Period
Extends:
A datebased amount of time, such as '2 years, 3 months and 4 days'.
This class models a quantity or amount of time in terms of years, months and days. See Duration for the timebased equivalent to this class.
Durations and period differ in their treatment of daylight savings time when added to ZonedDateTime. A {@code Duration} will add an exact number of seconds, thus a duration of one day is always exactly 24 hours. By contrast, a Period will add a conceptual day, trying to maintain the local time.
For example, consider adding a period of one day and a duration of one day to 18:00 on the evening before a daylight savings gap. The Period will add the conceptual day and result in a {@code ZonedDateTime} at 18:00 the following day. By contrast, the {@code Duration} will add exactly 24 hours, resulting in a {@code ZonedDateTime} at 19:00 the following day (assuming a one hour DST gap).
The supported units of a period are {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}. All three fields are always present, but may be set to zero.
The period may be used with any calendar system. The meaning of a 'year' or 'month' is only applied when the object is added to a date.
The period is modeled as a directed amount of time, meaning that individual parts of the period may be negative.
The months and years fields may be {@linkplain #normalized() normalized}. The normalization assumes a 12 month year, so is not appropriate for all calendar systems.
Static properties of Class Period
Period.ZERO
A constant for a period of zero.
Static Method Summary
Static Public Methods  
public static 
Obtains a Period consisting of the number of years, months, and days between two dates. 

public static 
Creates an instance. 

public static 
from(amount: TemporalAmount): Period Obtains an instance of Period from a temporal amount. 

public static 
Obtains a Period representing a number of years, months and days. 

public static 
Obtains a Period representing a number of days. 

public static 
Obtains a Period representing a number of months. 

public static 
Obtains a Period representing a number of weeks. 

public static 
Obtains a Period representing a number of years. 

public static 
Obtains a Period from a text string such as {@code PnYnMnD}. 
Method Summary
Public Methods  
public 
Adds this period to the specified temporal object. 

public 
Gets the chronology that defines the meaning of the supported units. 

public 
Gets the amount of days of this period. 

public 
Checks if this period is equal to another period. 

public 
get(unit: TemporalUnit): number Gets the value of the requested unit. 

public 
A hash code for this period. 

public 
Checks if any of the three units of this period are negative. 

public 
Checks if all three units of this period are zero. 

public 
minus(amountToSubtract: TemporalAmount): Period Returns a copy of this period with the specified amount subtracted. 

public 
Returns a copy of this period with the specified days subtracted. 

public 
minusMonths(monthsToSubtract: number): Period Returns a copy of this period with the specified months subtracted. 

public 
minusYears(yearsToSubtract: number): Period Returns a copy of this period with the specified years subtracted. 

public 
Gets the amount of months of this period. 

public 
multipliedBy(scalar: number): Period Returns a new instance with each element in this period multiplied by the specified scalar. 

public 
Returns a new instance with each amount in this period negated. 

public 
normalized(): Period Returns a copy of this period with the years and months normalized using a 12 month year. 

public 
plus(amountToAdd: TemporalAmount): Period Returns a copy of this period with the specified amount added. 

public 
Returns a copy of this period with the specified days added. 

public 
plusMonths(monthsToAdd: number): Period Returns a copy of this period with the specified months added. 

public 
Returns a copy of this period with the specified years added. 

public 
subtractFrom(temporal: Temporal): Temporal Subtracts this period from the specified temporal object. 

public 
Outputs this period as a {@code String}, such as {@code P6Y3M1D}. 

public 
Gets the total number of months in this period using a 12 month year. 

public 
units(): ChronoUnit[] Gets the list of units, from largest to smallest, that fully define this amount. 

public 
Returns a copy of this period with the specified amount of days. 

public 
withMonths(months: number): Period Returns a copy of this period with the specified amount of months. 

public 
Returns a copy of this period with the specified amount of years. 

public 
Gets the amount of years of this period. 
Inherited Summary
From class TemporalAmount  
public 
Adds to the specified temporal object. 

public 
get(unit: TemporalUnit): number Returns the value of the requested unit. 

public 
getUnits(): TemporalUnit[] Returns the list of units uniquely defining the value of this TemporalAmount. 

public 
subtractFrom(temporal: Temporal): Temporal Subtracts this object from the specified temporal object. 
Static Public Methods
public static between(startDate: LocalDate, endDate: LocalDate): Period source
Obtains a Period consisting of the number of years, months, and days between two dates.
The start date is included, but the end date is not. The period is calculated by removing complete months, then calculating the remaining number of days, adjusting to ensure that both have the same sign. The number of months is then split into years and months based on a 12 month year. A month is considered if the end dayofmonth is greater than or equal to the start dayofmonth. For example, from {@code 20100115} to {@code 20110318} is one year, two months and three days.
The result of this method can be a negative period if the end is before the start. The negative sign will be the same in each of year, month and day.
see ChronoLocalDate.until
public static create(years: number, months: number, days: number): Duration source
Creates an instance.
public static from(amount: TemporalAmount): Period source
Obtains an instance of Period from a temporal amount.
This obtains a period based on the specified amount. A {@code TemporalAmount} represents an  amount of time, which may be datebased or timebased, which this factory extracts to a Period.
The conversion loops around the set of units from the amount and uses the {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS} units to create a period. If any other units are found then an exception is thrown.
If the amount is a {@code ChronoPeriod} then it must use the ISO chronology.
Params:
Name  Type  Attribute  Description 
amount  TemporalAmount  the temporal amount to convert, not null 
Throw:
* 
DateTimeException if unable to convert to a Period 
* 
ArithmeticException if the amount of years, months or days exceeds an int 
public static of(years: number, months: number, days: number): Period source
Obtains a Period representing a number of years, months and days.
This creates an instance based on years, months and days.
public static ofDays(days: number): Period source
Obtains a Period representing a number of days.
The resulting period will have the specified days. The years and months units will be zero.
Params:
Name  Type  Attribute  Description 
days  number  the number of days, positive or negative 
public static ofMonths(months: number): Period source
Obtains a Period representing a number of months.
The resulting period will have the specified months. The years and days units will be zero.
Params:
Name  Type  Attribute  Description 
months  number  the number of months, positive or negative 
public static ofWeeks(weeks: number): Period source
Obtains a Period representing a number of weeks.
The resulting period will have days equal to the weeks multiplied by seven. The years and months units will be zero.
Params:
Name  Type  Attribute  Description 
weeks  number  the number of weeks, positive or negative 
public static ofYears(years: number): Period source
Obtains a Period representing a number of years.
The resulting period will have the specified years. The months and days units will be zero.
Params:
Name  Type  Attribute  Description 
years  number  the number of years, positive or negative 
public static parse(text: string): Period source
Obtains a Period from a text string such as {@code PnYnMnD}.
This will parse the string produced by {@code toString()} which is based on the ISO8601 period formats {@code PnYnMnD} and {@code PnW}.
The string starts with an optional sign, denoted by the ASCII negative or positive symbol. If negative, the whole period is negated. The ASCII letter 'P' is next in upper or lower case. There are then four sections, each consisting of a number and a suffix. At least one of the four sections must be present. The sections have suffixes in ASCII of 'Y', 'M', 'W' and 'D' for years, months, weeks and days, accepted in upper or lower case. The suffixes must occur in order. The number part of each section must consist of ASCII digits. The number may be prefixed by the ASCII negative or positive symbol. The number must parse to an {@code int}.
The leading plus/minus sign, and negative values for other units are not part of the ISO8601 standard. In addition, ISO8601 does not permit mixing between the {@code PnYnMnD} and {@code PnW} formats. Any weekbased input is multiplied by 7 and treated as a number of days.
For example, the following are valid inputs:
'P2Y'  Period.ofYears(2) 'P3M'  Period.ofMonths(3) 'P4W'  Period.ofWeeks(4) 'P5D'  Period.ofDays(5) 'P1Y2M3D'  Period.of(1, 2, 3) 'P1Y2M3W4D'  Period.of(1, 2, 25) 'P1Y2M'  Period.of(1, 2, 0) 'P1Y2M'  Period.of(1, 2, 0)
Params:
Name  Type  Attribute  Description 
text  string  the text to parse, not null 
Throw:
* 
DateTimeParseException if the text cannot be parsed to a period 
Public Methods
public addTo(temporal: Temporal): Temporal source
Adds this period to the specified temporal object.
This returns a temporal object of the same observable type as the input with this period added.
In most cases, it is clearer to reverse the calling pattern by using {@link Temporal#plus(TemporalAmount)}.
// these two lines are equivalent, but the second approach is recommended dateTime = thisPeriod.addTo(dateTime); dateTime = dateTime.plus(thisPeriod);
The calculation will add the years, then months, then days. Only nonzero amounts will be added. If the datetime has a calendar system with a fixed number of months in a year, then the years and months will be combined before being added.
This instance is immutable and unaffected by this method call.
Override:
TemporalAmount#addToParams:
Name  Type  Attribute  Description 
temporal  Temporal  the temporal object to adjust, not null 
Throw:
* 
DateTimeException if unable to add 
* 
ArithmeticException if numeric overflow occurs 
public chronology(): IsoChronology source
Gets the chronology that defines the meaning of the supported units.
The period is defined by the chronology. It controls the supported units and restricts addition/subtraction to {@code ChronoLocalDate} instances of the same chronology.
public equals(obj: *): boolean source
Checks if this period is equal to another period.
The comparison is based on the amounts held in the period. To be equal, the years, months and days units must be individually equal. Note that this means that a period of '15 Months' is not equal to a period of '1 Year and 3 Months'.
Params:
Name  Type  Attribute  Description 
obj  *  the object to check, null returns false 
public get(unit: TemporalUnit): number source
Gets the value of the requested unit.
The supported units are chronology specific. They will typically be {@link ChronoUnit#YEARS YEARS}, {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}. Requesting an unsupported unit will throw an exception.
Override:
TemporalAmount#getParams:
Name  Type  Attribute  Description 
unit  TemporalUnit  the {@code TemporalUnit} for which to return the value 
Throw:
* 
DateTimeException if the unit is not supported 
* 
UnsupportedTemporalTypeException if the unit is not supported 
public isNegative(): boolean source
Checks if any of the three units of this period are negative.
This checks whether the years, months or days units are less than zero.
public isZero(): boolean source
Checks if all three units of this period are zero.
A zero period has the value zero for the years, months and days units.
public minus(amountToSubtract: TemporalAmount): Period source
Returns a copy of this period with the specified amount subtracted.
This input amount is converted to a Period using {@code from(TemporalAmount)}. This operates separately on the years, months and days.
For example, '1 year, 6 months and 3 days' minus '2 years, 2 months and 2 days' returns '1 years, 4 months and 1 day'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
amountToSubtract  TemporalAmount  the period to subtract, not null 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public minusDays(daysToSubtract: number): Period source
Returns a copy of this period with the specified days subtracted.
This subtracts the amount from the days unit in a copy of this period. The years and months units are unaffected. For example, '1 year, 6 months and 3 days' minus 2 days returns '1 year, 6 months and 1 day'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
daysToSubtract  number  the months to subtract, positive or negative 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public minusMonths(monthsToSubtract: number): Period source
Returns a copy of this period with the specified months subtracted.
This subtracts the amount from the months unit in a copy of this period. The years and days units are unaffected. For example, '1 year, 6 months and 3 days' minus 2 months returns '1 year, 4 months and 3 days'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
monthsToSubtract  number  the years to subtract, positive or negative 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public minusYears(yearsToSubtract: number): Period source
Returns a copy of this period with the specified years subtracted.
This subtracts the amount from the years unit in a copy of this period. The months and days units are unaffected. For example, '1 year, 6 months and 3 days' minus 2 years returns '1 years, 6 months and 3 days'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
yearsToSubtract  number  the years to subtract, positive or negative 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public months(): number source
Gets the amount of months of this period.
This returns the months unit.
The months unit is not normalized with the years unit. This means that a period of '15 months' is different to a period of '1 year and 3 months'.
public multipliedBy(scalar: number): Period source
Returns a new instance with each element in this period multiplied by the specified scalar.
This simply multiplies each field, years, months, days and normalized time, by the scalar. No normalization is performed.
Params:
Name  Type  Attribute  Description 
scalar  number  the scalar to multiply by, not null 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public negated(): Period source
Returns a new instance with each amount in this period negated.
Throw:
* 
ArithmeticException if numeric overflow occurs 
public normalized(): Period source
Returns a copy of this period with the years and months normalized using a 12 month year.
This normalizes the years and months units, leaving the days unit unchanged. The months unit is adjusted to have an absolute value less than 11, with the years unit being adjusted to compensate. For example, a period of '1 Year and 15 months' will be normalized to '2 years and 3 months'.
The sign of the years and months units will be the same after normalization. For example, a period of '1 year and 25 months' will be normalized to '1 year and 1 month'.
This normalization uses a 12 month year which is not valid for all calendar systems.
This instance is immutable and unaffected by this method call.
Throw:
* 
ArithmeticException if numeric overflow occurs 
public plus(amountToAdd: TemporalAmount): Period source
Returns a copy of this period with the specified amount added.
This input amount is converted to a Period using {@code from(TemporalAmount)}. This operates separately on the years, months and days.
For example, '1 year, 6 months and 3 days' plus '2 years, 2 months and 2 days' returns '3 years, 8 months and 5 days'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
amountToAdd  TemporalAmount  the period to add, not null 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public plusDays(daysToAdd: number): Period source
Returns a copy of this period with the specified days added.
This adds the amount to the days unit in a copy of this period. The years and months units are unaffected. For example, '1 year, 6 months and 3 days' plus 2 days returns '1 year, 6 months and 5 days'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
daysToAdd  number  the days to add, positive or negative 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public plusMonths(monthsToAdd: number): Period source
Returns a copy of this period with the specified months added.
This adds the amount to the months unit in a copy of this period. The years and days units are unaffected. For example, '1 year, 6 months and 3 days' plus 2 months returns '1 year, 8 months and 3 days'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
monthsToAdd  number  the months to add, positive or negative 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public plusYears(yearsToAdd: number): Period source
Returns a copy of this period with the specified years added.
This adds the amount to the years unit in a copy of this period. The months and days units are unaffected. For example, '1 year, 6 months and 3 days' plus 2 years returns '3 years, 6 months and 3 days'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
yearsToAdd  number  the years to add, positive or negative 
Throw:
* 
ArithmeticException if numeric overflow occurs 
public subtractFrom(temporal: Temporal): Temporal source
Subtracts this period from the specified temporal object.
This returns a temporal object of the same observable type as the input with this period subtracted.
In most cases, it is clearer to reverse the calling pattern by using {@link Temporal#minus(TemporalAmount)}.
// these two lines are equivalent, but the second approach is recommended dateTime = thisPeriod.subtractFrom(dateTime); dateTime = dateTime.minus(thisPeriod);
The calculation operates as follows. First, the chronology of the temporal is checked to ensure it is ISO chronology or null. Second, if the months are zero, the years are added if nonzero, otherwise the combination of years and months is added if nonzero. Finally, any days are added.
The calculation will subtract the years, then months, then days. Only nonzero amounts will be subtracted. If the datetime has a calendar system with a fixed number of months in a year, then the years and months will be combined before being subtracted.
This instance is immutable and unaffected by this method call.
Override:
TemporalAmount#subtractFromParams:
Name  Type  Attribute  Description 
temporal  Temporal  the temporal object to adjust, not null 
Throw:
* 
DateTimeException if unable to subtract 
* 
ArithmeticException if numeric overflow occurs 
public toString(): string source
Outputs this period as a {@code String}, such as {@code P6Y3M1D}.
The output will be in the ISO8601 period format. A zero period will be represented as zero days, 'P0D'.
public toTotalMonths(): number source
Gets the total number of months in this period using a 12 month year.
This returns the total number of months in the period by multiplying the number of years by 12 and adding the number of months.
This uses a 12 month year which is not valid for all calendar systems.
This instance is immutable and unaffected by this method call.
public units(): ChronoUnit[] source
Gets the list of units, from largest to smallest, that fully define this amount.
public withDays(days: number): Period source
Returns a copy of this period with the specified amount of days.
This sets the amount of the days unit in a copy of this period. The years and months units are unaffected.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
days  number  the days to represent, may be negative 
public withMonths(months: number): Period source
Returns a copy of this period with the specified amount of months.
This sets the amount of the months unit in a copy of this period. The years and days units are unaffected.
The months unit is not normalized with the years unit. This means that a period of '15 months' is different to a period of '1 year and 3 months'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
months  number  the months to represent, may be negative 
public withYears(years: number): Period source
Returns a copy of this period with the specified amount of years.
This sets the amount of the years unit in a copy of this period. The months and days units are unaffected.
The months unit is not normalized with the years unit. This means that a period of '15 months' is different to a period of '1 year and 3 months'.
This instance is immutable and unaffected by this method call.
Params:
Name  Type  Attribute  Description 
years  number  the years to represent, may be negative 