* 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 * {@link Chrono#eras Chrono.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 {@code Era} may be compared using the {@code ==} operator. * *
* 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: *
* * @return the numeric era value */ int getValue(); /** * Gets the chronology of this era. *
* The {@code Chrono} represents the calendar system in use. * This always returns the standard form of the chronology. * * @return the chronology, not null */ C getChrono(); //----------------------------------------------------------------------- /** * Obtains a date in this era given the year-of-era, month, and day. *
* This era is combined with the given date fields to form a date. * The year specified must be the year-of-era. * Methods to create a date from the proleptic-year are on {@code Chrono}. * This always uses the standard form of the chronology. *
* This default implementation invokes the factory method on {@link Chrono}.
*
* @param yearOfEra the calendar system year-of-era
* @param month the calendar system month-of-year
* @param day the calendar system day-of-month
* @return a local date based on this era and the specified year-of-era, month and day
*/
public default ChronoLocalDate
* This era is combined with the given date fields to form a date.
* The year specified must be the year-of-era.
* Methods to create a date from the proleptic-year are on {@code Chrono}.
* This always uses the standard form of the chronology.
*
* This default implementation invokes the factory method on {@link Chrono}.
*
* @param yearOfEra the calendar system year-of-era
* @param dayOfYear the calendar system day-of-year
* @return a local date based on this era and the specified year-of-era and day-of-year
*/
public default ChronoLocalDate
* This checks if this era can be queried for the specified field.
* If false, then calling the {@link #range(TemporalField) range} and
* {@link #get(TemporalField) get} methods will throw an exception.
*
* If the field is a {@link ChronoField} then the query is implemented here.
* The {@code ERA} field returns true.
* All other {@code ChronoField} instances will return false.
*
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.doIsSupported(TemporalAccessor)}
* passing {@code this} as the argument.
* Whether the field is supported is determined by the field.
*
* @param field the field to check, null returns false
* @return true if the field is supported on this era, false if not
*/
@Override
public default boolean isSupported(TemporalField field) {
if (field instanceof ChronoField) {
return field == ERA;
}
return field != null && field.doIsSupported(this);
}
/**
* 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 {@link ChronoField} then the query is implemented here.
* The {@code ERA} field returns the range.
* All other {@code ChronoField} instances will throw a {@code DateTimeException}.
*
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.doRange(TemporalAccessor)}
* passing {@code this} as the argument.
* Whether the range can be obtained is determined by the field.
*
* @param field the field to query the range for, not null
* @return the range of valid values for the field, not null
* @throws DateTimeException if the range for the field cannot be obtained
*/
@Override // override for Javadoc
public default ValueRange range(TemporalField field) {
return TemporalAccessor.super.range(field);
}
/**
* Gets the value of the specified field from this era as an {@code int}.
*
* This queries this era for the value for 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 {@link ChronoField} then the query is implemented here.
* The {@code ERA} field returns the value of the era.
* All other {@code ChronoField} instances will throw a {@code DateTimeException}.
*
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.doGet(TemporalAccessor)}
* passing {@code this} as the argument. Whether the value can be obtained,
* and what the value represents, is determined by the field.
*
* @param field the field to get, not null
* @return the value for the field
* @throws DateTimeException if a value for the field cannot be obtained
* @throws ArithmeticException if numeric overflow occurs
*/
@Override // override for Javadoc and performance
public default int get(TemporalField field) {
if (field == ERA) {
return getValue();
}
return range(field).checkValidIntValue(getLong(field), field);
}
/**
* Gets the value of the specified field from this era as a {@code long}.
*
* This queries this era for the value for 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 {@link ChronoField} then the query is implemented here.
* The {@code ERA} field returns the value of the era.
* All other {@code ChronoField} instances will throw a {@code DateTimeException}.
*
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.doGet(TemporalAccessor)}
* passing {@code this} as the argument. Whether the value can be obtained,
* and what the value represents, is determined by the field.
*
* @param field the field to get, not null
* @return the value for the field
* @throws DateTimeException if a value for the field cannot be obtained
* @throws ArithmeticException if numeric overflow occurs
*/
@Override
public default long getLong(TemporalField field) {
if (field == ERA) {
return getValue();
} else if (field instanceof ChronoField) {
throw new DateTimeException("Unsupported field: " + field.getName());
}
return field.doGet(this);
}
//-----------------------------------------------------------------------
/**
* Queries this era using the specified query.
*
* This queries this era using the specified query strategy object.
* The {@code 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
* {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
* specified query passing {@code this} as the argument.
*
* @param
* 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 {@link Temporal#with(TemporalField, long)}
* passing {@link ChronoField#ERA} as the field.
*
* In most cases, it is clearer to reverse the calling pattern by using
* {@link Temporal#with(TemporalAdjuster)}:
*
* This instance is immutable and unaffected by this method call.
*
* @param temporal the target object to be adjusted, not null
* @return the adjusted object, not null
* @throws DateTimeException if unable to make the adjustment
* @throws ArithmeticException if numeric overflow occurs
*/
@Override
public default Temporal adjustInto(Temporal temporal) {
return temporal.with(ERA, getValue());
}
//-----------------------------------------------------------------------
/**
* Gets the textual representation of this era.
*
* This returns the textual name used to identify the era.
* The parameters control the style of the returned text and the locale.
*
* If no textual mapping is found then the {@link #getValue() numeric value} is returned.
*
* This default implementation is suitable for all implementations.
*
* @param style the style of the text required, not null
* @param locale the locale to use, not null
* @return the text value of the era, not null
*/
public default String getText(TextStyle style, Locale locale) {
return new DateTimeFormatterBuilder().appendText(ERA, style).toFormatter(locale).print(this);
}
// NOTE: methods to convert year-of-era/proleptic-year cannot be here as they may depend on month/day (Japanese)
}
* // these two lines are equivalent, but the second approach is recommended
* temporal = thisEra.adjustInto(temporal);
* temporal = temporal.with(thisEra);
*
*