formatter");
return
formatter.
parse(
text,
YearMonth::from);
}
//-----------------------------------------------------------------------
/**
* Constructor.
*
* @param year the year to represent, validated from MIN_YEAR to MAX_YEAR
* @param month the month-of-year to represent, validated from 1 (January) to 12 (December)
*/
private
YearMonth(int
year, int
month) {
this.
year =
year;
this.
month =
month;
}
/**
* Returns a copy of this year-month with the new year and month, checking
* to see if a new object is in fact required.
*
* @param newYear the year to represent, validated from MIN_YEAR to MAX_YEAR
* @param newMonth the month-of-year to represent, validated not null
* @return the year-month, not null
*/
private
YearMonth with(int
newYear, int
newMonth) {
if (
year ==
newYear &&
month ==
newMonth) {
return this;
}
return new
YearMonth(
newYear,
newMonth);
}
//-----------------------------------------------------------------------
/**
* Checks if the specified field is supported.
* <p>
* This checks if this year-month 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 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 year-month, false if not
*/
@
Override
public boolean
isSupported(
TemporalField field) {
if (
field instanceof
ChronoField) {
return
field ==
YEAR ||
field ==
MONTH_OF_YEAR ||
field ==
PROLEPTIC_MONTH ||
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-month.
* 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 MONTHS}
* <li>{@code YEARS}
* <li>{@code DECADES}
* <li>{@code CENTURIES}
* <li>{@code MILLENNIA}
* <li>{@code ERAS}
* </ul>
* All other {@code ChronoUnit} instances will return false.
* <p>
* If the unit is not a {@code ChronoUnit}, then the result of this method
* is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
* passing {@code this} as the argument.
* Whether the unit is supported is determined by the unit.
*
* @param unit the unit to check, null returns false
* @return true if the unit can be added/subtracted, false if not
*/
@
Override
public boolean
isSupported(
TemporalUnit unit) {
if (
unit instanceof
ChronoUnit) {
return
unit ==
MONTHS ||
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-month 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 (
getYear() <= 0 ?
ValueRange.
of(1,
Year.
MAX_VALUE + 1) :
ValueRange.
of(1,
Year.
MAX_VALUE));
}
return
Temporal.super.range(
field);
}
/**
* Gets the value of the specified field from this year-month as an {@code int}.
* <p>
* This queries this year-month 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-month, except {@code PROLEPTIC_MONTH} which is too
* large to fit in an {@code int} and throw a {@code DateTimeException}.
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
* passing {@code this} as the argument. Whether the value can be obtained,
* and what the value represents, is determined by the field.
*
* @param field the field to get, not null
* @return the value for the field
* @throws DateTimeException if a value for the field cannot be obtained or
* the value is outside the range of valid values for the field
* @throws UnsupportedTemporalTypeException if the field is not supported or
* the range of values exceeds an {@code int}
* @throws ArithmeticException if numeric overflow occurs
*/
@
Override // override for Javadoc
public int
get(
TemporalField field) {
return
range(
field).
checkValidIntValue(
getLong(
field),
field);
}
/**
* Gets the value of the specified field from this year-month as a {@code long}.
* <p>
* This queries this year-month 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-month.
* 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
MONTH_OF_YEAR: return
month;
case
PROLEPTIC_MONTH: return
getProlepticMonth();
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);
}
private long
getProlepticMonth() {
return (
year * 12L +
month - 1);
}
//-----------------------------------------------------------------------
/**
* Gets the year field.
* <p>
* This method returns the primitive {@code int} value for the year.
* <p>
* The year returned by this method is proleptic as per {@code get(YEAR)}.
*
* @return the year, from MIN_YEAR to MAX_YEAR
*/
public int
getYear() {
return
year;
}
/**
* Gets the month-of-year field from 1 to 12.
* <p>
* This method returns the month as an {@code int} from 1 to 12.
* Application code is frequently clearer if the enum {@link Month}
* is used by calling {@link #getMonth()}.
*
* @return the month-of-year, from 1 to 12
* @see #getMonth()
*/
public int
getMonthValue() {
return
month;
}
/**
* Gets the month-of-year field using the {@code Month} enum.
* <p>
* This method returns the enum {@link Month} for the month.
* This avoids confusion as to what {@code int} values mean.
* If you need access to the primitive {@code int} value then the enum
* provides the {@link Month#getValue() int value}.
*
* @return the month-of-year, not null
* @see #getMonthValue()
*/
public
Month getMonth() {
return
Month.
of(
month);
}
//-----------------------------------------------------------------------
/**
* 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
isLeapYear() {
return
IsoChronology.
INSTANCE.
isLeapYear(
year);
}
/**
* Checks if the day-of-month is valid for this year-month.
* <p>
* This method checks whether this year and month and the input day form
* a valid date.
*
* @param dayOfMonth the day-of-month to validate, from 1 to 31, invalid value returns false
* @return true if the day is valid for this year-month
*/
public boolean
isValidDay(int
dayOfMonth) {
return
dayOfMonth >= 1 &&
dayOfMonth <=
lengthOfMonth();
}
/**
* Returns the length of the month, taking account of the year.
* <p>
* This returns the length of the month in days.
* For example, a date in January would return 31.
*
* @return the length of the month in days, from 28 to 31
*/
public int
lengthOfMonth() {
return
getMonth().
length(
isLeapYear());
}
/**
* Returns the length of the year.
* <p>
* This returns the length of the year in days, either 365 or 366.
*
* @return 366 if the year is leap, 365 otherwise
*/
public int
lengthOfYear() {
return (
isLeapYear() ? 366 : 365);
}
//-----------------------------------------------------------------------
/**
* Returns an adjusted copy of this year-month.
* <p>
* This returns a {@code YearMonth}, based on this one, with the year-month adjusted.
* The adjustment takes place using the specified adjuster strategy object.
* Read the documentation of the adjuster to understand what adjustment will be made.
* <p>
* A simple adjuster might simply set the one of the fields, such as the year field.
* A more complex adjuster might set the year-month to the next month that
* Halley's comet will pass the Earth.
* <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 YearMonth} 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
YearMonth with(
TemporalAdjuster adjuster) {
return (
YearMonth)
adjuster.
adjustInto(this);
}
/**
* Returns a copy of this year-month with the specified field set to a new value.
* <p>
* This returns a {@code YearMonth}, based on this one, with the value
* for the specified field changed.
* This can be used to change any supported field, such as the year or month.
* If it is not possible to set the value, because the field is not supported or for
* some other reason, an exception is thrown.
* <p>
* If the field is a {@link ChronoField} then the adjustment is implemented here.
* The supported fields behave as follows:
* <ul>
* <li>{@code MONTH_OF_YEAR} -
* Returns a {@code YearMonth} with the specified month-of-year.
* The year will be unchanged.
* <li>{@code PROLEPTIC_MONTH} -
* Returns a {@code YearMonth} with the specified proleptic-month.
* This completely replaces the year and month of this object.
* <li>{@code YEAR_OF_ERA} -
* Returns a {@code YearMonth} with the specified year-of-era
* The month and era will be unchanged.
* <li>{@code YEAR} -
* Returns a {@code YearMonth} with the specified year.
* The month will be unchanged.
* <li>{@code ERA} -
* Returns a {@code YearMonth} with the specified era.
* The month and 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 YearMonth} 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
YearMonth with(
TemporalField field, long
newValue) {
if (
field instanceof
ChronoField) {
ChronoField f = (
ChronoField)
field;
f.
checkValidValue(
newValue);
switch (
f) {
case
MONTH_OF_YEAR: return
withMonth((int)
newValue);
case
PROLEPTIC_MONTH: return
plusMonths(
newValue -
getProlepticMonth());
case
YEAR_OF_ERA: return
withYear((int) (
year < 1 ? 1 -
newValue :
newValue));
case
YEAR: return
withYear((int)
newValue);
case
ERA: return (
getLong(
ERA) ==
newValue ? this :
withYear(1 -
year));
}
throw new
UnsupportedTemporalTypeException("Unsupported field: " +
field);
}
return
field.
adjustInto(this,
newValue);
}
//-----------------------------------------------------------------------
/**
* Returns a copy of this {@code YearMonth} with the year altered.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param year the year to set in the returned year-month, from MIN_YEAR to MAX_YEAR
* @return a {@code YearMonth} based on this year-month with the requested year, not null
* @throws DateTimeException if the year value is invalid
*/
public
YearMonth withYear(int
year) {
YEAR.
checkValidValue(
year);
return
with(
year,
month);
}
/**
* Returns a copy of this {@code YearMonth} with the month-of-year altered.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param month the month-of-year to set in the returned year-month, from 1 (January) to 12 (December)
* @return a {@code YearMonth} based on this year-month with the requested month, not null
* @throws DateTimeException if the month-of-year value is invalid
*/
public
YearMonth withMonth(int
month) {
MONTH_OF_YEAR.
checkValidValue(
month);
return
with(
year,
month);
}
//-----------------------------------------------------------------------
/**
* Returns a copy of this year-month with the specified amount added.
* <p>
* This returns a {@code YearMonth}, 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 YearMonth} based on this year-month with the addition made, not null
* @throws DateTimeException if the addition cannot be made
* @throws ArithmeticException if numeric overflow occurs
*/
@
Override
public
YearMonth plus(
TemporalAmount amountToAdd) {
return (
YearMonth)
amountToAdd.
addTo(this);
}
/**
* Returns a copy of this year-month with the specified amount added.
* <p>
* This returns a {@code YearMonth}, 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 MONTHS} -
* Returns a {@code YearMonth} with the specified number of months added.
* This is equivalent to {@link #plusMonths(long)}.
* <li>{@code YEARS} -
* Returns a {@code YearMonth} with the specified number of years added.
* This is equivalent to {@link #plusYears(long)}.
* <li>{@code DECADES} -
* Returns a {@code YearMonth} 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 YearMonth} 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 YearMonth} 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 YearMonth} 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 YearMonth} based on this year-month 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
YearMonth plus(long
amountToAdd,
TemporalUnit unit) {
if (
unit instanceof
ChronoUnit) {
switch ((
ChronoUnit)
unit) {
case
MONTHS: return
plusMonths(
amountToAdd);
case
YEARS: return
plusYears(
amountToAdd);
case
DECADES: return
plusYears(
Math.
multiplyExact(
amountToAdd, 10));
case
CENTURIES: return
plusYears(
Math.
multiplyExact(
amountToAdd, 100));
case
MILLENNIA: return
plusYears(
Math.
multiplyExact(
amountToAdd, 1000));
case
ERAS: return
with(
ERA,
Math.
addExact(
getLong(
ERA),
amountToAdd));
}
throw new
UnsupportedTemporalTypeException("Unsupported unit: " +
unit);
}
return
unit.
addTo(this,
amountToAdd);
}
/**
* Returns a copy of this {@code YearMonth} 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 YearMonth} based on this year-month with the years added, not null
* @throws DateTimeException if the result exceeds the supported range
*/
public
YearMonth plusYears(long
yearsToAdd) {
if (
yearsToAdd == 0) {
return this;
}
int
newYear =
YEAR.
checkValidIntValue(
year +
yearsToAdd); // safe overflow
return
with(
newYear,
month);
}
/**
* Returns a copy of this {@code YearMonth} with the specified number of months added.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param monthsToAdd the months to add, may be negative
* @return a {@code YearMonth} based on this year-month with the months added, not null
* @throws DateTimeException if the result exceeds the supported range
*/
public
YearMonth plusMonths(long
monthsToAdd) {
if (
monthsToAdd == 0) {
return this;
}
long
monthCount =
year * 12L + (
month - 1);
long
calcMonths =
monthCount +
monthsToAdd; // safe overflow
int
newYear =
YEAR.
checkValidIntValue(
Math.
floorDiv(
calcMonths, 12));
int
newMonth = (int)
Math.
floorMod(
calcMonths, 12) + 1;
return
with(
newYear,
newMonth);
}
//-----------------------------------------------------------------------
/**
* Returns a copy of this year-month with the specified amount subtracted.
* <p>
* This returns a {@code YearMonth}, 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 YearMonth} based on this year-month with the subtraction made, not null
* @throws DateTimeException if the subtraction cannot be made
* @throws ArithmeticException if numeric overflow occurs
*/
@
Override
public
YearMonth minus(
TemporalAmount amountToSubtract) {
return (
YearMonth)
amountToSubtract.
subtractFrom(this);
}
/**
* Returns a copy of this year-month with the specified amount subtracted.
* <p>
* This returns a {@code YearMonth}, 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 YearMonth} based on this year-month 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
YearMonth 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 YearMonth} 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 YearMonth} based on this year-month with the years subtracted, not null
* @throws DateTimeException if the result exceeds the supported range
*/
public
YearMonth minusYears(long
yearsToSubtract) {
return (
yearsToSubtract ==
Long.
MIN_VALUE ?
plusYears(
Long.
MAX_VALUE).
plusYears(1) :
plusYears(-
yearsToSubtract));
}
/**
* Returns a copy of this {@code YearMonth} with the specified number of months subtracted.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param monthsToSubtract the months to subtract, may be negative
* @return a {@code YearMonth} based on this year-month with the months subtracted, not null
* @throws DateTimeException if the result exceeds the supported range
*/
public
YearMonth minusMonths(long
monthsToSubtract) {
return (
monthsToSubtract ==
Long.
MIN_VALUE ?
plusMonths(
Long.
MAX_VALUE).
plusMonths(1) :
plusMonths(-
monthsToSubtract));
}
//-----------------------------------------------------------------------
/**
* Queries this year-month using the specified query.
* <p>
* This queries this year-month 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)
MONTHS;
}
return
Temporal.super.query(
query);
}
/**
* Adjusts the specified temporal object to have this year-month.
* <p>
* This returns a temporal object of the same observable type as the input
* with the year and month changed to be the same as this.
* <p>
* The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
* passing {@link ChronoField#PROLEPTIC_MONTH} 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 = thisYearMonth.adjustInto(temporal);
* temporal = temporal.with(thisYearMonth);
* </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(
PROLEPTIC_MONTH,
getProlepticMonth());
}
/**
* Calculates the amount of time until another year-month in terms of the specified unit.
* <p>
* This calculates the amount of time between two {@code YearMonth}
* objects in terms of a single {@code TemporalUnit}.
* The start and end points are {@code this} and the specified year-month.
* The result will be negative if the end is before the start.
* The {@code Temporal} passed to this method is converted to a
* {@code YearMonth} using {@link #from(TemporalAccessor)}.
* For example, the amount in years between two year-months can be calculated
* using {@code startYearMonth.until(endYearMonth, YEARS)}.
* <p>
* The calculation returns a whole number, representing the number of
* complete units between the two year-months.
* For example, the amount in decades between 2012-06 and 2032-05
* will only be one decade as it is one month 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, MONTHS);
* amount = MONTHS.between(start, end);
* </pre>
* The choice should be made based on which makes the code more readable.
* <p>
* The calculation is implemented in this method for {@link ChronoUnit}.
* The units {@code MONTHS}, {@code YEARS}, {@code DECADES},
* {@code CENTURIES}, {@code MILLENNIA} and {@code ERAS} are supported.
* Other {@code ChronoUnit} values will throw an exception.
* <p>
* If the unit is not a {@code ChronoUnit}, then the result of this method
* is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
* passing {@code this} as the first argument and the converted input temporal
* as the second argument.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param endExclusive the end date, exclusive, which is converted to a {@code YearMonth}, not null
* @param unit the unit to measure the amount in, not null
* @return the amount of time between this year-month and the end year-month
* @throws DateTimeException if the amount cannot be calculated, or the end
* temporal cannot be converted to a {@code YearMonth}
* @throws UnsupportedTemporalTypeException if the unit is not supported
* @throws ArithmeticException if numeric overflow occurs
*/
@
Override
public long
until(
Temporal endExclusive,
TemporalUnit unit) {
YearMonth end =
YearMonth.
from(
endExclusive);
if (
unit instanceof
ChronoUnit) {
long
monthsUntil =
end.
getProlepticMonth() -
getProlepticMonth(); // no overflow
switch ((
ChronoUnit)
unit) {
case
MONTHS: return
monthsUntil;
case
YEARS: return
monthsUntil / 12;
case
DECADES: return
monthsUntil / 120;
case
CENTURIES: return
monthsUntil / 1200;
case
MILLENNIA: return
monthsUntil / 12000;
case
ERAS: return
end.
getLong(
ERA) -
getLong(
ERA);
}
throw new
UnsupportedTemporalTypeException("Unsupported unit: " +
unit);
}
return
unit.
between(this,
end);
}
/**
* Formats this year-month using the specified formatter.
* <p>
* This year-month will be passed to the formatter to produce a string.
*
* @param formatter the formatter to use, not null
* @return the formatted year-month 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-month with a day-of-month to create a {@code LocalDate}.
* <p>
* This returns a {@code LocalDate} formed from this year-month and the specified day-of-month.
* <p>
* The day-of-month value must be valid for the year-month.
* <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 dayOfMonth the day-of-month to use, from 1 to 31
* @return the date formed from this year-month and the specified day, not null
* @throws DateTimeException if the day is invalid for the year-month
* @see #isValidDay(int)
*/
public
LocalDate atDay(int
dayOfMonth) {
return
LocalDate.
of(
year,
month,
dayOfMonth);
}
/**
* Returns a {@code LocalDate} at the end of the month.
* <p>
* This returns a {@code LocalDate} based on this year-month.
* The day-of-month is set to the last valid day of the month, taking
* into account leap years.
* <p>
* This method can be used as part of a chain to produce a date:
* <pre>
* LocalDate date = year.atMonth(month).atEndOfMonth();
* </pre>
*
* @return the last valid date of this year-month, not null
*/
public
LocalDate atEndOfMonth() {
return
LocalDate.
of(
year,
month,
lengthOfMonth());
}
//-----------------------------------------------------------------------
/**
* Compares this year-month to another year-month.
* <p>
* The comparison is based first on the value of the year, then on the value of the month.
* It is "consistent with equals", as defined by {@link Comparable}.
*
* @param other the other year-month to compare to, not null
* @return the comparator value, negative if less, positive if greater
*/
@
Override
public int
compareTo(
YearMonth other) {
int
cmp = (
year -
other.
year);
if (
cmp == 0) {
cmp = (
month -
other.
month);
}
return
cmp;
}
/**
* Checks if this year-month is after the specified year-month.
*
* @param other the other year-month to compare to, not null
* @return true if this is after the specified year-month
*/
public boolean
isAfter(
YearMonth other) {
return
compareTo(
other) > 0;
}
/**
* Checks if this year-month is before the specified year-month.
*
* @param other the other year-month to compare to, not null
* @return true if this point is before the specified year-month
*/
public boolean
isBefore(
YearMonth other) {
return
compareTo(
other) < 0;
}
//-----------------------------------------------------------------------
/**
* Checks if this year-month is equal to another year-month.
* <p>
* The comparison is based on the time-line position of the year-months.
*
* @param obj the object to check, null returns false
* @return true if this is equal to the other year-month
*/
@
Override
public boolean
equals(
Object obj) {
if (this ==
obj) {
return true;
}
if (
obj instanceof
YearMonth) {
YearMonth other = (
YearMonth)
obj;
return
year ==
other.
year &&
month ==
other.
month;
}
return false;
}
/**
* A hash code for this year-month.
*
* @return a suitable hash code
*/
@
Override
public int
hashCode() {
return
year ^ (
month << 27);
}
//-----------------------------------------------------------------------
/**
* Outputs this year-month as a {@code String}, such as {@code 2007-12}.
* <p>
* The output will be in the format {@code uuuu-MM}:
*
* @return a string representation of this year-month, not null
*/
@
Override
public
String toString() {
int
absYear =
Math.
abs(
year);
StringBuilder buf = new
StringBuilder(9);
if (
absYear < 1000) {
if (
year < 0) {
buf.
append(
year - 10000).
deleteCharAt(1);
} else {
buf.
append(
year + 10000).
deleteCharAt(0);
}
} else {
buf.
append(
year);
}
return
buf.
append(
month < 10 ? "-0" : "-")
.
append(
month)
.
toString();
}
//-----------------------------------------------------------------------
/**
* Writes the object using a
* <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
* @serialData
* <pre>
* out.writeByte(12); // identifies a YearMonth
* out.writeInt(year);
* out.writeByte(month);
* </pre>
*
* @return the instance of {@code Ser}, not null
*/
private
Object writeReplace() {
return new
Ser(
Ser.
YEAR_MONTH_TYPE, this);
}
/**
* Defend against malicious streams.
*
* @param s the stream to read
* @throws InvalidObjectException always
*/
private void
readObject(
ObjectInputStream s) throws
InvalidObjectException {
throw new
InvalidObjectException("Deserialization via serialization delegate");
}
void
writeExternal(
DataOutput out) throws
IOException {
out.
writeInt(
year);
out.
writeByte(
month);
}
static
YearMonth readExternal(
DataInput in) throws
IOException {
int
year =
in.
readInt();
byte
month =
in.
readByte();
return
YearMonth.
of(
year,
month);
}
}