Module java.base
Package java.time.temporal

Interface Temporal

  • All Superinterfaces:
    TemporalAccessor
    All Known Subinterfaces:
    ChronoLocalDate, ChronoLocalDateTime<D>, ChronoZonedDateTime<D>
    All Known Implementing Classes:
    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 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.

    Implementation Requirements:
    This interface places no restrictions on the mutability of implementations, however immutability is strongly recommended. All implementations must be Comparable.
    Since:
    1.8

    • Method Detail

      • isSupported

        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.

        Implementation Requirements:
        Implementations must check and handle all units defined in ChronoUnit. If the unit is supported, then true must be returned, otherwise false must be returned.

        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 ensure that no observable state is altered when this read-only method is invoked.

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

      • with

        default 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

        Implementation Requirements:

        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.

        The default implementation must behave equivalent to this code: 

          return adjuster.adjustInto(this);

        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.

        Implementation Requirements:
        Implementations must check and handle all fields defined in ChronoField. If the field is supported, then the adjustment must be performed. If unsupported, then an UnsupportedTemporalTypeException 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 this 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
        UnsupportedTemporalTypeException - if the field is not supported
        ArithmeticException - if numeric overflow occurs

      • plus

        default 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.

        Implementation Requirements:

        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.

        The default implementation must behave equivalent to this code: 

          return amount.addTo(this);

        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.

        Implementation Requirements:
        Implementations must check and handle all units defined in ChronoUnit. If the unit is supported, then the addition must be performed. If unsupported, then an UnsupportedTemporalTypeException 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 this 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 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

      • minus

        default 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.

        Implementation Requirements:

        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.

        The default implementation must behave equivalent to this code: 

          return amount.subtractFrom(this);

        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

        default 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.

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

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

        The default implementation must behave equivalent to this code: 

          return (amountToSubtract == Long.MIN_VALUE ?
      plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));

        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

      • until

        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 TemporalUnit.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);

        Implementation Requirements:
        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. An UnsupportedTemporalTypeException 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 converted input temporal as the second argument.

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

          // convert the end temporal to the same type as this class
  if (unit instanceof ChronoUnit) {
    // if unit is supported, then calculate and return result
    // else throw UnsupportedTemporalTypeException for unsupported units
  }
  return unit.between(this, convertedEndTemporal);

        Note that the unit's between method must only be invoked if the two temporal objects have exactly the same type evaluated by getClass().

        Implementations must ensure that no observable state is altered when this read-only method is invoked.

        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