Period
public
final
class
Period
extends Object
implements
ChronoPeriod,
Serializable
java.lang.Object  
↳  java.time.Period 
A datebased amount of time in the ISO8601 calendar system, 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 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 ISO8601 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.
Summary
Fields  

public
static
final
Period 
ZERO
A constant for a period of zero. 
Public methods  

Temporal

addTo(Temporal temporal)
Adds this period to the specified temporal object. 
static
Period

between(LocalDate startDateInclusive, LocalDate endDateExclusive)
Obtains a 
boolean

equals(Object obj)
Checks if this period is equal to another period. 
static
Period

from(TemporalAmount amount)
Obtains an instance of 
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 
static
Period

ofDays(int days)
Obtains a 
static
Period

ofMonths(int months)
Obtains a 
static
Period

ofWeeks(int weeks)
Obtains a 
static
Period

ofYears(int years)
Obtains a 
static
Period

parse(CharSequence text)
Obtains a 
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 
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. 
Inherited methods  

Fields
Public methods
addTo
public Temporal addTo (Temporal temporal)
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 nonzero, otherwise the combination of years and months is added if nonzero. 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.
Parameters  

temporal 
Temporal : the temporal object to adjust, not null 
Returns  

Temporal 
an object of the same type with the adjustment made, not null 
Throws  

DateTimeException 
if unable to add 
ArithmeticException 
if numeric overflow occurs 
between
public static Period between (LocalDate startDateInclusive, LocalDate endDateExclusive)
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 20100115
to 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.
Parameters  

startDateInclusive 
LocalDate : the start date, inclusive, not null 
endDateExclusive 
LocalDate : the end date, exclusive, not null 
Returns  

Period 
the period between this date and the end date, not null 
See also:
equals
public boolean equals (Object obj)
Checks if this period is equal to another period.
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".
Parameters  

obj 
Object : the object to check, null returns false 
Returns  

boolean 
true if this is equal to the other period 
from
public static Period from (TemporalAmount amount)
Obtains an instance of Period
from a temporal amount.
This obtains a period based on the specified amount.
A 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 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.
Parameters  

amount 
TemporalAmount : the temporal amount to convert, not null 
Returns  

Period 
the equivalent period, not null 
Throws  

DateTimeException 
if unable to convert to a Period 
ArithmeticException 
if the amount of years, months or days exceeds an int 
get
public long get (TemporalUnit unit)
Gets the value of the requested unit.
This returns a value for each of the three supported units,
YEARS
, MONTHS
and
DAYS
.
All other units throw an exception.
Parameters  

unit 
TemporalUnit : the TemporalUnit for which to return the value 
Returns  

long 
the long value of the unit 
Throws  

DateTimeException 
if the unit is not supported 
UnsupportedTemporalTypeException 
if the unit is not supported 
getChronology
public IsoChronology getChronology ()
Gets the chronology of this period, which is the ISO calendar system.
The Chronology
represents the calendar system in use.
The ISO8601 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.
Returns  

IsoChronology 
the ISO chronology, not null 
getDays
public int getDays ()
Gets the amount of days of this period.
This returns the days unit.
Returns  

int 
the amount of days of this period, may be negative 
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  

int 
the amount of months of this period, may be negative 
getUnits
public List<TemporalUnit> getUnits ()
Gets the set of units supported by this period.
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.
Returns  

List<TemporalUnit> 
a list containing the years, months and days units, not null 
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  

int 
the amount of years of this period, may be negative 
hashCode
public int hashCode ()
A hash code for this period.
Returns  

int 
a suitable hash code 
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.
Returns  

boolean 
true if any unit of this period is negative 
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.
Returns  

boolean 
true if this period is zerolength 
minus
public Period minus (TemporalAmount amountToSubtract)
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 using from(TemporalAmount)
.
This instance is immutable and unaffected by this method call.
Parameters  

amountToSubtract 
TemporalAmount : the amount to subtract, not null 
Returns  

Period 
a Period based on this period with the requested period subtracted, not null 
Throws  

DateTimeException 
if the specified amount has a nonISO chronology or contains an invalid unit 
ArithmeticException 
if numeric overflow occurs 
minusDays
public Period minusDays (long daysToSubtract)
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 
long : the months to subtract, positive or negative 
Returns  

Period 
a Period based on this period with the specified days subtracted, not null 
Throws  

ArithmeticException 
if numeric overflow occurs 
minusMonths
public Period minusMonths (long monthsToSubtract)
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 
long : the years to subtract, positive or negative 
Returns  

Period 
a Period based on this period with the specified months subtracted, not null 
Throws  

ArithmeticException 
if numeric overflow occurs 
minusYears
public Period minusYears (long yearsToSubtract)
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 
long : the years to subtract, positive or negative 
Returns  

Period 
a Period based on this period with the specified years subtracted, not null 
Throws  

ArithmeticException 
if numeric overflow occurs 
multipliedBy
public Period multipliedBy (int scalar)
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.
Parameters  

scalar 
int : the scalar to multiply by, not null 
Returns  

Period 
a Period based on this period with the amounts multiplied by the scalar, not null 
Throws  

ArithmeticException 
if numeric overflow occurs 
negated
public Period 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.
Returns  

Period 
a Period based 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 value Long.MIN_VALUE

normalized
public Period 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 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.
Returns  

Period 
a Period based on this period with excess months normalized to years, not null 
Throws  

ArithmeticException 
if numeric overflow occurs 
of
public static Period of (int years, int months, int days)
Obtains a Period
representing a number of years, months and days.
This creates an instance based on years, months and days.
Parameters  

years 
int : the amount of years, may be negative 
months 
int : the amount of months, may be negative 
days 
int : the amount of days, may be negative 
Returns  

Period 
the period of years, months and days, not null 
ofDays
public static Period ofDays (int days)
Obtains a Period
representing a number of days.
The resulting period will have the specified days. The years and months units will be zero.
Parameters  

days 
int : the number of days, positive or negative 
Returns  

Period 
the period of days, not null 
ofMonths
public static Period ofMonths (int months)
Obtains a Period
representing a number of months.
The resulting period will have the specified months. The years and days units will be zero.
Parameters  

months 
int : the number of months, positive or negative 
Returns  

Period 
the period of months, not null 
ofWeeks
public static Period ofWeeks (int weeks)
Obtains a Period
representing a number of weeks.
The resulting period will be daybased, with the amount of days equal to the number of weeks multiplied by 7. The years and months units will be zero.
Parameters  

weeks 
int : the number of weeks, positive or negative 
Returns  

Period 
the period, with the input weeks converted to days, not null 
ofYears
public static Period ofYears (int years)
Obtains a Period
representing a number of years.
The resulting period will have the specified years. The months and days units will be zero.
Parameters  

years 
int : the number of years, positive or negative 
Returns  

Period 
the period of years, not null 
parse
public static Period parse (CharSequence text)
Obtains a Period
from a text string such as PnYnMnD
.
This will parse the string produced by toString()
which is
based on the ISO8601 period formats PnYnMnD
and 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 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 PnYnMnD
and 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)
Parameters  

text 
CharSequence : the text to parse, not null 
Returns  

Period 
the parsed period, not null 
Throws  

DateTimeParseException 
if the text cannot be parsed to a period 
plus
public Period plus (TemporalAmount amountToAdd)
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 using from(TemporalAmount)
.
This instance is immutable and unaffected by this method call.
Parameters  

amountToAdd 
TemporalAmount : the amount to add, not null 
Returns  

Period 
a Period based on this period with the requested period added, not null 
Throws  

DateTimeException 
if the specified amount has a nonISO chronology or contains an invalid unit 
ArithmeticException 
if numeric overflow occurs 
plusDays
public Period plusDays (long daysToAdd)
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 
long : the days to add, positive or negative 
Returns  

Period 
a Period based on this period with the specified days added, not null 
Throws  

ArithmeticException 
if numeric overflow occurs 
plusMonths
public Period plusMonths (long monthsToAdd)
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 
long : the months to add, positive or negative 
Returns  

Period 
a Period based on this period with the specified months added, not null 
Throws  

ArithmeticException 
if numeric overflow occurs 
plusYears
public Period plusYears (long yearsToAdd)
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 
long : the years to add, positive or negative 
Returns  

Period 
a Period based on this period with the specified years added, not null 
Throws  

ArithmeticException 
if numeric overflow occurs 
subtractFrom
public Temporal subtractFrom (Temporal temporal)
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 nonzero, otherwise the combination of years and months is subtracted if nonzero. 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.
Parameters  

temporal 
Temporal : the temporal object to adjust, not null 
Returns  

Temporal 
an object of the same type with the adjustment made, not null 
Throws  

DateTimeException 
if unable to subtract 
ArithmeticException 
if numeric overflow occurs 
toString
public String toString ()
Outputs this period as a String
, such as P6Y3M1D
.
The output will be in the ISO8601 period format. A zero period will be represented as zero days, 'P0D'.
Returns  

String 
a string representation of this period, not null 
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  

long 
the total number of months in the period, may be negative 
withDays
public Period withDays (int days)
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 
int : the days to represent, may be negative 
Returns  

Period 
a Period based on this period with the requested days, not null

withMonths
public Period withMonths (int months)
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 
int : the months to represent, may be negative 
Returns  

Period 
a Period based on this period with the requested months, not null

withYears
public Period withYears (int years)
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 
int : the years to represent, may be negative 
Returns  

Period 
a Period based on this period with the requested years, not null

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