- All Superinterfaces:
TemporalAccessor
,TemporalAdjuster
- All Known Implementing Classes:
HijrahEra
,IsoEra
,JapaneseEra
,MinguoEra
,ThaiBuddhistEra
public interface Era extends TemporalAccessor, TemporalAdjuster
Most calendar systems have a single epoch dividing the time-line into two eras.
However, some calendar systems, have multiple eras, such as one for the reign
of each leader.
In all cases, the era is conceptually the largest division of the time-line.
Each chronology defines the Era's that are known Eras and a
Chronology.eras
to get the valid eras.
For example, the Thai Buddhist calendar system divides time into two eras, before and after a single date. By contrast, the Japanese calendar system has one era for the reign of each Emperor.
Instances of Era
may be compared using the ==
operator.
- Implementation Requirements:
- This interface must be implemented with care to ensure other classes operate correctly. All implementations must be singletons - final, immutable and thread-safe. It is recommended to use an enum whenever possible.
- Since:
- 1.8
-
Method Summary
Modifier and TypeMethodDescriptiondefault Temporal
adjustInto(Temporal temporal)
Adjusts the specified temporal object to have the same era as this object.default int
get(TemporalField field)
Gets the value of the specified field from this era as anint
.default String
getDisplayName(TextStyle style, Locale locale)
Gets the textual representation of this era.default long
getLong(TemporalField field)
Gets the value of the specified field from this era as along
.int
getValue()
Gets the numeric value associated with the era as defined by the chronology.default boolean
isSupported(TemporalField field)
Checks if the specified field is supported.default <R> R
query(TemporalQuery<R> query)
Queries this era using the specified query.default ValueRange
range(TemporalField field)
Gets the range of valid values for the specified field.
-
Method Details
-
getValue
int getValue()Gets the numeric value associated with the era as defined by the chronology. Each chronology defines the predefined Eras and methods to list the Eras of the chronology.All fields, including eras, have an associated numeric value. The meaning of the numeric value for era is determined by the chronology according to these principles:
- The era in use at the epoch 1970-01-01 (ISO) has the value 1.
- Later eras have sequentially higher values.
- Earlier eras have sequentially lower values, which may be negative.
- Returns:
- the numeric era value
-
isSupported
Checks if the specified field is supported.This checks if this era can be queried for the specified field. If false, then calling the
range
andget
methods will throw an exception.If the field is a
ChronoField
then the query is implemented here. TheERA
field returns true. All otherChronoField
instances will return false.If the field is not a
ChronoField
, then the result of this method is obtained by invokingTemporalField.isSupportedBy(TemporalAccessor)
passingthis
as the argument. Whether the field is supported is determined by the field.- Specified by:
isSupported
in interfaceTemporalAccessor
- Parameters:
field
- the field to check, null returns false- Returns:
- true if the field is supported on this era, false if not
-
range
Gets the range of valid values for the specified field.The range object expresses the minimum and maximum valid values for a field. This era is used to enhance the accuracy of the returned range. If it is not possible to return the range, because the field is not supported or for some other reason, an exception is thrown.
If the field is a
ChronoField
then the query is implemented here. TheERA
field returns the range. All otherChronoField
instances will throw anUnsupportedTemporalTypeException
.If the field is not a
ChronoField
, then the result of this method is obtained by invokingTemporalField.rangeRefinedBy(TemporalAccessor)
passingthis
as the argument. Whether the range can be obtained is determined by the field.The default implementation must return a range for
ERA
from zero to one, suitable for two era calendar systems such as ISO.- Specified by:
range
in interfaceTemporalAccessor
- 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 obtainedUnsupportedTemporalTypeException
- if the unit is not supported
-
get
Gets the value of the specified field from this era as anint
.This queries this era for the value of the specified field. The returned value will always be within the valid range of values for the field. If it is not possible to return the value, because the field is not supported or for some other reason, an exception is thrown.
If the field is a
ChronoField
then the query is implemented here. TheERA
field returns the value of the era. All otherChronoField
instances will throw anUnsupportedTemporalTypeException
.If the field is not a
ChronoField
, then the result of this method is obtained by invokingTemporalField.getFrom(TemporalAccessor)
passingthis
as the argument. Whether the value can be obtained, and what the value represents, is determined by the field.- Specified by:
get
in interfaceTemporalAccessor
- 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 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 anint
ArithmeticException
- if numeric overflow occurs
-
getLong
Gets the value of the specified field from this era as along
.This queries this era for the value of the specified field. If it is not possible to return the value, because the field is not supported or for some other reason, an exception is thrown.
If the field is a
ChronoField
then the query is implemented here. TheERA
field returns the value of the era. All otherChronoField
instances will throw anUnsupportedTemporalTypeException
.If the field is not a
ChronoField
, then the result of this method is obtained by invokingTemporalField.getFrom(TemporalAccessor)
passingthis
as the argument. Whether the value can be obtained, and what the value represents, is determined by the field.- Specified by:
getLong
in interfaceTemporalAccessor
- Parameters:
field
- the field to get, not null- Returns:
- the value for the field
- Throws:
DateTimeException
- if a value for the field cannot be obtainedUnsupportedTemporalTypeException
- if the field is not supportedArithmeticException
- if numeric overflow occurs
-
query
Queries this era using the specified query.This queries this era using the specified query strategy object. The
TemporalQuery
object defines the logic to be used to obtain the result. Read the documentation of the query to understand what the result of this method will be.The result of this method is obtained by invoking the
TemporalQuery.queryFrom(TemporalAccessor)
method on the specified query passingthis
as the argument.- Specified by:
query
in interfaceTemporalAccessor
- 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 (defined by the query)ArithmeticException
- if numeric overflow occurs (defined by the query)
-
adjustInto
Adjusts the specified temporal object to have the same era as this object.This returns a temporal object of the same observable type as the input with the era changed to be the same as this.
The adjustment is equivalent to using
Temporal.with(TemporalField, long)
passingChronoField.ERA
as the field.In most cases, it is clearer to reverse the calling pattern by using
Temporal.with(TemporalAdjuster)
:// these two lines are equivalent, but the second approach is recommended temporal = thisEra.adjustInto(temporal); temporal = temporal.with(thisEra);
This instance is immutable and unaffected by this method call.
- Specified by:
adjustInto
in interfaceTemporalAdjuster
- Parameters:
temporal
- the target object to be adjusted, not null- Returns:
- the adjusted object, not null
- Throws:
DateTimeException
- if unable to make the adjustmentArithmeticException
- if numeric overflow occurs
-
getDisplayName
Gets the textual representation of this era.This returns the textual name used to identify the era, suitable for presentation to the user. The parameters control the style of the returned text and the locale.
If no textual mapping is found then the
numeric value
is returned.- API Note:
- This default implementation is suitable for most implementations.
- Parameters:
style
- the style of the text required, not nulllocale
- the locale to use, not null- Returns:
- the text value of the era, not null
-