src/java.base/share/classes/java/time/ZonedDateTime.java
changeset 47216 71c04702a3d5
parent 37880 60ec48925dc6
child 49433 b6671a111395
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/time/ZonedDateTime.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,2265 @@
+/*
+ * 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) 2007-2012, 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;
+
+import static java.time.temporal.ChronoField.INSTANT_SECONDS;
+import static java.time.temporal.ChronoField.NANO_OF_SECOND;
+import static java.time.temporal.ChronoField.OFFSET_SECONDS;
+
+import java.io.DataOutput;
+import java.io.IOException;
+import java.io.ObjectInput;
+import java.io.InvalidObjectException;
+import java.io.ObjectInputStream;
+import java.io.Serializable;
+import java.time.chrono.ChronoZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+import java.time.temporal.ChronoField;
+import java.time.temporal.ChronoUnit;
+import java.time.temporal.Temporal;
+import java.time.temporal.TemporalAccessor;
+import java.time.temporal.TemporalAdjuster;
+import java.time.temporal.TemporalAmount;
+import java.time.temporal.TemporalField;
+import java.time.temporal.TemporalQueries;
+import java.time.temporal.TemporalQuery;
+import java.time.temporal.TemporalUnit;
+import java.time.temporal.UnsupportedTemporalTypeException;
+import java.time.temporal.ValueRange;
+import java.time.zone.ZoneOffsetTransition;
+import java.time.zone.ZoneRules;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * A date-time with a time-zone in the ISO-8601 calendar system,
+ * such as {@code 2007-12-03T10:15:30+01:00 Europe/Paris}.
+ * <p>
+ * {@code ZonedDateTime} is an immutable representation of a date-time with a time-zone.
+ * This class stores all date and time fields, to a precision of nanoseconds,
+ * and a time-zone, with a zone offset used to handle ambiguous local date-times.
+ * For example, the value
+ * "2nd October 2007 at 13:45.30.123456789 +02:00 in the Europe/Paris time-zone"
+ * can be stored in a {@code ZonedDateTime}.
+ * <p>
+ * This class handles conversion from the local time-line of {@code LocalDateTime}
+ * to the instant time-line of {@code Instant}.
+ * The difference between the two time-lines is the offset from UTC/Greenwich,
+ * represented by a {@code ZoneOffset}.
+ * <p>
+ * Converting between the two time-lines involves calculating the offset using the
+ * {@link ZoneRules rules} accessed from the {@code ZoneId}.
+ * Obtaining the offset for an instant is simple, as there is exactly one valid
+ * offset for each instant. By contrast, obtaining the offset for a local date-time
+ * is not straightforward. There are three cases:
+ * <ul>
+ * <li>Normal, with one valid offset. For the vast majority of the year, the normal
+ *  case applies, where there is a single valid offset for the local date-time.</li>
+ * <li>Gap, with zero valid offsets. This is when clocks jump forward typically
+ *  due to the spring daylight savings change from "winter" to "summer".
+ *  In a gap there are local date-time values with no valid offset.</li>
+ * <li>Overlap, with two valid offsets. This is when clocks are set back typically
+ *  due to the autumn daylight savings change from "summer" to "winter".
+ *  In an overlap there are local date-time values with two valid offsets.</li>
+ * </ul>
+ * <p>
+ * Any method that converts directly or implicitly from a local date-time to an
+ * instant by obtaining the offset has the potential to be complicated.
+ * <p>
+ * For Gaps, the general strategy is that if the local date-time falls in the
+ * middle of a Gap, then the resulting zoned date-time will have a local date-time
+ * shifted forwards by the length of the Gap, resulting in a date-time in the later
+ * offset, typically "summer" time.
+ * <p>
+ * For Overlaps, the general strategy is that if the local date-time falls in the
+ * middle of an Overlap, then the previous offset will be retained. If there is no
+ * previous offset, or the previous offset is invalid, then the earlier offset is
+ * used, typically "summer" time.. Two additional methods,
+ * {@link #withEarlierOffsetAtOverlap()} and {@link #withLaterOffsetAtOverlap()},
+ * help manage the case of an overlap.
+ * <p>
+ * In terms of design, this class should be viewed primarily as the combination
+ * of a {@code LocalDateTime} and a {@code ZoneId}. The {@code ZoneOffset} is
+ * a vital, but secondary, piece of information, used to ensure that the class
+ * represents an instant, especially during a daylight savings overlap.
+ *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code ZonedDateTime} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
+ * @implSpec
+ * A {@code ZonedDateTime} holds state equivalent to three separate objects,
+ * a {@code LocalDateTime}, a {@code ZoneId} and the resolved {@code ZoneOffset}.
+ * The offset and local date-time are used to define an instant when necessary.
+ * The zone ID is used to obtain the rules for how and when the offset changes.
+ * The offset cannot be freely set, as the zone controls which offsets are valid.
+ * <p>
+ * This class is immutable and thread-safe.
+ *
+ * @since 1.8
+ */
+public final class ZonedDateTime
+        implements Temporal, ChronoZonedDateTime<LocalDate>, Serializable {
+
+    /**
+     * Serialization version.
+     */
+    private static final long serialVersionUID = -6260982410461394882L;
+
+    /**
+     * The local date-time.
+     */
+    private final LocalDateTime dateTime;
+    /**
+     * The offset from UTC/Greenwich.
+     */
+    private final ZoneOffset offset;
+    /**
+     * The time-zone.
+     */
+    private final ZoneId zone;
+
+    //-----------------------------------------------------------------------
+    /**
+     * Obtains the current date-time from the system clock in the default time-zone.
+     * <p>
+     * This will query the {@link Clock#systemDefaultZone() system clock} in the default
+     * time-zone to obtain the current date-time.
+     * The zone and offset will be set based on the time-zone in the clock.
+     * <p>
+     * Using this method will prevent the ability to use an alternate clock for testing
+     * because the clock is hard-coded.
+     *
+     * @return the current date-time using the system clock, not null
+     */
+    public static ZonedDateTime now() {
+        return now(Clock.systemDefaultZone());
+    }
+
+    /**
+     * Obtains the current date-time from the system clock in the specified time-zone.
+     * <p>
+     * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current date-time.
+     * Specifying the time-zone avoids dependence on the default time-zone.
+     * The offset will be calculated from the specified time-zone.
+     * <p>
+     * Using this method will prevent the ability to use an alternate clock for testing
+     * because the clock is hard-coded.
+     *
+     * @param zone  the zone ID to use, not null
+     * @return the current date-time using the system clock, not null
+     */
+    public static ZonedDateTime now(ZoneId zone) {
+        return now(Clock.system(zone));
+    }
+
+    /**
+     * Obtains the current date-time from the specified clock.
+     * <p>
+     * This will query the specified clock to obtain the current date-time.
+     * The zone and offset will be set based on the time-zone in the clock.
+     * <p>
+     * Using this method allows the use of an alternate clock for testing.
+     * The alternate clock may be introduced using {@link Clock dependency injection}.
+     *
+     * @param clock  the clock to use, not null
+     * @return the current date-time, not null
+     */
+    public static ZonedDateTime now(Clock clock) {
+        Objects.requireNonNull(clock, "clock");
+        final Instant now = clock.instant();  // called once
+        return ofInstant(now, clock.getZone());
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from a local date and time.
+     * <p>
+     * This creates a zoned date-time matching the input local date and time as closely as possible.
+     * Time-zone rules, such as daylight savings, mean that not every local date-time
+     * is valid for the specified zone, thus the local date-time may be adjusted.
+     * <p>
+     * The local date time and first combined to form a local date-time.
+     * The local date-time is then resolved to a single instant on the time-line.
+     * This is achieved by finding a valid offset from UTC/Greenwich for the local
+     * date-time as defined by the {@link ZoneRules rules} of the zone ID.
+     *<p>
+     * In most cases, there is only one valid offset for a local date-time.
+     * In the case of an overlap, when clocks are set back, there are two valid offsets.
+     * This method uses the earlier offset typically corresponding to "summer".
+     * <p>
+     * In the case of a gap, when clocks jump forward, there is no valid offset.
+     * Instead, the local date-time is adjusted to be later by the length of the gap.
+     * For a typical one hour daylight savings change, the local date-time will be
+     * moved one hour later into the offset typically corresponding to "summer".
+     *
+     * @param date  the local date, not null
+     * @param time  the local time, not null
+     * @param zone  the time-zone, not null
+     * @return the offset date-time, not null
+     */
+    public static ZonedDateTime of(LocalDate date, LocalTime time, ZoneId zone) {
+        return of(LocalDateTime.of(date, time), zone);
+    }
+
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from a local date-time.
+     * <p>
+     * This creates a zoned date-time matching the input local date-time as closely as possible.
+     * Time-zone rules, such as daylight savings, mean that not every local date-time
+     * is valid for the specified zone, thus the local date-time may be adjusted.
+     * <p>
+     * The local date-time is resolved to a single instant on the time-line.
+     * This is achieved by finding a valid offset from UTC/Greenwich for the local
+     * date-time as defined by the {@link ZoneRules rules} of the zone ID.
+     *<p>
+     * In most cases, there is only one valid offset for a local date-time.
+     * In the case of an overlap, when clocks are set back, there are two valid offsets.
+     * This method uses the earlier offset typically corresponding to "summer".
+     * <p>
+     * In the case of a gap, when clocks jump forward, there is no valid offset.
+     * Instead, the local date-time is adjusted to be later by the length of the gap.
+     * For a typical one hour daylight savings change, the local date-time will be
+     * moved one hour later into the offset typically corresponding to "summer".
+     *
+     * @param localDateTime  the local date-time, not null
+     * @param zone  the time-zone, not null
+     * @return the zoned date-time, not null
+     */
+    public static ZonedDateTime of(LocalDateTime localDateTime, ZoneId zone) {
+        return ofLocal(localDateTime, zone, null);
+    }
+
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from a year, month, day,
+     * hour, minute, second, nanosecond and time-zone.
+     * <p>
+     * This creates a zoned date-time matching the local date-time of the seven
+     * specified fields as closely as possible.
+     * Time-zone rules, such as daylight savings, mean that not every local date-time
+     * is valid for the specified zone, thus the local date-time may be adjusted.
+     * <p>
+     * The local date-time is resolved to a single instant on the time-line.
+     * This is achieved by finding a valid offset from UTC/Greenwich for the local
+     * date-time as defined by the {@link ZoneRules rules} of the zone ID.
+     *<p>
+     * In most cases, there is only one valid offset for a local date-time.
+     * In the case of an overlap, when clocks are set back, there are two valid offsets.
+     * This method uses the earlier offset typically corresponding to "summer".
+     * <p>
+     * In the case of a gap, when clocks jump forward, there is no valid offset.
+     * Instead, the local date-time is adjusted to be later by the length of the gap.
+     * For a typical one hour daylight savings change, the local date-time will be
+     * moved one hour later into the offset typically corresponding to "summer".
+     * <p>
+     * This method exists primarily for writing test cases.
+     * Non test-code will typically use other methods to create an offset time.
+     * {@code LocalDateTime} has five additional convenience variants of the
+     * equivalent factory method taking fewer arguments.
+     * They are not provided here to reduce the footprint of the API.
+     *
+     * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
+     * @param month  the month-of-year to represent, from 1 (January) to 12 (December)
+     * @param dayOfMonth  the day-of-month to represent, from 1 to 31
+     * @param hour  the hour-of-day to represent, from 0 to 23
+     * @param minute  the minute-of-hour to represent, from 0 to 59
+     * @param second  the second-of-minute to represent, from 0 to 59
+     * @param nanoOfSecond  the nano-of-second to represent, from 0 to 999,999,999
+     * @param zone  the time-zone, not null
+     * @return the offset date-time, not null
+     * @throws DateTimeException if the value of any field is out of range, or
+     *  if the day-of-month is invalid for the month-year
+     */
+    public static ZonedDateTime of(
+            int year, int month, int dayOfMonth,
+            int hour, int minute, int second, int nanoOfSecond, ZoneId zone) {
+        LocalDateTime dt = LocalDateTime.of(year, month, dayOfMonth, hour, minute, second, nanoOfSecond);
+        return ofLocal(dt, zone, null);
+    }
+
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from a local date-time
+     * using the preferred offset if possible.
+     * <p>
+     * The local date-time is resolved to a single instant on the time-line.
+     * This is achieved by finding a valid offset from UTC/Greenwich for the local
+     * date-time as defined by the {@link ZoneRules rules} of the zone ID.
+     *<p>
+     * In most cases, there is only one valid offset for a local date-time.
+     * In the case of an overlap, where clocks are set back, there are two valid offsets.
+     * If the preferred offset is one of the valid offsets then it is used.
+     * Otherwise the earlier valid offset is used, typically corresponding to "summer".
+     * <p>
+     * In the case of a gap, where clocks jump forward, there is no valid offset.
+     * Instead, the local date-time is adjusted to be later by the length of the gap.
+     * For a typical one hour daylight savings change, the local date-time will be
+     * moved one hour later into the offset typically corresponding to "summer".
+     *
+     * @param localDateTime  the local date-time, not null
+     * @param zone  the time-zone, not null
+     * @param preferredOffset  the zone offset, null if no preference
+     * @return the zoned date-time, not null
+     */
+    public static ZonedDateTime ofLocal(LocalDateTime localDateTime, ZoneId zone, ZoneOffset preferredOffset) {
+        Objects.requireNonNull(localDateTime, "localDateTime");
+        Objects.requireNonNull(zone, "zone");
+        if (zone instanceof ZoneOffset) {
+            return new ZonedDateTime(localDateTime, (ZoneOffset) zone, zone);
+        }
+        ZoneRules rules = zone.getRules();
+        List<ZoneOffset> validOffsets = rules.getValidOffsets(localDateTime);
+        ZoneOffset offset;
+        if (validOffsets.size() == 1) {
+            offset = validOffsets.get(0);
+        } else if (validOffsets.size() == 0) {
+            ZoneOffsetTransition trans = rules.getTransition(localDateTime);
+            localDateTime = localDateTime.plusSeconds(trans.getDuration().getSeconds());
+            offset = trans.getOffsetAfter();
+        } else {
+            if (preferredOffset != null && validOffsets.contains(preferredOffset)) {
+                offset = preferredOffset;
+            } else {
+                offset = Objects.requireNonNull(validOffsets.get(0), "offset");  // protect against bad ZoneRules
+            }
+        }
+        return new ZonedDateTime(localDateTime, offset, zone);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from an {@code Instant}.
+     * <p>
+     * This creates a zoned date-time with the same instant as that specified.
+     * Calling {@link #toInstant()} will return an instant equal to the one used here.
+     * <p>
+     * Converting an instant to a zoned date-time is simple as there is only one valid
+     * offset for each instant.
+     *
+     * @param instant  the instant to create the date-time from, not null
+     * @param zone  the time-zone, not null
+     * @return the zoned date-time, not null
+     * @throws DateTimeException if the result exceeds the supported range
+     */
+    public static ZonedDateTime ofInstant(Instant instant, ZoneId zone) {
+        Objects.requireNonNull(instant, "instant");
+        Objects.requireNonNull(zone, "zone");
+        return create(instant.getEpochSecond(), instant.getNano(), zone);
+    }
+
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from the instant formed by combining
+     * the local date-time and offset.
+     * <p>
+     * This creates a zoned date-time by {@link LocalDateTime#toInstant(ZoneOffset) combining}
+     * the {@code LocalDateTime} and {@code ZoneOffset}.
+     * This combination uniquely specifies an instant without ambiguity.
+     * <p>
+     * Converting an instant to a zoned date-time is simple as there is only one valid
+     * offset for each instant. If the valid offset is different to the offset specified,
+     * then the date-time and offset of the zoned date-time will differ from those specified.
+     * <p>
+     * If the {@code ZoneId} to be used is a {@code ZoneOffset}, this method is equivalent
+     * to {@link #of(LocalDateTime, ZoneId)}.
+     *
+     * @param localDateTime  the local date-time, not null
+     * @param offset  the zone offset, not null
+     * @param zone  the time-zone, not null
+     * @return the zoned date-time, not null
+     */
+    public static ZonedDateTime ofInstant(LocalDateTime localDateTime, ZoneOffset offset, ZoneId zone) {
+        Objects.requireNonNull(localDateTime, "localDateTime");
+        Objects.requireNonNull(offset, "offset");
+        Objects.requireNonNull(zone, "zone");
+        if (zone.getRules().isValidOffset(localDateTime, offset)) {
+            return new ZonedDateTime(localDateTime, offset, zone);
+        }
+        return create(localDateTime.toEpochSecond(offset), localDateTime.getNano(), zone);
+    }
+
+    /**
+     * Obtains an instance of {@code ZonedDateTime} using seconds from the
+     * epoch of 1970-01-01T00:00:00Z.
+     *
+     * @param epochSecond  the number of seconds from the epoch of 1970-01-01T00:00:00Z
+     * @param nanoOfSecond  the nanosecond within the second, from 0 to 999,999,999
+     * @param zone  the time-zone, not null
+     * @return the zoned date-time, not null
+     * @throws DateTimeException if the result exceeds the supported range
+     */
+    private static ZonedDateTime create(long epochSecond, int nanoOfSecond, ZoneId zone) {
+        ZoneRules rules = zone.getRules();
+        Instant instant = Instant.ofEpochSecond(epochSecond, nanoOfSecond);  // TODO: rules should be queryable by epochSeconds
+        ZoneOffset offset = rules.getOffset(instant);
+        LocalDateTime ldt = LocalDateTime.ofEpochSecond(epochSecond, nanoOfSecond, offset);
+        return new ZonedDateTime(ldt, offset, zone);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Obtains an instance of {@code ZonedDateTime} strictly validating the
+     * combination of local date-time, offset and zone ID.
+     * <p>
+     * This creates a zoned date-time ensuring that the offset is valid for the
+     * local date-time according to the rules of the specified zone.
+     * If the offset is invalid, an exception is thrown.
+     *
+     * @param localDateTime  the local date-time, not null
+     * @param offset  the zone offset, not null
+     * @param zone  the time-zone, not null
+     * @return the zoned date-time, not null
+     * @throws DateTimeException if the combination of arguments is invalid
+     */
+    public static ZonedDateTime ofStrict(LocalDateTime localDateTime, ZoneOffset offset, ZoneId zone) {
+        Objects.requireNonNull(localDateTime, "localDateTime");
+        Objects.requireNonNull(offset, "offset");
+        Objects.requireNonNull(zone, "zone");
+        ZoneRules rules = zone.getRules();
+        if (rules.isValidOffset(localDateTime, offset) == false) {
+            ZoneOffsetTransition trans = rules.getTransition(localDateTime);
+            if (trans != null && trans.isGap()) {
+                // error message says daylight savings for simplicity
+                // even though there are other kinds of gaps
+                throw new DateTimeException("LocalDateTime '" + localDateTime +
+                        "' does not exist in zone '" + zone +
+                        "' due to a gap in the local time-line, typically caused by daylight savings");
+            }
+            throw new DateTimeException("ZoneOffset '" + offset + "' is not valid for LocalDateTime '" +
+                    localDateTime + "' in zone '" + zone + "'");
+        }
+        return new ZonedDateTime(localDateTime, offset, zone);
+    }
+
+    /**
+     * Obtains an instance of {@code ZonedDateTime} leniently, for advanced use cases,
+     * allowing any combination of local date-time, offset and zone ID.
+     * <p>
+     * This creates a zoned date-time with no checks other than no nulls.
+     * This means that the resulting zoned date-time may have an offset that is in conflict
+     * with the zone ID.
+     * <p>
+     * This method is intended for advanced use cases.
+     * For example, consider the case where a zoned date-time with valid fields is created
+     * and then stored in a database or serialization-based store. At some later point,
+     * the object is then re-loaded. However, between those points in time, the government
+     * that defined the time-zone has changed the rules, such that the originally stored
+     * local date-time now does not occur. This method can be used to create the object
+     * in an "invalid" state, despite the change in rules.
+     *
+     * @param localDateTime  the local date-time, not null
+     * @param offset  the zone offset, not null
+     * @param zone  the time-zone, not null
+     * @return the zoned date-time, not null
+     */
+    private static ZonedDateTime ofLenient(LocalDateTime localDateTime, ZoneOffset offset, ZoneId zone) {
+        Objects.requireNonNull(localDateTime, "localDateTime");
+        Objects.requireNonNull(offset, "offset");
+        Objects.requireNonNull(zone, "zone");
+        if (zone instanceof ZoneOffset && offset.equals(zone) == false) {
+            throw new IllegalArgumentException("ZoneId must match ZoneOffset");
+        }
+        return new ZonedDateTime(localDateTime, offset, zone);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from a temporal object.
+     * <p>
+     * This obtains a zoned date-time based on the specified temporal.
+     * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
+     * which this factory converts to an instance of {@code ZonedDateTime}.
+     * <p>
+     * The conversion will first obtain a {@code ZoneId} from the temporal object,
+     * falling back to a {@code ZoneOffset} if necessary. It will then try to obtain
+     * an {@code Instant}, falling back to a {@code LocalDateTime} if necessary.
+     * The result will be either the combination of {@code ZoneId} or {@code ZoneOffset}
+     * with {@code Instant} or {@code LocalDateTime}.
+     * Implementations are permitted to perform optimizations such as accessing
+     * those fields that are equivalent to the relevant objects.
+     * <p>
+     * This method matches the signature of the functional interface {@link TemporalQuery}
+     * allowing it to be used as a query via method reference, {@code ZonedDateTime::from}.
+     *
+     * @param temporal  the temporal object to convert, not null
+     * @return the zoned date-time, not null
+     * @throws DateTimeException if unable to convert to an {@code ZonedDateTime}
+     */
+    public static ZonedDateTime from(TemporalAccessor temporal) {
+        if (temporal instanceof ZonedDateTime) {
+            return (ZonedDateTime) temporal;
+        }
+        try {
+            ZoneId zone = ZoneId.from(temporal);
+            if (temporal.isSupported(INSTANT_SECONDS)) {
+                long epochSecond = temporal.getLong(INSTANT_SECONDS);
+                int nanoOfSecond = temporal.get(NANO_OF_SECOND);
+                return create(epochSecond, nanoOfSecond, zone);
+            } else {
+                LocalDate date = LocalDate.from(temporal);
+                LocalTime time = LocalTime.from(temporal);
+                return of(date, time, zone);
+            }
+        } catch (DateTimeException ex) {
+            throw new DateTimeException("Unable to obtain ZonedDateTime from TemporalAccessor: " +
+                    temporal + " of type " + temporal.getClass().getName(), ex);
+        }
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from a text string such as
+     * {@code 2007-12-03T10:15:30+01:00[Europe/Paris]}.
+     * <p>
+     * The string must represent a valid date-time and is parsed using
+     * {@link java.time.format.DateTimeFormatter#ISO_ZONED_DATE_TIME}.
+     *
+     * @param text  the text to parse such as "2007-12-03T10:15:30+01:00[Europe/Paris]", not null
+     * @return the parsed zoned date-time, not null
+     * @throws DateTimeParseException if the text cannot be parsed
+     */
+    public static ZonedDateTime parse(CharSequence text) {
+        return parse(text, DateTimeFormatter.ISO_ZONED_DATE_TIME);
+    }
+
+    /**
+     * Obtains an instance of {@code ZonedDateTime} from a text string using a specific formatter.
+     * <p>
+     * The text is parsed using the formatter, returning a date-time.
+     *
+     * @param text  the text to parse, not null
+     * @param formatter  the formatter to use, not null
+     * @return the parsed zoned date-time, not null
+     * @throws DateTimeParseException if the text cannot be parsed
+     */
+    public static ZonedDateTime parse(CharSequence text, DateTimeFormatter formatter) {
+        Objects.requireNonNull(formatter, "formatter");
+        return formatter.parse(text, ZonedDateTime::from);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Constructor.
+     *
+     * @param dateTime  the date-time, validated as not null
+     * @param offset  the zone offset, validated as not null
+     * @param zone  the time-zone, validated as not null
+     */
+    private ZonedDateTime(LocalDateTime dateTime, ZoneOffset offset, ZoneId zone) {
+        this.dateTime = dateTime;
+        this.offset = offset;
+        this.zone = zone;
+    }
+
+    /**
+     * Resolves the new local date-time using this zone ID, retaining the offset if possible.
+     *
+     * @param newDateTime  the new local date-time, not null
+     * @return the zoned date-time, not null
+     */
+    private ZonedDateTime resolveLocal(LocalDateTime newDateTime) {
+        return ofLocal(newDateTime, zone, offset);
+    }
+
+    /**
+     * Resolves the new local date-time using the offset to identify the instant.
+     *
+     * @param newDateTime  the new local date-time, not null
+     * @return the zoned date-time, not null
+     */
+    private ZonedDateTime resolveInstant(LocalDateTime newDateTime) {
+        return ofInstant(newDateTime, offset, zone);
+    }
+
+    /**
+     * Resolves the offset into this zoned date-time for the with methods.
+     * <p>
+     * This typically ignores the offset, unless it can be used to switch offset in a DST overlap.
+     *
+     * @param offset  the offset, not null
+     * @return the zoned date-time, not null
+     */
+    private ZonedDateTime resolveOffset(ZoneOffset offset) {
+        if (offset.equals(this.offset) == false && zone.getRules().isValidOffset(dateTime, offset)) {
+            return new ZonedDateTime(dateTime, offset, zone);
+        }
+        return this;
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Checks if the specified field is supported.
+     * <p>
+     * This checks if this date-time can be queried for the specified field.
+     * If false, then calling the {@link #range(TemporalField) range},
+     * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
+     * methods will throw an exception.
+     * <p>
+     * If the field is a {@link ChronoField} then the query is implemented here.
+     * The supported fields are:
+     * <ul>
+     * <li>{@code NANO_OF_SECOND}
+     * <li>{@code NANO_OF_DAY}
+     * <li>{@code MICRO_OF_SECOND}
+     * <li>{@code MICRO_OF_DAY}
+     * <li>{@code MILLI_OF_SECOND}
+     * <li>{@code MILLI_OF_DAY}
+     * <li>{@code SECOND_OF_MINUTE}
+     * <li>{@code SECOND_OF_DAY}
+     * <li>{@code MINUTE_OF_HOUR}
+     * <li>{@code MINUTE_OF_DAY}
+     * <li>{@code HOUR_OF_AMPM}
+     * <li>{@code CLOCK_HOUR_OF_AMPM}
+     * <li>{@code HOUR_OF_DAY}
+     * <li>{@code CLOCK_HOUR_OF_DAY}
+     * <li>{@code AMPM_OF_DAY}
+     * <li>{@code DAY_OF_WEEK}
+     * <li>{@code ALIGNED_DAY_OF_WEEK_IN_MONTH}
+     * <li>{@code ALIGNED_DAY_OF_WEEK_IN_YEAR}
+     * <li>{@code DAY_OF_MONTH}
+     * <li>{@code DAY_OF_YEAR}
+     * <li>{@code EPOCH_DAY}
+     * <li>{@code ALIGNED_WEEK_OF_MONTH}
+     * <li>{@code ALIGNED_WEEK_OF_YEAR}
+     * <li>{@code MONTH_OF_YEAR}
+     * <li>{@code PROLEPTIC_MONTH}
+     * <li>{@code YEAR_OF_ERA}
+     * <li>{@code YEAR}
+     * <li>{@code ERA}
+     * <li>{@code INSTANT_SECONDS}
+     * <li>{@code OFFSET_SECONDS}
+     * </ul>
+     * All other {@code ChronoField} instances will return false.
+     * <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.
+     * 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 date-time, false if not
+     */
+    @Override
+    public boolean isSupported(TemporalField field) {
+        return field instanceof ChronoField || (field != null && field.isSupportedBy(this));
+    }
+
+    /**
+     * Checks if the specified unit is supported.
+     * <p>
+     * This checks if the specified unit can be added to, or subtracted from, this date-time.
+     * If false, then calling the {@link #plus(long, TemporalUnit)} and
+     * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
+     * <p>
+     * If the unit is a {@link ChronoUnit} then the query is implemented here.
+     * The supported units are:
+     * <ul>
+     * <li>{@code NANOS}
+     * <li>{@code MICROS}
+     * <li>{@code MILLIS}
+     * <li>{@code SECONDS}
+     * <li>{@code MINUTES}
+     * <li>{@code HOURS}
+     * <li>{@code HALF_DAYS}
+     * <li>{@code DAYS}
+     * <li>{@code WEEKS}
+     * <li>{@code MONTHS}
+     * <li>{@code YEARS}
+     * <li>{@code DECADES}
+     * <li>{@code CENTURIES}
+     * <li>{@code MILLENNIA}
+     * <li>{@code ERAS}
+     * </ul>
+     * All other {@code ChronoUnit} instances will return false.
+     * <p>
+     * If the unit is not a {@code ChronoUnit}, then the result of this method
+     * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
+     * passing {@code this} as the argument.
+     * Whether the unit is supported is determined by the unit.
+     *
+     * @param unit  the unit to check, null returns false
+     * @return true if the unit can be added/subtracted, false if not
+     */
+    @Override  // override for Javadoc
+    public boolean isSupported(TemporalUnit unit) {
+        return ChronoZonedDateTime.super.isSupported(unit);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the range of valid values for the specified field.
+     * <p>
+     * The range object expresses the minimum and maximum valid values for a field.
+     * This date-time 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.
+     * <p>
+     * If the field is a {@link ChronoField} then the query is implemented here.
+     * The {@link #isSupported(TemporalField) supported fields} will return
+     * appropriate range instances.
+     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
+     * <p>
+     * If the field is not a {@code ChronoField}, then the result of this method
+     * is obtained by invoking {@code TemporalField.rangeRefinedBy(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
+     * @throws UnsupportedTemporalTypeException if the field is not supported
+     */
+    @Override
+    public ValueRange range(TemporalField field) {
+        if (field instanceof ChronoField) {
+            if (field == INSTANT_SECONDS || field == OFFSET_SECONDS) {
+                return field.range();
+            }
+            return dateTime.range(field);
+        }
+        return field.rangeRefinedBy(this);
+    }
+
+    /**
+     * Gets the value of the specified field from this date-time as an {@code int}.
+     * <p>
+     * This queries this 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 it is not possible to return the value, because the field is not supported
+     * or for some other reason, an exception is thrown.
+     * <p>
+     * If the field is a {@link ChronoField} then the query is implemented here.
+     * The {@link #isSupported(TemporalField) supported fields} will return valid
+     * values based on this date-time, except {@code NANO_OF_DAY}, {@code MICRO_OF_DAY},
+     * {@code EPOCH_DAY}, {@code PROLEPTIC_MONTH} and {@code INSTANT_SECONDS} which are too
+     * large to fit in an {@code int} and throw an {@code UnsupportedTemporalTypeException}.
+     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
+     * <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. 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 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
+     */
+    @Override  // override for Javadoc and performance
+    public int get(TemporalField field) {
+        if (field instanceof ChronoField) {
+            switch ((ChronoField) field) {
+                case INSTANT_SECONDS:
+                    throw new UnsupportedTemporalTypeException("Invalid field 'InstantSeconds' for get() method, use getLong() instead");
+                case OFFSET_SECONDS:
+                    return getOffset().getTotalSeconds();
+            }
+            return dateTime.get(field);
+        }
+        return ChronoZonedDateTime.super.get(field);
+    }
+
+    /**
+     * Gets the value of the specified field from this date-time as a {@code long}.
+     * <p>
+     * This queries this date-time 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.
+     * <p>
+     * If the field is a {@link ChronoField} then the query is implemented here.
+     * The {@link #isSupported(TemporalField) supported fields} will return valid
+     * values based on this date-time.
+     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
+     * <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. 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 UnsupportedTemporalTypeException if the field is not supported
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public long getLong(TemporalField field) {
+        if (field instanceof ChronoField) {
+            switch ((ChronoField) field) {
+                case INSTANT_SECONDS: return toEpochSecond();
+                case OFFSET_SECONDS: return getOffset().getTotalSeconds();
+            }
+            return dateTime.getLong(field);
+        }
+        return field.getFrom(this);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the zone offset, such as '+01:00'.
+     * <p>
+     * This is the offset of the local date-time from UTC/Greenwich.
+     *
+     * @return the zone offset, not null
+     */
+    @Override
+    public ZoneOffset getOffset() {
+        return offset;
+    }
+
+    /**
+     * Returns a copy of this date-time changing the zone offset to the
+     * earlier of the two valid offsets at a local time-line overlap.
+     * <p>
+     * This method only has any effect when the local time-line overlaps, such as
+     * at an autumn daylight savings cutover. In this scenario, there are two
+     * valid offsets for the local date-time. Calling this method will return
+     * a zoned date-time with the earlier of the two selected.
+     * <p>
+     * If this method is called when it is not an overlap, {@code this}
+     * is returned.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @return a {@code ZonedDateTime} based on this date-time with the earlier offset, not null
+     */
+    @Override
+    public ZonedDateTime withEarlierOffsetAtOverlap() {
+        ZoneOffsetTransition trans = getZone().getRules().getTransition(dateTime);
+        if (trans != null && trans.isOverlap()) {
+            ZoneOffset earlierOffset = trans.getOffsetBefore();
+            if (earlierOffset.equals(offset) == false) {
+                return new ZonedDateTime(dateTime, earlierOffset, zone);
+            }
+        }
+        return this;
+    }
+
+    /**
+     * Returns a copy of this date-time changing the zone offset to the
+     * later of the two valid offsets at a local time-line overlap.
+     * <p>
+     * This method only has any effect when the local time-line overlaps, such as
+     * at an autumn daylight savings cutover. In this scenario, there are two
+     * valid offsets for the local date-time. Calling this method will return
+     * a zoned date-time with the later of the two selected.
+     * <p>
+     * If this method is called when it is not an overlap, {@code this}
+     * is returned.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @return a {@code ZonedDateTime} based on this date-time with the later offset, not null
+     */
+    @Override
+    public ZonedDateTime withLaterOffsetAtOverlap() {
+        ZoneOffsetTransition trans = getZone().getRules().getTransition(toLocalDateTime());
+        if (trans != null) {
+            ZoneOffset laterOffset = trans.getOffsetAfter();
+            if (laterOffset.equals(offset) == false) {
+                return new ZonedDateTime(dateTime, laterOffset, zone);
+            }
+        }
+        return this;
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the time-zone, such as 'Europe/Paris'.
+     * <p>
+     * This returns the zone ID. This identifies the time-zone {@link ZoneRules rules}
+     * that determine when and how the offset from UTC/Greenwich changes.
+     * <p>
+     * The zone ID may be same as the {@linkplain #getOffset() offset}.
+     * If this is true, then any future calculations, such as addition or subtraction,
+     * have no complex edge cases due to time-zone rules.
+     * See also {@link #withFixedOffsetZone()}.
+     *
+     * @return the time-zone, not null
+     */
+    @Override
+    public ZoneId getZone() {
+        return zone;
+    }
+
+    /**
+     * Returns a copy of this date-time with a different time-zone,
+     * retaining the local date-time if possible.
+     * <p>
+     * This method changes the time-zone and retains the local date-time.
+     * The local date-time is only changed if it is invalid for the new zone,
+     * determined using the same approach as
+     * {@link #ofLocal(LocalDateTime, ZoneId, ZoneOffset)}.
+     * <p>
+     * To change the zone and adjust the local date-time,
+     * use {@link #withZoneSameInstant(ZoneId)}.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param zone  the time-zone to change to, not null
+     * @return a {@code ZonedDateTime} based on this date-time with the requested zone, not null
+     */
+    @Override
+    public ZonedDateTime withZoneSameLocal(ZoneId zone) {
+        Objects.requireNonNull(zone, "zone");
+        return this.zone.equals(zone) ? this : ofLocal(dateTime, zone, offset);
+    }
+
+    /**
+     * Returns a copy of this date-time with a different time-zone,
+     * retaining the instant.
+     * <p>
+     * This method changes the time-zone and retains the instant.
+     * This normally results in a change to the local date-time.
+     * <p>
+     * This method is based on retaining the same instant, thus gaps and overlaps
+     * in the local time-line have no effect on the result.
+     * <p>
+     * To change the offset while keeping the local time,
+     * use {@link #withZoneSameLocal(ZoneId)}.
+     *
+     * @param zone  the time-zone to change to, not null
+     * @return a {@code ZonedDateTime} based on this date-time with the requested zone, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    @Override
+    public ZonedDateTime withZoneSameInstant(ZoneId zone) {
+        Objects.requireNonNull(zone, "zone");
+        return this.zone.equals(zone) ? this :
+            create(dateTime.toEpochSecond(offset), dateTime.getNano(), zone);
+    }
+
+    /**
+     * Returns a copy of this date-time with the zone ID set to the offset.
+     * <p>
+     * This returns a zoned date-time where the zone ID is the same as {@link #getOffset()}.
+     * The local date-time, offset and instant of the result will be the same as in this date-time.
+     * <p>
+     * Setting the date-time to a fixed single offset means that any future
+     * calculations, such as addition or subtraction, have no complex edge cases
+     * due to time-zone rules.
+     * This might also be useful when sending a zoned date-time across a network,
+     * as most protocols, such as ISO-8601, only handle offsets,
+     * and not region-based zone IDs.
+     * <p>
+     * This is equivalent to {@code ZonedDateTime.of(zdt.toLocalDateTime(), zdt.getOffset())}.
+     *
+     * @return a {@code ZonedDateTime} with the zone ID set to the offset, not null
+     */
+    public ZonedDateTime withFixedOffsetZone() {
+        return this.zone.equals(offset) ? this : new ZonedDateTime(dateTime, offset, offset);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the {@code LocalDateTime} part of this date-time.
+     * <p>
+     * This returns a {@code LocalDateTime} with the same year, month, day and time
+     * as this date-time.
+     *
+     * @return the local date-time part of this date-time, not null
+     */
+    @Override  // override for return type
+    public LocalDateTime toLocalDateTime() {
+        return dateTime;
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the {@code LocalDate} part of this date-time.
+     * <p>
+     * This returns a {@code LocalDate} with the same year, month and day
+     * as this date-time.
+     *
+     * @return the date part of this date-time, not null
+     */
+    @Override  // override for return type
+    public LocalDate toLocalDate() {
+        return dateTime.toLocalDate();
+    }
+
+    /**
+     * Gets the year field.
+     * <p>
+     * This method returns the primitive {@code int} value for the year.
+     * <p>
+     * The year returned by this method is proleptic as per {@code get(YEAR)}.
+     * To obtain the year-of-era, use {@code get(YEAR_OF_ERA)}.
+     *
+     * @return the year, from MIN_YEAR to MAX_YEAR
+     */
+    public int getYear() {
+        return dateTime.getYear();
+    }
+
+    /**
+     * Gets the month-of-year field from 1 to 12.
+     * <p>
+     * This method returns the month as an {@code int} from 1 to 12.
+     * Application code is frequently clearer if the enum {@link Month}
+     * is used by calling {@link #getMonth()}.
+     *
+     * @return the month-of-year, from 1 to 12
+     * @see #getMonth()
+     */
+    public int getMonthValue() {
+        return dateTime.getMonthValue();
+    }
+
+    /**
+     * Gets the month-of-year field using the {@code Month} enum.
+     * <p>
+     * This method returns the enum {@link Month} for the month.
+     * This avoids confusion as to what {@code int} values mean.
+     * If you need access to the primitive {@code int} value then the enum
+     * provides the {@link Month#getValue() int value}.
+     *
+     * @return the month-of-year, not null
+     * @see #getMonthValue()
+     */
+    public Month getMonth() {
+        return dateTime.getMonth();
+    }
+
+    /**
+     * Gets the day-of-month field.
+     * <p>
+     * This method returns the primitive {@code int} value for the day-of-month.
+     *
+     * @return the day-of-month, from 1 to 31
+     */
+    public int getDayOfMonth() {
+        return dateTime.getDayOfMonth();
+    }
+
+    /**
+     * Gets the day-of-year field.
+     * <p>
+     * This method returns the primitive {@code int} value for the day-of-year.
+     *
+     * @return the day-of-year, from 1 to 365, or 366 in a leap year
+     */
+    public int getDayOfYear() {
+        return dateTime.getDayOfYear();
+    }
+
+    /**
+     * Gets the day-of-week field, which is an enum {@code DayOfWeek}.
+     * <p>
+     * This method returns the enum {@link DayOfWeek} for the day-of-week.
+     * This avoids confusion as to what {@code int} values mean.
+     * If you need access to the primitive {@code int} value then the enum
+     * provides the {@link DayOfWeek#getValue() int value}.
+     * <p>
+     * Additional information can be obtained from the {@code DayOfWeek}.
+     * This includes textual names of the values.
+     *
+     * @return the day-of-week, not null
+     */
+    public DayOfWeek getDayOfWeek() {
+        return dateTime.getDayOfWeek();
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the {@code LocalTime} part of this date-time.
+     * <p>
+     * This returns a {@code LocalTime} with the same hour, minute, second and
+     * nanosecond as this date-time.
+     *
+     * @return the time part of this date-time, not null
+     */
+    @Override  // override for Javadoc and performance
+    public LocalTime toLocalTime() {
+        return dateTime.toLocalTime();
+    }
+
+    /**
+     * Gets the hour-of-day field.
+     *
+     * @return the hour-of-day, from 0 to 23
+     */
+    public int getHour() {
+        return dateTime.getHour();
+    }
+
+    /**
+     * Gets the minute-of-hour field.
+     *
+     * @return the minute-of-hour, from 0 to 59
+     */
+    public int getMinute() {
+        return dateTime.getMinute();
+    }
+
+    /**
+     * Gets the second-of-minute field.
+     *
+     * @return the second-of-minute, from 0 to 59
+     */
+    public int getSecond() {
+        return dateTime.getSecond();
+    }
+
+    /**
+     * Gets the nano-of-second field.
+     *
+     * @return the nano-of-second, from 0 to 999,999,999
+     */
+    public int getNano() {
+        return dateTime.getNano();
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns an adjusted copy of this date-time.
+     * <p>
+     * This returns a {@code ZonedDateTime}, based on this one, with the date-time adjusted.
+     * The adjustment takes place using the specified adjuster strategy object.
+     * Read the documentation of the adjuster to understand what adjustment will be made.
+     * <p>
+     * A simple adjuster might simply set the one of the fields, such as the year field.
+     * A more complex adjuster might set the date to the last day of the month.
+     * A selection of common adjustments is provided in
+     * {@link java.time.temporal.TemporalAdjusters TemporalAdjusters}.
+     * These include finding the "last day of the month" and "next Wednesday".
+     * Key date-time classes also implement the {@code TemporalAdjuster} interface,
+     * such as {@link Month} and {@link java.time.MonthDay MonthDay}.
+     * The adjuster is responsible for handling special cases, such as the varying
+     * lengths of month and leap years.
+     * <p>
+     * For example this code returns a date on the last day of July:
+     * <pre>
+     *  import static java.time.Month.*;
+     *  import static java.time.temporal.TemporalAdjusters.*;
+     *
+     *  result = zonedDateTime.with(JULY).with(lastDayOfMonth());
+     * </pre>
+     * <p>
+     * The classes {@link LocalDate} and {@link LocalTime} implement {@code TemporalAdjuster},
+     * thus this method can be used to change the date, time or offset:
+     * <pre>
+     *  result = zonedDateTime.with(date);
+     *  result = zonedDateTime.with(time);
+     * </pre>
+     * <p>
+     * {@link ZoneOffset} also implements {@code TemporalAdjuster} however using it
+     * as an argument typically has no effect. The offset of a {@code ZonedDateTime} is
+     * controlled primarily by the time-zone. As such, changing the offset does not generally
+     * make sense, because there is only one valid offset for the local date-time and zone.
+     * If the zoned date-time is in a daylight savings overlap, then the offset is used
+     * to switch between the two valid offsets. In all other cases, the offset is ignored.
+     * <p>
+     * The result of this method is obtained by invoking the
+     * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
+     * specified adjuster passing {@code this} as the argument.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param adjuster the adjuster to use, not null
+     * @return a {@code ZonedDateTime} based on {@code this} with the adjustment made, not null
+     * @throws DateTimeException if the adjustment cannot be made
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public ZonedDateTime with(TemporalAdjuster adjuster) {
+        // optimizations
+        if (adjuster instanceof LocalDate) {
+            return resolveLocal(LocalDateTime.of((LocalDate) adjuster, dateTime.toLocalTime()));
+        } else if (adjuster instanceof LocalTime) {
+            return resolveLocal(LocalDateTime.of(dateTime.toLocalDate(), (LocalTime) adjuster));
+        } else if (adjuster instanceof LocalDateTime) {
+            return resolveLocal((LocalDateTime) adjuster);
+        } else if (adjuster instanceof OffsetDateTime) {
+            OffsetDateTime odt = (OffsetDateTime) adjuster;
+            return ofLocal(odt.toLocalDateTime(), zone, odt.getOffset());
+        } else if (adjuster instanceof Instant) {
+            Instant instant = (Instant) adjuster;
+            return create(instant.getEpochSecond(), instant.getNano(), zone);
+        } else if (adjuster instanceof ZoneOffset) {
+            return resolveOffset((ZoneOffset) adjuster);
+        }
+        return (ZonedDateTime) adjuster.adjustInto(this);
+    }
+
+    /**
+     * Returns a copy of this date-time with the specified field set to a new value.
+     * <p>
+     * This returns a {@code ZonedDateTime}, based on this one, with the value
+     * for the specified field changed.
+     * This can be used to change any supported field, such as the year, month or day-of-month.
+     * If it is not possible to set the value, because the field is not supported or for
+     * some other reason, an exception is thrown.
+     * <p>
+     * In some cases, changing the specified field can cause the resulting date-time to become invalid,
+     * such as changing the month from 31st January to February would make the day-of-month invalid.
+     * In cases like this, the field is responsible for resolving the date. Typically it will choose
+     * the previous valid date, which would be the last valid day of February in this example.
+     * <p>
+     * If the field is a {@link ChronoField} then the adjustment is implemented here.
+     * <p>
+     * The {@code INSTANT_SECONDS} field will return a date-time with the specified instant.
+     * The zone and nano-of-second are unchanged.
+     * The result will have an offset derived from the new instant and original zone.
+     * If the new instant value is outside the valid range then a {@code DateTimeException} will be thrown.
+     * <p>
+     * The {@code OFFSET_SECONDS} field will typically be ignored.
+     * The offset of a {@code ZonedDateTime} is controlled primarily by the time-zone.
+     * As such, changing the offset does not generally make sense, because there is only
+     * one valid offset for the local date-time and zone.
+     * If the zoned date-time is in a daylight savings overlap, then the offset is used
+     * to switch between the two valid offsets. In all other cases, the offset is ignored.
+     * If the new offset value is outside the valid range then a {@code DateTimeException} will be thrown.
+     * <p>
+     * The other {@link #isSupported(TemporalField) supported fields} will behave as per
+     * the matching method on {@link LocalDateTime#with(TemporalField, long) LocalDateTime}.
+     * The zone is not part of the calculation and will be unchanged.
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
+     * <p>
+     * If the field is not a {@code ChronoField}, then the result of this method
+     * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
+     * passing {@code this} as the argument. In this case, the field determines
+     * whether and how to adjust the instant.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param field  the field to set in the result, not null
+     * @param newValue  the new value of the field in the result
+     * @return a {@code ZonedDateTime} based on {@code this} with the specified field set, not null
+     * @throws DateTimeException if the field cannot be set
+     * @throws UnsupportedTemporalTypeException if the field is not supported
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public ZonedDateTime with(TemporalField field, long newValue) {
+        if (field instanceof ChronoField) {
+            ChronoField f = (ChronoField) field;
+            switch (f) {
+                case INSTANT_SECONDS:
+                    return create(newValue, getNano(), zone);
+                case OFFSET_SECONDS:
+                    ZoneOffset offset = ZoneOffset.ofTotalSeconds(f.checkValidIntValue(newValue));
+                    return resolveOffset(offset);
+            }
+            return resolveLocal(dateTime.with(field, newValue));
+        }
+        return field.adjustInto(this, newValue);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the year altered.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#withYear(int) changing the year} of the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param year  the year to set in the result, from MIN_YEAR to MAX_YEAR
+     * @return a {@code ZonedDateTime} based on this date-time with the requested year, not null
+     * @throws DateTimeException if the year value is invalid
+     */
+    public ZonedDateTime withYear(int year) {
+        return resolveLocal(dateTime.withYear(year));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the month-of-year altered.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#withMonth(int) changing the month} of the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param month  the month-of-year to set in the result, from 1 (January) to 12 (December)
+     * @return a {@code ZonedDateTime} based on this date-time with the requested month, not null
+     * @throws DateTimeException if the month-of-year value is invalid
+     */
+    public ZonedDateTime withMonth(int month) {
+        return resolveLocal(dateTime.withMonth(month));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the day-of-month altered.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#withDayOfMonth(int) changing the day-of-month} of the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param dayOfMonth  the day-of-month to set in the result, from 1 to 28-31
+     * @return a {@code ZonedDateTime} based on this date-time with the requested day, not null
+     * @throws DateTimeException if the day-of-month value is invalid,
+     *  or if the day-of-month is invalid for the month-year
+     */
+    public ZonedDateTime withDayOfMonth(int dayOfMonth) {
+        return resolveLocal(dateTime.withDayOfMonth(dayOfMonth));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the day-of-year altered.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#withDayOfYear(int) changing the day-of-year} of the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param dayOfYear  the day-of-year to set in the result, from 1 to 365-366
+     * @return a {@code ZonedDateTime} based on this date with the requested day, not null
+     * @throws DateTimeException if the day-of-year value is invalid,
+     *  or if the day-of-year is invalid for the year
+     */
+    public ZonedDateTime withDayOfYear(int dayOfYear) {
+        return resolveLocal(dateTime.withDayOfYear(dayOfYear));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the hour-of-day altered.
+     * <p>
+     * This operates on the local time-line,
+     * {@linkplain LocalDateTime#withHour(int) changing the time} of the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param hour  the hour-of-day to set in the result, from 0 to 23
+     * @return a {@code ZonedDateTime} based on this date-time with the requested hour, not null
+     * @throws DateTimeException if the hour value is invalid
+     */
+    public ZonedDateTime withHour(int hour) {
+        return resolveLocal(dateTime.withHour(hour));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the minute-of-hour altered.
+     * <p>
+     * This operates on the local time-line,
+     * {@linkplain LocalDateTime#withMinute(int) changing the time} of the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param minute  the minute-of-hour to set in the result, from 0 to 59
+     * @return a {@code ZonedDateTime} based on this date-time with the requested minute, not null
+     * @throws DateTimeException if the minute value is invalid
+     */
+    public ZonedDateTime withMinute(int minute) {
+        return resolveLocal(dateTime.withMinute(minute));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the second-of-minute altered.
+     * <p>
+     * This operates on the local time-line,
+     * {@linkplain LocalDateTime#withSecond(int) changing the time} of the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param second  the second-of-minute to set in the result, from 0 to 59
+     * @return a {@code ZonedDateTime} based on this date-time with the requested second, not null
+     * @throws DateTimeException if the second value is invalid
+     */
+    public ZonedDateTime withSecond(int second) {
+        return resolveLocal(dateTime.withSecond(second));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the nano-of-second altered.
+     * <p>
+     * This operates on the local time-line,
+     * {@linkplain LocalDateTime#withNano(int) changing the time} of the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param nanoOfSecond  the nano-of-second to set in the result, from 0 to 999,999,999
+     * @return a {@code ZonedDateTime} based on this date-time with the requested nanosecond, not null
+     * @throws DateTimeException if the nano value is invalid
+     */
+    public ZonedDateTime withNano(int nanoOfSecond) {
+        return resolveLocal(dateTime.withNano(nanoOfSecond));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the time truncated.
+     * <p>
+     * Truncation returns a copy of the original date-time with fields
+     * smaller than the specified unit set to zero.
+     * For example, truncating with the {@link ChronoUnit#MINUTES minutes} unit
+     * will set the second-of-minute and nano-of-second field to zero.
+     * <p>
+     * The unit must have a {@linkplain TemporalUnit#getDuration() duration}
+     * that divides into the length of a standard day without remainder.
+     * This includes all supplied time units on {@link ChronoUnit} and
+     * {@link ChronoUnit#DAYS DAYS}. Other units throw an exception.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#truncatedTo(TemporalUnit) truncating}
+     * the underlying local date-time. This is then converted back to a
+     * {@code ZonedDateTime}, using the zone ID to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param unit  the unit to truncate to, not null
+     * @return a {@code ZonedDateTime} based on this date-time with the time truncated, not null
+     * @throws DateTimeException if unable to truncate
+     * @throws UnsupportedTemporalTypeException if the unit is not supported
+     */
+    public ZonedDateTime truncatedTo(TemporalUnit unit) {
+        return resolveLocal(dateTime.truncatedTo(unit));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this date-time with the specified amount added.
+     * <p>
+     * This returns a {@code ZonedDateTime}, based on this one, with the specified amount added.
+     * The amount is typically {@link Period} or {@link Duration} but may be
+     * any other type implementing the {@link TemporalAmount} interface.
+     * <p>
+     * The calculation is delegated to the amount object by calling
+     * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
+     * to implement the addition in any way it wishes, however it typically
+     * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
+     * of the amount implementation to determine if it can be successfully added.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param amountToAdd  the amount to add, not null
+     * @return a {@code ZonedDateTime} based on this date-time with the addition made, not null
+     * @throws DateTimeException if the addition cannot be made
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public ZonedDateTime plus(TemporalAmount amountToAdd) {
+        if (amountToAdd instanceof Period) {
+            Period periodToAdd = (Period) amountToAdd;
+            return resolveLocal(dateTime.plus(periodToAdd));
+        }
+        Objects.requireNonNull(amountToAdd, "amountToAdd");
+        return (ZonedDateTime) amountToAdd.addTo(this);
+    }
+
+    /**
+     * Returns a copy of this date-time with the specified amount added.
+     * <p>
+     * This returns a {@code ZonedDateTime}, based on this one, with the amount
+     * in terms of the unit added. If it is not possible to add the amount, because the
+     * unit is not supported or for some other reason, an exception is thrown.
+     * <p>
+     * If the field is a {@link ChronoUnit} then the addition is implemented here.
+     * The zone is not part of the calculation and will be unchanged in the result.
+     * The calculation for date and time units differ.
+     * <p>
+     * Date units operate on the local time-line.
+     * The period is first added to the local date-time, then converted back
+     * to a zoned date-time using the zone ID.
+     * The conversion uses {@link #ofLocal(LocalDateTime, ZoneId, ZoneOffset)}
+     * with the offset before the addition.
+     * <p>
+     * Time units operate on the instant time-line.
+     * The period is first added to the local date-time, then converted back to
+     * a zoned date-time using the zone ID.
+     * The conversion uses {@link #ofInstant(LocalDateTime, ZoneOffset, ZoneId)}
+     * with the offset before the addition.
+     * <p>
+     * If the field is not a {@code ChronoUnit}, then the result of this method
+     * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
+     * passing {@code this} as the argument. In this case, the unit determines
+     * whether and how to perform the addition.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param amountToAdd  the amount of the unit to add to the result, may be negative
+     * @param unit  the unit of the amount to add, not null
+     * @return a {@code ZonedDateTime} based on this date-time with the specified amount added, not null
+     * @throws DateTimeException if the addition cannot be made
+     * @throws UnsupportedTemporalTypeException if the unit is not supported
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public ZonedDateTime plus(long amountToAdd, TemporalUnit unit) {
+        if (unit instanceof ChronoUnit) {
+            if (unit.isDateBased()) {
+                return resolveLocal(dateTime.plus(amountToAdd, unit));
+            } else {
+                return resolveInstant(dateTime.plus(amountToAdd, unit));
+            }
+        }
+        return unit.addTo(this, amountToAdd);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of years added.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#plusYears(long) adding years} to the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param years  the years to add, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the years added, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime plusYears(long years) {
+        return resolveLocal(dateTime.plusYears(years));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of months added.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#plusMonths(long) adding months} to the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param months  the months to add, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the months added, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime plusMonths(long months) {
+        return resolveLocal(dateTime.plusMonths(months));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of weeks added.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#plusWeeks(long) adding weeks} to the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param weeks  the weeks to add, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the weeks added, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime plusWeeks(long weeks) {
+        return resolveLocal(dateTime.plusWeeks(weeks));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of days added.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#plusDays(long) adding days} to the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param days  the days to add, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the days added, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime plusDays(long days) {
+        return resolveLocal(dateTime.plusDays(days));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of hours added.
+     * <p>
+     * This operates on the instant time-line, such that adding one hour will
+     * always be a duration of one hour later.
+     * This may cause the local date-time to change by an amount other than one hour.
+     * Note that this is a different approach to that used by days, months and years,
+     * thus adding one day is not the same as adding 24 hours.
+     * <p>
+     * For example, consider a time-zone, such as 'Europe/Paris', where the
+     * Autumn DST cutover means that the local times 02:00 to 02:59 occur twice
+     * changing from offset +02:00 in summer to +01:00 in winter.
+     * <ul>
+     * <li>Adding one hour to 01:30+02:00 will result in 02:30+02:00
+     *     (both in summer time)
+     * <li>Adding one hour to 02:30+02:00 will result in 02:30+01:00
+     *     (moving from summer to winter time)
+     * <li>Adding one hour to 02:30+01:00 will result in 03:30+01:00
+     *     (both in winter time)
+     * <li>Adding three hours to 01:30+02:00 will result in 03:30+01:00
+     *     (moving from summer to winter time)
+     * </ul>
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param hours  the hours to add, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the hours added, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime plusHours(long hours) {
+        return resolveInstant(dateTime.plusHours(hours));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of minutes added.
+     * <p>
+     * This operates on the instant time-line, such that adding one minute will
+     * always be a duration of one minute later.
+     * This may cause the local date-time to change by an amount other than one minute.
+     * Note that this is a different approach to that used by days, months and years.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param minutes  the minutes to add, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the minutes added, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime plusMinutes(long minutes) {
+        return resolveInstant(dateTime.plusMinutes(minutes));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of seconds added.
+     * <p>
+     * This operates on the instant time-line, such that adding one second will
+     * always be a duration of one second later.
+     * This may cause the local date-time to change by an amount other than one second.
+     * Note that this is a different approach to that used by days, months and years.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param seconds  the seconds to add, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the seconds added, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime plusSeconds(long seconds) {
+        return resolveInstant(dateTime.plusSeconds(seconds));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of nanoseconds added.
+     * <p>
+     * This operates on the instant time-line, such that adding one nano will
+     * always be a duration of one nano later.
+     * This may cause the local date-time to change by an amount other than one nano.
+     * Note that this is a different approach to that used by days, months and years.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param nanos  the nanos to add, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the nanoseconds added, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime plusNanos(long nanos) {
+        return resolveInstant(dateTime.plusNanos(nanos));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this date-time with the specified amount subtracted.
+     * <p>
+     * This returns a {@code ZonedDateTime}, based on this one, with the specified amount subtracted.
+     * The amount is typically {@link Period} or {@link Duration} but may be
+     * any other type implementing the {@link TemporalAmount} interface.
+     * <p>
+     * The calculation is delegated to the amount object by calling
+     * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
+     * to implement the subtraction in any way it wishes, however it typically
+     * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
+     * of the amount implementation to determine if it can be successfully subtracted.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param amountToSubtract  the amount to subtract, not null
+     * @return a {@code ZonedDateTime} based on this date-time with the subtraction made, not null
+     * @throws DateTimeException if the subtraction cannot be made
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public ZonedDateTime minus(TemporalAmount amountToSubtract) {
+        if (amountToSubtract instanceof Period) {
+            Period periodToSubtract = (Period) amountToSubtract;
+            return resolveLocal(dateTime.minus(periodToSubtract));
+        }
+        Objects.requireNonNull(amountToSubtract, "amountToSubtract");
+        return (ZonedDateTime) amountToSubtract.subtractFrom(this);
+    }
+
+    /**
+     * Returns a copy of this date-time with the specified amount subtracted.
+     * <p>
+     * This returns a {@code ZonedDateTime}, based on this one, with the amount
+     * in terms of the unit subtracted. If it is not possible to subtract the amount,
+     * because the unit is not supported or for some other reason, an exception is thrown.
+     * <p>
+     * The calculation for date and time units differ.
+     * <p>
+     * Date units operate on the local time-line.
+     * The period is first subtracted from the local date-time, then converted back
+     * to a zoned date-time using the zone ID.
+     * The conversion uses {@link #ofLocal(LocalDateTime, ZoneId, ZoneOffset)}
+     * with the offset before the subtraction.
+     * <p>
+     * Time units operate on the instant time-line.
+     * The period is first subtracted from the local date-time, then converted back to
+     * a zoned date-time using the zone ID.
+     * The conversion uses {@link #ofInstant(LocalDateTime, ZoneOffset, ZoneId)}
+     * with the offset before the subtraction.
+     * <p>
+     * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
+     * See that method for a full description of how addition, and thus subtraction, works.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param amountToSubtract  the amount of the unit to subtract from the result, may be negative
+     * @param unit  the unit of the amount to subtract, not null
+     * @return a {@code ZonedDateTime} based on this date-time with the specified amount subtracted, not null
+     * @throws DateTimeException if the subtraction cannot be made
+     * @throws UnsupportedTemporalTypeException if the unit is not supported
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public ZonedDateTime minus(long amountToSubtract, TemporalUnit unit) {
+        return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of years subtracted.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#minusYears(long) subtracting years} to the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param years  the years to subtract, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the years subtracted, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime minusYears(long years) {
+        return (years == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-years));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of months subtracted.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#minusMonths(long) subtracting months} to the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param months  the months to subtract, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the months subtracted, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime minusMonths(long months) {
+        return (months == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-months));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of weeks subtracted.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#minusWeeks(long) subtracting weeks} to the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param weeks  the weeks to subtract, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the weeks subtracted, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime minusWeeks(long weeks) {
+        return (weeks == Long.MIN_VALUE ? plusWeeks(Long.MAX_VALUE).plusWeeks(1) : plusWeeks(-weeks));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of days subtracted.
+     * <p>
+     * This operates on the local time-line,
+     * {@link LocalDateTime#minusDays(long) subtracting days} to the local date-time.
+     * This is then converted back to a {@code ZonedDateTime}, using the zone ID
+     * to obtain the offset.
+     * <p>
+     * When converting back to {@code ZonedDateTime}, if the local date-time is in an overlap,
+     * then the offset will be retained if possible, otherwise the earlier offset will be used.
+     * If in a gap, the local date-time will be adjusted forward by the length of the gap.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param days  the days to subtract, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the days subtracted, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime minusDays(long days) {
+        return (days == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-days));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of hours subtracted.
+     * <p>
+     * This operates on the instant time-line, such that subtracting one hour will
+     * always be a duration of one hour earlier.
+     * This may cause the local date-time to change by an amount other than one hour.
+     * Note that this is a different approach to that used by days, months and years,
+     * thus subtracting one day is not the same as adding 24 hours.
+     * <p>
+     * For example, consider a time-zone, such as 'Europe/Paris', where the
+     * Autumn DST cutover means that the local times 02:00 to 02:59 occur twice
+     * changing from offset +02:00 in summer to +01:00 in winter.
+     * <ul>
+     * <li>Subtracting one hour from 03:30+01:00 will result in 02:30+01:00
+     *     (both in winter time)
+     * <li>Subtracting one hour from 02:30+01:00 will result in 02:30+02:00
+     *     (moving from winter to summer time)
+     * <li>Subtracting one hour from 02:30+02:00 will result in 01:30+02:00
+     *     (both in summer time)
+     * <li>Subtracting three hours from 03:30+01:00 will result in 01:30+02:00
+     *     (moving from winter to summer time)
+     * </ul>
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param hours  the hours to subtract, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the hours subtracted, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime minusHours(long hours) {
+        return (hours == Long.MIN_VALUE ? plusHours(Long.MAX_VALUE).plusHours(1) : plusHours(-hours));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of minutes subtracted.
+     * <p>
+     * This operates on the instant time-line, such that subtracting one minute will
+     * always be a duration of one minute earlier.
+     * This may cause the local date-time to change by an amount other than one minute.
+     * Note that this is a different approach to that used by days, months and years.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param minutes  the minutes to subtract, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the minutes subtracted, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime minusMinutes(long minutes) {
+        return (minutes == Long.MIN_VALUE ? plusMinutes(Long.MAX_VALUE).plusMinutes(1) : plusMinutes(-minutes));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of seconds subtracted.
+     * <p>
+     * This operates on the instant time-line, such that subtracting one second will
+     * always be a duration of one second earlier.
+     * This may cause the local date-time to change by an amount other than one second.
+     * Note that this is a different approach to that used by days, months and years.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param seconds  the seconds to subtract, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the seconds subtracted, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime minusSeconds(long seconds) {
+        return (seconds == Long.MIN_VALUE ? plusSeconds(Long.MAX_VALUE).plusSeconds(1) : plusSeconds(-seconds));
+    }
+
+    /**
+     * Returns a copy of this {@code ZonedDateTime} with the specified number of nanoseconds subtracted.
+     * <p>
+     * This operates on the instant time-line, such that subtracting one nano will
+     * always be a duration of one nano earlier.
+     * This may cause the local date-time to change by an amount other than one nano.
+     * Note that this is a different approach to that used by days, months and years.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param nanos  the nanos to subtract, may be negative
+     * @return a {@code ZonedDateTime} based on this date-time with the nanoseconds subtracted, not null
+     * @throws DateTimeException if the result exceeds the supported date range
+     */
+    public ZonedDateTime minusNanos(long nanos) {
+        return (nanos == Long.MIN_VALUE ? plusNanos(Long.MAX_VALUE).plusNanos(1) : plusNanos(-nanos));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Queries this date-time using the specified query.
+     * <p>
+     * This queries this date-time 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.
+     * <p>
+     * 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 <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 (defined by the query)
+     * @throws ArithmeticException if numeric overflow occurs (defined by the query)
+     */
+    @SuppressWarnings("unchecked")
+    @Override  // override for Javadoc
+    public <R> R query(TemporalQuery<R> query) {
+        if (query == TemporalQueries.localDate()) {
+            return (R) toLocalDate();
+        }
+        return ChronoZonedDateTime.super.query(query);
+    }
+
+    /**
+     * Calculates the amount of time until another date-time in terms of the specified unit.
+     * <p>
+     * This calculates the amount of time between two {@code ZonedDateTime}
+     * objects in terms of a single {@code TemporalUnit}.
+     * The start and end points are {@code this} and the specified date-time.
+     * The result will be negative if the end is before the start.
+     * For example, the amount in days between two date-times can be calculated
+     * using {@code startDateTime.until(endDateTime, DAYS)}.
+     * <p>
+     * The {@code Temporal} passed to this method is converted to a
+     * {@code ZonedDateTime} using {@link #from(TemporalAccessor)}.
+     * If the time-zone differs between the two zoned date-times, the specified
+     * end date-time is normalized to have the same zone as this date-time.
+     * <p>
+     * The calculation returns a whole number, representing the number of
+     * complete units between the two date-times.
+     * For example, the amount in months between 2012-06-15T00:00Z and 2012-08-14T23:59Z
+     * will only be one month as it is one minute short of two months.
+     * <p>
+     * There are two equivalent ways of using this method.
+     * The first is to invoke this method.
+     * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
+     * <pre>
+     *   // these two lines are equivalent
+     *   amount = start.until(end, MONTHS);
+     *   amount = MONTHS.between(start, end);
+     * </pre>
+     * The choice should be made based on which makes the code more readable.
+     * <p>
+     * The calculation is implemented in this method for {@link ChronoUnit}.
+     * The units {@code NANOS}, {@code MICROS}, {@code MILLIS}, {@code SECONDS},
+     * {@code MINUTES}, {@code HOURS} and {@code HALF_DAYS}, {@code DAYS},
+     * {@code WEEKS}, {@code MONTHS}, {@code YEARS}, {@code DECADES},
+     * {@code CENTURIES}, {@code MILLENNIA} and {@code ERAS} are supported.
+     * Other {@code ChronoUnit} values will throw an exception.
+     * <p>
+     * The calculation for date and time units differ.
+     * <p>
+     * Date units operate on the local time-line, using the local date-time.
+     * For example, the period from noon on day 1 to noon the following day
+     * in days will always be counted as exactly one day, irrespective of whether
+     * there was a daylight savings change or not.
+     * <p>
+     * Time units operate on the instant time-line.
+     * The calculation effectively converts both zoned date-times to instants
+     * and then calculates the period between the instants.
+     * For example, the period from noon on day 1 to noon the following day
+     * in hours may be 23, 24 or 25 hours (or some other amount) depending on
+     * whether there was a daylight savings change or not.
+     * <p>
+     * If the unit is not a {@code ChronoUnit}, then the result of this method
+     * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
+     * passing {@code this} as the first argument and the converted input temporal
+     * as the second argument.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param endExclusive  the end date, exclusive, which is converted to a {@code ZonedDateTime}, not null
+     * @param unit  the unit to measure the amount in, not null
+     * @return the amount of time between this date-time and the end date-time
+     * @throws DateTimeException if the amount cannot be calculated, or the end
+     *  temporal cannot be converted to a {@code ZonedDateTime}
+     * @throws UnsupportedTemporalTypeException if the unit is not supported
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public long until(Temporal endExclusive, TemporalUnit unit) {
+        ZonedDateTime end = ZonedDateTime.from(endExclusive);
+        if (unit instanceof ChronoUnit) {
+            end = end.withZoneSameInstant(zone);
+            if (unit.isDateBased()) {
+                return dateTime.until(end.dateTime, unit);
+            } else {
+                return toOffsetDateTime().until(end.toOffsetDateTime(), unit);
+            }
+        }
+        return unit.between(this, end);
+    }
+
+    /**
+     * Formats this date-time using the specified formatter.
+     * <p>
+     * This date-time will be passed to the formatter to produce a string.
+     *
+     * @param formatter  the formatter to use, not null
+     * @return the formatted date-time string, not null
+     * @throws DateTimeException if an error occurs during printing
+     */
+    @Override  // override for Javadoc and performance
+    public String format(DateTimeFormatter formatter) {
+        Objects.requireNonNull(formatter, "formatter");
+        return formatter.format(this);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Converts this date-time to an {@code OffsetDateTime}.
+     * <p>
+     * This creates an offset date-time using the local date-time and offset.
+     * The zone ID is ignored.
+     *
+     * @return an offset date-time representing the same local date-time and offset, not null
+     */
+    public OffsetDateTime toOffsetDateTime() {
+        return OffsetDateTime.of(dateTime, offset);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Checks if this date-time is equal to another date-time.
+     * <p>
+     * The comparison is based on the offset date-time and the zone.
+     * Only objects of type {@code ZonedDateTime} are compared, other types return false.
+     *
+     * @param obj  the object to check, null returns false
+     * @return true if this is equal to the other date-time
+     */
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj instanceof ZonedDateTime) {
+            ZonedDateTime other = (ZonedDateTime) obj;
+            return dateTime.equals(other.dateTime) &&
+                offset.equals(other.offset) &&
+                zone.equals(other.zone);
+        }
+        return false;
+    }
+
+    /**
+     * A hash code for this date-time.
+     *
+     * @return a suitable hash code
+     */
+    @Override
+    public int hashCode() {
+        return dateTime.hashCode() ^ offset.hashCode() ^ Integer.rotateLeft(zone.hashCode(), 3);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Outputs this date-time as a {@code String}, such as
+     * {@code 2007-12-03T10:15:30+01:00[Europe/Paris]}.
+     * <p>
+     * The format consists of the {@code LocalDateTime} followed by the {@code ZoneOffset}.
+     * If the {@code ZoneId} is not the same as the offset, then the ID is output.
+     * The output is compatible with ISO-8601 if the offset and ID are the same.
+     *
+     * @return a string representation of this date-time, not null
+     */
+    @Override  // override for Javadoc
+    public String toString() {
+        String str = dateTime.toString() + offset.toString();
+        if (offset != zone) {
+            str += '[' + zone.toString() + ']';
+        }
+        return str;
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Writes the object using a
+     * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
+     * @serialData
+     * <pre>
+     *  out.writeByte(6);  // identifies a ZonedDateTime
+     *  // the <a href="../../serialized-form.html#java.time.LocalDateTime">dateTime</a> excluding the one byte header
+     *  // the <a href="../../serialized-form.html#java.time.ZoneOffset">offset</a> excluding the one byte header
+     *  // the <a href="../../serialized-form.html#java.time.ZoneId">zone ID</a> excluding the one byte header
+     * </pre>
+     *
+     * @return the instance of {@code Ser}, not null
+     */
+    private Object writeReplace() {
+        return new Ser(Ser.ZONE_DATE_TIME_TYPE, this);
+    }
+
+    /**
+     * Defend against malicious streams.
+     *
+     * @param s the stream to read
+     * @throws InvalidObjectException always
+     */
+    private void readObject(ObjectInputStream s) throws InvalidObjectException {
+        throw new InvalidObjectException("Deserialization via serialization delegate");
+    }
+
+    void writeExternal(DataOutput out) throws IOException {
+        dateTime.writeExternal(out);
+        offset.writeExternal(out);
+        zone.write(out);
+    }
+
+    static ZonedDateTime readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
+        LocalDateTime dateTime = LocalDateTime.readExternal(in);
+        ZoneOffset offset = ZoneOffset.readExternal(in);
+        ZoneId zone = (ZoneId) Ser.read(in);
+        return ZonedDateTime.ofLenient(dateTime, offset, zone);
+    }
+
+}