Package org.threeten.bp.temporal

Interface TemporalAccessor

All Known Subinterfaces:

Era, Temporal

All Known Implementing Classes:

ChronoLocalDate, ChronoLocalDateTime, ChronoZonedDateTime, DayOfWeek, DefaultInterfaceEra, DefaultInterfaceTemporal, DefaultInterfaceTemporalAccessor, HijrahDate, HijrahEra, Instant, IsoEra, JapaneseDate, JapaneseEra, LocalDate, LocalDateTime, LocalTime, MinguoDate, MinguoEra, Month, MonthDay, OffsetDateTime, OffsetTime, ThaiBuddhistDate, ThaiBuddhistEra, Year, YearMonth, ZonedDateTime, ZoneOffset

public interface TemporalAccessor

Framework-level interface defining read-only 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. It is implemented by those classes that can provide information as fields or queries.

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 TemporalQueries.

A sub-interface, Temporal, extends this definition to one that also supports adjustment and manipulation on more complete temporal objects.

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.

Specification for implementors

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

Method Summary

Modifier and Type	Method	Description
int	get(TemporalField field)	Gets the value of the specified field as an int.
long	getLong(TemporalField field)	Gets the value of the specified field as a long.
boolean	isSupported(TemporalField field)	Checks if the specified field is supported.
<R> R	query(TemporalQuery<R> query)	Queries this date-time.
ValueRange	range(TemporalField field)	Gets the range of valid values for the specified field.

Method Detail

isSupported

boolean isSupported(TemporalField field)

Checks if the specified field is supported.

This checks if the date-time can be queried for the specified field. If false, then calling the range and get methods will throw an exception.

Specification for implementors

Implementations must check and handle all fields defined in ChronoField. If the field is supported, then true is returned, otherwise false

If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.isSupportedBy(TemporalAccessor) passing this as the argument.

Implementations must not alter this object.

Parameters:

field - the field to check, null returns false

Returns:

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

range

ValueRange range(TemporalField field)

Gets the range of valid values for the specified field.

All fields can be expressed as a long integer. This method returns an object that describes the valid range for that value. The value of this temporal object is used to enhance the accuracy of the returned range. If the date-time cannot return the range, because the field is unsupported or for some other reason, an exception will be thrown.

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.

Specification for implementors

Implementations must check and handle all fields defined in ChronoField. If the field is supported, then the range of the field must be returned. If unsupported, then a DateTimeException must be thrown.

If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.rangeRefinedBy(TemporalAccessorl) passing this as the argument.

Implementations must not alter either this object.

Parameters:

field - the field to query the range for, not null

Returns:

the range of valid values for the field, not null

Throws:

DateTimeException - if the range for the field cannot be obtained

get

int get(TemporalField field)

Gets the value of the specified field as an int.

This queries the date-time for the value for the specified field. The returned value will always be within the valid range of values for the field. If the date-time cannot return the value, because the field is unsupported or for some other reason, an exception will be thrown.

Specification for implementors

Implementations must check and handle all fields defined in ChronoField. If the field is supported and has an int range, then the value of the field must be returned. If unsupported, then a DateTimeException must be thrown.

If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.getFrom(TemporalAccessor) passing this as the argument.

Implementations must not alter either this object.

Parameters:

field - the field to get, not null

Returns:

the value for the field, within the valid range of values

Throws:

DateTimeException - if a value for the field cannot be obtained

DateTimeException - if the range of valid values for the field exceeds an int

DateTimeException - if the value is outside the range of valid values for the field

ArithmeticException - if numeric overflow occurs

getLong

long getLong(TemporalField field)

Gets the value of the specified field as a long.

This queries the date-time for the value for the specified field. The returned value may be outside the valid range of values for the field. If the date-time cannot return the value, because the field is unsupported or for some other reason, an exception will be thrown.

Specification for implementors

Implementations must check and handle all fields defined in ChronoField. If the field is supported, then the value of the field must be returned. If unsupported, then a DateTimeException must be thrown.

If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.getFrom(TemporalAccessor) passing this as the argument.

Implementations must not alter either this object.

Parameters:

field - the field to get, not null

Returns:

the value for the field

Throws:

DateTimeException - if a value for the field cannot be obtained

ArithmeticException - if numeric overflow occurs

query

<R> R query(TemporalQuery<R> query)

Queries this date-time.

This queries this date-time using the specified query strategy object.

Queries are a key tool for extracting information from date-times. They exists to externalize the process of querying, permitting different approaches, as per the strategy design pattern. Examples might be a query that checks if the date is the day before February 29th in a leap year, or calculates the number of days to your next birthday.

The most common query implementations are method references, such as LocalDate::from and ZoneId::from. Further implementations are on TemporalQueries. Queries may also be defined by applications.

Specification for implementors

Implementations of this method must behave as follows:

   public <R> R query(TemporalQuery<R> type) {
     // only include an if statement if the implementation can return it
     if (query == TemporalQueries.zoneId())  return // the ZoneId
     if (query == TemporalQueries.chronology())  return // the Chrono
     if (query == TemporalQueries.precision())  return // the precision
     // call default method
     return super.query(query);
   }
 

Type Parameters:

R - the type of the result

Parameters:

query - the query to invoke, not null

Returns:

the query result, null may be returned (defined by the query)

Throws:

DateTimeException - if unable to query

ArithmeticException - if numeric overflow occurs