public interface TemporalAccessor
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 TemporalQuery.
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.
This interface places no restrictions on the mutability of implementations, however immutability is strongly recommended.
| Modifier and Type | Method and 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.
|
int get(TemporalField field)
int.
This queries the date-time for the value of 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.
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 an UnsupportedTemporalTypeException 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 ensure that no observable state is altered when this read-only method is invoked.
The default implementation must behave equivalent to this code:
if (range(field).isIntValue()) {
return range(field).checkValidIntValue(getLong(field), field);
}
throw new UnsupportedTemporalTypeException(
"Invalid field " + field + " + for get() method, use getLong() instead");
field - the field to get, not nullDateTimeException - if a value for the field cannot be obtained or the value is outside the range of valid values for the
fieldUnsupportedTemporalTypeException - if the field is not supported or the range of values exceeds an intlong getLong(TemporalField field)
long.
This queries the date-time for the value of 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.
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 an
UnsupportedTemporalTypeException 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 ensure that no observable state is altered when this read-only method is invoked.
field - the field to get, not nullDateTimeException - if a value for the field cannot be obtainedUnsupportedTemporalTypeException - if the field is not supportedboolean isSupported(@Nullable TemporalField field)
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.
Implementations must check and handle all fields defined in ChronoField. If the field is
supported, then true must be returned, otherwise false must be returned.
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 ensure that no observable state is altered when this read-only method is invoked.
field - the field to check, null returns false@Nullable <R> R query(TemporalQuery<R> query)
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. Additional implementations are provided as static methods on TemporalQuery.
The default implementation must behave equivalent to this code:
if (query == TemporalQueries.zoneId() || query == TemporalQueries.chronology()
|| query == TemporalQueries.precision()) {
return null;
}
return query.queryFrom(this);
Future versions are permitted to add further queries to the if statement.
All classes implementing this interface and overriding this method must call
TemporalAccessor.super.query(query). JDK classes may avoid calling super if they provide
behavior equivalent to the default behaviour, however non-JDK classes may not utilize this optimization
and must call super.
If the implementation can supply a value for one of the queries listed in the if statement of the
default implementation, then it must do so. For example, an application-defined HourMin class
storing the hour and minute must override this method as follows:
if (query == TemporalQueries.precision()) {
return MINUTES;
}
return TemporalAccessor.super.query(query);
Implementations must ensure that no observable state is altered when this read-only method is invoked.
R - the type of the resultquery - the query to invoke, not nullDateTimeException - if unable to queryValueRange range(TemporalField 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.
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 an
UnsupportedTemporalTypeException 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 ensure that no observable state is altered when this read-only method is invoked.
The default implementation must behave equivalent to this code:
if (field instanceof ChronoField) {
if (isSupported(field)) {
return field.range();
}
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return field.rangeRefinedBy(this);
field - the field to query the range for, not nullDateTimeException - if the range for the field cannot be obtainedUnsupportedTemporalTypeException - if the field is not supported