- All Implemented Interfaces:
Serializable,ChronoPeriod,TemporalAmount
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; programmers should treat instances that are
equal as interchangeable and should not
use instances for synchronization, or unpredictable behavior may
occur. For example, in a future release, synchronization may fail.
The equals method should be used for comparisons.
- Implementation Requirements:
- This class is immutable and thread-safe.
- Since:
- 1.8
- See Also:
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Field Summary
Fields -
Method Summary
Modifier and TypeMethodDescriptionAdds this period to the specified temporal object.static PeriodObtains aPeriodconsisting of the number of years, months, and days between two dates.booleanChecks if this period is equal to another period.static Periodfrom(TemporalAmount amount) Obtains an instance ofPeriodfrom a temporal amount.longget(TemporalUnit unit) Gets the value of the requested unit.Gets the chronology of this period, which is the ISO calendar system.intgetDays()Gets the amount of days of this period.intGets the amount of months of this period.getUnits()Gets the set of units supported by this period.intgetYears()Gets the amount of years of this period.inthashCode()A hash code for this period.booleanChecks if any of the three units of this period are negative.booleanisZero()Checks if all three units of this period are zero.minus(TemporalAmount amountToSubtract) Returns a copy of this period with the specified period subtracted.minusDays(long daysToSubtract) Returns a copy of this period with the specified days subtracted.minusMonths(long monthsToSubtract) Returns a copy of this period with the specified months subtracted.minusYears(long yearsToSubtract) Returns a copy of this period with the specified years subtracted.multipliedBy(int scalar) Returns a new instance with each element in this period multiplied by the specified scalar.negated()Returns a new instance with each amount in this period negated.Returns a copy of this period with the years and months normalized.static Periodof(int years, int months, int days) Obtains aPeriodrepresenting a number of years, months and days.static PeriodofDays(int days) Obtains aPeriodrepresenting a number of days.static PeriodofMonths(int months) Obtains aPeriodrepresenting a number of months.static PeriodofWeeks(int weeks) Obtains aPeriodrepresenting a number of weeks.static PeriodofYears(int years) Obtains aPeriodrepresenting a number of years.static Periodparse(CharSequence text) Obtains aPeriodfrom a text string such asPnYnMnD.plus(TemporalAmount amountToAdd) Returns a copy of this period with the specified period added.plusDays(long daysToAdd) Returns a copy of this period with the specified days added.plusMonths(long monthsToAdd) Returns a copy of this period with the specified months added.plusYears(long yearsToAdd) Returns a copy of this period with the specified years added.subtractFrom(Temporal temporal) Subtracts this period from the specified temporal object.toString()Outputs this period as aString, such asP6Y3M1D.longGets the total number of months in this period.withDays(int days) Returns a copy of this period with the specified amount of days.withMonths(int months) Returns a copy of this period with the specified amount of months.withYears(int years) Returns a copy of this period with the specified amount of years.
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Field Details
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ZERO
A constant for a period of zero.
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Method Details
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ofYears
Obtains aPeriodrepresenting a number of years.The resulting period will have the specified years. The months and days units will be zero.
- Parameters:
years- the number of years, positive or negative- Returns:
- the period of years, not null
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ofMonths
Obtains aPeriodrepresenting a number of months.The resulting period will have the specified months. The years and days units will be zero.
- Parameters:
months- the number of months, positive or negative- Returns:
- the period of months, not null
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ofWeeks
Obtains aPeriodrepresenting 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.
- Parameters:
weeks- the number of weeks, positive or negative- Returns:
- the period, with the input weeks converted to days, not null
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ofDays
Obtains aPeriodrepresenting a number of days.The resulting period will have the specified days. The years and months units will be zero.
- Parameters:
days- the number of days, positive or negative- Returns:
- the period of days, not null
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of
Obtains aPeriodrepresenting a number of years, months and days.This creates an instance based on years, months and days.
- Parameters:
years- the amount of years, may be negativemonths- the amount of months, may be negativedays- the amount of days, may be negative- Returns:
- the period of years, months and days, not null
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from
Obtains an instance ofPeriodfrom a temporal amount.This obtains a period based on the specified amount. A
TemporalAmountrepresents an amount of time, which may be date-based or time-based, which this factory extracts to aPeriod.The conversion loops around the set of units from the amount and uses the
YEARS,MONTHSandDAYSunits to create a period. If any other units are found then an exception is thrown.If the amount is a
ChronoPeriodthen it must use the ISO chronology.- Parameters:
amount- the temporal amount to convert, not null- Returns:
- the equivalent period, not null
- Throws:
DateTimeException- if unable to convert to aPeriodArithmeticException- if the amount of years, months or days exceeds an int
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parse
Obtains aPeriodfrom a text string such asPnYnMnD.This will parse the string produced by
toString()which is based on the ISO-8601 period formatsPnYnMnDandPnW.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
int.The leading plus/minus sign, and negative values for other units are not part of the ISO-8601 standard. In addition, ISO-8601 does not permit mixing between the
PnYnMnDandPnWformats. Any week-based 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) "P-1Y2M" -- Period.of(-1, 2, 0) "-P1Y2M" -- Period.of(-1, -2, 0)
- Parameters:
text- the text to parse, not null- Returns:
- the parsed period, not null
- Throws:
DateTimeParseException- if the text cannot be parsed to a period
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between
Obtains aPeriodconsisting 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
2010-01-15to2011-03-18is 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.
- Parameters:
startDateInclusive- the start date, inclusive, not nullendDateExclusive- the end date, exclusive, not null- Returns:
- the period between this date and the end date, not null
- See Also:
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get
Gets the value of the requested unit.This returns a value for each of the three supported units,
YEARS,MONTHSandDAYS. All other units throw an exception.- Specified by:
getin interfaceChronoPeriod- Specified by:
getin interfaceTemporalAmount- Parameters:
unit- theTemporalUnitfor which to return the value- Returns:
- the long value of the unit
- Throws:
DateTimeException- if the unit is not supportedUnsupportedTemporalTypeException- if the unit is not supported
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getUnits
Gets the set of units supported by this period.The supported units are
YEARS,MONTHSandDAYS. 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.- Specified by:
getUnitsin interfaceChronoPeriod- Specified by:
getUnitsin interfaceTemporalAmount- Returns:
- a list containing the years, months and days units, not null
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getChronology
Gets the chronology of this period, which is the ISO calendar system.The
Chronologyrepresents 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.- Specified by:
getChronologyin interfaceChronoPeriod- Returns:
- the ISO chronology, not null
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isZero
public boolean isZero()Checks if all three units of this period are zero.A zero period has the value zero for the years, months and days units.
- Specified by:
isZeroin interfaceChronoPeriod- Returns:
- true if this period is zero-length
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isNegative
public boolean isNegative()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.
- Specified by:
isNegativein interfaceChronoPeriod- Returns:
- true if any unit of this period is negative
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getYears
public int getYears()Gets the amount of years of this period.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".
- Returns:
- the amount of years of this period, may be negative
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getMonths
public int getMonths()Gets the amount of months of this period.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".
- Returns:
- the amount of months of this period, may be negative
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getDays
public int getDays()Gets the amount of days of this period.This returns the days unit.
- Returns:
- the amount of days of this period, may be negative
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withYears
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 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.
- Parameters:
years- the years to represent, may be negative- Returns:
- a
Periodbased on this period with the requested years, not null
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withMonths
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 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.
- Parameters:
months- the months to represent, may be negative- Returns:
- a
Periodbased on this period with the requested months, not null
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withDays
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.
- Parameters:
days- the days to represent, may be negative- Returns:
- a
Periodbased on this period with the requested days, not null
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plus
Returns a copy of this period with the specified period added.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 usingfrom(TemporalAmount).This instance is immutable and unaffected by this method call.
- Specified by:
plusin interfaceChronoPeriod- Parameters:
amountToAdd- the amount to add, not null- Returns:
- a
Periodbased on this period with the requested period added, not null - Throws:
DateTimeException- if the specified amount has a non-ISO chronology or contains an invalid unitArithmeticException- if numeric overflow occurs
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plusYears
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.
- Parameters:
yearsToAdd- the years to add, positive or negative- Returns:
- a
Periodbased on this period with the specified years added, not null - Throws:
ArithmeticException- if numeric overflow occurs
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plusMonths
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.
- Parameters:
monthsToAdd- the months to add, positive or negative- Returns:
- a
Periodbased on this period with the specified months added, not null - Throws:
ArithmeticException- if numeric overflow occurs
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plusDays
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.
- Parameters:
daysToAdd- the days to add, positive or negative- Returns:
- a
Periodbased on this period with the specified days added, not null - Throws:
ArithmeticException- if numeric overflow occurs
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minus
Returns a copy of this period with the specified period subtracted.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 usingfrom(TemporalAmount).This instance is immutable and unaffected by this method call.
- Specified by:
minusin interfaceChronoPeriod- Parameters:
amountToSubtract- the amount to subtract, not null- Returns:
- a
Periodbased on this period with the requested period subtracted, not null - Throws:
DateTimeException- if the specified amount has a non-ISO chronology or contains an invalid unitArithmeticException- if numeric overflow occurs
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minusYears
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.
- Parameters:
yearsToSubtract- the years to subtract, positive or negative- Returns:
- a
Periodbased on this period with the specified years subtracted, not null - Throws:
ArithmeticException- if numeric overflow occurs
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minusMonths
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.
- Parameters:
monthsToSubtract- the years to subtract, positive or negative- Returns:
- a
Periodbased on this period with the specified months subtracted, not null - Throws:
ArithmeticException- if numeric overflow occurs
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minusDays
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.
- Parameters:
daysToSubtract- the months to subtract, positive or negative- Returns:
- a
Periodbased on this period with the specified days subtracted, not null - Throws:
ArithmeticException- if numeric overflow occurs
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multipliedBy
Returns a new instance with each element in this period multiplied by the specified 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.
- Specified by:
multipliedByin interfaceChronoPeriod- Parameters:
scalar- the scalar to multiply by, not null- Returns:
- a
Periodbased on this period with the amounts multiplied by the scalar, not null - Throws:
ArithmeticException- if numeric overflow occurs
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negated
Returns a new instance with each amount in this 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.
- Specified by:
negatedin interfaceChronoPeriod- Returns:
- a
Periodbased on this period with the amounts negated, not null - Throws:
ArithmeticException- if numeric overflow occurs, which only happens if one of the units has the valueInteger.MIN_VALUE
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normalized
Returns a copy of this period with the years and months 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 12, 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.
- Specified by:
normalizedin interfaceChronoPeriod- Returns:
- a
Periodbased on this period with excess months normalized to years, not null - Throws:
ArithmeticException- if numeric overflow occurs
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toTotalMonths
public long toTotalMonths()Gets the total number of months in this period.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.
- Returns:
- the total number of months in the period, may be negative
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addTo
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. 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.
- Specified by:
addToin interfaceChronoPeriod- Specified by:
addToin interfaceTemporalAmount- Parameters:
temporal- the temporal object to adjust, not null- Returns:
- an object of the same type with the adjustment made, not null
- Throws:
DateTimeException- if unable to addArithmeticException- if numeric overflow occurs
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subtractFrom
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. 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.
- Specified by:
subtractFromin interfaceChronoPeriod- Specified by:
subtractFromin interfaceTemporalAmount- Parameters:
temporal- the temporal object to adjust, not null- Returns:
- an object of the same type with the adjustment made, not null
- Throws:
DateTimeException- if unable to subtractArithmeticException- if numeric overflow occurs
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equals
Checks if this period is equal to another period.The comparison is based on the type
Periodand 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".- Specified by:
equalsin interfaceChronoPeriod- Overrides:
equalsin classObject- Parameters:
obj- the object to check, null returns false- Returns:
- true if this is equal to the other period
- See Also:
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hashCode
public int hashCode()A hash code for this period.- Specified by:
hashCodein interfaceChronoPeriod- Overrides:
hashCodein classObject- Returns:
- a suitable hash code
- See Also:
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toString
Outputs this period as aString, such asP6Y3M1D.The output will be in the ISO-8601 period format. A zero period will be represented as zero days, 'P0D'.
- Specified by:
toStringin interfaceChronoPeriod- Overrides:
toStringin classObject- Returns:
- a string representation of this period, not null
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