public final class Period extends Object implements ChronoPeriod, Serializable
This class models a quantity or amount of time in terms of years, months and days.
See Duration for the time-based equivalent to this class.
Durations and periods differ in their treatment of daylight savings time
when added to ZonedDateTime. A 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 ZonedDateTime at 18:00 the following day.
By contrast, the Duration will add exactly 24 hours, resulting in a
ZonedDateTime at 19:00 the following day (assuming a one hour DST gap).
The supported units of a period are YEARS,
MONTHS and DAYS.
All three fields are always present, but may be set to zero.
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.
The period is modeled as a directed amount of time, meaning that individual parts of the period may be negative.
This is a value-based
class; use of identity-sensitive operations (including reference equality
(==), identity hash code, or synchronization) on instances of
Period may have unpredictable results and should be avoided.
The equals method should be used for comparisons.
This class is immutable and thread-safe.
| Modifier and Type | Field and Description |
|---|---|
static Period |
ZERO
A constant for a period of zero.
|
| Modifier and Type | Method and Description |
|---|---|
Temporal |
addTo(Temporal temporal)
Adds this period to the specified temporal object.
|
static Period |
between(LocalDate startDateInclusive,
LocalDate endDateExclusive)
Obtains a
Period consisting of the number of years, months,
and days between two dates. |
boolean |
equals(Object obj)
Checks if this period is equal to another period.
|
static Period |
from(TemporalAmount amount)
Obtains an instance of
Period from a temporal amount. |
long |
get(TemporalUnit unit)
Gets the value of the requested unit.
|
IsoChronology |
getChronology()
Gets the chronology of this period, which is the ISO calendar system.
|
int |
getDays()
Gets the amount of days of this period.
|
int |
getMonths()
Gets the amount of months of this period.
|
List<TemporalUnit> |
getUnits()
Gets the set of units supported by this period.
|
int |
getYears()
Gets the amount of years of this period.
|
int |
hashCode()
A hash code for this period.
|
boolean |
isNegative()
Checks if any of the three units of this period are negative.
|
boolean |
isZero()
Checks if all three units of this period are zero.
|
Period |
minus(TemporalAmount amountToSubtract)
Returns a copy of this period with the specified period subtracted.
|
Period |
minusDays(long daysToSubtract)
Returns a copy of this period with the specified days subtracted.
|
Period |
minusMonths(long monthsToSubtract)
Returns a copy of this period with the specified months subtracted.
|
Period |
minusYears(long yearsToSubtract)
Returns a copy of this period with the specified years subtracted.
|
Period |
multipliedBy(int scalar)
Returns a new instance with each element in this period multiplied
by the specified scalar.
|
Period |
negated()
Returns a new instance with each amount in this period negated.
|
Period |
normalized()
Returns a copy of this period with the years and months normalized.
|
static Period |
of(int years,
int months,
int days)
Obtains a
Period representing a number of years, months and days. |
static Period |
ofDays(int days)
Obtains a
Period representing a number of days. |
static Period |
ofMonths(int months)
Obtains a
Period representing a number of months. |
static Period |
ofWeeks(int weeks)
Obtains a
Period representing a number of weeks. |
static Period |
ofYears(int years)
Obtains a
Period representing a number of years. |
Period |
plus(TemporalAmount amountToAdd)
Returns a copy of this period with the specified period added.
|
Period |
plusDays(long daysToAdd)
Returns a copy of this period with the specified days added.
|
Period |
plusMonths(long monthsToAdd)
Returns a copy of this period with the specified months added.
|
Period |
plusYears(long yearsToAdd)
Returns a copy of this period with the specified years added.
|
Temporal |
subtractFrom(Temporal temporal)
Subtracts this period from the specified temporal object.
|
String |
toString()
Outputs this period as a
String, such as P6Y3M1D. |
long |
toTotalMonths()
Gets the total number of months in this period.
|
Period |
withDays(int days)
Returns a copy of this period with the specified amount of days.
|
Period |
withMonths(int months)
Returns a copy of this period with the specified amount of months.
|
Period |
withYears(int years)
Returns a copy of this period with the specified amount of years.
|
public static final Period ZERO
public Temporal addTo(Temporal temporal)
This returns a temporal object of the same observable type as the input with this period added. If the temporal has a chronology, it must be the ISO chronology.
In most cases, it is clearer to reverse the calling pattern by using
Temporal.plus(TemporalAmount).
// these two lines are equivalent, but the second approach is recommended dateTime = thisPeriod.addTo(dateTime); dateTime = dateTime.plus(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 non-zero, otherwise the combination of years and months is added if non-zero. Finally, any days are added.
This approach ensures that a partial period can be added to a partial date.
For example, a period of years and/or months can be added to a YearMonth,
but a period including days cannot.
The approach also adds years and months together when necessary, which ensures
correct behaviour at the end of the month.
This instance is immutable and unaffected by this method call.
addTo in interface ChronoPeriodaddTo in interface TemporalAmounttemporal - the temporal object to adjust, not nullDateTimeException - if unable to addpublic static Period between(LocalDate startDateInclusive, LocalDate endDateExclusive)
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 day-of-month is greater than or equal to the start day-of-month.
For example, from 2010-01-15 to 2011-03-18 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.
startDateInclusive - the start date, inclusive, not nullendDateExclusive - the end date, exclusive, not nullChronoLocalDate.until(ChronoLocalDate)public boolean equals(@Nullable Object obj)
The comparison is based on the type Period and each of the three amounts.
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".
equals in interface ChronoPeriodequals in class Objectobj - the object to check, null returns falseObject.hashCode(),
HashMappublic static Period from(TemporalAmount amount)
Period from a temporal amount.
This obtains a period based on the specified amount.
A TemporalAmount represents an amount of time, which may be
date-based or time-based, which this factory extracts to a Period.
The conversion loops around the set of units from the amount and uses
the YEARS, MONTHS
and DAYS units to create a period.
If any other units are found then an exception is thrown.
If the amount is a ChronoPeriod then it must use the ISO chronology.
amount - the temporal amount to convert, not nullDateTimeException - if unable to convert to a Periodpublic long get(TemporalUnit unit)
This returns a value for each of the three supported units,
YEARS, MONTHS and
DAYS.
All other units throw an exception.
get in interface ChronoPeriodget in interface TemporalAmountunit - the TemporalUnit for which to return the valueDateTimeException - if the unit is not supportedUnsupportedTemporalTypeException - if the unit is not supportedpublic IsoChronology getChronology()
The Chronology represents the calendar system in use.
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.
getChronology in interface ChronoPeriodpublic int getDays()
This returns the days unit.
public int getMonths()
This returns the months unit.
The months unit is not automatically 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 List<TemporalUnit> getUnits()
The supported units are YEARS,
MONTHS and DAYS.
They are returned in the order years, months, days.
This set can be used in conjunction with get(TemporalUnit)
to access the entire state of the period.
getUnits in interface ChronoPeriodgetUnits in interface TemporalAmountpublic int getYears()
This returns the years unit.
The months unit is not automatically 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 int hashCode()
hashCode in interface ChronoPeriodhashCode in class ObjectObject.equals(java.lang.Object),
System.identityHashCode(java.lang.Object)public boolean isNegative()
This checks whether the years, months or days units are less than zero.
isNegative in interface ChronoPeriodpublic boolean isZero()
A zero period has the value zero for the years, months and days units.
isZero in interface ChronoPeriodpublic Period minus(TemporalAmount amountToSubtract)
This operates separately on the years, months and days. No normalization is performed.
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".
The specified amount is typically an instance of Period.
Other types are interpreted using from(TemporalAmount).
This instance is immutable and unaffected by this method call.
minus in interface ChronoPeriodamountToSubtract - the amount to subtract, not nullPeriod based on this period with the requested period subtracted, not nullDateTimeException - if the specified amount has a non-ISO chronology or
contains an invalid unitpublic Period minusDays(long daysToSubtract)
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.
daysToSubtract - the months to subtract, positive or negativePeriod based on this period with the specified days subtracted, not nullpublic Period minusMonths(long monthsToSubtract)
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.
monthsToSubtract - the years to subtract, positive or negativePeriod based on this period with the specified months subtracted, not nullpublic Period minusYears(long yearsToSubtract)
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.
yearsToSubtract - the years to subtract, positive or negativePeriod based on this period with the specified years subtracted, not nullpublic Period multipliedBy(int scalar)
This returns a period with each of the years, months and days units individually multiplied. For example, a period of "2 years, -3 months and 4 days" multiplied by 3 will return "6 years, -9 months and 12 days". No normalization is performed.
multipliedBy in interface ChronoPeriodscalar - the scalar to multiply by, not nullPeriod based on this period with the amounts multiplied by the scalar, not nullpublic Period negated()
This returns a period with each of the years, months and days units individually negated. For example, a period of "2 years, -3 months and 4 days" will be negated to "-2 years, 3 months and -4 days". No normalization is performed.
negated in interface ChronoPeriodPeriod based on this period with the amounts negated, not null
one of the units has the value Long.MIN_VALUEpublic Period normalized()
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 instance is immutable and unaffected by this method call.
normalized in interface ChronoPeriodPeriod based on this period with excess months normalized to years, not nullpublic static Period of(int years, int months, int days)
Period representing a number of years, months and days.
This creates an instance based on years, months and days.
years - the amount of years, may be negativemonths - the amount of months, may be negativedays - the amount of days, may be negativepublic static Period ofDays(int days)
Period representing a number of days.
The resulting period will have the specified days. The years and months units will be zero.
days - the number of days, positive or negativepublic static Period ofMonths(int months)
Period representing a number of months.
The resulting period will have the specified months. The years and days units will be zero.
months - the number of months, positive or negativepublic static Period ofWeeks(int weeks)
Period representing a number of weeks.
The resulting period will be day-based, with the amount of days equal to the number of weeks multiplied by 7. The years and months units will be zero.
weeks - the number of weeks, positive or negativepublic static Period ofYears(int years)
Period representing a number of years.
The resulting period will have the specified years. The months and days units will be zero.
years - the number of years, positive or negativepublic Period plus(TemporalAmount amountToAdd)
This operates separately on the years, months and days. No normalization is performed.
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".
The specified amount is typically an instance of Period.
Other types are interpreted using from(TemporalAmount).
This instance is immutable and unaffected by this method call.
plus in interface ChronoPeriodamountToAdd - the amount to add, not nullPeriod based on this period with the requested period added, not nullDateTimeException - if the specified amount has a non-ISO chronology or
contains an invalid unitpublic Period plusDays(long daysToAdd)
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.
daysToAdd - the days to add, positive or negativePeriod based on this period with the specified days added, not nullpublic Period plusMonths(long monthsToAdd)
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.
monthsToAdd - the months to add, positive or negativePeriod based on this period with the specified months added, not nullpublic Period plusYears(long yearsToAdd)
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.
yearsToAdd - the years to add, positive or negativePeriod based on this period with the specified years added, not nullpublic Temporal subtractFrom(Temporal temporal)
This returns a temporal object of the same observable type as the input with this period subtracted. If the temporal has a chronology, it must be the ISO chronology.
In most cases, it is clearer to reverse the calling pattern by using
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 subtracted if non-zero, otherwise the combination of years and months is subtracted if non-zero. Finally, any days are subtracted.
This approach ensures that a partial period can be subtracted from a partial date.
For example, a period of years and/or months can be subtracted from a YearMonth,
but a period including days cannot.
The approach also subtracts years and months together when necessary, which ensures
correct behaviour at the end of the month.
This instance is immutable and unaffected by this method call.
subtractFrom in interface ChronoPeriodsubtractFrom in interface TemporalAmounttemporal - the temporal object to adjust, not nullDateTimeException - if unable to subtractpublic String toString()
String, such as P6Y3M1D.
The output will be in the ISO-8601 period format. A zero period will be represented as zero days, 'P0D'.
toString in interface ChronoPeriodtoString in class Objectpublic long toTotalMonths()
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 instance is immutable and unaffected by this method call.
public Period withDays(int 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.
days - the days to represent, may be negativePeriod based on this period with the requested days, not nullpublic Period withMonths(int 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 automatically 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.
months - the months to represent, may be negativePeriod based on this period with the requested months, not nullpublic Period withYears(int 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 automatically 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.
years - the years to represent, may be negativePeriod based on this period with the requested years, not null