Enum Class ChronoUnit
- All Implemented Interfaces:
Serializable
,Comparable<ChronoUnit>
,Constable
,TemporalUnit
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.
- Implementation Requirements:
- This is a final, immutable and thread-safe enum.
- Since:
- 1.8
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Nested Class Summary
Nested classes/interfaces declared in class java.lang.Enum
Enum.EnumDesc<E extends Enum<E>>
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Enum Constant Summary
Enum ConstantDescriptionUnit that represents the concept of a century.Unit that represents the concept of a day.Unit that represents the concept of a decade.Unit that represents the concept of an era.Artificial unit that represents the concept of forever.Unit that represents the concept of half a day, as used in AM/PM.Unit that represents the concept of an hour.Unit that represents the concept of a microsecond.Unit that represents the concept of a millennium.Unit that represents the concept of a millisecond.Unit that represents the concept of a minute.Unit that represents the concept of a month.Unit that represents the concept of a nanosecond, the smallest supported unit of time.Unit that represents the concept of a second.Unit that represents the concept of a week.Unit that represents the concept of a year. -
Method Summary
Modifier and TypeMethodDescription<R extends Temporal>
RaddTo
(R temporal, long amount) Returns a copy of the specified temporal object with the specified period added.long
Calculates the amount of time between two temporal objects.Gets the estimated duration of this unit in the ISO calendar system.boolean
Checks if this unit is a date unit.boolean
Checks if the duration of the unit is an estimate.boolean
Checks if this unit is a time unit.toString()
Returns the name of this enum constant, as contained in the declaration.static ChronoUnit
Returns the enum constant of this class with the specified name.static ChronoUnit[]
values()
Returns an array containing the constants of this enum class, in the order they are declared.Methods declared in class java.lang.Enum
clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf
Methods declared in interface java.time.temporal.TemporalUnit
isSupportedBy
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Enum Constant Details
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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. -
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. -
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. -
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. -
MINUTES
Unit that represents the concept of a minute. For the ISO calendar system, it is equal to 60 seconds. -
HOURS
Unit that represents the concept of an hour. For the ISO calendar system, it is equal to 60 minutes. -
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. -
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 is24 Hours
.When used with other calendar systems it must correspond to the day defined by the rising and setting of the Sun on Earth. It is not required that days begin at midnight - when converting between calendar systems, the date should be equivalent at midday.
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WEEKS
Unit that represents the concept of a week. For the ISO calendar system, it is equal to 7 days.When used with other calendar systems it must correspond to an integral number of days.
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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 of365.2425 Days
.When used with other calendar systems it must correspond to an integral number of days.
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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 is365.2425 Days
.When used with other calendar systems it must correspond to an integral number of days or months roughly equal to a year defined by the passage of the Earth around the Sun.
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DECADES
Unit that represents the concept of a decade. For the ISO calendar system, it is equal to 10 years.When used with other calendar systems it must correspond to an integral number of days and is normally an integral number of years.
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CENTURIES
Unit that represents the concept of a century. For the ISO calendar system, it is equal to 100 years.When used with other calendar systems it must correspond to an integral number of days and is normally an integral number of years.
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MILLENNIA
Unit that represents the concept of a millennium. For the ISO calendar system, it is equal to 1000 years.When used with other calendar systems it must correspond to an integral number of days and is normally an integral number of years.
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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 as1,000,000,000 Years
.When used with other calendar systems there are no restrictions on the unit.
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FOREVER
Artificial unit that represents the concept of forever. This is primarily used withTemporalField
to represent unbounded fields such as the year or era. The estimated duration of this unit is artificially defined as the largest duration supported byDuration
.
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Method Details
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values
Returns an array containing the constants of this enum class, in the order they are declared.- Returns:
- an array containing the constants of this enum class, in the order they are declared
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valueOf
Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)- Parameters:
name
- the name of the enum constant to be returned.- Returns:
- the enum constant with the specified name
- Throws:
IllegalArgumentException
- if this enum class has no constant with the specified nameNullPointerException
- if the argument is null
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getDuration
Gets the estimated duration of this unit in the ISO calendar system.All of the units in this class have an estimated duration. Days vary due to daylight saving time, while months have different lengths.
- Specified by:
getDuration
in interfaceTemporalUnit
- Returns:
- the estimated duration of this unit, not null
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isDurationEstimated
public boolean isDurationEstimated()Checks if the duration of the unit is an estimate.All time units in this class are considered to be accurate, while all date units in this class are considered to be estimated.
This definition ignores leap seconds, but considers that Days vary due to daylight saving time and months have different lengths.
- Specified by:
isDurationEstimated
in interfaceTemporalUnit
- Returns:
- true if the duration is estimated, false if accurate
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isDateBased
public boolean isDateBased()Checks if this unit is a date unit.All units from days to eras inclusive are date-based. Time-based units and
FOREVER
return false.- Specified by:
isDateBased
in interfaceTemporalUnit
- Returns:
- true if a date unit, false if a time unit
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isTimeBased
public boolean isTimeBased()Checks if this unit is a time unit.All units from nanos to half-days inclusive are time-based. Date-based units and
FOREVER
return false.- Specified by:
isTimeBased
in interfaceTemporalUnit
- Returns:
- true if a time unit, false if a date unit
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addTo
Description copied from interface:TemporalUnit
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(long, TemporalUnit)
:// these two lines are equivalent, but the second approach is recommended temporal = thisUnit.addTo(temporal); temporal = temporal.plus(thisUnit);
It is recommended to use the second approach,plus(TemporalUnit)
, 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 inChronoField
. If the unit is not supported anUnsupportedTemporalTypeException
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.
- Specified by:
addTo
in interfaceTemporalUnit
- Type Parameters:
R
- the type of the Temporal object- Parameters:
temporal
- the temporal object to adjust, not nullamount
- the amount of this unit to add, positive or negative- Returns:
- the adjusted temporal object, not null
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between
Description copied from interface:TemporalUnit
Calculates the amount of time between two temporal objects.This calculates the amount in terms of this unit. The start and end points are supplied as temporal objects and must be of compatible types. The implementation will convert the second type to be an instance of the first type before the calculating the amount. The result will be negative if the end is before the start. For example, the amount in hours between two temporal objects can be calculated using
HOURS.between(startTime, endTime)
.The calculation returns a whole number, representing the number of complete units between the two temporals. For example, the amount 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(Temporal, TemporalUnit)
:// 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 inChronoField
. If the unit is not supported anUnsupportedTemporalTypeException
must be thrown. Implementations must not alter the specified temporal objects.- Specified by:
between
in interfaceTemporalUnit
- Parameters:
temporal1Inclusive
- the base temporal object, not nulltemporal2Exclusive
- the other temporal object, exclusive, not null- Returns:
- the amount of time between temporal1Inclusive and temporal2Exclusive in terms of this unit; positive if temporal2Exclusive is later than temporal1Inclusive, negative if earlier
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toString
Description copied from class:Enum
Returns the name of this enum constant, as contained in the declaration. This method may be overridden, though it typically isn't necessary or desirable. An enum class should override this method when a more "programmer-friendly" string form exists.- Specified by:
toString
in interfaceTemporalUnit
- Overrides:
toString
in classEnum<ChronoUnit>
- Returns:
- the name of this enum constant
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