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/*
* 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
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*
* * 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
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package org.threeten.bp.temporal;
import java.util.List;
import org.threeten.bp.DateTimeException;
import org.threeten.bp.Duration;
import org.threeten.bp.Period;
/**
* Framework-level interface defining an amount of time,
* such as "6 hours", "8 days" or "2 years and 3 months".
*
* This is the base interface type for amounts of time.
* An amount is distinct from a date or time-of-day in that it is not tied
* to any specific point on the time-line.
*
* The amount can be thought of as a Map of {@code TemporalUnit} to long,
* exposed via {@link #getUnits()} and {@link #get(TemporalUnit)}.
* A simple case might have a single unit-value pair, such as "6 hours".
* A more complex case may have multiple unit-value pairs, such as "7 years, 3 months and 5 days".
*
* There are two common implementations.
* {@link Period} is a date-based implementation, storing years, months and days.
* {@link Duration} is a time-based implementation, storing seconds and
* nanoseconds, but providing some access using other duration based units
* such as minutes, hours and fixed 24-hour days.
*
* 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 {@code Period} and {@code Duration}.
*
*
Specification for implementors
* This interface places no restrictions on the mutability of implementations,
* however immutability is strongly recommended.
*/
public interface TemporalAmount {
/**
* Gets the list of units, from largest to smallest, that fully define this amount.
*
* @return the list of units.
*/
List getUnits();
/**
* Gets the amount associated with the specified unit.
*
* @param unit the unit to get, not null
* @return the amount of the unit
* @throws DateTimeException if the amount cannot be obtained
*/
long get(TemporalUnit unit);
/**
* Adds to the specified temporal object.
*
* This adds to the specified temporal object using the logic
* encapsulated in the implementing class.
*
* 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(TemporalAmount)}:
*
* // these two lines are equivalent, but the second approach is recommended
* dateTime = amount.addTo(dateTime);
* dateTime = dateTime.plus(amount);
*
* It is recommended to use the second approach, {@code plus(TemporalAmount)},
* as it is a lot clearer to read in code.
*
* Specification for implementors
* The implementation must take the input object and add to it.
* The implementation defines the logic of the addition and is responsible for
* documenting that logic. It may use any method on {@code Temporal} to
* query the temporal object and perform the addition.
* The returned object must have the same observable type as the input object
*
* The input object must not be altered.
* Instead, an adjusted copy of the original must be returned.
* This provides equivalent, safe behavior for immutable and mutable temporal objects.
*
* The input temporal object may be in a calendar system other than ISO.
* Implementations may choose to document compatibility with other calendar systems,
* or reject non-ISO temporal objects by {@link TemporalQueries#chronology() querying the chronology}.
*
* This method may be called from multiple threads in parallel.
* It must be thread-safe when invoked.
*
* @param temporal the temporal object to adjust, not null
* @return an object of the same observable type with the addition made, not null
* @throws DateTimeException if unable to add
* @throws ArithmeticException if numeric overflow occurs
*/
Temporal addTo(Temporal temporal);
/**
* Subtracts this object from the specified temporal object.
*
* This adds to the specified temporal object using the logic
* encapsulated in the implementing class.
*
* There are two equivalent ways of using this method.
* The first is to invoke this method directly.
* The second is to use {@link Temporal#minus(TemporalAmount)}:
*
* // these two lines are equivalent, but the second approach is recommended
* dateTime = amount.subtractFrom(dateTime);
* dateTime = dateTime.minus(amount);
*
* It is recommended to use the second approach, {@code minus(TemporalAmount)},
* as it is a lot clearer to read in code.
*
* Specification for implementors
* The implementation must take the input object and subtract from it.
* The implementation defines the logic of the subtraction and is responsible for
* documenting that logic. It may use any method on {@code Temporal} to
* query the temporal object and perform the subtraction.
* The returned object must have the same observable type as the input object
*
* The input object must not be altered.
* Instead, an adjusted copy of the original must be returned.
* This provides equivalent, safe behavior for immutable and mutable temporal objects.
*
* The input temporal object may be in a calendar system other than ISO.
* Implementations may choose to document compatibility with other calendar systems,
* or reject non-ISO temporal objects by {@link TemporalQueries#chronology() querying the chronology}.
*
* This method may be called from multiple threads in parallel.
* It must be thread-safe when invoked.
*
* @param temporal the temporal object to adjust, not null
* @return an object of the same observable type with the subtraction made, not null
* @throws DateTimeException if unable to subtract
* @throws ArithmeticException if numeric overflow occurs
*/
Temporal subtractFrom(Temporal temporal);
}