import {TemporalField} from '@js-joda/root/packages/core/src/temporal/TemporalField.js'

public interface | source

TemporalField

Direct Subclass:

ChronoField, packages/core/src/temporal/IsoFields.js~Field

Indirect Subclass:

packages/core/src/temporal/IsoFields.js~DAY_OF_QUARTER_FIELD, packages/core/src/temporal/IsoFields.js~QUARTER_OF_YEAR_FIELD, packages/core/src/temporal/IsoFields.js~WEEK_BASED_YEAR_FIELD, packages/core/src/temporal/IsoFields.js~WEEK_OF_WEEK_BASED_YEAR_FIELD

A field of date-time, such as month-of-year or hour-of-minute.

Date and time is expressed using fields which partition the time-line into something meaningful for humans. Implementations of this interface represent those fields.

The most commonly used units are defined in ChronoField. Further fields are supplied in IsoFields, WeekFields and JulianFields. Fields can also be written by application code by implementing this interface.

The field works using double dispatch. Client code calls methods on a date-time like LocalDateTime which check if the field is a ChronoField. If it is, then the date-time must handle it. Otherwise, the method call is re-dispatched to the matching method in this interface.

Method Summary

Public Methods
public	adjustInto(temporal: Temporal, newValue: number): Temporal Returns a copy of the specified temporal object with the value of this field set.
public	baseUnit(): TemporalUnit Gets the unit that the field is measured in.
public	displayName(): string
public	equals(other: *): boolean
public	getFrom(temporal: TemporalAccesor): number Gets the value of this field from the specified temporal object.
public	isDateBased(): boolean Checks if this field represents a component of a date.
public	isSupportedBy(temporal: TemporalAccesor): boolean Checks if this field is supported by the temporal object.
public	isTimeBased(): boolean Checks if this field represents a component of a time.
public	name(): string
public	range(): ValueRange Gets the range of valid values for the field.
public	rangeRefinedBy(temporal: TemporalAccessor): ValueRange Get the range of valid values for this field using the temporal object to refine the result.
public	rangeUnit(): TemporalUnit Gets the range that the field is bound by.

Public Methods

public adjustInto(temporal: Temporal, newValue: number): Temporal source

Returns a copy of the specified temporal object with the value of this field set.

This returns a new temporal object based on the specified one with the value for this field changed. For example, on a LocalDate, this could be used to set the year, month or day-of-month. The returned object has the same observable type as the specified 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 implementation 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.

There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use Temporal#with:

  // these two lines are equivalent, but the second approach is recommended
  temporal = thisField.adjustInto(temporal);
  temporal = temporal.with(thisField);

It is recommended to use the second approach, with(temporal), as it is a lot clearer to read in code.

Implementations should perform any queries or calculations using the fields available in ChronoField. If the field is not supported a 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.

Params:

Name	Type	Attribute	Description
temporal	Temporal	nullable: false	the temporal object to adjust.
newValue	number	nullable: false	the new value of the field.

Return:

Temporal

the adjusted temporal object.

Throw:

DateTimeException

if the field cannot be set.

public baseUnit(): TemporalUnit source

Gets the unit that the field is measured in.

The unit of the field is the period that varies within the range. For example, in the field 'MonthOfYear', the unit is 'Months'. See also rangeUnit.

Return:

TemporalUnit

the period unit defining the base unit of the field.

public displayName(): string source

Return:

string

public equals(other: *): boolean source

Params:

Name	Type	Attribute	Description
other	*

Return:

boolean

public getFrom(temporal: TemporalAccesor): number source

Gets the value of this field from the specified temporal object.

This queries the temporal object for the value of this field.

There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use TemporalAccessor#get:

  // these two lines are equivalent, but the second approach is recommended
  temporal = thisField.getFrom(temporal);
  temporal = temporal.get(thisField);

It is recommended to use the second approach, as it is a lot clearer to read in code.

Implementations should perform any queries or calculations using the fields available in ChronoField. If the field is not supported a DateTimeException must be thrown.

Params:

Name	Type	Attribute	Description
temporal	TemporalAccesor	nullable: false	the temporal object to query.

Return:

number

the value of this field.

Throw:

DateTimeException

if a value for the field cannot be obtained.

public isDateBased(): boolean source

Checks if this field represents a component of a date.

Return:

boolean

true if it is a component of a date, false otherwise.

public isSupportedBy(temporal: TemporalAccesor): boolean source

Checks if this field is supported by the temporal object.

This determines whether the temporal accessor supports this field. If this returns false, the the temporal cannot be queried for this field.

There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use TemporalAccessor#isSupported:

  // these two lines are equivalent, but the second approach is recommended
  temporal = thisField.isSupportedBy(temporal);
  temporal = temporal.isSupported(thisField);

It is recommended to use the second approach, isSupported(temporal), as it is a lot clearer to read in code.

Implementations should determine whether they are supported using the fields available in ChronoField.

Params:

Name	Type	Attribute	Description
temporal	TemporalAccesor	nullable: false	the temporal object to query.

Return:

boolean

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

public isTimeBased(): boolean source

Checks if this field represents a component of a time.

Return:

boolean

true if it is a component of a time, false otherwise.

public name(): string source

Return:

string

public range(): ValueRange source

Gets the range of valid values for the field.

All fields can be expressed as an integer. This method returns an object that describes the valid range for that value. This method is generally only applicable to the ISO-8601 calendar system.

Note that the result only describes the minimum and maximum valid values and it is important not to read too much into them. For example, there could be values within the range that are invalid for the field.

Return:

ValueRange

the range of valid values for the field.

public rangeRefinedBy(temporal: TemporalAccessor): ValueRange source

Get the range of valid values for this field using the temporal object to refine the result.

This uses the temporal object to find the range of valid values for the field. This is similar to range, however this method refines the result using the temporal. For example, if the field is DAY_OF_MONTH the range method is not accurate as there are four possible month lengths, 28, 29, 30 and 31 days. Using this method with a date allows the range to be accurate, returning just one of those four options.

There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use TemporalAccessor#range:

  // these two lines are equivalent, but the second approach is recommended
  temporal = thisField.rangeRefinedBy(temporal);
  temporal = temporal.range(thisField);

It is recommended to use the second approach, range, as it is a lot clearer to read in code.

Implementations should perform any queries or calculations using the fields available in ChronoField. If the field is not supported a DateTimeException must be thrown.

Params:

Name	Type	Attribute	Description
temporal	TemporalAccessor	nullable: false	the temporal object used to refine the result.

Return:

ValueRange

the range of valid values for this field.

Throw:

DateTimeException

if the range for the field cannot be obtained.

public rangeUnit(): TemporalUnit source

Gets the range that the field is bound by.

The range of the field is the period that the field varies within. For example, in the field 'MonthOfYear', the range is 'Years'. See also baseUnit.

The range is never null. For example, the 'Year' field is shorthand for 'YearOfForever'. It therefore has a unit of 'Years' and a range of 'Forever'.

Return:

TemporalUnit

the period unit defining the range of the field.