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ChronoUnit

Extends:

TemporalUnit → ChronoUnit

A standard set of date periods units.

This set of units provide unit-based access to manipulate a date, time or date-time. The standard set of units can be extended by implementing TemporalUnit.

These units are intended to be applicable in multiple calendar systems. For example, most non-ISO calendar systems define units of years, months and days, just with slightly different rules. The documentation of each unit explains how it operates.

Static properties:

  • ChronoUnit.CENTURIES: Unit that represents the concept of a century. For the ISO calendar system, it is equal to 100 years.

  • ChronoUnit.DAYS: Unit that represents the concept of a day. For the ISO calendar system, it is the standard day from midnight to midnight. The estimated duration of a day is 24 Hours.

  • ChronoUnit.DECADES: Unit that represents the concept of a decade. For the ISO calendar system, it is equal to 10 years.

  • ChronoUnit.ERAS: Unit that represents the concept of an era. The ISO calendar system doesn't have eras thus it is impossible to add an era to a date or date-time. The estimated duration of the era is artificially defined as 1,000,000,000 Years.

  • ChronoUnit.FOREVER: Artificial unit that represents the concept of forever. This is primarily used with TemporalField to represent unbounded fields such as the year or era. The estimated duration of the era is artificially defined as the largest duration supported by Duration.

  • ChronoUnit.HALF_DAYS: Unit that represents the concept of half a day, as used in AM/PM. For the ISO calendar system, it is equal to 12 hours.

  • ChronoUnit.HOURS: Unit that represents the concept of an hour. For the ISO calendar system, it is equal to 60 minutes.

  • ChronoUnit.MICROS: Unit that represents the concept of a microsecond. For the ISO calendar system, it is equal to the 1,000,000th part of the second unit.

  • ChronoUnit.MILLENNIA: Unit that represents the concept of a millennium. For the ISO calendar system, it is equal to 1,000 years.

  • ChronoUnit.MILLIS: Unit that represents the concept of a millisecond. For the ISO calendar system, it is equal to the 1000th part of the second unit.

  • ChronoUnit.MINUTES: Unit that represents the concept of a minute. For the ISO calendar system, it is equal to 60 seconds.

  • ChronoUnit.MONTHS: Unit that represents the concept of a month. For the ISO calendar system, the length of the month varies by month-of-year. The estimated duration of a month is one twelfth of 365.2425 Days.

  • ChronoUnit.NANOS: Unit that represents the concept of a nanosecond, the smallest supported unit of time. For the ISO calendar system, it is equal to the 1,000,000,000th part of the second unit.

  • ChronoUnit.SECONDS: Unit that represents the concept of a second. For the ISO calendar system, it is equal to the second in the SI system of units, except around a leap-second.

  • ChronoUnit.WEEKS: Unit that represents the concept of a week. For the ISO calendar system, it is equal to 7 Days.

  • ChronoUnit.YEARS: Unit that represents the concept of a year. For the ISO calendar system, it is equal to 12 months. The estimated duration of a year is 365.2425 Days.

Method Summary

Public Methods
public

addTo(temporal: Temporal, amount: number): Temporal

public

between(temporal1: Temporal, temporal2: Temporal): number

public

compareTo(other: TemporalUnit): *

Compares this ChronoUnit to the specified TemporalUnit.

public
public

isDateBased(): boolean

public

isDurationEstimated(): boolean

public

isSupportedBy(temporal: Temporal): boolean

public

isTimeBased(): boolean

Checks if this unit is a time unit.

public

toString(): *

Inherited Summary

From class TemporalUnit
public

addTo(dateTime: Temporal, periodToAdd: number): Temporal

Returns a copy of the specified temporal object with the specified period added.

public

between(temporal1: Temporal, temporal2: Temporal): number

Calculates the period in terms of this unit between two temporal objects of the same type.

public

Gets the duration of this unit, which may be an estimate.

public

isDateBased(): boolean

Checks if this unit is date-based.

public

isDurationEstimated(): boolean

Checks if the duration of the unit is an estimate.

public

isSupportedBy(temporal: Temporal): boolean

Checks if this unit is supported by the specified temporal object.

public

isTimeBased(): boolean

Checks if this unit is time-based.

Public Methods

public addTo(temporal: Temporal, amount: number): Temporal source

Returns a copy of the specified temporal object with the specified period added.

The period added is a multiple of this unit. For example, this method could be used to add "3 days" to a date by calling this method on the instance representing "days", passing the date and the period "3". The period to be added may be negative, which is equivalent to subtraction.

There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use Temporal#plus:

  // these two lines are equivalent, but the second approach is recommended
  temporal = thisUnit.doPlus(temporal);
  temporal = temporal.plus(thisUnit);
It is recommended to use the second approach, plus, as it is a lot clearer to read in code.

Implementations should perform any queries or calculations using the units available in ChronoUnit or the fields available in ChronoField. If the field is not supported a DateTimeException must be thrown.

Implementations must not alter the specified temporal object. Instead, an adjusted copy of the original must be returned. This provides equivalent, safe behavior for immutable and mutable implementations.

Override:

TemporalUnit#addTo

Params:

NameTypeAttributeDescription
temporal Temporal
  • nullable: false

the temporal object to adjust.

amount number

the period of this unit to add, positive or negative.

Return:

Temporal

the adjusted temporal object.

Throw:

*

DateTimeException if the period cannot be added.

public between(temporal1: Temporal, temporal2: Temporal): number source

Calculates the period in terms of this unit between two temporal objects of the same type.

This calculates the period between two temporals in terms of this unit. The start and end points are supplied as temporal objects and must be of the same type. The result will be negative if the end is before the start. For example, the period in hours between two temporal objects can be calculated using HOURS.between.

The calculation returns a whole number, representing the number of complete units between the two temporals. For example, the period in hours between the times 11:30 and 13:29 will only be one hour as it is one minute short of two hours.

There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use Temporal#until:

  // these two lines are equivalent
  between = thisUnit.between(start, end);
  between = start.until(end, thisUnit);
The choice should be made based on which makes the code more readable.

For example, this method allows the number of days between two dates to be calculated:

  long daysBetween = DAYS.between(start, end);
  // or alternatively
  long daysBetween = start.until(end, DAYS);
Implementations should perform any queries or calculations using the units available in ChronoUnit or the fields available in ChronoField. If the unit is not supported a DateTimeException must be thrown. Implementations must not alter the specified temporal objects.

Override:

TemporalUnit#between

Params:

NameTypeAttributeDescription
temporal1 Temporal
  • nullable: false

the base temporal object.

temporal2 Temporal
  • nullable: false

the other temporal object.

Return:

number

the period between temporal1 and temporal2 in terms of this unit; positive if temporal2 is later than temporal1, negative if earlier.

Throw:

*

DateTimeException if the period cannot be calculated.

*

ArithmeticException if numeric overflow occurs.

public compareTo(other: TemporalUnit): * source

Compares this ChronoUnit to the specified TemporalUnit.

The comparison is based on the total length of the durations.

Params:

NameTypeAttributeDescription
other TemporalUnit
  • nullable: false

the other unit to compare to.

Return:

*

the comparator value, negative if less, positive if greater.

public duration(): Duration source

Gets the duration of this unit, which may be an estimate.

All units return a duration measured in standard nanoseconds from this method. The duration will be positive and non-zero. For example, an hour has a duration of 60 * 60 * 1,000,000,000 ns.

Some units may return an accurate duration while others return an estimate. For example, days have an estimated duration due to the possibility of daylight saving time changes. To determine if the duration is an estimate, use isDurationEstimated.

Override:

TemporalUnit#duration

Return:

Duration

the duration of this unit, which may be an estimate.

public isDateBased(): boolean source

Checks if this unit is date-based.

Override:

TemporalUnit#isDateBased

Return:

boolean

true if date unit, false if a time unit.

public isDurationEstimated(): boolean source

Checks if the duration of the unit is an estimate.

All units have a duration, however the duration is not always accurate. For example, days have an estimated duration due to the possibility of daylight saving time changes. This method returns true if the duration is an estimate and false if it is accurate. Note that accurate/estimated ignores leap seconds.

Override:

TemporalUnit#isDurationEstimated

Return:

boolean

true if the duration is estimated, false if accurate.

public isSupportedBy(temporal: Temporal): boolean source

Checks if this unit is supported by the specified temporal object.

This checks that the implementing date-time can add/subtract this unit. This can be used to avoid throwing an exception.

Override:

TemporalUnit#isSupportedBy

Params:

NameTypeAttributeDescription
temporal Temporal
  • nullable: false

the temporal object to check.

Return:

boolean

true if the unit is supported.

public isTimeBased(): boolean source

Checks if this unit is a time unit.

Override:

TemporalUnit#isTimeBased

Return:

boolean

true if time unit, false if a date unit.

public toString(): * source

Return:

*