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/* * 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.time.chrono.Chronology; import java.time.format.ResolverStyle; import java.util.Locale; import java.util.Map; import java.util.Objects; /** * A field of date-time, such as month-of-year or hour-of-minute. * <p> * Date and time is expressed using fields which partition the time-line into something * meaningful for humans. Implementations of this interface represent those fields. * <p> * The most commonly used units are defined in {@link ChronoField}. * Further fields are supplied in {@link IsoFields}, {@link WeekFields} and {@link JulianFields}. * Fields can also be written by application code by implementing this interface. * <p> * The field works using double dispatch. Client code calls methods on a date-time like * {@code LocalDateTime} which check if the field is a {@code ChronoField}. * If it is, then the date-time must handle it. * Otherwise, the method call is re-dispatched to the matching method in this interface. * * @implSpec * This interface must be implemented with care to ensure other classes operate correctly. * All implementations that can be instantiated must be final, immutable and thread-safe. * Implementations should be {@code Serializable} where possible. * An enum is as effective implementation choice. * * @since 1.8 */ public interface TemporalField { /** * Gets the display name for the field in the requested locale. * <p> * If there is no display name for the locale then a suitable default must be returned. * <p> * The default implementation must check the locale is not null * and return {@code toString()}. * * @param locale the locale to use, not null * @return the display name for the locale or a suitable default, not null */ default String getDisplayName(Locale locale) { Objects.requireNonNull(locale, "locale"); return toString(); } /** * Gets the unit that the field is measured in. * <p> * The unit of the field is the period that varies within the range. * For example, in the field 'MonthOfYear', the unit is 'Months'. * See also {@link #getRangeUnit()}. * * @return the unit defining the base unit of the field, not null */ TemporalUnit getBaseUnit(); /** * Gets the range that the field is bound by. * <p> * The range of the field is the period that the field varies within. * For example, in the field 'MonthOfYear', the range is 'Years'. * See also {@link #getBaseUnit()}. * <p> * The range is never null. For example, the 'Year' field is shorthand for * 'YearOfForever'. It therefore has a unit of 'Years' and a range of 'Forever'. * * @return the unit defining the range of the field, not null */ TemporalUnit getRangeUnit(); /** * Gets the range of valid values for the 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. * This method is generally only applicable to the ISO-8601 calendar system. * <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. * * @return the range of valid values for the field, not null */ ValueRange range(); //----------------------------------------------------------------------- /** * Checks if this field represents a component of a date. * <p> * A field is date-based if it can be derived from * {@link ChronoField#EPOCH_DAY EPOCH_DAY}. * Note that it is valid for both {@code isDateBased()} and {@code isTimeBased()} * to return false, such as when representing a field like minute-of-week. * * @return true if this field is a component of a date */ boolean isDateBased(); /** * Checks if this field represents a component of a time. * <p> * A field is time-based if it can be derived from * {@link ChronoField#NANO_OF_DAY NANO_OF_DAY}. * Note that it is valid for both {@code isDateBased()} and {@code isTimeBased()} * to return false, such as when representing a field like minute-of-week. * * @return true if this field is a component of a time */ boolean isTimeBased(); //----------------------------------------------------------------------- /** * Checks if this field is supported by the temporal object. * <p> * This determines whether the temporal accessor supports this field. * If this returns false, then the temporal cannot be queried for this field. * <p> * There are two equivalent ways of using this method. * The first is to invoke this method directly. * The second is to use {@link TemporalAccessor#isSupported(TemporalField)}: * <pre> * // these two lines are equivalent, but the second approach is recommended * temporal = thisField.isSupportedBy(temporal); * temporal = temporal.isSupported(thisField); * </pre> * It is recommended to use the second approach, {@code isSupported(TemporalField)}, * as it is a lot clearer to read in code. * <p> * Implementations should determine whether they are supported using the fields * available in {@link ChronoField}. * * @param temporal the temporal object to query, not null * @return true if the date-time can be queried for this field, false if not */ boolean isSupportedBy(TemporalAccessor temporal); /** * Get the range of valid values for this field using the temporal object to * refine the result. * <p> * This uses the temporal object to find the range of valid values for the field. * This is similar to {@link #range()}, however this method refines the result * using the temporal. For example, if the field is {@code DAY_OF_MONTH} the * {@code range} method is not accurate as there are four possible month lengths, * 28, 29, 30 and 31 days. Using this method with a date allows the range to be * accurate, returning just one of those four options. * <p> * There are two equivalent ways of using this method. * The first is to invoke this method directly. * The second is to use {@link TemporalAccessor#range(TemporalField)}: * <pre> * // these two lines are equivalent, but the second approach is recommended * temporal = thisField.rangeRefinedBy(temporal); * temporal = temporal.range(thisField); * </pre> * It is recommended to use the second approach, {@code range(TemporalField)}, * as it is a lot clearer to read in code. * <p> * Implementations should perform any queries or calculations using the fields * available in {@link ChronoField}. * If the field is not supported an {@code UnsupportedTemporalTypeException} must be thrown. * * @param temporal the temporal object used to refine the result, not null * @return the range of valid values for this field, not null * @throws DateTimeException if the range for the field cannot be obtained * @throws UnsupportedTemporalTypeException if the field is not supported by the temporal */ ValueRange rangeRefinedBy(TemporalAccessor temporal); /** * Gets the value of this field from the specified temporal object. * <p> * This queries the temporal object for the value of this field. * <p> * There are two equivalent ways of using this method. * The first is to invoke this method directly. * The second is to use {@link TemporalAccessor#getLong(TemporalField)} * (or {@link TemporalAccessor#get(TemporalField)}): * <pre> * // these two lines are equivalent, but the second approach is recommended * temporal = thisField.getFrom(temporal); * temporal = temporal.getLong(thisField); * </pre> * It is recommended to use the second approach, {@code getLong(TemporalField)}, * as it is a lot clearer to read in code. * <p> * Implementations should perform any queries or calculations using the fields * available in {@link ChronoField}. * If the field is not supported an {@code UnsupportedTemporalTypeException} must be thrown. * * @param temporal the temporal object to query, not null * @return the value of this field, not null * @throws DateTimeException if a value for the field cannot be obtained * @throws UnsupportedTemporalTypeException if the field is not supported by the temporal * @throws ArithmeticException if numeric overflow occurs */ long getFrom(TemporalAccessor temporal); /** * Returns a copy of the specified temporal object with the value of this field set. * <p> * This returns a new temporal object based on the specified one with the value for * this field changed. For example, on a {@code LocalDate}, this could be used to * set the year, month or day-of-month. * The returned object has the same observable type as the specified object. * <p> * In some cases, changing a field is not fully defined. For example, if the target object is * a date representing the 31st January, then changing the month to February would be unclear. * In cases like this, the implementation is responsible for resolving the result. * Typically it will choose the previous valid date, which would be the last valid * day of February in this example. * <p> * There are two equivalent ways of using this method. * The first is to invoke this method directly. * The second is to use {@link Temporal#with(TemporalField, long)}: * <pre> * // these two lines are equivalent, but the second approach is recommended * temporal = thisField.adjustInto(temporal); * temporal = temporal.with(thisField); * </pre> * It is recommended to use the second approach, {@code with(TemporalField)}, * as it is a lot clearer to read in code. * <p> * Implementations should perform any queries or calculations using the fields * available in {@link ChronoField}. * If the field is not supported an {@code UnsupportedTemporalTypeException} must be thrown. * <p> * Implementations must not alter the specified temporal object. * Instead, an adjusted copy of the original must be returned. * This provides equivalent, safe behavior for immutable and mutable implementations. * * @param <R> the type of the Temporal object * @param temporal the temporal object to adjust, not null * @param newValue the new value of the field * @return the adjusted temporal object, not null * @throws DateTimeException if the field cannot be set * @throws UnsupportedTemporalTypeException if the field is not supported by the temporal * @throws ArithmeticException if numeric overflow occurs */ <R extends Temporal> R adjustInto(R temporal, long newValue); /** * Resolves this field to provide a simpler alternative or a date. * <p> * This method is invoked during the resolve phase of parsing. * It is designed to allow application defined fields to be simplified into * more standard fields, such as those on {@code ChronoField}, or into a date. * <p> * Applications should not normally invoke this method directly. * * @implSpec * If an implementation represents a field that can be simplified, or * combined with others, then this method must be implemented. * <p> * The specified map contains the current state of the parse. * The map is mutable and must be mutated to resolve the field and * any related fields. This method will only be invoked during parsing * if the map contains this field, and implementations should therefore * assume this field is present. * <p> * Resolving a field will consist of looking at the value of this field, * and potentially other fields, and either updating the map with a * simpler value, such as a {@code ChronoField}, or returning a * complete {@code ChronoLocalDate}. If a resolve is successful, * the code must remove all the fields that were resolved from the map, * including this field. * <p> * For example, the {@code IsoFields} class contains the quarter-of-year * and day-of-quarter fields. The implementation of this method in that class * resolves the two fields plus the {@link ChronoField#YEAR YEAR} into a * complete {@code LocalDate}. The resolve method will remove all three * fields from the map before returning the {@code LocalDate}. * <p> * A partially complete temporal is used to allow the chronology and zone * to be queried. In general, only the chronology will be needed. * Querying items other than the zone or chronology is undefined and * must not be relied on. * The behavior of other methods such as {@code get}, {@code getLong}, * {@code range} and {@code isSupported} is unpredictable and the results undefined. * <p> * If resolution should be possible, but the data is invalid, the resolver * style should be used to determine an appropriate level of leniency, which * may require throwing a {@code DateTimeException} or {@code ArithmeticException}. * If no resolution is possible, the resolve method must return null. * <p> * When resolving time fields, the map will be altered and null returned. * When resolving date fields, the date is normally returned from the method, * with the map altered to remove the resolved fields. However, it would also * be acceptable for the date fields to be resolved into other {@code ChronoField} * instances that can produce a date, such as {@code EPOCH_DAY}. * <p> * Not all {@code TemporalAccessor} implementations are accepted as return values. * Implementations that call this method must accept {@code ChronoLocalDate}, * {@code ChronoLocalDateTime}, {@code ChronoZonedDateTime} and {@code LocalTime}. * <p> * The default implementation must return null. * * @param fieldValues the map of fields to values, which can be updated, not null * @param partialTemporal the partially complete temporal to query for zone and * chronology; querying for other things is undefined and not recommended, not null * @param resolverStyle the requested type of resolve, not null * @return the resolved temporal object; null if resolving only * changed the map, or no resolve occurred * @throws ArithmeticException if numeric overflow occurs * @throws DateTimeException if resolving results in an error. This must not be thrown * by querying a field on the temporal without first checking if it is supported */ default TemporalAccessor resolve(Map<TemporalField, Long> fieldValues, TemporalAccessor partialTemporal, ResolverStyle resolverStyle) { return null; } /** * Gets a descriptive name for the field. * <p> * The should be of the format 'BaseOfRange', such as 'MonthOfYear', * unless the field has a range of {@code FOREVER}, when only * the base unit is mentioned, such as 'Year' or 'Era'. * * @return the name of the field, not null */ @Override String toString(); }