Back to index...

	/*
	* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file:
	*
	* Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
	*
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are met:
	*
	* * Redistributions of source code must retain the above copyright notice,
	* this list of conditions and the following disclaimer.
	*
	* * Redistributions in binary form must reproduce the above copyright notice,
	* this list of conditions and the following disclaimer in the documentation
	* and/or other materials provided with the distribution.
	*
	* * Neither the name of JSR-310 nor the names of its contributors
	* may be used to endorse or promote products derived from this software
	* without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
	* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
	* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
	* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/
	package java.time.temporal;

	import java.time.DateTimeException;
	import java.util.Objects;

	/**
	* Framework-level interface defining read-only access to a temporal object,
	* such as a date, time, offset or some combination of these.
	* <p>
	* 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}.
	* <p>
	* 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.
	* <p>
	* 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}.
	* <p>
	* A sub-interface, {@link Temporal}, extends this definition to one that also
	* supports adjustment and manipulation on more complete temporal objects.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* Implementations must ensure that no observable state is altered when this
	* read-only method is invoked.
	* <p>
	* The default implementation must behave equivalent to this code:
	* <pre>
	* if (field instanceof ChronoField) {
	* if (isSupported(field)) {
	* return field.range();
	* }
	* throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
	* }
	* return field.rangeRefinedBy(this);
	* </pre>
	*
	* @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}.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* Implementations must ensure that no observable state is altered when this
	* read-only method is invoked.
	* <p>
	* The default implementation must behave equivalent to this code:
	* <pre>
	* if (range(field).isIntValue()) {
	* return range(field).checkValidIntValue(getLong(field), field);
	* }
	* throw new UnsupportedTemporalTypeException("Invalid field " + field + " + for get() method, use getLong() instead");
	* </pre>
	*
	* @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}.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* 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.
	* <p>
	* This queries this date-time using the specified query strategy object.
	* <p>
	* 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.
	* <p>
	* 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:
	* <pre>
	* if (query == TemporalQueries.zoneId() \|\|
	* query == TemporalQueries.chronology() \|\| query == TemporalQueries.precision()) {
	* return null;
	* }
	* return query.queryFrom(this);
	* </pre>
	* Future versions are permitted to add further queries to the if statement.
	* <p>
	* 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}.
	* <p>
	* 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:
	* <pre>
	* if (query == TemporalQueries.precision()) {
	* return MINUTES;
	* }
	* return TemporalAccessor.super.query(query);
	* </pre>
	* <p>
	* Implementations must ensure that no observable state is altered when this
	* read-only method is invoked.
	*
	* @param <R> the type of the result
	* @param query the query to invoke, not null
	* @return the query result, null may be returned (defined by the query)
	* @throws DateTimeException if unable to query
	* @throws ArithmeticException if numeric overflow occurs
	*/
	default <R> R query(TemporalQuery<R> query) {
	if (query == TemporalQueries.zoneId()
	\|\| query == TemporalQueries.chronology()
	\|\| query == TemporalQueries.precision()) {
	return null;
	}
	return query.queryFrom(this);
	}

	}

Back to index...