Module java.base

Package java.time.chrono

Interface ChronoPeriod

All Superinterfaces:

TemporalAmount

All Known Implementing Classes:

Period

public interface ChronoPeriod
extends TemporalAmount

A date-based amount of time, such as '3 years, 4 months and 5 days' in an arbitrary chronology, intended for advanced globalization use cases.

This interface models a date-based amount of time in a calendar system. While most calendar systems use years, months and days, some do not. Therefore, this interface operates solely in terms of a set of supported units that are defined by the Chronology. The set of supported units is fixed for a given chronology. The amount of a supported unit may be set to zero.

The period is modeled as a directed amount of time, meaning that individual parts of the period may be negative.

Implementation Requirements:

This interface must be implemented with care to ensure other classes operate correctly. All implementations that can be instantiated must be final, immutable and thread-safe. Subclasses should be Serializable wherever possible.

Since:

1.8

Method Summary

Modifier and Type	Method	Description
Temporal	addTo(Temporal temporal)	Adds this period to the specified temporal object.
static ChronoPeriod	between(ChronoLocalDate startDateInclusive, ChronoLocalDate endDateExclusive)	Obtains a ChronoPeriod consisting of amount of time between two dates.
boolean	equals(Object obj)	Checks if this period is equal to another period, including the chronology.
long	get(TemporalUnit unit)	Gets the value of the requested unit.
Chronology	getChronology()	Gets the chronology that defines the meaning of the supported units.
List<TemporalUnit>	getUnits()	Gets the set of units supported by this period.
int	hashCode()	A hash code for this period.
default boolean	isNegative()	Checks if any of the supported units of this period are negative.
default boolean	isZero()	Checks if all the supported units of this period are zero.
ChronoPeriod	minus(TemporalAmount amountToSubtract)	Returns a copy of this period with the specified period subtracted.
ChronoPeriod	multipliedBy(int scalar)	Returns a new instance with each amount in this period in this period multiplied by the specified scalar.
default ChronoPeriod	negated()	Returns a new instance with each amount in this period negated.
ChronoPeriod	normalized()	Returns a copy of this period with the amounts of each unit normalized.
ChronoPeriod	plus(TemporalAmount amountToAdd)	Returns a copy of this period with the specified period added.
Temporal	subtractFrom(Temporal temporal)	Subtracts this period from the specified temporal object.
String	toString()	Outputs this period as a String.

Method Details

between

static ChronoPeriod between(ChronoLocalDate startDateInclusive,
 ChronoLocalDate endDateExclusive)

Obtains a ChronoPeriod consisting of amount of time between two dates.

The start date is included, but the end date is not. The period is calculated using ChronoLocalDate.until(ChronoLocalDate). As such, the calculation is chronology specific.

The chronology of the first date is used. The chronology of the second date is ignored, with the date being converted to the target chronology system before the calculation starts.

The result of this method can be a negative period if the end is before the start. In most cases, the positive/negative sign will be the same in each of the supported fields.

Parameters:

startDateInclusive - the start date, inclusive, specifying the chronology of the calculation, not null

endDateExclusive - the end date, exclusive, in any chronology, not null

Returns:

the period between this date and the end date, not null

See Also:

• ChronoLocalDate.until(ChronoLocalDate)

get

long get(TemporalUnit unit)

Gets the value of the requested unit.

The supported units are chronology specific. They will typically be YEARS, MONTHS and DAYS. Requesting an unsupported unit will throw an exception.

Specified by:

get in interface TemporalAmount

Parameters:

unit - the TemporalUnit for which to return the value

Returns:

the long value of the unit

Throws:

DateTimeException - if the unit is not supported

UnsupportedTemporalTypeException - if the unit is not supported

getUnits

List<TemporalUnit> getUnits()

Gets the set of units supported by this period.

The supported units are chronology specific. They will typically be YEARS, MONTHS and DAYS. They are returned in order from largest to smallest.

This set can be used in conjunction with get(TemporalUnit) to access the entire state of the period.

Specified by:

getUnits in interface TemporalAmount

Returns:

a list containing the supported units, not null

getChronology

Chronology getChronology()

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 ChronoLocalDate instances of the same chronology.

Returns:

the chronology defining the period, not null

isZero

default boolean isZero()

Checks if all the supported units of this period are zero.

Returns:

true if this period is zero-length

isNegative

default boolean isNegative()

Checks if any of the supported units of this period are negative.

Returns:

true if any unit of this period is negative

plus

ChronoPeriod plus(TemporalAmount amountToAdd)

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

If the specified amount is a ChronoPeriod then it must have the same chronology as this period. Implementations may choose to accept or reject other TemporalAmount implementations.

This instance is immutable and unaffected by this method call.

Parameters:

amountToAdd - the period to add, not null

Returns:

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

Throws:

ArithmeticException - if numeric overflow occurs

minus

ChronoPeriod minus(TemporalAmount amountToSubtract)

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

If the specified amount is a ChronoPeriod then it must have the same chronology as this period. Implementations may choose to accept or reject other TemporalAmount implementations.

This instance is immutable and unaffected by this method call.

Parameters:

amountToSubtract - the period to subtract, not null

Returns:

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

Throws:

ArithmeticException - if numeric overflow occurs

multipliedBy

ChronoPeriod multipliedBy(int scalar)

Returns a new instance with each amount in this period in this period multiplied by the specified scalar.

This returns a period with each supported unit 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 - the scalar to multiply by, not null

Returns:

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

Throws:

ArithmeticException - if numeric overflow occurs

negated

default ChronoPeriod negated()

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

This returns a period with each supported unit 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:

a ChronoPeriod 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

ChronoPeriod normalized()

Returns a copy of this period with the amounts of each unit normalized.

The process of normalization is specific to each calendar system. For example, in the ISO calendar system, the years and months are normalized but the days are not, such that "15 months" would be normalized to "1 year and 3 months".

This instance is immutable and unaffected by this method call.

Returns:

a ChronoPeriod based on this period with the amounts of each unit normalized, not null

Throws:

ArithmeticException - if numeric overflow occurs

addTo

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.

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 specified temporal must have the same chronology as this period. This returns a temporal with the non-zero supported units added.

This instance is immutable and unaffected by this method call.

Specified by:

addTo in interface TemporalAmount

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 add

ArithmeticException - if numeric overflow occurs

subtractFrom

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.

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 specified temporal must have the same chronology as this period. This returns a temporal with the non-zero supported units subtracted.

This instance is immutable and unaffected by this method call.

Specified by:

subtractFrom in interface TemporalAmount

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 subtract

ArithmeticException - if numeric overflow occurs

equals

boolean equals(Object obj)

Checks if this period is equal to another period, including the chronology.

Compares this period with another ensuring that the type, each amount and the chronology are the same. Note that this means that a period of "15 Months" is not equal to a period of "1 Year and 3 Months".

Overrides:

equals in class Object

Parameters:

obj - the object to check, null returns false

Returns:

true if this is equal to the other period

See Also:

• Object.hashCode()
• HashMap

hashCode

int hashCode()

A hash code for this period.

Overrides:

hashCode in class Object

Returns:

a suitable hash code

See Also:

• Object.equals(java.lang.Object)
• System.identityHashCode(java.lang.Object)

toString

String toString()

Outputs this period as a String.

The output will include the period amounts and chronology.

Overrides:

toString in class Object

Returns:

a string representation of this period, not null