Temporal

public interface Temporal implements TemporalAccessor
Known Indirect Subclasses

Framework-level interface defining read-write access to a temporal object, such as a date, time, offset or some combination of these.

This is the base interface type for date, time and offset objects that are complete enough to be manipulated using plus and minus. It is implemented by those classes that can provide and manipulate information as {@linkplain TemporalField fields} or {@linkplain TemporalQuery queries}. See TemporalAccessor for the read-only version of this interface.

Most date and time information can be represented as a number. These are modeled using TemporalField with the number held using a long to handle large values. Year, month and day-of-month are simple examples of fields, but they also include instant and offsets. See ChronoField for the standard set of fields.

Two pieces of date/time information cannot be represented by numbers, the {@linkplain java.time.chrono.Chronology chronology} and the {@linkplain java.time.ZoneId time-zone}. These can be accessed via queries using the static methods defined on TemporalQuery.

This interface is a framework-level interface that should not be widely used in application code. Instead, applications should create and pass around instances of concrete types, such as LocalDate. There are many reasons for this, part of which is that implementations of this interface may be in calendar systems other than ISO. See ChronoLocalDate for a fuller discussion of the issues.

When to implement

A class should implement this interface if it meets three criteria:

  • it provides access to date/time/offset information, as per TemporalAccessor
  • the set of fields are contiguous from the largest to the smallest
  • the set of fields are complete, such that no other field is needed to define the valid range of values for the fields that are represented

Four examples make this clear:

  • LocalDate implements this interface as it represents a set of fields that are contiguous from days to forever and require no external information to determine the validity of each date. It is therefore able to implement plus/minus correctly.
  • LocalTime implements this interface as it represents a set of fields that are contiguous from nanos to within days and require no external information to determine validity. It is able to implement plus/minus correctly, by wrapping around the day.
  • MonthDay, the combination of month-of-year and day-of-month, does not implement this interface. While the combination is contiguous, from days to months within years, the combination does not have sufficient information to define the valid range of values for day-of-month. As such, it is unable to implement plus/minus correctly.
  • The combination day-of-week and day-of-month ("Friday the 13th") should not implement this interface. It does not represent a contiguous set of fields, as days to weeks overlaps days to months.

Public Method Summary

abstract boolean
isSupported(TemporalUnit unit)
Checks if the specified unit is supported.
Temporal
minus(TemporalAmount amount)
Returns an object of the same type as this object with an amount subtracted.
Temporal
minus(long amountToSubtract, TemporalUnit unit)
Returns an object of the same type as this object with the specified period subtracted.
abstract Temporal
plus(long amountToAdd, TemporalUnit unit)
Returns an object of the same type as this object with the specified period added.
Temporal
plus(TemporalAmount amount)
Returns an object of the same type as this object with an amount added.
abstract long
until(Temporal endExclusive, TemporalUnit unit)
Calculates the amount of time until another temporal in terms of the specified unit.
abstract Temporal
with(TemporalField field, long newValue)
Returns an object of the same type as this object with the specified field altered.
Temporal
with(TemporalAdjuster adjuster)
Returns an adjusted object of the same type as this object with the adjustment made.

Inherited Method Summary

Public Methods

public abstract boolean isSupported (TemporalUnit unit)

Checks if the specified unit is supported.

This checks if the specified unit can be added to, or subtracted from, this date-time. If false, then calling the plus(long, TemporalUnit) and minus methods will throw an exception.

Parameters
unit the unit to check, null returns false
Returns
  • true if the unit can be added/subtracted, false if not

public Temporal minus (TemporalAmount amount)

Returns an object of the same type as this object with an amount subtracted.

This adjusts this temporal, subtracting according to the rules of the specified amount. The amount is typically a Period but may be any other type implementing the TemporalAmount interface, such as Duration.

Some example code indicating how and why this method is used:

  date = date.minus(period);               // subtract a Period instance
  date = date.minus(duration);             // subtract a Duration instance
  date = date.minus(workingDays(6));       // example user-written workingDays method
 

Note that calling plus followed by minus is not guaranteed to return the same date-time.

Parameters
amount the amount to subtract, not null
Returns
  • an object of the same type with the specified adjustment made, not null
Throws
DateTimeException if the subtraction cannot be made
ArithmeticException if numeric overflow occurs

public Temporal minus (long amountToSubtract, TemporalUnit unit)

Returns an object of the same type as this object with the specified period subtracted.

This method returns a new object based on this one with the specified period subtracted. For example, on a LocalDate, this could be used to subtract a number of years, months or days. The returned object will have the same observable type as this object.

In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st March, then subtracting one month would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February in this example.

Parameters
amountToSubtract the amount of the specified unit to subtract, may be negative
unit the unit of the amount to subtract, not null
Returns
  • an object of the same type with the specified period subtracted, not null
Throws
DateTimeException if the unit cannot be subtracted
UnsupportedTemporalTypeException if the unit is not supported
ArithmeticException if numeric overflow occurs

public abstract Temporal plus (long amountToAdd, TemporalUnit unit)

Returns an object of the same type as this object with the specified period added.

This method returns a new object based on this one with the specified period added. For example, on a LocalDate, this could be used to add a number of years, months or days. The returned object will have the same observable type as this object.

In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st January, then adding one month would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February in this example.

Parameters
amountToAdd the amount of the specified unit to add, may be negative
unit the unit of the amount to add, not null
Returns
  • an object of the same type with the specified period added, not null
Throws
DateTimeException if the unit cannot be added
UnsupportedTemporalTypeException if the unit is not supported
ArithmeticException if numeric overflow occurs

public Temporal plus (TemporalAmount amount)

Returns an object of the same type as this object with an amount added.

This adjusts this temporal, adding according to the rules of the specified amount. The amount is typically a Period but may be any other type implementing the TemporalAmount interface, such as Duration.

Some example code indicating how and why this method is used:

  date = date.plus(period);                // add a Period instance
  date = date.plus(duration);              // add a Duration instance
  date = date.plus(workingDays(6));        // example user-written workingDays method
 

Note that calling plus followed by minus is not guaranteed to return the same date-time.

Parameters
amount the amount to add, not null
Returns
  • an object of the same type with the specified adjustment made, not null
Throws
DateTimeException if the addition cannot be made
ArithmeticException if numeric overflow occurs

public abstract long until (Temporal endExclusive, TemporalUnit unit)

Calculates the amount of time until another temporal in terms of the specified unit.

This calculates the amount of time between two temporal objects in terms of a single TemporalUnit. The start and end points are this and the specified temporal. The end point is converted to be of the same type as the start point if different. 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 startTime.until(endTime, HOURS).

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 between(Temporal, Temporal):

   // these two lines are equivalent
   temporal = start.until(end, unit);
   temporal = unit.between(start, end);
 
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 = start.until(end, DAYS);
  // or alternatively
  long daysBetween = DAYS.between(start, end);
 

Parameters
endExclusive the end temporal, exclusive, converted to be of the same type as this object, not null
unit the unit to measure the amount in, not null
Returns
  • the amount of time between this temporal object and the specified one in terms of the unit; positive if the specified object is later than this one, negative if it is earlier than this one
Throws
DateTimeException if the amount cannot be calculated, or the end temporal cannot be converted to the same type as this temporal
UnsupportedTemporalTypeException if the unit is not supported
ArithmeticException if numeric overflow occurs

public abstract Temporal with (TemporalField field, long newValue)

Returns an object of the same type as this object with the specified field altered.

This returns a new object based on this one with the value for the specified field changed. For example, on a LocalDate, this could be used to set the year, month or day-of-month. The returned object will have the same observable type as this object.

In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st January, then changing the month to February would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February in this example.

Parameters
field the field to set in the result, not null
newValue the new value of the field in the result
Returns
  • an object of the same type with the specified field set, not null
Throws
DateTimeException if the field cannot be set
UnsupportedTemporalTypeException if the field is not supported
ArithmeticException if numeric overflow occurs

public Temporal with (TemporalAdjuster adjuster)

Returns an adjusted object of the same type as this object with the adjustment made.

This adjusts this date-time according to the rules of the specified adjuster. A simple adjuster might simply set the one of the fields, such as the year field. A more complex adjuster might set the date to the last day of the month. A selection of common adjustments is provided in TemporalAdjusters. These include finding the "last day of the month" and "next Wednesday". The adjuster is responsible for handling special cases, such as the varying lengths of month and leap years.

Some example code indicating how and why this method is used:

  date = date.with(Month.JULY);        // most key classes implement TemporalAdjuster
  date = date.with(lastDayOfMonth());  // static import from Adjusters
  date = date.with(next(WEDNESDAY));   // static import from Adjusters and DayOfWeek
 

Parameters
adjuster the adjuster to use, not null
Returns
  • an object of the same type with the specified adjustment made, not null
Throws
DateTimeException if unable to make the adjustment
ArithmeticException if numeric overflow occurs