org.threeten.bp.temporal.TemporalUnit Maven / Gradle / Ivy
Show all versions of threetenbp Show documentation
/*
* Copyright (c) 2007-present, Stephen Colebourne & Michael Nascimento Santos
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of JSR-310 nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.threeten.bp.temporal;
import org.threeten.bp.DateTimeException;
import org.threeten.bp.Duration;
import org.threeten.bp.Period;
/**
* A unit of date-time, such as Days or Hours.
*
* Measurement of time is built on units, such as years, months, days, hours, minutes and seconds.
* Implementations of this interface represent those units.
*
* An instance of this interface represents the unit itself, rather than an amount of the unit.
* See {@link Period} for a class that represents an amount in terms of the common units.
*
* The most commonly used units are defined in {@link ChronoUnit}.
* Further units are supplied in {@link IsoFields}.
* Units can also be written by application code by implementing this interface.
*
* The unit works using double dispatch. Client code calls methods on a date-time like
* {@code LocalDateTime} which check if the unit is a {@code ChronoUnit}.
* If it is, then the date-time must handle it.
* Otherwise, the method call is re-dispatched to the matching method in this interface.
*
*
Specification for implementors
* This interface must be implemented with care to ensure other classes operate correctly.
* All implementations that can be instantiated must be final, immutable and thread-safe.
* It is recommended to use an enum where possible.
*/
public interface TemporalUnit {
/**
* 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 {@code 60 * 60 * 1,000,000,000ns}.
*
* 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 {@link #isDurationEstimated()}.
*
* @return the duration of this unit, which may be an estimate, not null
*/
Duration getDuration();
/**
* 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.
*
* @return true if the duration is estimated, false if accurate
*/
boolean isDurationEstimated();
//-----------------------------------------------------------------------
/**
* Checks if this unit is date-based.
*
* @return true if date-based
*/
boolean isDateBased();
/**
* Checks if this unit is time-based.
*
* @return true if time-based
*/
boolean isTimeBased();
//-----------------------------------------------------------------------
/**
* 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.
*
* @param temporal the temporal object to check, not null
* @return true if the unit is supported
*/
boolean isSupportedBy(Temporal temporal);
/**
* 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 {@link Temporal#plus(long, TemporalUnit)}:
*
* // 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, {@code plus(TemporalUnit)},
* as it is a lot clearer to read in code.
*
* Implementations should perform any queries or calculations using the units
* available in {@link ChronoUnit} or the fields available in {@link ChronoField}.
* If the field is not supported a {@code 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.
*
* @param the type of the Temporal object
* @param dateTime the temporal object to adjust, not null
* @param periodToAdd the period of this unit to add, positive or negative
* @return the adjusted temporal object, not null
* @throws DateTimeException if the period cannot be added
*/
R addTo(R dateTime, long periodToAdd);
//-----------------------------------------------------------------------
/**
* 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 {@code HOURS.between(startTime, endTime)}.
*
* 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 b
* 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 {@link 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
* {@link ChronoUnit} or the fields available in {@link ChronoField}.
* If the unit is not supported a DateTimeException must be thrown.
* Implementations must not alter the specified temporal objects.
*
* @param temporal1 the base temporal object, not null
* @param temporal2 the other temporal object, not null
* @return the period between temporal1 and temporal2 in terms of this unit;
* positive if temporal2 is later than temporal1, negative if earlier
* @throws DateTimeException if the period cannot be calculated
* @throws ArithmeticException if numeric overflow occurs
*/
long between(Temporal temporal1, Temporal temporal2);
//-----------------------------------------------------------------------
/**
* Outputs this unit as a {@code String} using the name.
*
* @return the name of this unit, not null
*/
@Override
String toString();
}