org.threeten.bp.temporal
Interface Temporal

All Superinterfaces:

TemporalAccessor

All Known Implementing Classes:

ChronoLocalDate, ChronoLocalDateTime, ChronoZonedDateTime, DefaultInterfaceTemporal, HijrahDate, Instant, JapaneseDate, LocalDate, LocalDateTime, LocalTime, MinguoDate, OffsetDateTime, OffsetTime, ThaiBuddhistDate, Year, YearMonth, ZonedDateTime

public interface Temporal
extends TemporalAccessor

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 fields or 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 chronology and the time-zone. These can be accessed via queries using the static methods defined on TemporalQueries.

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.

Specification for implementors

isSupported

boolean isSupported(TemporalUnit unit)

Checks if the specified unit is supported.

This checks if the date-time can be queried for the specified unit. If false, then calling the plus and minus methods will throw an exception.

Specification for implementors

Implementations must check and handle all fields defined in ChronoUnit. If the field is supported, then true is returned, otherwise false

If the field is not a ChronoUnit, then the result of this method is obtained by invoking TemporalUnit.isSupportedBy(Temporal) passing this as the argument.

Implementations must not alter this object.

Parameters:

unit - the unit to check, null returns false

Returns:

true if this date-time can be queried for the unit, false if not

with

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 TemporalAdjusters
  date = date.with(next(WEDNESDAY));   // static import from TemporalAdjusters and DayOfWeek
 

Specification for implementors

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

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

with

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.

Specification for implementors

Implementations must check and handle all fields defined in ChronoField. If the field is supported, then the adjustment must be performed. If unsupported, then a DateTimeException must be thrown.

If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.adjustInto(Temporal, long) passing this as the first argument.

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

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

ArithmeticException - if numeric overflow occurs

plus

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.

Specification for implementors

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

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

plus

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.

If the implementation represents a date-time that has boundaries, such as LocalTime, then the permitted units must include the boundary unit, but no multiples of the boundary unit. For example, LocalTime must accept DAYS but not WEEKS or MONTHS.

Specification for implementors

Implementations must check and handle all units defined in ChronoUnit. If the unit is supported, then the addition must be performed. If unsupported, then a DateTimeException must be thrown.

If the unit is not a ChronoUnit, then the result of this method is obtained by invoking TemporalUnit.addTo(Temporal, long) passing this as the first argument.

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

Parameters:

amountToAdd - the amount of the specified unit to add, may be negative

unit - the unit of the period 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

ArithmeticException - if numeric overflow occurs

minus

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.

Specification for implementors

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

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

minus

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.

If the implementation represents a date-time that has boundaries, such as LocalTime, then the permitted units must include the boundary unit, but no multiples of the boundary unit. For example, LocalTime must accept DAYS but not WEEKS or MONTHS.

Specification for implementors

Implementations must behave in a manor equivalent to the default method behavior.

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

Parameters:

amountToSubtract - the amount of the specified unit to subtract, may be negative

unit - the unit of the period 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

ArithmeticException - if numeric overflow occurs

until

long until(Temporal endTemporal,
           TemporalUnit unit)

Calculates the period between this temporal and another temporal in terms of the specified unit.

This calculates the period between two temporals in terms of a single unit. The start and end points are this and the specified temporal. 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 startTime.until(endTime, HOURS).

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 TemporalUnit.between(Temporal, Temporal):

   // 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);
 

Specification for implementors

Implementations must begin by checking to ensure that the input temporal object is of the same observable type as the implementation. They must then perform the calculation for all instances of ChronoUnit. A DateTimeException must be thrown for ChronoUnit instances that are unsupported.

If the unit is not a ChronoUnit, then the result of this method is obtained by invoking TemporalUnit.between(Temporal, Temporal) passing this as the first argument and the input temporal as the second argument.

In summary, implementations must behave in a manner equivalent to this code:

  // check input temporal is the same type as this class
  if (unit instanceof ChronoUnit) {
    // if unit is supported, then calculate and return result
    // else throw DateTimeException for unsupported units
  }
  return unit.between(this, endTemporal);
 

The target object must not be altered by this method.

Parameters:

endTemporal - the end temporal, of the same type as this object, not null

unit - the unit to measure the period in, not null

Returns:

the amount of the period between this and the end

Throws:

DateTimeException - if the period cannot be calculated

ArithmeticException - if numeric overflow occurs