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.
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.
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.
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>
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>
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}.
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.
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.
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}.
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()}.
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)}.
Checks if this year-month is after the specified year-month.
Checks if this year-month is before the specified year-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.
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.
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.
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.
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.
Returns the length of the year. !(p) This returns the length of the year _in days, either 365 or 366.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
A hash code for this year-month.
Outputs this year-month as a {@code string}, such as {@code 2007-12}. !(p) The output will be _in the format {@code uuuu-MM}:
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.
Returns a copy of this {@code YearMonth} with the month-of-year altered. !(p) This instance is immutable and unaffected by this method call.
Returns a copy of this {@code YearMonth} with the year altered. !(p) This instance is immutable and unaffected by this method call.
Defend against malicious streams.
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}.
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.
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.
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}.
Obtains an instance of {@code YearMonth} from a year and month.
Obtains an instance of {@code YearMonth} from a year and month.
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.
Returns an adjusted object of the same type as this object with the adjustment made. !(p) This adjusts this date-time according to the rules of the specified adjuster. A simple adjuster might simply set the one of the fields, such as the year field. A more complex adjuster might set the date to the last day of the month. A selection of common adjustments is provided _in {@link hunt.time.temporal.TemporalAdjusters TemporalAdjusters}. These include finding the "last day of the month" and "next Wednesday". The adjuster is responsible for handling special cases, such as the varying lengths of month and leap years. !(p) Some example code indicating how and why this method is used: !(pre) date = date._with(Month.JULY); // most key classes implement TemporalAdjuster date = date._with(lastDayOfMonth()); // static import from Adjusters date = date._with(next(WEDNESDAY)); // static import from Adjusters and DayOfWeek </pre>
Returns an object of the same type as this object with the specified field altered. !(p) This returns a new object based on this one with the value for the specified field changed. For example, on a {@code LocalDate}, this could be used to set the year, month or day-of-month. The returned object will have the same observable type as this object. !(p) In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st January, then changing the month to February would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February _in this example.
Returns an object of the same type as this object with an amount added. !(p) This adjusts this temporal, adding according to the rules of the specified amount. The amount is typically a {@link hunt.time.Period} but may be any other type implementing the {@link TemporalAmount} interface, such as {@link hunt.time.Duration}. !(p) Some example code indicating how and why this method is used: !(pre) date = date.plus(period); // add a Period instance date = date.plus(duration); // add a Duration instance date = date.plus(workingDays(6)); // example user-written workingDays method </pre> !(p) Note that calling {@code plus} followed by {@code minus} is not guaranteed to return the same date-time.
Returns an object of the same type as this object with the specified period added. !(p) This method returns a new object based on this one with the specified period added. For example, on a {@code LocalDate}, this could be used to add a number of years, months or days. The returned object will have the same observable type as this object. !(p) In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st January, then adding one month would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February _in this example.
Returns an object of the same type as this object with an amount subtracted. !(p) This adjusts this temporal, subtracting according to the rules of the specified amount. The amount is typically a {@link hunt.time.Period} but may be any other type implementing the {@link TemporalAmount} interface, such as {@link hunt.time.Duration}. !(p) Some example code indicating how and why this method is used: !(pre) date = date.minus(period); // subtract a Period instance date = date.minus(duration); // subtract a Duration instance date = date.minus(workingDays(6)); // example user-written workingDays method </pre> !(p) Note that calling {@code plus} followed by {@code minus} is not guaranteed to return the same date-time.
Returns an object of the same type as this object with the specified period subtracted. !(p) This method returns a new object based on this one with the specified period subtracted. For example, on a {@code LocalDate}, this could be used to subtract a number of years, months or days. The returned object will have the same observable type as this object. !(p) In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st March, then subtracting one month would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February _in this example.
Calculates the amount of time until another temporal _in terms of the specified unit. !(p) This calculates the amount of time between two temporal objects _in terms of a single {@code TemporalUnit}. The start and end points are {@code this} and the specified temporal. The end point is converted to be of the same type as the start point if different. The result will be negative if the end is before the start. For example, the amount _in hours between two temporal objects can be calculated using {@code startTime.until(endTime, HOURS)}. !(p) The calculation returns a whole number, representing the number of complete units between the two temporals. For example, the amount _in hours between the times 11:30 and 13:29 will only be one hour as it is one minute short of two hours. !(p) There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use {@link TemporalUnit#between(Temporal, Temporal)}: !(pre) // these two lines are equivalent temporal = start.until(end, unit); temporal = unit.between(start, end); </pre> The choice should be made based on which makes the code more readable. !(p) For example, this method allows the number of days between two dates to be calculated: !(pre) long daysBetween = start.until(end, DAYS); // or alternatively long daysBetween = DAYS.between(start, end); </pre>
Adjusts the specified temporal object. !(p) This adjusts the specified temporal object using the logic encapsulated _in the implementing class. Examples might be an adjuster that sets the date avoiding weekends, or one that sets the date to the last day of the month. !(p) There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use {@link Temporal#_with(TemporalAdjuster)}: !(pre) // these two lines are equivalent, but the second approach is recommended temporal = thisAdjuster.adjustInto(temporal); temporal = temporal._with(thisAdjuster); </pre> It is recommended to use the second approach, {@code _with(TemporalAdjuster)}, as it is a lot clearer to read _in code.
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.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 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