java.time.temporal

Interface TemporalAmount

All Known Implementing Classes:

ChronoPeriod, Duration, Period

public interface TemporalAmount

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 TemporalUnit to long, exposed via getUnits() and 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. Period is a date-based implementation, storing years, months and days. 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 Period and Duration.

Specification for implementors

This interface places no restrictions on the mutability of implementations, however immutability is strongly recommended.

Method Summary

Methods

Modifier and Type	Method and Description
Temporal	addTo(Temporal temporal) Adds to the specified temporal object.
long	get(TemporalUnit unit) Gets the amount associated with the specified unit.
java.util.List<TemporalUnit>	getUnits() Gets the list of units, from largest to smallest, that fully define this amount.
Temporal	subtractFrom(Temporal temporal) Subtracts this object from the specified temporal object.

Method Detail

getUnits

java.util.List<TemporalUnit> getUnits()

Gets the list of units, from largest to smallest, that fully define this amount.

Returns:

the list of units.

get

long get(TemporalUnit unit)

Gets the amount associated with the specified unit.

Parameters:

unit - the unit to get, not null

Returns:

the amount of the unit

Throws:

DateTimeException - if the amount cannot be obtained

addTo

Temporal addTo(Temporal temporal)

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 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, 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 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 querying the chronology.

This method may be called from multiple threads in parallel. It must be thread-safe when invoked.

Parameters:

temporal - the temporal object to adjust, not null

Returns:

an object of the same observable type with the addition made, not null

Throws:

DateTimeException - if unable to add

java.lang.ArithmeticException - if numeric overflow occurs

subtractFrom

Temporal subtractFrom(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 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, 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 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 querying the chronology.

This method may be called from multiple threads in parallel. It must be thread-safe when invoked.

Parameters:

temporal - the temporal object to adjust, not null

Returns:

an object of the same observable type with the subtraction made, not null

Throws:

DateTimeException - if unable to subtract

java.lang.ArithmeticException - if numeric overflow occurs