1 /*
   2  * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 /*
  27  * This file is available under and governed by the GNU General Public
  28  * License version 2 only, as published by the Free Software Foundation.
  29  * However, the following notice accompanied the original version of this
  30  * file:
  31  *
  32  * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
  33  *
  34  * All rights reserved.
  35  *
  36  * Redistribution and use in source and binary forms, with or without
  37  * modification, are permitted provided that the following conditions are met:
  38  *
  39  *  * Redistributions of source code must retain the above copyright notice,
  40  *    this list of conditions and the following disclaimer.
  41  *
  42  *  * Redistributions in binary form must reproduce the above copyright notice,
  43  *    this list of conditions and the following disclaimer in the documentation
  44  *    and/or other materials provided with the distribution.
  45  *
  46  *  * Neither the name of JSR-310 nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  51  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  52  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  53  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  54  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  55  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  56  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  57  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  58  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  59  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  60  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  61  */
  62 package java.time;
  63 
  64 import static java.time.LocalTime.MICROS_PER_SECOND;
  65 import static java.time.LocalTime.MILLIS_PER_SECOND;
  66 import static java.time.LocalTime.NANOS_PER_SECOND;
  67 import static java.time.LocalTime.SECONDS_PER_DAY;
  68 import static java.time.LocalTime.SECONDS_PER_HOUR;
  69 import static java.time.LocalTime.SECONDS_PER_MINUTE;
  70 import static java.time.temporal.ChronoField.INSTANT_SECONDS;
  71 import static java.time.temporal.ChronoField.MICRO_OF_SECOND;
  72 import static java.time.temporal.ChronoField.MILLI_OF_SECOND;
  73 import static java.time.temporal.ChronoField.NANO_OF_SECOND;
  74 import static java.time.temporal.ChronoUnit.DAYS;
  75 import static java.time.temporal.ChronoUnit.NANOS;
  76 
  77 import java.io.DataInput;
  78 import java.io.DataOutput;
  79 import java.io.IOException;
  80 import java.io.InvalidObjectException;
  81 import java.io.ObjectInputStream;
  82 import java.io.Serializable;
  83 import java.time.format.DateTimeFormatter;
  84 import java.time.format.DateTimeParseException;
  85 import java.time.temporal.ChronoField;
  86 import java.time.temporal.ChronoUnit;
  87 import java.time.temporal.Temporal;
  88 import java.time.temporal.TemporalAccessor;
  89 import java.time.temporal.TemporalAdjuster;
  90 import java.time.temporal.TemporalAmount;
  91 import java.time.temporal.TemporalField;
  92 import java.time.temporal.TemporalQueries;
  93 import java.time.temporal.TemporalQuery;
  94 import java.time.temporal.TemporalUnit;
  95 import java.time.temporal.UnsupportedTemporalTypeException;
  96 import java.time.temporal.ValueRange;
  97 import java.util.Objects;
  98 
  99 /**
 100  * An instantaneous point on the time-line.
 101  * <p>
 102  * This class models a single instantaneous point on the time-line.
 103  * This might be used to record event time-stamps in the application.
 104  * <p>
 105  * The range of an instant requires the storage of a number larger than a {@code long}.
 106  * To achieve this, the class stores a {@code long} representing epoch-seconds and an
 107  * {@code int} representing nanosecond-of-second, which will always be between 0 and 999,999,999.
 108  * The epoch-seconds are measured from the standard Java epoch of {@code 1970-01-01T00:00:00Z}
 109  * where instants after the epoch have positive values, and earlier instants have negative values.
 110  * For both the epoch-second and nanosecond parts, a larger value is always later on the time-line
 111  * than a smaller value.
 112  *
 113  * <h2>Time-scale</h2>
 114  * <p>
 115  * The length of the solar day is the standard way that humans measure time.
 116  * This has traditionally been subdivided into 24 hours of 60 minutes of 60 seconds,
 117  * forming a 86400 second day.
 118  * <p>
 119  * Modern timekeeping is based on atomic clocks which precisely define an SI second
 120  * relative to the transitions of a Caesium atom. The length of an SI second was defined
 121  * to be very close to the 86400th fraction of a day.
 122  * <p>
 123  * Unfortunately, as the Earth rotates the length of the day varies.
 124  * In addition, over time the average length of the day is getting longer as the Earth slows.
 125  * As a result, the length of a solar day in 2012 is slightly longer than 86400 SI seconds.
 126  * The actual length of any given day and the amount by which the Earth is slowing
 127  * are not predictable and can only be determined by measurement.
 128  * The UT1 time-scale captures the accurate length of day, but is only available some
 129  * time after the day has completed.
 130  * <p>
 131  * The UTC time-scale is a standard approach to bundle up all the additional fractions
 132  * of a second from UT1 into whole seconds, known as <i>leap-seconds</i>.
 133  * A leap-second may be added or removed depending on the Earth's rotational changes.
 134  * As such, UTC permits a day to have 86399 SI seconds or 86401 SI seconds where
 135  * necessary in order to keep the day aligned with the Sun.
 136  * <p>
 137  * The modern UTC time-scale was introduced in 1972, introducing the concept of whole leap-seconds.
 138  * Between 1958 and 1972, the definition of UTC was complex, with minor sub-second leaps and
 139  * alterations to the length of the notional second. As of 2012, discussions are underway
 140  * to change the definition of UTC again, with the potential to remove leap seconds or
 141  * introduce other changes.
 142  * <p>
 143  * Given the complexity of accurate timekeeping described above, this Java API defines
 144  * its own time-scale, the <i>Java Time-Scale</i>.
 145  * <p>
 146  * The Java Time-Scale divides each calendar day into exactly 86400
 147  * subdivisions, known as seconds.  These seconds may differ from the
 148  * SI second.  It closely matches the de facto international civil time
 149  * scale, the definition of which changes from time to time.
 150  * <p>
 151  * The Java Time-Scale has slightly different definitions for different
 152  * segments of the time-line, each based on the consensus international
 153  * time scale that is used as the basis for civil time. Whenever the
 154  * internationally-agreed time scale is modified or replaced, a new
 155  * segment of the Java Time-Scale must be defined for it.  Each segment
 156  * must meet these requirements:
 157  * <ul>
 158  * <li>the Java Time-Scale shall closely match the underlying international
 159  *  civil time scale;</li>
 160  * <li>the Java Time-Scale shall exactly match the international civil
 161  *  time scale at noon each day;</li>
 162  * <li>the Java Time-Scale shall have a precisely-defined relationship to
 163  *  the international civil time scale.</li>
 164  * </ul>
 165  * There are currently, as of 2013, two segments in the Java time-scale.
 166  * <p>
 167  * For the segment from 1972-11-03 (exact boundary discussed below) until
 168  * further notice, the consensus international time scale is UTC (with
 169  * leap seconds).  In this segment, the Java Time-Scale is identical to
 170  * <a href="http://www.cl.cam.ac.uk/~mgk25/time/utc-sls/">UTC-SLS</a>.
 171  * This is identical to UTC on days that do not have a leap second.
 172  * On days that do have a leap second, the leap second is spread equally
 173  * over the last 1000 seconds of the day, maintaining the appearance of
 174  * exactly 86400 seconds per day.
 175  * <p>
 176  * For the segment prior to 1972-11-03, extending back arbitrarily far,
 177  * the consensus international time scale is defined to be UT1, applied
 178  * proleptically, which is equivalent to the (mean) solar time on the
 179  * prime meridian (Greenwich). In this segment, the Java Time-Scale is
 180  * identical to the consensus international time scale. The exact
 181  * boundary between the two segments is the instant where UT1 = UTC
 182  * between 1972-11-03T00:00 and 1972-11-04T12:00.
 183  * <p>
 184  * Implementations of the Java time-scale using the JSR-310 API are not
 185  * required to provide any clock that is sub-second accurate, or that
 186  * progresses monotonically or smoothly. Implementations are therefore
 187  * not required to actually perform the UTC-SLS slew or to otherwise be
 188  * aware of leap seconds. JSR-310 does, however, require that
 189  * implementations must document the approach they use when defining a
 190  * clock representing the current instant.
 191  * See {@link Clock} for details on the available clocks.
 192  * <p>
 193  * The Java time-scale is used for all date-time classes.
 194  * This includes {@code Instant}, {@code LocalDate}, {@code LocalTime}, {@code OffsetDateTime},
 195  * {@code ZonedDateTime} and {@code Duration}.
 196  * <p>
 197  * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
 198  * class; programmers should treat instances that are
 199  * {@linkplain #equals(Object) equal} as interchangeable and should not
 200  * use instances for synchronization, or unpredictable behavior may
 201  * occur. For example, in a future release, synchronization may fail.
 202  * The {@code equals} method should be used for comparisons.
 203  *
 204  * @implSpec
 205  * This class is immutable and thread-safe.
 206  *
 207  * @since 1.8
 208  */
 209 @jdk.internal.ValueBased
 210 public final class Instant
 211         implements Temporal, TemporalAdjuster, Comparable<Instant>, Serializable {
 212 
 213     /**
 214      * Constant for the 1970-01-01T00:00:00Z epoch instant.
 215      */
 216     public static final Instant EPOCH = new Instant(0, 0);
 217     /**
 218      * The minimum supported epoch second.
 219      */
 220     private static final long MIN_SECOND = -31557014167219200L;
 221     /**
 222      * The maximum supported epoch second.
 223      */
 224     private static final long MAX_SECOND = 31556889864403199L;
 225     /**
 226      * The minimum supported {@code Instant}, '-1000000000-01-01T00:00Z'.
 227      * This could be used by an application as a "far past" instant.
 228      * <p>
 229      * This is one year earlier than the minimum {@code LocalDateTime}.
 230      * This provides sufficient values to handle the range of {@code ZoneOffset}
 231      * which affect the instant in addition to the local date-time.
 232      * The value is also chosen such that the value of the year fits in
 233      * an {@code int}.
 234      */
 235     public static final Instant MIN = Instant.ofEpochSecond(MIN_SECOND, 0);
 236     /**
 237      * The maximum supported {@code Instant}, '1000000000-12-31T23:59:59.999999999Z'.
 238      * This could be used by an application as a "far future" instant.
 239      * <p>
 240      * This is one year later than the maximum {@code LocalDateTime}.
 241      * This provides sufficient values to handle the range of {@code ZoneOffset}
 242      * which affect the instant in addition to the local date-time.
 243      * The value is also chosen such that the value of the year fits in
 244      * an {@code int}.
 245      */
 246     public static final Instant MAX = Instant.ofEpochSecond(MAX_SECOND, 999_999_999);
 247 
 248     /**
 249      * Serialization version.
 250      */
 251     @java.io.Serial
 252     private static final long serialVersionUID = -665713676816604388L;
 253 
 254     /**
 255      * The number of seconds from the epoch of 1970-01-01T00:00:00Z.
 256      */
 257     private final long seconds;
 258     /**
 259      * The number of nanoseconds, later along the time-line, from the seconds field.
 260      * This is always positive, and never exceeds 999,999,999.
 261      */
 262     private final int nanos;
 263 
 264     //-----------------------------------------------------------------------
 265     /**
 266      * Obtains the current instant from the system clock.
 267      * <p>
 268      * This will query the {@link Clock#systemUTC() system UTC clock} to
 269      * obtain the current instant.
 270      * <p>
 271      * Using this method will prevent the ability to use an alternate time-source for
 272      * testing because the clock is effectively hard-coded.
 273      *
 274      * @return the current instant using the system clock, not null
 275      */
 276     public static Instant now() {
 277         return Clock.currentInstant();
 278     }
 279 
 280     /**
 281      * Obtains the current instant from the specified clock.
 282      * <p>
 283      * This will query the specified clock to obtain the current time.
 284      * <p>
 285      * Using this method allows the use of an alternate clock for testing.
 286      * The alternate clock may be introduced using {@link Clock dependency injection}.
 287      *
 288      * @param clock  the clock to use, not null
 289      * @return the current instant, not null
 290      */
 291     public static Instant now(Clock clock) {
 292         Objects.requireNonNull(clock, "clock");
 293         return clock.instant();
 294     }
 295 
 296     //-----------------------------------------------------------------------
 297     /**
 298      * Obtains an instance of {@code Instant} using seconds from the
 299      * epoch of 1970-01-01T00:00:00Z.
 300      * <p>
 301      * The nanosecond field is set to zero.
 302      *
 303      * @param epochSecond  the number of seconds from 1970-01-01T00:00:00Z
 304      * @return an instant, not null
 305      * @throws DateTimeException if the instant exceeds the maximum or minimum instant
 306      */
 307     public static Instant ofEpochSecond(long epochSecond) {
 308         return create(epochSecond, 0);
 309     }
 310 
 311     /**
 312      * Obtains an instance of {@code Instant} using seconds from the
 313      * epoch of 1970-01-01T00:00:00Z and nanosecond fraction of second.
 314      * <p>
 315      * This method allows an arbitrary number of nanoseconds to be passed in.
 316      * The factory will alter the values of the second and nanosecond in order
 317      * to ensure that the stored nanosecond is in the range 0 to 999,999,999.
 318      * For example, the following will result in exactly the same instant:
 319      * <pre>
 320      *  Instant.ofEpochSecond(3, 1);
 321      *  Instant.ofEpochSecond(4, -999_999_999);
 322      *  Instant.ofEpochSecond(2, 1000_000_001);
 323      * </pre>
 324      *
 325      * @param epochSecond  the number of seconds from 1970-01-01T00:00:00Z
 326      * @param nanoAdjustment  the nanosecond adjustment to the number of seconds, positive or negative
 327      * @return an instant, not null
 328      * @throws DateTimeException if the instant exceeds the maximum or minimum instant
 329      * @throws ArithmeticException if numeric overflow occurs
 330      */
 331     public static Instant ofEpochSecond(long epochSecond, long nanoAdjustment) {
 332         long secs = Math.addExact(epochSecond, Math.floorDiv(nanoAdjustment, NANOS_PER_SECOND));
 333         int nos = (int)Math.floorMod(nanoAdjustment, NANOS_PER_SECOND);
 334         return create(secs, nos);
 335     }
 336 
 337     /**
 338      * Obtains an instance of {@code Instant} using milliseconds from the
 339      * epoch of 1970-01-01T00:00:00Z.
 340      * <p>
 341      * The seconds and nanoseconds are extracted from the specified milliseconds.
 342      *
 343      * @param epochMilli  the number of milliseconds from 1970-01-01T00:00:00Z
 344      * @return an instant, not null
 345      */
 346     public static Instant ofEpochMilli(long epochMilli) {
 347         long secs = Math.floorDiv(epochMilli, 1000);
 348         int mos = Math.floorMod(epochMilli, 1000);
 349         return create(secs, mos * 1000_000);
 350     }
 351 
 352     //-----------------------------------------------------------------------
 353     /**
 354      * Obtains an instance of {@code Instant} from a temporal object.
 355      * <p>
 356      * This obtains an instant based on the specified temporal.
 357      * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
 358      * which this factory converts to an instance of {@code Instant}.
 359      * <p>
 360      * The conversion extracts the {@link ChronoField#INSTANT_SECONDS INSTANT_SECONDS}
 361      * and {@link ChronoField#NANO_OF_SECOND NANO_OF_SECOND} fields.
 362      * <p>
 363      * This method matches the signature of the functional interface {@link TemporalQuery}
 364      * allowing it to be used as a query via method reference, {@code Instant::from}.
 365      *
 366      * @param temporal  the temporal object to convert, not null
 367      * @return the instant, not null
 368      * @throws DateTimeException if unable to convert to an {@code Instant}
 369      */
 370     public static Instant from(TemporalAccessor temporal) {
 371         if (temporal instanceof Instant) {
 372             return (Instant) temporal;
 373         }
 374         Objects.requireNonNull(temporal, "temporal");
 375         try {
 376             long instantSecs = temporal.getLong(INSTANT_SECONDS);
 377             int nanoOfSecond = temporal.get(NANO_OF_SECOND);
 378             return Instant.ofEpochSecond(instantSecs, nanoOfSecond);
 379         } catch (DateTimeException ex) {
 380             throw new DateTimeException("Unable to obtain Instant from TemporalAccessor: " +
 381                     temporal + " of type " + temporal.getClass().getName(), ex);
 382         }
 383     }
 384 
 385     //-----------------------------------------------------------------------
 386     /**
 387      * Obtains an instance of {@code Instant} from a text string such as
 388      * {@code 2007-12-03T10:15:30.00Z}.
 389      * <p>
 390      * The string must represent a valid instant in UTC and is parsed using
 391      * {@link DateTimeFormatter#ISO_INSTANT}.
 392      *
 393      * @param text  the text to parse, not null
 394      * @return the parsed instant, not null
 395      * @throws DateTimeParseException if the text cannot be parsed
 396      */
 397     public static Instant parse(final CharSequence text) {
 398         return DateTimeFormatter.ISO_INSTANT.parse(text, Instant::from);
 399     }
 400 
 401     //-----------------------------------------------------------------------
 402     /**
 403      * Obtains an instance of {@code Instant} using seconds and nanoseconds.
 404      *
 405      * @param seconds  the length of the duration in seconds
 406      * @param nanoOfSecond  the nano-of-second, from 0 to 999,999,999
 407      * @throws DateTimeException if the instant exceeds the maximum or minimum instant
 408      */
 409     private static Instant create(long seconds, int nanoOfSecond) {
 410         if ((seconds | nanoOfSecond) == 0) {
 411             return EPOCH;
 412         }
 413         if (seconds < MIN_SECOND || seconds > MAX_SECOND) {
 414             throw new DateTimeException("Instant exceeds minimum or maximum instant");
 415         }
 416         return new Instant(seconds, nanoOfSecond);
 417     }
 418 
 419     /**
 420      * Constructs an instance of {@code Instant} using seconds from the epoch of
 421      * 1970-01-01T00:00:00Z and nanosecond fraction of second.
 422      *
 423      * @param epochSecond  the number of seconds from 1970-01-01T00:00:00Z
 424      * @param nanos  the nanoseconds within the second, must be positive
 425      */
 426     private Instant(long epochSecond, int nanos) {
 427         this.seconds = epochSecond;
 428         this.nanos = nanos;
 429     }
 430 
 431     //-----------------------------------------------------------------------
 432     /**
 433      * Checks if the specified field is supported.
 434      * <p>
 435      * This checks if this instant can be queried for the specified field.
 436      * If false, then calling the {@link #range(TemporalField) range},
 437      * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
 438      * methods will throw an exception.
 439      * <p>
 440      * If the field is a {@link ChronoField} then the query is implemented here.
 441      * The supported fields are:
 442      * <ul>
 443      * <li>{@code NANO_OF_SECOND}
 444      * <li>{@code MICRO_OF_SECOND}
 445      * <li>{@code MILLI_OF_SECOND}
 446      * <li>{@code INSTANT_SECONDS}
 447      * </ul>
 448      * All other {@code ChronoField} instances will return false.
 449      * <p>
 450      * If the field is not a {@code ChronoField}, then the result of this method
 451      * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
 452      * passing {@code this} as the argument.
 453      * Whether the field is supported is determined by the field.
 454      *
 455      * @param field  the field to check, null returns false
 456      * @return true if the field is supported on this instant, false if not
 457      */
 458     @Override
 459     public boolean isSupported(TemporalField field) {
 460         if (field instanceof ChronoField) {
 461             return field == INSTANT_SECONDS || field == NANO_OF_SECOND || field == MICRO_OF_SECOND || field == MILLI_OF_SECOND;
 462         }
 463         return field != null && field.isSupportedBy(this);
 464     }
 465 
 466     /**
 467      * Checks if the specified unit is supported.
 468      * <p>
 469      * This checks if the specified unit can be added to, or subtracted from, this date-time.
 470      * If false, then calling the {@link #plus(long, TemporalUnit)} and
 471      * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
 472      * <p>
 473      * If the unit is a {@link ChronoUnit} then the query is implemented here.
 474      * The supported units are:
 475      * <ul>
 476      * <li>{@code NANOS}
 477      * <li>{@code MICROS}
 478      * <li>{@code MILLIS}
 479      * <li>{@code SECONDS}
 480      * <li>{@code MINUTES}
 481      * <li>{@code HOURS}
 482      * <li>{@code HALF_DAYS}
 483      * <li>{@code DAYS}
 484      * </ul>
 485      * All other {@code ChronoUnit} instances will return false.
 486      * <p>
 487      * If the unit is not a {@code ChronoUnit}, then the result of this method
 488      * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
 489      * passing {@code this} as the argument.
 490      * Whether the unit is supported is determined by the unit.
 491      *
 492      * @param unit  the unit to check, null returns false
 493      * @return true if the unit can be added/subtracted, false if not
 494      */
 495     @Override
 496     public boolean isSupported(TemporalUnit unit) {
 497         if (unit instanceof ChronoUnit) {
 498             return unit.isTimeBased() || unit == DAYS;
 499         }
 500         return unit != null && unit.isSupportedBy(this);
 501     }
 502 
 503     //-----------------------------------------------------------------------
 504     /**
 505      * Gets the range of valid values for the specified field.
 506      * <p>
 507      * The range object expresses the minimum and maximum valid values for a field.
 508      * This instant is used to enhance the accuracy of the returned range.
 509      * If it is not possible to return the range, because the field is not supported
 510      * or for some other reason, an exception is thrown.
 511      * <p>
 512      * If the field is a {@link ChronoField} then the query is implemented here.
 513      * The {@link #isSupported(TemporalField) supported fields} will return
 514      * appropriate range instances.
 515      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 516      * <p>
 517      * If the field is not a {@code ChronoField}, then the result of this method
 518      * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
 519      * passing {@code this} as the argument.
 520      * Whether the range can be obtained is determined by the field.
 521      *
 522      * @param field  the field to query the range for, not null
 523      * @return the range of valid values for the field, not null
 524      * @throws DateTimeException if the range for the field cannot be obtained
 525      * @throws UnsupportedTemporalTypeException if the field is not supported
 526      */
 527     @Override  // override for Javadoc
 528     public ValueRange range(TemporalField field) {
 529         return Temporal.super.range(field);
 530     }
 531 
 532     /**
 533      * Gets the value of the specified field from this instant as an {@code int}.
 534      * <p>
 535      * This queries this instant for the value of the specified field.
 536      * The returned value will always be within the valid range of values for the field.
 537      * If it is not possible to return the value, because the field is not supported
 538      * or for some other reason, an exception is thrown.
 539      * <p>
 540      * If the field is a {@link ChronoField} then the query is implemented here.
 541      * The {@link #isSupported(TemporalField) supported fields} will return valid
 542      * values based on this date-time, except {@code INSTANT_SECONDS} which is too
 543      * large to fit in an {@code int} and throws a {@code DateTimeException}.
 544      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 545      * <p>
 546      * If the field is not a {@code ChronoField}, then the result of this method
 547      * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
 548      * passing {@code this} as the argument. Whether the value can be obtained,
 549      * and what the value represents, is determined by the field.
 550      *
 551      * @param field  the field to get, not null
 552      * @return the value for the field
 553      * @throws DateTimeException if a value for the field cannot be obtained or
 554      *         the value is outside the range of valid values for the field
 555      * @throws UnsupportedTemporalTypeException if the field is not supported or
 556      *         the range of values exceeds an {@code int}
 557      * @throws ArithmeticException if numeric overflow occurs
 558      */
 559     @Override  // override for Javadoc and performance
 560     public int get(TemporalField field) {
 561         if (field instanceof ChronoField chronoField) {
 562             return switch (chronoField) {
 563                 case NANO_OF_SECOND -> nanos;
 564                 case MICRO_OF_SECOND -> nanos / 1000;
 565                 case MILLI_OF_SECOND -> nanos / 1000_000;
 566                 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 567             };
 568         }
 569         return range(field).checkValidIntValue(field.getFrom(this), field);
 570     }
 571 
 572     /**
 573      * Gets the value of the specified field from this instant as a {@code long}.
 574      * <p>
 575      * This queries this instant for the value of the specified field.
 576      * If it is not possible to return the value, because the field is not supported
 577      * or for some other reason, an exception is thrown.
 578      * <p>
 579      * If the field is a {@link ChronoField} then the query is implemented here.
 580      * The {@link #isSupported(TemporalField) supported fields} will return valid
 581      * values based on this date-time.
 582      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 583      * <p>
 584      * If the field is not a {@code ChronoField}, then the result of this method
 585      * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
 586      * passing {@code this} as the argument. Whether the value can be obtained,
 587      * and what the value represents, is determined by the field.
 588      *
 589      * @param field  the field to get, not null
 590      * @return the value for the field
 591      * @throws DateTimeException if a value for the field cannot be obtained
 592      * @throws UnsupportedTemporalTypeException if the field is not supported
 593      * @throws ArithmeticException if numeric overflow occurs
 594      */
 595     @Override
 596     public long getLong(TemporalField field) {
 597         if (field instanceof ChronoField chronoField) {
 598             return switch (chronoField) {
 599                 case NANO_OF_SECOND -> nanos;
 600                 case MICRO_OF_SECOND -> nanos / 1000;
 601                 case MILLI_OF_SECOND -> nanos / 1000_000;
 602                 case INSTANT_SECONDS -> seconds;
 603                 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 604             };
 605         }
 606         return field.getFrom(this);
 607     }
 608 
 609     //-----------------------------------------------------------------------
 610     /**
 611      * Gets the number of seconds from the Java epoch of 1970-01-01T00:00:00Z.
 612      * <p>
 613      * The epoch second count is a simple incrementing count of seconds where
 614      * second 0 is 1970-01-01T00:00:00Z.
 615      * The nanosecond part is returned by {@link #getNano}.
 616      *
 617      * @return the seconds from the epoch of 1970-01-01T00:00:00Z
 618      */
 619     public long getEpochSecond() {
 620         return seconds;
 621     }
 622 
 623     /**
 624      * Gets the number of nanoseconds, later along the time-line, from the start
 625      * of the second.
 626      * <p>
 627      * The nanosecond-of-second value measures the total number of nanoseconds from
 628      * the second returned by {@link #getEpochSecond}.
 629      *
 630      * @return the nanoseconds within the second, always positive, never exceeds 999,999,999
 631      */
 632     public int getNano() {
 633         return nanos;
 634     }
 635 
 636     //-------------------------------------------------------------------------
 637     /**
 638      * Returns an adjusted copy of this instant.
 639      * <p>
 640      * This returns an {@code Instant}, based on this one, with the instant adjusted.
 641      * The adjustment takes place using the specified adjuster strategy object.
 642      * Read the documentation of the adjuster to understand what adjustment will be made.
 643      * <p>
 644      * The result of this method is obtained by invoking the
 645      * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
 646      * specified adjuster passing {@code this} as the argument.
 647      * <p>
 648      * This instance is immutable and unaffected by this method call.
 649      *
 650      * @param adjuster the adjuster to use, not null
 651      * @return an {@code Instant} based on {@code this} with the adjustment made, not null
 652      * @throws DateTimeException if the adjustment cannot be made
 653      * @throws ArithmeticException if numeric overflow occurs
 654      */
 655     @Override
 656     public Instant with(TemporalAdjuster adjuster) {
 657         return (Instant) adjuster.adjustInto(this);
 658     }
 659 
 660     /**
 661      * Returns a copy of this instant with the specified field set to a new value.
 662      * <p>
 663      * This returns an {@code Instant}, based on this one, with the value
 664      * for the specified field changed.
 665      * If it is not possible to set the value, because the field is not supported or for
 666      * some other reason, an exception is thrown.
 667      * <p>
 668      * If the field is a {@link ChronoField} then the adjustment is implemented here.
 669      * The supported fields behave as follows:
 670      * <ul>
 671      * <li>{@code NANO_OF_SECOND} -
 672      *  Returns an {@code Instant} with the specified nano-of-second.
 673      *  The epoch-second will be unchanged.
 674      * <li>{@code MICRO_OF_SECOND} -
 675      *  Returns an {@code Instant} with the nano-of-second replaced by the specified
 676      *  micro-of-second multiplied by 1,000. The epoch-second will be unchanged.
 677      * <li>{@code MILLI_OF_SECOND} -
 678      *  Returns an {@code Instant} with the nano-of-second replaced by the specified
 679      *  milli-of-second multiplied by 1,000,000. The epoch-second will be unchanged.
 680      * <li>{@code INSTANT_SECONDS} -
 681      *  Returns an {@code Instant} with the specified epoch-second.
 682      *  The nano-of-second will be unchanged.
 683      * </ul>
 684      * <p>
 685      * In all cases, if the new value is outside the valid range of values for the field
 686      * then a {@code DateTimeException} will be thrown.
 687      * <p>
 688      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 689      * <p>
 690      * If the field is not a {@code ChronoField}, then the result of this method
 691      * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
 692      * passing {@code this} as the argument. In this case, the field determines
 693      * whether and how to adjust the instant.
 694      * <p>
 695      * This instance is immutable and unaffected by this method call.
 696      *
 697      * @param field  the field to set in the result, not null
 698      * @param newValue  the new value of the field in the result
 699      * @return an {@code Instant} based on {@code this} with the specified field set, not null
 700      * @throws DateTimeException if the field cannot be set
 701      * @throws UnsupportedTemporalTypeException if the field is not supported
 702      * @throws ArithmeticException if numeric overflow occurs
 703      */
 704     @Override
 705     public Instant with(TemporalField field, long newValue) {
 706         if (field instanceof ChronoField chronoField) {
 707             chronoField.checkValidValue(newValue);
 708             return switch (chronoField) {
 709                 case MILLI_OF_SECOND -> {
 710                     int nval = (int) newValue * 1000_000;
 711                     yield nval != nanos ? create(seconds, nval) : this;
 712                 }
 713                 case MICRO_OF_SECOND -> {
 714                     int nval = (int) newValue * 1000;
 715                     yield nval != nanos ? create(seconds, nval) : this;
 716                 }
 717                 case NANO_OF_SECOND -> newValue != nanos ? create(seconds, (int) newValue) : this;
 718                 case INSTANT_SECONDS -> newValue != seconds ? create(newValue, nanos) : this;
 719                 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 720             };
 721         }
 722         return field.adjustInto(this, newValue);
 723     }
 724 
 725     //-----------------------------------------------------------------------
 726     /**
 727      * Returns a copy of this {@code Instant} truncated to the specified unit.
 728      * <p>
 729      * Truncating the instant returns a copy of the original with fields
 730      * smaller than the specified unit set to zero.
 731      * The fields are calculated on the basis of using a UTC offset as seen
 732      * in {@code toString}.
 733      * For example, truncating with the {@link ChronoUnit#MINUTES MINUTES} unit will
 734      * round down to the nearest minute, setting the seconds and nanoseconds to zero.
 735      * <p>
 736      * The unit must have a {@linkplain TemporalUnit#getDuration() duration}
 737      * that divides into the length of a standard day without remainder.
 738      * This includes all supplied time units on {@link ChronoUnit} and
 739      * {@link ChronoUnit#DAYS DAYS}. Other units throw an exception.
 740      * <p>
 741      * This instance is immutable and unaffected by this method call.
 742      *
 743      * @param unit  the unit to truncate to, not null
 744      * @return an {@code Instant} based on this instant with the time truncated, not null
 745      * @throws DateTimeException if the unit is invalid for truncation
 746      * @throws UnsupportedTemporalTypeException if the unit is not supported
 747      */
 748     public Instant truncatedTo(TemporalUnit unit) {
 749         if (unit == ChronoUnit.NANOS) {
 750             return this;
 751         }
 752         Duration unitDur = unit.getDuration();
 753         if (unitDur.getSeconds() > LocalTime.SECONDS_PER_DAY) {
 754             throw new UnsupportedTemporalTypeException("Unit is too large to be used for truncation");
 755         }
 756         long dur = unitDur.toNanos();
 757         if ((LocalTime.NANOS_PER_DAY % dur) != 0) {
 758             throw new UnsupportedTemporalTypeException("Unit must divide into a standard day without remainder");
 759         }
 760         long nod = (seconds % LocalTime.SECONDS_PER_DAY) * LocalTime.NANOS_PER_SECOND + nanos;
 761         long result = Math.floorDiv(nod, dur) * dur;
 762         return plusNanos(result - nod);
 763     }
 764 
 765     //-----------------------------------------------------------------------
 766     /**
 767      * Returns a copy of this instant with the specified amount added.
 768      * <p>
 769      * This returns an {@code Instant}, based on this one, with the specified amount added.
 770      * The amount is typically {@link Duration} but may be any other type implementing
 771      * the {@link TemporalAmount} interface.
 772      * <p>
 773      * The calculation is delegated to the amount object by calling
 774      * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
 775      * to implement the addition in any way it wishes, however it typically
 776      * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
 777      * of the amount implementation to determine if it can be successfully added.
 778      * <p>
 779      * This instance is immutable and unaffected by this method call.
 780      *
 781      * @param amountToAdd  the amount to add, not null
 782      * @return an {@code Instant} based on this instant with the addition made, not null
 783      * @throws DateTimeException if the addition cannot be made
 784      * @throws ArithmeticException if numeric overflow occurs
 785      */
 786     @Override
 787     public Instant plus(TemporalAmount amountToAdd) {
 788         return (Instant) amountToAdd.addTo(this);
 789     }
 790 
 791     /**
 792      * Returns a copy of this instant with the specified amount added.
 793      * <p>
 794      * This returns an {@code Instant}, based on this one, with the amount
 795      * in terms of the unit added. If it is not possible to add the amount, because the
 796      * unit is not supported or for some other reason, an exception is thrown.
 797      * <p>
 798      * If the field is a {@link ChronoUnit} then the addition is implemented here.
 799      * The supported fields behave as follows:
 800      * <ul>
 801      * <li>{@code NANOS} -
 802      *  Returns an {@code Instant} with the specified number of nanoseconds added.
 803      *  This is equivalent to {@link #plusNanos(long)}.
 804      * <li>{@code MICROS} -
 805      *  Returns an {@code Instant} with the specified number of microseconds added.
 806      *  This is equivalent to {@link #plusNanos(long)} with the amount
 807      *  multiplied by 1,000.
 808      * <li>{@code MILLIS} -
 809      *  Returns an {@code Instant} with the specified number of milliseconds added.
 810      *  This is equivalent to {@link #plusNanos(long)} with the amount
 811      *  multiplied by 1,000,000.
 812      * <li>{@code SECONDS} -
 813      *  Returns an {@code Instant} with the specified number of seconds added.
 814      *  This is equivalent to {@link #plusSeconds(long)}.
 815      * <li>{@code MINUTES} -
 816      *  Returns an {@code Instant} with the specified number of minutes added.
 817      *  This is equivalent to {@link #plusSeconds(long)} with the amount
 818      *  multiplied by 60.
 819      * <li>{@code HOURS} -
 820      *  Returns an {@code Instant} with the specified number of hours added.
 821      *  This is equivalent to {@link #plusSeconds(long)} with the amount
 822      *  multiplied by 3,600.
 823      * <li>{@code HALF_DAYS} -
 824      *  Returns an {@code Instant} with the specified number of half-days added.
 825      *  This is equivalent to {@link #plusSeconds(long)} with the amount
 826      *  multiplied by 43,200 (12 hours).
 827      * <li>{@code DAYS} -
 828      *  Returns an {@code Instant} with the specified number of days added.
 829      *  This is equivalent to {@link #plusSeconds(long)} with the amount
 830      *  multiplied by 86,400 (24 hours).
 831      * </ul>
 832      * <p>
 833      * All other {@code ChronoUnit} instances will throw an {@code UnsupportedTemporalTypeException}.
 834      * <p>
 835      * If the field is not a {@code ChronoUnit}, then the result of this method
 836      * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
 837      * passing {@code this} as the argument. In this case, the unit determines
 838      * whether and how to perform the addition.
 839      * <p>
 840      * This instance is immutable and unaffected by this method call.
 841      *
 842      * @param amountToAdd  the amount of the unit to add to the result, may be negative
 843      * @param unit  the unit of the amount to add, not null
 844      * @return an {@code Instant} based on this instant with the specified amount added, not null
 845      * @throws DateTimeException if the addition cannot be made
 846      * @throws UnsupportedTemporalTypeException if the unit is not supported
 847      * @throws ArithmeticException if numeric overflow occurs
 848      */
 849     @Override
 850     public Instant plus(long amountToAdd, TemporalUnit unit) {
 851         if (unit instanceof ChronoUnit chronoUnit) {
 852             return switch (chronoUnit) {
 853                 case NANOS     -> plusNanos(amountToAdd);
 854                 case MICROS    -> plus(amountToAdd / 1000_000, (amountToAdd % 1000_000) * 1000);
 855                 case MILLIS    -> plusMillis(amountToAdd);
 856                 case SECONDS   -> plusSeconds(amountToAdd);
 857                 case MINUTES   -> plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_MINUTE));
 858                 case HOURS     -> plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_HOUR));
 859                 case HALF_DAYS -> plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_DAY / 2));
 860                 case DAYS      -> plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_DAY));
 861                 default -> throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
 862             };
 863         }
 864         return unit.addTo(this, amountToAdd);
 865     }
 866 
 867     //-----------------------------------------------------------------------
 868     /**
 869      * Returns a copy of this instant with the specified duration in seconds added.
 870      * <p>
 871      * This instance is immutable and unaffected by this method call.
 872      *
 873      * @param secondsToAdd  the seconds to add, positive or negative
 874      * @return an {@code Instant} based on this instant with the specified seconds added, not null
 875      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 876      * @throws ArithmeticException if numeric overflow occurs
 877      */
 878     public Instant plusSeconds(long secondsToAdd) {
 879         if (secondsToAdd == 0) {
 880             return this;
 881         }
 882         long epochSec = Math.addExact(seconds, secondsToAdd);
 883         return create(epochSec, nanos);
 884     }
 885 
 886     /**
 887      * Returns a copy of this instant with the specified duration in milliseconds added.
 888      * <p>
 889      * This instance is immutable and unaffected by this method call.
 890      *
 891      * @param millisToAdd  the milliseconds to add, positive or negative
 892      * @return an {@code Instant} based on this instant with the specified milliseconds added, not null
 893      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 894      * @throws ArithmeticException if numeric overflow occurs
 895      */
 896     public Instant plusMillis(long millisToAdd) {
 897         return plus(millisToAdd / 1000, (millisToAdd % 1000) * 1000_000);
 898     }
 899 
 900     /**
 901      * Returns a copy of this instant with the specified duration in nanoseconds added.
 902      * <p>
 903      * This instance is immutable and unaffected by this method call.
 904      *
 905      * @param nanosToAdd  the nanoseconds to add, positive or negative
 906      * @return an {@code Instant} based on this instant with the specified nanoseconds added, not null
 907      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 908      * @throws ArithmeticException if numeric overflow occurs
 909      */
 910     public Instant plusNanos(long nanosToAdd) {
 911         return plus(0, nanosToAdd);
 912     }
 913 
 914     /**
 915      * Returns a copy of this instant with the specified duration added.
 916      * <p>
 917      * This instance is immutable and unaffected by this method call.
 918      *
 919      * @param secondsToAdd  the seconds to add, positive or negative
 920      * @param nanosToAdd  the nanos to add, positive or negative
 921      * @return an {@code Instant} based on this instant with the specified seconds added, not null
 922      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 923      * @throws ArithmeticException if numeric overflow occurs
 924      */
 925     private Instant plus(long secondsToAdd, long nanosToAdd) {
 926         if ((secondsToAdd | nanosToAdd) == 0) {
 927             return this;
 928         }
 929         long epochSec = Math.addExact(seconds, secondsToAdd);
 930         epochSec = Math.addExact(epochSec, nanosToAdd / NANOS_PER_SECOND);
 931         nanosToAdd = nanosToAdd % NANOS_PER_SECOND;
 932         long nanoAdjustment = nanos + nanosToAdd;  // safe int+NANOS_PER_SECOND
 933         return ofEpochSecond(epochSec, nanoAdjustment);
 934     }
 935 
 936     //-----------------------------------------------------------------------
 937     /**
 938      * Returns a copy of this instant with the specified amount subtracted.
 939      * <p>
 940      * This returns an {@code Instant}, based on this one, with the specified amount subtracted.
 941      * The amount is typically {@link Duration} but may be any other type implementing
 942      * the {@link TemporalAmount} interface.
 943      * <p>
 944      * The calculation is delegated to the amount object by calling
 945      * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
 946      * to implement the subtraction in any way it wishes, however it typically
 947      * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
 948      * of the amount implementation to determine if it can be successfully subtracted.
 949      * <p>
 950      * This instance is immutable and unaffected by this method call.
 951      *
 952      * @param amountToSubtract  the amount to subtract, not null
 953      * @return an {@code Instant} based on this instant with the subtraction made, not null
 954      * @throws DateTimeException if the subtraction cannot be made
 955      * @throws ArithmeticException if numeric overflow occurs
 956      */
 957     @Override
 958     public Instant minus(TemporalAmount amountToSubtract) {
 959         return (Instant) amountToSubtract.subtractFrom(this);
 960     }
 961 
 962     /**
 963      * Returns a copy of this instant with the specified amount subtracted.
 964      * <p>
 965      * This returns an {@code Instant}, based on this one, with the amount
 966      * in terms of the unit subtracted. If it is not possible to subtract the amount,
 967      * because the unit is not supported or for some other reason, an exception is thrown.
 968      * <p>
 969      * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
 970      * See that method for a full description of how addition, and thus subtraction, works.
 971      * <p>
 972      * This instance is immutable and unaffected by this method call.
 973      *
 974      * @param amountToSubtract  the amount of the unit to subtract from the result, may be negative
 975      * @param unit  the unit of the amount to subtract, not null
 976      * @return an {@code Instant} based on this instant with the specified amount subtracted, not null
 977      * @throws DateTimeException if the subtraction cannot be made
 978      * @throws UnsupportedTemporalTypeException if the unit is not supported
 979      * @throws ArithmeticException if numeric overflow occurs
 980      */
 981     @Override
 982     public Instant minus(long amountToSubtract, TemporalUnit unit) {
 983         return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
 984     }
 985 
 986     //-----------------------------------------------------------------------
 987     /**
 988      * Returns a copy of this instant with the specified duration in seconds subtracted.
 989      * <p>
 990      * This instance is immutable and unaffected by this method call.
 991      *
 992      * @param secondsToSubtract  the seconds to subtract, positive or negative
 993      * @return an {@code Instant} based on this instant with the specified seconds subtracted, not null
 994      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 995      * @throws ArithmeticException if numeric overflow occurs
 996      */
 997     public Instant minusSeconds(long secondsToSubtract) {
 998         if (secondsToSubtract == Long.MIN_VALUE) {
 999             return plusSeconds(Long.MAX_VALUE).plusSeconds(1);
1000         }
1001         return plusSeconds(-secondsToSubtract);
1002     }
1003 
1004     /**
1005      * Returns a copy of this instant with the specified duration in milliseconds subtracted.
1006      * <p>
1007      * This instance is immutable and unaffected by this method call.
1008      *
1009      * @param millisToSubtract  the milliseconds to subtract, positive or negative
1010      * @return an {@code Instant} based on this instant with the specified milliseconds subtracted, not null
1011      * @throws DateTimeException if the result exceeds the maximum or minimum instant
1012      * @throws ArithmeticException if numeric overflow occurs
1013      */
1014     public Instant minusMillis(long millisToSubtract) {
1015         if (millisToSubtract == Long.MIN_VALUE) {
1016             return plusMillis(Long.MAX_VALUE).plusMillis(1);
1017         }
1018         return plusMillis(-millisToSubtract);
1019     }
1020 
1021     /**
1022      * Returns a copy of this instant with the specified duration in nanoseconds subtracted.
1023      * <p>
1024      * This instance is immutable and unaffected by this method call.
1025      *
1026      * @param nanosToSubtract  the nanoseconds to subtract, positive or negative
1027      * @return an {@code Instant} based on this instant with the specified nanoseconds subtracted, not null
1028      * @throws DateTimeException if the result exceeds the maximum or minimum instant
1029      * @throws ArithmeticException if numeric overflow occurs
1030      */
1031     public Instant minusNanos(long nanosToSubtract) {
1032         if (nanosToSubtract == Long.MIN_VALUE) {
1033             return plusNanos(Long.MAX_VALUE).plusNanos(1);
1034         }
1035         return plusNanos(-nanosToSubtract);
1036     }
1037 
1038     //-------------------------------------------------------------------------
1039     /**
1040      * Queries this instant using the specified query.
1041      * <p>
1042      * This queries this instant using the specified query strategy object.
1043      * The {@code TemporalQuery} object defines the logic to be used to
1044      * obtain the result. Read the documentation of the query to understand
1045      * what the result of this method will be.
1046      * <p>
1047      * The result of this method is obtained by invoking the
1048      * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
1049      * specified query passing {@code this} as the argument.
1050      *
1051      * @param <R> the type of the result
1052      * @param query  the query to invoke, not null
1053      * @return the query result, null may be returned (defined by the query)
1054      * @throws DateTimeException if unable to query (defined by the query)
1055      * @throws ArithmeticException if numeric overflow occurs (defined by the query)
1056      */
1057     @SuppressWarnings("unchecked")
1058     @Override
1059     public <R> R query(TemporalQuery<R> query) {
1060         if (query == TemporalQueries.precision()) {
1061             return (R) NANOS;
1062         }
1063         // inline TemporalAccessor.super.query(query) as an optimization
1064         if (query == TemporalQueries.chronology() || query == TemporalQueries.zoneId() ||
1065                 query == TemporalQueries.zone() || query == TemporalQueries.offset() ||
1066                 query == TemporalQueries.localDate() || query == TemporalQueries.localTime()) {
1067             return null;
1068         }
1069         return query.queryFrom(this);
1070     }
1071 
1072     /**
1073      * Adjusts the specified temporal object to have this instant.
1074      * <p>
1075      * This returns a temporal object of the same observable type as the input
1076      * with the instant changed to be the same as this.
1077      * <p>
1078      * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
1079      * twice, passing {@link ChronoField#INSTANT_SECONDS} and
1080      * {@link ChronoField#NANO_OF_SECOND} as the fields.
1081      * <p>
1082      * In most cases, it is clearer to reverse the calling pattern by using
1083      * {@link Temporal#with(TemporalAdjuster)}:
1084      * <pre>
1085      *   // these two lines are equivalent, but the second approach is recommended
1086      *   temporal = thisInstant.adjustInto(temporal);
1087      *   temporal = temporal.with(thisInstant);
1088      * </pre>
1089      * <p>
1090      * This instance is immutable and unaffected by this method call.
1091      *
1092      * @param temporal  the target object to be adjusted, not null
1093      * @return the adjusted object, not null
1094      * @throws DateTimeException if unable to make the adjustment
1095      * @throws ArithmeticException if numeric overflow occurs
1096      */
1097     @Override
1098     public Temporal adjustInto(Temporal temporal) {
1099         return temporal.with(INSTANT_SECONDS, seconds).with(NANO_OF_SECOND, nanos);
1100     }
1101 
1102     /**
1103      * Calculates the amount of time until another instant in terms of the specified unit.
1104      * <p>
1105      * This calculates the amount of time between two {@code Instant}
1106      * objects in terms of a single {@code TemporalUnit}.
1107      * The start and end points are {@code this} and the specified instant.
1108      * The result will be negative if the end is before the start.
1109      * The calculation returns a whole number, representing the number of
1110      * complete units between the two instants.
1111      * The {@code Temporal} passed to this method is converted to a
1112      * {@code Instant} using {@link #from(TemporalAccessor)}.
1113      * For example, the amount in seconds between two dates can be calculated
1114      * using {@code startInstant.until(endInstant, SECONDS)}.
1115      * <p>
1116      * There are two equivalent ways of using this method.
1117      * The first is to invoke this method.
1118      * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
1119      * <pre>
1120      *   // these two lines are equivalent
1121      *   amount = start.until(end, SECONDS);
1122      *   amount = SECONDS.between(start, end);
1123      * </pre>
1124      * The choice should be made based on which makes the code more readable.
1125      * <p>
1126      * The calculation is implemented in this method for {@link ChronoUnit}.
1127      * The units {@code NANOS}, {@code MICROS}, {@code MILLIS}, {@code SECONDS},
1128      * {@code MINUTES}, {@code HOURS}, {@code HALF_DAYS} and {@code DAYS}
1129      * are supported. Other {@code ChronoUnit} values will throw an exception.
1130      * <p>
1131      * If the unit is not a {@code ChronoUnit}, then the result of this method
1132      * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
1133      * passing {@code this} as the first argument and the converted input temporal
1134      * as the second argument.
1135      * <p>
1136      * This instance is immutable and unaffected by this method call.
1137      *
1138      * @param endExclusive  the end date, exclusive, which is converted to an {@code Instant}, not null
1139      * @param unit  the unit to measure the amount in, not null
1140      * @return the amount of time between this instant and the end instant
1141      * @throws DateTimeException if the amount cannot be calculated, or the end
1142      *  temporal cannot be converted to an {@code Instant}
1143      * @throws UnsupportedTemporalTypeException if the unit is not supported
1144      * @throws ArithmeticException if numeric overflow occurs
1145      */
1146     @Override
1147     public long until(Temporal endExclusive, TemporalUnit unit) {
1148         Instant end = Instant.from(endExclusive);
1149         if (unit instanceof ChronoUnit chronoUnit) {
1150             return switch (chronoUnit) {
1151                 case NANOS     -> nanosUntil(end);
1152                 case MICROS    -> microsUntil(end);
1153                 case MILLIS    -> millisUntil(end);
1154                 case SECONDS   -> secondsUntil(end);
1155                 case MINUTES   -> secondsUntil(end) / SECONDS_PER_MINUTE;
1156                 case HOURS     -> secondsUntil(end) / SECONDS_PER_HOUR;
1157                 case HALF_DAYS -> secondsUntil(end) / (12 * SECONDS_PER_HOUR);
1158                 case DAYS      -> secondsUntil(end) / (SECONDS_PER_DAY);
1159                 default -> throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
1160             };
1161         }
1162         return unit.between(this, end);
1163     }
1164 
1165     private long nanosUntil(Instant end) {
1166         long secsDiff = Math.subtractExact(end.seconds, seconds);
1167         long totalNanos = Math.multiplyExact(secsDiff, NANOS_PER_SECOND);
1168         return Math.addExact(totalNanos, end.nanos - nanos);
1169     }
1170 
1171     private long microsUntil(Instant end) {
1172         long microsDiff = Math.multiplyExact(end.seconds - seconds, MICROS_PER_SECOND);
1173         int nanosDiff = end.nanos - nanos;
1174         if (microsDiff > 0 && nanosDiff < 0) {
1175             return (microsDiff - 1_000_000) + (nanosDiff + 1_000_000_000) / 1_000;
1176         } else if (microsDiff < 0 && nanosDiff > 0) {
1177             return (microsDiff + 1_000_000) + (nanosDiff - 1_000_000_000) / 1_000;
1178         }
1179         return Math.addExact(microsDiff, nanosDiff / 1_000);
1180     }
1181 
1182     private long millisUntil(Instant end) {
1183         long millisDiff = Math.multiplyExact(end.seconds - seconds, MILLIS_PER_SECOND);
1184         int nanosDiff = end.nanos - nanos;
1185         if (millisDiff > 0 && nanosDiff < 0) {
1186             return (millisDiff - 1_000) + (nanosDiff + 1_000_000_000) / 1_000_000;
1187         } else if (millisDiff < 0 && nanosDiff > 0) {
1188             return (millisDiff + 1_000) + (nanosDiff - 1_000_000_000) / 1_000_000;
1189         }
1190         return Math.addExact(millisDiff, nanosDiff / 1_000_000);
1191     }
1192 
1193     private long secondsUntil(Instant end) {
1194         long secsDiff = Math.subtractExact(end.seconds, seconds);
1195         int nanosDiff = end.nanos - nanos;
1196         if (secsDiff > 0 && nanosDiff < 0) {
1197             secsDiff--;
1198         } else if (secsDiff < 0 && nanosDiff > 0) {
1199             secsDiff++;
1200         }
1201         return secsDiff;
1202     }
1203 
1204     //-----------------------------------------------------------------------
1205     /**
1206      * Combines this instant with an offset to create an {@code OffsetDateTime}.
1207      * <p>
1208      * This returns an {@code OffsetDateTime} formed from this instant at the
1209      * specified offset from UTC/Greenwich. An exception will be thrown if the
1210      * instant is too large to fit into an offset date-time.
1211      * <p>
1212      * This method is equivalent to
1213      * {@link OffsetDateTime#ofInstant(Instant, ZoneId) OffsetDateTime.ofInstant(this, offset)}.
1214      *
1215      * @param offset  the offset to combine with, not null
1216      * @return the offset date-time formed from this instant and the specified offset, not null
1217      * @throws DateTimeException if the result exceeds the supported range
1218      */
1219     public OffsetDateTime atOffset(ZoneOffset offset) {
1220         return OffsetDateTime.ofInstant(this, offset);
1221     }
1222 
1223     /**
1224      * Combines this instant with a time-zone to create a {@code ZonedDateTime}.
1225      * <p>
1226      * This returns an {@code ZonedDateTime} formed from this instant at the
1227      * specified time-zone. An exception will be thrown if the instant is too
1228      * large to fit into a zoned date-time.
1229      * <p>
1230      * This method is equivalent to
1231      * {@link ZonedDateTime#ofInstant(Instant, ZoneId) ZonedDateTime.ofInstant(this, zone)}.
1232      *
1233      * @param zone  the zone to combine with, not null
1234      * @return the zoned date-time formed from this instant and the specified zone, not null
1235      * @throws DateTimeException if the result exceeds the supported range
1236      */
1237     public ZonedDateTime atZone(ZoneId zone) {
1238         return ZonedDateTime.ofInstant(this, zone);
1239     }
1240 
1241     //-----------------------------------------------------------------------
1242     /**
1243      * Converts this instant to the number of milliseconds from the epoch
1244      * of 1970-01-01T00:00:00Z.
1245      * <p>
1246      * If this instant represents a point on the time-line too far in the future
1247      * or past to fit in a {@code long} milliseconds, then an exception is thrown.
1248      * <p>
1249      * If this instant has greater than millisecond precision, then the conversion
1250      * will drop any excess precision information as though the amount in nanoseconds
1251      * was subject to integer division by one million.
1252      *
1253      * @return the number of milliseconds since the epoch of 1970-01-01T00:00:00Z
1254      * @throws ArithmeticException if numeric overflow occurs
1255      */
1256     public long toEpochMilli() {
1257         if (seconds < 0 && nanos > 0) {
1258             long millis = Math.multiplyExact(seconds+1, 1000);
1259             long adjustment = nanos / 1000_000 - 1000;
1260             return Math.addExact(millis, adjustment);
1261         } else {
1262             long millis = Math.multiplyExact(seconds, 1000);
1263             return Math.addExact(millis, nanos / 1000_000);
1264         }
1265     }
1266 
1267     //-----------------------------------------------------------------------
1268     /**
1269      * Compares this instant to the specified instant.
1270      * <p>
1271      * The comparison is based on the time-line position of the instants.
1272      * It is "consistent with equals", as defined by {@link Comparable}.
1273      *
1274      * @param otherInstant  the other instant to compare to, not null
1275      * @return the comparator value, that is less than zero if this instant is before {@code otherInstant},
1276      *          zero if they are equal, or greater than zero if this instant is after {@code otherInstant}
1277      * @throws NullPointerException if otherInstant is null
1278      * @see #isBefore
1279      * @see #isAfter
1280      */
1281     @Override
1282     public int compareTo(Instant otherInstant) {
1283         int cmp = Long.compare(seconds, otherInstant.seconds);
1284         if (cmp != 0) {
1285             return cmp;
1286         }
1287         return nanos - otherInstant.nanos;
1288     }
1289 
1290     /**
1291      * Checks if this instant is after the specified instant.
1292      * <p>
1293      * The comparison is based on the time-line position of the instants.
1294      *
1295      * @param otherInstant  the other instant to compare to, not null
1296      * @return true if this instant is after the specified instant
1297      * @throws NullPointerException if otherInstant is null
1298      */
1299     public boolean isAfter(Instant otherInstant) {
1300         return compareTo(otherInstant) > 0;
1301     }
1302 
1303     /**
1304      * Checks if this instant is before the specified instant.
1305      * <p>
1306      * The comparison is based on the time-line position of the instants.
1307      *
1308      * @param otherInstant  the other instant to compare to, not null
1309      * @return true if this instant is before the specified instant
1310      * @throws NullPointerException if otherInstant is null
1311      */
1312     public boolean isBefore(Instant otherInstant) {
1313         return compareTo(otherInstant) < 0;
1314     }
1315 
1316     //-----------------------------------------------------------------------
1317     /**
1318      * Checks if this instant is equal to the specified instant.
1319      * <p>
1320      * The comparison is based on the time-line position of the instants.
1321      *
1322      * @param other  the other instant, null returns false
1323      * @return true if the other instant is equal to this one
1324      */
1325     @Override
1326     public boolean equals(Object other) {
1327         if (this == other) {
1328             return true;
1329         }
1330         return (other instanceof Instant otherInstant)
1331                 && this.seconds == otherInstant.seconds
1332                 && this.nanos == otherInstant.nanos;
1333     }
1334 
1335     /**
1336      * Returns a hash code for this instant.
1337      *
1338      * @return a suitable hash code
1339      */
1340     @Override
1341     public int hashCode() {
1342         return ((int) (seconds ^ (seconds >>> 32))) + 51 * nanos;
1343     }
1344 
1345     //-----------------------------------------------------------------------
1346     /**
1347      * A string representation of this instant using ISO-8601 representation.
1348      * <p>
1349      * The format used is the same as {@link DateTimeFormatter#ISO_INSTANT}.
1350      *
1351      * @return an ISO-8601 representation of this instant, not null
1352      */
1353     @Override
1354     public String toString() {
1355         return DateTimeFormatter.ISO_INSTANT.format(this);
1356     }
1357 
1358     // -----------------------------------------------------------------------
1359     /**
1360      * Writes the object using a
1361      * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1362      * @serialData
1363      * <pre>
1364      *  out.writeByte(2);  // identifies an Instant
1365      *  out.writeLong(seconds);
1366      *  out.writeInt(nanos);
1367      * </pre>
1368      *
1369      * @return the instance of {@code Ser}, not null
1370      */
1371     @java.io.Serial
1372     private Object writeReplace() {
1373         return new Ser(Ser.INSTANT_TYPE, this);
1374     }
1375 
1376     /**
1377      * Defend against malicious streams.
1378      *
1379      * @param s the stream to read
1380      * @throws InvalidObjectException always
1381      */
1382     @java.io.Serial
1383     private void readObject(ObjectInputStream s) throws InvalidObjectException {
1384         throw new InvalidObjectException("Deserialization via serialization delegate");
1385     }
1386 
1387     void writeExternal(DataOutput out) throws IOException {
1388         out.writeLong(seconds);
1389         out.writeInt(nanos);
1390     }
1391 
1392     static Instant readExternal(DataInput in) throws IOException {
1393         long seconds = in.readLong();
1394         int nanos = in.readInt();
1395         return Instant.ofEpochSecond(seconds, nanos);
1396     }
1397 
1398 }