* This is the base interface type for date, time and offset objects. * It is implemented by those classes that can provide information * as {@linkplain TemporalField fields} or {@linkplain TemporalQuery queries}. *
* Most date and time information can be represented as a number. * These are modeled using {@code TemporalField} with the number held using * a {@code long} to handle large values. Year, month and day-of-month are * simple examples of fields, but they also include instant and offsets. * See {@link ChronoField} for the standard set of fields. *
* Two pieces of date/time information cannot be represented by numbers, * the {@linkplain java.time.chrono.Chronology chronology} and the * {@linkplain java.time.ZoneId time-zone}. * These can be accessed via {@linkplain #query(TemporalQuery) queries} using * the static methods defined on {@link TemporalQuery}. *
* A sub-interface, {@link 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 {@code 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 {@link java.time.chrono.ChronoLocalDate} for a fuller discussion of the issues. * * @implSpec * This interface places no restrictions on the mutability of implementations, * however immutability is strongly recommended. * * @since 1.8 */ public interface TemporalAccessor { /** * 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 {@link #range(TemporalField) range} and {@link #get(TemporalField) get} * methods will throw an exception. * * @implSpec * Implementations must check and handle all fields defined in {@link ChronoField}. * If the field is supported, then true must be returned, otherwise false must be returned. *
* If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)} * passing {@code this} as the argument. *
* Implementations must ensure that no observable state is altered when this * read-only method is invoked. * * @param field the field to check, null returns false * @return true if this date-time can be queried for the field, false if not */ boolean isSupported(TemporalField field); /** * Gets the range of valid values for the specified field. *
* All fields can be expressed as a {@code 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. * * @implSpec * Implementations must check and handle all fields defined in {@link ChronoField}. * If the field is supported, then the range of the field must be returned. * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown. *
* If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessorl)} * passing {@code 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);
*
*
* @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
* @throws UnsupportedTemporalTypeException if the field is not supported
*/
default ValueRange range(TemporalField field) {
if (field instanceof ChronoField) {
if (isSupported(field)) {
return field.range();
}
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
Objects.requireNonNull(field, "field");
return field.rangeRefinedBy(this);
}
/**
* Gets the value of the specified field as an {@code 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. * * @implSpec * Implementations must check and handle all fields defined in {@link ChronoField}. * If the field is supported and has an {@code int} range, then the value of * the field must be returned. * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown. *
* If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} * passing {@code 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");
*
*
* @param field the field to get, not null
* @return the value for the field, within the valid range of values
* @throws DateTimeException if a value for the field cannot be obtained or
* the value is outside the range of valid values for the field
* @throws UnsupportedTemporalTypeException if the field is not supported or
* the range of values exceeds an {@code int}
* @throws ArithmeticException if numeric overflow occurs
*/
default int get(TemporalField field) {
ValueRange range = range(field);
if (range.isIntValue() == false) {
throw new UnsupportedTemporalTypeException("Invalid field " + field + " for get() method, use getLong() instead");
}
long value = getLong(field);
if (range.isValidValue(value) == false) {
throw new DateTimeException("Invalid value for " + field + " (valid values " + range + "): " + value);
}
return (int) value;
}
/**
* Gets the value of the specified field as a {@code 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. * * @implSpec * Implementations must check and handle all fields defined in {@link ChronoField}. * If the field is supported, then the value of the field must be returned. * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown. *
* If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} * passing {@code this} as the argument. *
* Implementations must ensure that no observable state is altered when this * read-only method is invoked. * * @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 UnsupportedTemporalTypeException if the field is not supported * @throws ArithmeticException if numeric overflow occurs */ long getLong(TemporalField field); /** * 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 * {@code LocalDate::from} and {@code ZoneId::from}. * Additional implementations are provided as static methods on {@link TemporalQuery}. * * @implSpec * 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 * {@code 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 {@code 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 {@code 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.
*
* @param