1 /*
   2  * Copyright (c) 2012, 2024, 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 {@linkplain #equals(Object) equal}
 199  * as interchangeable and should not use instances for synchronization, mutexes, or
 200  * with {@linkplain java.lang.ref.Reference object references}.
 201  *
 202  * <div class="preview-block">
 203  *      <div class="preview-comment">
 204  *          When preview features are enabled, {@code Instant} is a {@linkplain Class#isValue value class}.
 205  *          Use of value class instances for synchronization, mutexes, or with
 206  *          {@linkplain java.lang.ref.Reference object references} result in
 207  *          {@link IdentityException}.
 208  *      </div>
 209  * </div>
 210  *
 211  * @implSpec
 212  * This class is immutable and thread-safe.
 213  *
 214  * @since 1.8
 215  */
 216 @jdk.internal.ValueBased
 217 @jdk.internal.MigratedValueClass
 218 public final class Instant
 219         implements Temporal, TemporalAdjuster, Comparable<Instant>, Serializable {
 220 
 221     /**
 222      * Constant for the 1970-01-01T00:00:00Z epoch instant.
 223      */
 224     public static final Instant EPOCH = new Instant(0, 0);
 225     /**
 226      * The minimum supported epoch second.
 227      */
 228     private static final long MIN_SECOND = -31557014167219200L;
 229     /**
 230      * The maximum supported epoch second.
 231      */
 232     private static final long MAX_SECOND = 31556889864403199L;
 233     /**
 234      * The minimum supported {@code Instant}, '-1000000000-01-01T00:00Z'.
 235      * This could be used by an application as a "far past" instant.
 236      * <p>
 237      * This is one year earlier than the minimum {@code LocalDateTime}.
 238      * This provides sufficient values to handle the range of {@code ZoneOffset}
 239      * which affect the instant in addition to the local date-time.
 240      * The value is also chosen such that the value of the year fits in
 241      * an {@code int}.
 242      */
 243     public static final Instant MIN = Instant.ofEpochSecond(MIN_SECOND, 0);
 244     /**
 245      * The maximum supported {@code Instant}, '1000000000-12-31T23:59:59.999999999Z'.
 246      * This could be used by an application as a "far future" instant.
 247      * <p>
 248      * This is one year later than the maximum {@code LocalDateTime}.
 249      * This provides sufficient values to handle the range of {@code ZoneOffset}
 250      * which affect the instant in addition to the local date-time.
 251      * The value is also chosen such that the value of the year fits in
 252      * an {@code int}.
 253      */
 254     public static final Instant MAX = Instant.ofEpochSecond(MAX_SECOND, 999_999_999);
 255 
 256     /**
 257      * Serialization version.
 258      */
 259     @java.io.Serial
 260     private static final long serialVersionUID = -665713676816604388L;
 261 
 262     /**
 263      * The number of seconds from the epoch of 1970-01-01T00:00:00Z.
 264      */
 265     private final long seconds;
 266     /**
 267      * The number of nanoseconds, later along the time-line, from the seconds field.
 268      * This is always positive, and never exceeds 999,999,999.
 269      */
 270     private final int nanos;
 271 
 272     //-----------------------------------------------------------------------
 273     /**
 274      * Obtains the current instant from the system clock.
 275      * <p>
 276      * This will query the {@link Clock#systemUTC() system UTC clock} to
 277      * obtain the current instant.
 278      * <p>
 279      * Using this method will prevent the ability to use an alternate time-source for
 280      * testing because the clock is effectively hard-coded.
 281      *
 282      * @return the current instant using the system clock, not null
 283      */
 284     public static Instant now() {
 285         return Clock.currentInstant();
 286     }
 287 
 288     /**
 289      * Obtains the current instant from the specified clock.
 290      * <p>
 291      * This will query the specified clock to obtain the current time.
 292      * <p>
 293      * Using this method allows the use of an alternate clock for testing.
 294      * The alternate clock may be introduced using {@link Clock dependency injection}.
 295      *
 296      * @param clock  the clock to use, not null
 297      * @return the current instant, not null
 298      */
 299     public static Instant now(Clock clock) {
 300         Objects.requireNonNull(clock, "clock");
 301         return clock.instant();
 302     }
 303 
 304     //-----------------------------------------------------------------------
 305     /**
 306      * Obtains an instance of {@code Instant} using seconds from the
 307      * epoch of 1970-01-01T00:00:00Z.
 308      * <p>
 309      * The nanosecond field is set to zero.
 310      *
 311      * @param epochSecond  the number of seconds from 1970-01-01T00:00:00Z
 312      * @return an instant, not null
 313      * @throws DateTimeException if the instant exceeds the maximum or minimum instant
 314      */
 315     public static Instant ofEpochSecond(long epochSecond) {
 316         return create(epochSecond, 0);
 317     }
 318 
 319     /**
 320      * Obtains an instance of {@code Instant} using seconds from the
 321      * epoch of 1970-01-01T00:00:00Z and nanosecond fraction of second.
 322      * <p>
 323      * This method allows an arbitrary number of nanoseconds to be passed in.
 324      * The factory will alter the values of the second and nanosecond in order
 325      * to ensure that the stored nanosecond is in the range 0 to 999,999,999.
 326      * For example, the following will result in exactly the same instant:
 327      * <pre>
 328      *  Instant.ofEpochSecond(3, 1);
 329      *  Instant.ofEpochSecond(4, -999_999_999);
 330      *  Instant.ofEpochSecond(2, 1000_000_001);
 331      * </pre>
 332      *
 333      * @param epochSecond  the number of seconds from 1970-01-01T00:00:00Z
 334      * @param nanoAdjustment  the nanosecond adjustment to the number of seconds, positive or negative
 335      * @return an instant, not null
 336      * @throws DateTimeException if the instant exceeds the maximum or minimum instant
 337      * @throws ArithmeticException if numeric overflow occurs
 338      */
 339     public static Instant ofEpochSecond(long epochSecond, long nanoAdjustment) {
 340         long secs = Math.addExact(epochSecond, Math.floorDiv(nanoAdjustment, NANOS_PER_SECOND));
 341         int nos = (int)Math.floorMod(nanoAdjustment, NANOS_PER_SECOND);
 342         return create(secs, nos);
 343     }
 344 
 345     /**
 346      * Obtains an instance of {@code Instant} using milliseconds from the
 347      * epoch of 1970-01-01T00:00:00Z.
 348      * <p>
 349      * The seconds and nanoseconds are extracted from the specified milliseconds.
 350      *
 351      * @param epochMilli  the number of milliseconds from 1970-01-01T00:00:00Z
 352      * @return an instant, not null
 353      */
 354     public static Instant ofEpochMilli(long epochMilli) {
 355         long secs = Math.floorDiv(epochMilli, 1000);
 356         int mos = Math.floorMod(epochMilli, 1000);
 357         return create(secs, mos * 1000_000);
 358     }
 359 
 360     //-----------------------------------------------------------------------
 361     /**
 362      * Obtains an instance of {@code Instant} from a temporal object.
 363      * <p>
 364      * This obtains an instant based on the specified temporal.
 365      * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
 366      * which this factory converts to an instance of {@code Instant}.
 367      * <p>
 368      * The conversion extracts the {@link ChronoField#INSTANT_SECONDS INSTANT_SECONDS}
 369      * and {@link ChronoField#NANO_OF_SECOND NANO_OF_SECOND} fields.
 370      * <p>
 371      * This method matches the signature of the functional interface {@link TemporalQuery}
 372      * allowing it to be used as a query via method reference, {@code Instant::from}.
 373      *
 374      * @param temporal  the temporal object to convert, not null
 375      * @return the instant, not null
 376      * @throws DateTimeException if unable to convert to an {@code Instant}
 377      */
 378     public static Instant from(TemporalAccessor temporal) {
 379         if (temporal instanceof Instant) {
 380             return (Instant) temporal;
 381         }
 382         Objects.requireNonNull(temporal, "temporal");
 383         try {
 384             long instantSecs = temporal.getLong(INSTANT_SECONDS);
 385             int nanoOfSecond = temporal.get(NANO_OF_SECOND);
 386             return Instant.ofEpochSecond(instantSecs, nanoOfSecond);
 387         } catch (DateTimeException ex) {
 388             throw new DateTimeException("Unable to obtain Instant from TemporalAccessor: " +
 389                     temporal + " of type " + temporal.getClass().getName(), ex);
 390         }
 391     }
 392 
 393     //-----------------------------------------------------------------------
 394     /**
 395      * Obtains an instance of {@code Instant} from a text string such as
 396      * {@code 2007-12-03T10:15:30.00Z}.
 397      * <p>
 398      * The string must represent a valid instant in UTC and is parsed using
 399      * {@link DateTimeFormatter#ISO_INSTANT}.
 400      *
 401      * @param text  the text to parse, not null
 402      * @return the parsed instant, not null
 403      * @throws DateTimeParseException if the text cannot be parsed
 404      */
 405     public static Instant parse(final CharSequence text) {
 406         return DateTimeFormatter.ISO_INSTANT.parse(text, Instant::from);
 407     }
 408 
 409     //-----------------------------------------------------------------------
 410     /**
 411      * Obtains an instance of {@code Instant} using seconds and nanoseconds.
 412      *
 413      * @param seconds  the length of the duration in seconds
 414      * @param nanoOfSecond  the nano-of-second, from 0 to 999,999,999
 415      * @throws DateTimeException if the instant exceeds the maximum or minimum instant
 416      */
 417     private static Instant create(long seconds, int nanoOfSecond) {
 418         if ((seconds | nanoOfSecond) == 0) {
 419             return EPOCH;
 420         }
 421         if (seconds < MIN_SECOND || seconds > MAX_SECOND) {
 422             throw new DateTimeException("Instant exceeds minimum or maximum instant");
 423         }
 424         return new Instant(seconds, nanoOfSecond);
 425     }
 426 
 427     /**
 428      * Constructs an instance of {@code Instant} using seconds from the epoch of
 429      * 1970-01-01T00:00:00Z and nanosecond fraction of second.
 430      *
 431      * @param epochSecond  the number of seconds from 1970-01-01T00:00:00Z
 432      * @param nanos  the nanoseconds within the second, must be positive
 433      */
 434     private Instant(long epochSecond, int nanos) {
 435         this.seconds = epochSecond;
 436         this.nanos = nanos;
 437     }
 438 
 439     //-----------------------------------------------------------------------
 440     /**
 441      * Checks if the specified field is supported.
 442      * <p>
 443      * This checks if this instant can be queried for the specified field.
 444      * If false, then calling the {@link #range(TemporalField) range},
 445      * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
 446      * methods will throw an exception.
 447      * <p>
 448      * If the field is a {@link ChronoField} then the query is implemented here.
 449      * The supported fields are:
 450      * <ul>
 451      * <li>{@code NANO_OF_SECOND}
 452      * <li>{@code MICRO_OF_SECOND}
 453      * <li>{@code MILLI_OF_SECOND}
 454      * <li>{@code INSTANT_SECONDS}
 455      * </ul>
 456      * All other {@code ChronoField} instances will return false.
 457      * <p>
 458      * If the field is not a {@code ChronoField}, then the result of this method
 459      * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
 460      * passing {@code this} as the argument.
 461      * Whether the field is supported is determined by the field.
 462      *
 463      * @param field  the field to check, null returns false
 464      * @return true if the field is supported on this instant, false if not
 465      */
 466     @Override
 467     public boolean isSupported(TemporalField field) {
 468         if (field instanceof ChronoField) {
 469             return field == INSTANT_SECONDS || field == NANO_OF_SECOND || field == MICRO_OF_SECOND || field == MILLI_OF_SECOND;
 470         }
 471         return field != null && field.isSupportedBy(this);
 472     }
 473 
 474     /**
 475      * Checks if the specified unit is supported.
 476      * <p>
 477      * This checks if the specified unit can be added to, or subtracted from, this date-time.
 478      * If false, then calling the {@link #plus(long, TemporalUnit)} and
 479      * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
 480      * <p>
 481      * If the unit is a {@link ChronoUnit} then the query is implemented here.
 482      * The supported units are:
 483      * <ul>
 484      * <li>{@code NANOS}
 485      * <li>{@code MICROS}
 486      * <li>{@code MILLIS}
 487      * <li>{@code SECONDS}
 488      * <li>{@code MINUTES}
 489      * <li>{@code HOURS}
 490      * <li>{@code HALF_DAYS}
 491      * <li>{@code DAYS}
 492      * </ul>
 493      * All other {@code ChronoUnit} instances will return false.
 494      * <p>
 495      * If the unit is not a {@code ChronoUnit}, then the result of this method
 496      * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
 497      * passing {@code this} as the argument.
 498      * Whether the unit is supported is determined by the unit.
 499      *
 500      * @param unit  the unit to check, null returns false
 501      * @return true if the unit can be added/subtracted, false if not
 502      */
 503     @Override
 504     public boolean isSupported(TemporalUnit unit) {
 505         if (unit instanceof ChronoUnit) {
 506             return unit.isTimeBased() || unit == DAYS;
 507         }
 508         return unit != null && unit.isSupportedBy(this);
 509     }
 510 
 511     //-----------------------------------------------------------------------
 512     /**
 513      * Gets the range of valid values for the specified field.
 514      * <p>
 515      * The range object expresses the minimum and maximum valid values for a field.
 516      * This instant is used to enhance the accuracy of the returned range.
 517      * If it is not possible to return the range, because the field is not supported
 518      * or for some other reason, an exception is thrown.
 519      * <p>
 520      * If the field is a {@link ChronoField} then the query is implemented here.
 521      * The {@link #isSupported(TemporalField) supported fields} will return
 522      * appropriate range instances.
 523      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 524      * <p>
 525      * If the field is not a {@code ChronoField}, then the result of this method
 526      * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
 527      * passing {@code this} as the argument.
 528      * Whether the range can be obtained is determined by the field.
 529      *
 530      * @param field  the field to query the range for, not null
 531      * @return the range of valid values for the field, not null
 532      * @throws DateTimeException if the range for the field cannot be obtained
 533      * @throws UnsupportedTemporalTypeException if the field is not supported
 534      */
 535     @Override  // override for Javadoc
 536     public ValueRange range(TemporalField field) {
 537         return Temporal.super.range(field);
 538     }
 539 
 540     /**
 541      * Gets the value of the specified field from this instant as an {@code int}.
 542      * <p>
 543      * This queries this instant for the value of the specified field.
 544      * The returned value will always be within the valid range of values for the field.
 545      * If it is not possible to return the value, because the field is not supported
 546      * or for some other reason, an exception is thrown.
 547      * <p>
 548      * If the field is a {@link ChronoField} then the query is implemented here.
 549      * The {@link #isSupported(TemporalField) supported fields} will return valid
 550      * values based on this date-time, except {@code INSTANT_SECONDS} which is too
 551      * large to fit in an {@code int} and throws a {@code DateTimeException}.
 552      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 553      * <p>
 554      * If the field is not a {@code ChronoField}, then the result of this method
 555      * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
 556      * passing {@code this} as the argument. Whether the value can be obtained,
 557      * and what the value represents, is determined by the field.
 558      *
 559      * @param field  the field to get, not null
 560      * @return the value for the field
 561      * @throws DateTimeException if a value for the field cannot be obtained or
 562      *         the value is outside the range of valid values for the field
 563      * @throws UnsupportedTemporalTypeException if the field is not supported or
 564      *         the range of values exceeds an {@code int}
 565      * @throws ArithmeticException if numeric overflow occurs
 566      */
 567     @Override  // override for Javadoc and performance
 568     public int get(TemporalField field) {
 569         if (field instanceof ChronoField chronoField) {
 570             return switch (chronoField) {
 571                 case NANO_OF_SECOND -> nanos;
 572                 case MICRO_OF_SECOND -> nanos / 1000;
 573                 case MILLI_OF_SECOND -> nanos / 1000_000;
 574                 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 575             };
 576         }
 577         return range(field).checkValidIntValue(field.getFrom(this), field);
 578     }
 579 
 580     /**
 581      * Gets the value of the specified field from this instant as a {@code long}.
 582      * <p>
 583      * This queries this instant for the value of the specified field.
 584      * If it is not possible to return the value, because the field is not supported
 585      * or for some other reason, an exception is thrown.
 586      * <p>
 587      * If the field is a {@link ChronoField} then the query is implemented here.
 588      * The {@link #isSupported(TemporalField) supported fields} will return valid
 589      * values based on this date-time.
 590      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 591      * <p>
 592      * If the field is not a {@code ChronoField}, then the result of this method
 593      * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
 594      * passing {@code this} as the argument. Whether the value can be obtained,
 595      * and what the value represents, is determined by the field.
 596      *
 597      * @param field  the field to get, not null
 598      * @return the value for the field
 599      * @throws DateTimeException if a value for the field cannot be obtained
 600      * @throws UnsupportedTemporalTypeException if the field is not supported
 601      * @throws ArithmeticException if numeric overflow occurs
 602      */
 603     @Override
 604     public long getLong(TemporalField field) {
 605         if (field instanceof ChronoField chronoField) {
 606             return switch (chronoField) {
 607                 case NANO_OF_SECOND -> nanos;
 608                 case MICRO_OF_SECOND -> nanos / 1000;
 609                 case MILLI_OF_SECOND -> nanos / 1000_000;
 610                 case INSTANT_SECONDS -> seconds;
 611                 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 612             };
 613         }
 614         return field.getFrom(this);
 615     }
 616 
 617     //-----------------------------------------------------------------------
 618     /**
 619      * Gets the number of seconds from the Java epoch of 1970-01-01T00:00:00Z.
 620      * <p>
 621      * The epoch second count is a simple incrementing count of seconds where
 622      * second 0 is 1970-01-01T00:00:00Z.
 623      * The nanosecond part is returned by {@link #getNano}.
 624      *
 625      * @return the seconds from the epoch of 1970-01-01T00:00:00Z
 626      */
 627     public long getEpochSecond() {
 628         return seconds;
 629     }
 630 
 631     /**
 632      * Gets the number of nanoseconds, later along the time-line, from the start
 633      * of the second.
 634      * <p>
 635      * The nanosecond-of-second value measures the total number of nanoseconds from
 636      * the second returned by {@link #getEpochSecond}.
 637      *
 638      * @return the nanoseconds within the second, always positive, never exceeds 999,999,999
 639      */
 640     public int getNano() {
 641         return nanos;
 642     }
 643 
 644     //-------------------------------------------------------------------------
 645     /**
 646      * Returns an adjusted copy of this instant.
 647      * <p>
 648      * This returns an {@code Instant}, based on this one, with the instant adjusted.
 649      * The adjustment takes place using the specified adjuster strategy object.
 650      * Read the documentation of the adjuster to understand what adjustment will be made.
 651      * <p>
 652      * The result of this method is obtained by invoking the
 653      * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
 654      * specified adjuster passing {@code this} as the argument.
 655      * <p>
 656      * This instance is immutable and unaffected by this method call.
 657      *
 658      * @param adjuster the adjuster to use, not null
 659      * @return an {@code Instant} based on {@code this} with the adjustment made, not null
 660      * @throws DateTimeException if the adjustment cannot be made
 661      * @throws ArithmeticException if numeric overflow occurs
 662      */
 663     @Override
 664     public Instant with(TemporalAdjuster adjuster) {
 665         return (Instant) adjuster.adjustInto(this);
 666     }
 667 
 668     /**
 669      * Returns a copy of this instant with the specified field set to a new value.
 670      * <p>
 671      * This returns an {@code Instant}, based on this one, with the value
 672      * for the specified field changed.
 673      * If it is not possible to set the value, because the field is not supported or for
 674      * some other reason, an exception is thrown.
 675      * <p>
 676      * If the field is a {@link ChronoField} then the adjustment is implemented here.
 677      * The supported fields behave as follows:
 678      * <ul>
 679      * <li>{@code NANO_OF_SECOND} -
 680      *  Returns an {@code Instant} with the specified nano-of-second.
 681      *  The epoch-second will be unchanged.
 682      * <li>{@code MICRO_OF_SECOND} -
 683      *  Returns an {@code Instant} with the nano-of-second replaced by the specified
 684      *  micro-of-second multiplied by 1,000. The epoch-second will be unchanged.
 685      * <li>{@code MILLI_OF_SECOND} -
 686      *  Returns an {@code Instant} with the nano-of-second replaced by the specified
 687      *  milli-of-second multiplied by 1,000,000. The epoch-second will be unchanged.
 688      * <li>{@code INSTANT_SECONDS} -
 689      *  Returns an {@code Instant} with the specified epoch-second.
 690      *  The nano-of-second will be unchanged.
 691      * </ul>
 692      * <p>
 693      * In all cases, if the new value is outside the valid range of values for the field
 694      * then a {@code DateTimeException} will be thrown.
 695      * <p>
 696      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 697      * <p>
 698      * If the field is not a {@code ChronoField}, then the result of this method
 699      * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
 700      * passing {@code this} as the argument. In this case, the field determines
 701      * whether and how to adjust the instant.
 702      * <p>
 703      * This instance is immutable and unaffected by this method call.
 704      *
 705      * @param field  the field to set in the result, not null
 706      * @param newValue  the new value of the field in the result
 707      * @return an {@code Instant} based on {@code this} with the specified field set, not null
 708      * @throws DateTimeException if the field cannot be set
 709      * @throws UnsupportedTemporalTypeException if the field is not supported
 710      * @throws ArithmeticException if numeric overflow occurs
 711      */
 712     @Override
 713     public Instant with(TemporalField field, long newValue) {
 714         if (field instanceof ChronoField chronoField) {
 715             chronoField.checkValidValue(newValue);
 716             return switch (chronoField) {
 717                 case MILLI_OF_SECOND -> {
 718                     int nval = (int) newValue * 1000_000;
 719                     yield nval != nanos ? create(seconds, nval) : this;
 720                 }
 721                 case MICRO_OF_SECOND -> {
 722                     int nval = (int) newValue * 1000;
 723                     yield nval != nanos ? create(seconds, nval) : this;
 724                 }
 725                 case NANO_OF_SECOND -> newValue != nanos ? create(seconds, (int) newValue) : this;
 726                 case INSTANT_SECONDS -> newValue != seconds ? create(newValue, nanos) : this;
 727                 default -> throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
 728             };
 729         }
 730         return field.adjustInto(this, newValue);
 731     }
 732 
 733     //-----------------------------------------------------------------------
 734     /**
 735      * Returns a copy of this {@code Instant} truncated to the specified unit.
 736      * <p>
 737      * Truncating the instant returns a copy of the original with fields
 738      * smaller than the specified unit set to zero.
 739      * The fields are calculated on the basis of using a UTC offset as seen
 740      * in {@code toString}.
 741      * For example, truncating with the {@link ChronoUnit#MINUTES MINUTES} unit will
 742      * round down to the nearest minute, setting the seconds and nanoseconds to zero.
 743      * <p>
 744      * The unit must have a {@linkplain TemporalUnit#getDuration() duration}
 745      * that divides into the length of a standard day without remainder.
 746      * This includes all supplied time units on {@link ChronoUnit} and
 747      * {@link ChronoUnit#DAYS DAYS}. Other units throw an exception.
 748      * <p>
 749      * This instance is immutable and unaffected by this method call.
 750      *
 751      * @param unit  the unit to truncate to, not null
 752      * @return an {@code Instant} based on this instant with the time truncated, not null
 753      * @throws DateTimeException if the unit is invalid for truncation
 754      * @throws UnsupportedTemporalTypeException if the unit is not supported
 755      */
 756     public Instant truncatedTo(TemporalUnit unit) {
 757         if (unit == ChronoUnit.NANOS) {
 758             return this;
 759         }
 760         Duration unitDur = unit.getDuration();
 761         if (unitDur.getSeconds() > LocalTime.SECONDS_PER_DAY) {
 762             throw new UnsupportedTemporalTypeException("Unit is too large to be used for truncation");
 763         }
 764         long dur = unitDur.toNanos();
 765         if ((LocalTime.NANOS_PER_DAY % dur) != 0) {
 766             throw new UnsupportedTemporalTypeException("Unit must divide into a standard day without remainder");
 767         }
 768         long nod = (seconds % LocalTime.SECONDS_PER_DAY) * LocalTime.NANOS_PER_SECOND + nanos;
 769         long result = Math.floorDiv(nod, dur) * dur;
 770         return plusNanos(result - nod);
 771     }
 772 
 773     //-----------------------------------------------------------------------
 774     /**
 775      * Returns a copy of this instant with the specified amount added.
 776      * <p>
 777      * This returns an {@code Instant}, based on this one, with the specified amount added.
 778      * The amount is typically {@link Duration} but may be any other type implementing
 779      * the {@link TemporalAmount} interface.
 780      * <p>
 781      * The calculation is delegated to the amount object by calling
 782      * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
 783      * to implement the addition in any way it wishes, however it typically
 784      * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
 785      * of the amount implementation to determine if it can be successfully added.
 786      * <p>
 787      * This instance is immutable and unaffected by this method call.
 788      *
 789      * @param amountToAdd  the amount to add, not null
 790      * @return an {@code Instant} based on this instant with the addition made, not null
 791      * @throws DateTimeException if the addition cannot be made
 792      * @throws ArithmeticException if numeric overflow occurs
 793      */
 794     @Override
 795     public Instant plus(TemporalAmount amountToAdd) {
 796         return (Instant) amountToAdd.addTo(this);
 797     }
 798 
 799     /**
 800      * Returns a copy of this instant with the specified amount added.
 801      * <p>
 802      * This returns an {@code Instant}, based on this one, with the amount
 803      * in terms of the unit added. If it is not possible to add the amount, because the
 804      * unit is not supported or for some other reason, an exception is thrown.
 805      * <p>
 806      * If the field is a {@link ChronoUnit} then the addition is implemented here.
 807      * The supported fields behave as follows:
 808      * <ul>
 809      * <li>{@code NANOS} -
 810      *  Returns an {@code Instant} with the specified number of nanoseconds added.
 811      *  This is equivalent to {@link #plusNanos(long)}.
 812      * <li>{@code MICROS} -
 813      *  Returns an {@code Instant} with the specified number of microseconds added.
 814      *  This is equivalent to {@link #plusNanos(long)} with the amount
 815      *  multiplied by 1,000.
 816      * <li>{@code MILLIS} -
 817      *  Returns an {@code Instant} with the specified number of milliseconds added.
 818      *  This is equivalent to {@link #plusNanos(long)} with the amount
 819      *  multiplied by 1,000,000.
 820      * <li>{@code SECONDS} -
 821      *  Returns an {@code Instant} with the specified number of seconds added.
 822      *  This is equivalent to {@link #plusSeconds(long)}.
 823      * <li>{@code MINUTES} -
 824      *  Returns an {@code Instant} with the specified number of minutes added.
 825      *  This is equivalent to {@link #plusSeconds(long)} with the amount
 826      *  multiplied by 60.
 827      * <li>{@code HOURS} -
 828      *  Returns an {@code Instant} with the specified number of hours added.
 829      *  This is equivalent to {@link #plusSeconds(long)} with the amount
 830      *  multiplied by 3,600.
 831      * <li>{@code HALF_DAYS} -
 832      *  Returns an {@code Instant} with the specified number of half-days added.
 833      *  This is equivalent to {@link #plusSeconds(long)} with the amount
 834      *  multiplied by 43,200 (12 hours).
 835      * <li>{@code DAYS} -
 836      *  Returns an {@code Instant} with the specified number of days added.
 837      *  This is equivalent to {@link #plusSeconds(long)} with the amount
 838      *  multiplied by 86,400 (24 hours).
 839      * </ul>
 840      * <p>
 841      * All other {@code ChronoUnit} instances will throw an {@code UnsupportedTemporalTypeException}.
 842      * <p>
 843      * If the field is not a {@code ChronoUnit}, then the result of this method
 844      * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
 845      * passing {@code this} as the argument. In this case, the unit determines
 846      * whether and how to perform the addition.
 847      * <p>
 848      * This instance is immutable and unaffected by this method call.
 849      *
 850      * @param amountToAdd  the amount of the unit to add to the result, may be negative
 851      * @param unit  the unit of the amount to add, not null
 852      * @return an {@code Instant} based on this instant with the specified amount added, not null
 853      * @throws DateTimeException if the addition cannot be made
 854      * @throws UnsupportedTemporalTypeException if the unit is not supported
 855      * @throws ArithmeticException if numeric overflow occurs
 856      */
 857     @Override
 858     public Instant plus(long amountToAdd, TemporalUnit unit) {
 859         if (unit instanceof ChronoUnit chronoUnit) {
 860             return switch (chronoUnit) {
 861                 case NANOS     -> plusNanos(amountToAdd);
 862                 case MICROS    -> plus(amountToAdd / 1000_000, (amountToAdd % 1000_000) * 1000);
 863                 case MILLIS    -> plusMillis(amountToAdd);
 864                 case SECONDS   -> plusSeconds(amountToAdd);
 865                 case MINUTES   -> plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_MINUTE));
 866                 case HOURS     -> plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_HOUR));
 867                 case HALF_DAYS -> plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_DAY / 2));
 868                 case DAYS      -> plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_DAY));
 869                 default -> throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
 870             };
 871         }
 872         return unit.addTo(this, amountToAdd);
 873     }
 874 
 875     //-----------------------------------------------------------------------
 876     /**
 877      * Returns a copy of this instant with the specified duration in seconds added.
 878      * <p>
 879      * This instance is immutable and unaffected by this method call.
 880      *
 881      * @param secondsToAdd  the seconds to add, positive or negative
 882      * @return an {@code Instant} based on this instant with the specified seconds added, not null
 883      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 884      * @throws ArithmeticException if numeric overflow occurs
 885      */
 886     public Instant plusSeconds(long secondsToAdd) {
 887         if (secondsToAdd == 0) {
 888             return this;
 889         }
 890         long epochSec = Math.addExact(seconds, secondsToAdd);
 891         return create(epochSec, nanos);
 892     }
 893 
 894     /**
 895      * Returns a copy of this instant with the specified duration in milliseconds added.
 896      * <p>
 897      * This instance is immutable and unaffected by this method call.
 898      *
 899      * @param millisToAdd  the milliseconds to add, positive or negative
 900      * @return an {@code Instant} based on this instant with the specified milliseconds added, not null
 901      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 902      * @throws ArithmeticException if numeric overflow occurs
 903      */
 904     public Instant plusMillis(long millisToAdd) {
 905         return plus(millisToAdd / 1000, (millisToAdd % 1000) * 1000_000);
 906     }
 907 
 908     /**
 909      * Returns a copy of this instant with the specified duration in nanoseconds added.
 910      * <p>
 911      * This instance is immutable and unaffected by this method call.
 912      *
 913      * @param nanosToAdd  the nanoseconds to add, positive or negative
 914      * @return an {@code Instant} based on this instant with the specified nanoseconds added, not null
 915      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 916      * @throws ArithmeticException if numeric overflow occurs
 917      */
 918     public Instant plusNanos(long nanosToAdd) {
 919         return plus(0, nanosToAdd);
 920     }
 921 
 922     /**
 923      * Returns a copy of this instant with the specified duration added.
 924      * <p>
 925      * This instance is immutable and unaffected by this method call.
 926      *
 927      * @param secondsToAdd  the seconds to add, positive or negative
 928      * @param nanosToAdd  the nanos to add, positive or negative
 929      * @return an {@code Instant} based on this instant with the specified seconds added, not null
 930      * @throws DateTimeException if the result exceeds the maximum or minimum instant
 931      * @throws ArithmeticException if numeric overflow occurs
 932      */
 933     private Instant plus(long secondsToAdd, long nanosToAdd) {
 934         if ((secondsToAdd | nanosToAdd) == 0) {
 935             return this;
 936         }
 937         long epochSec = Math.addExact(seconds, secondsToAdd);
 938         epochSec = Math.addExact(epochSec, nanosToAdd / NANOS_PER_SECOND);
 939         nanosToAdd = nanosToAdd % NANOS_PER_SECOND;
 940         long nanoAdjustment = nanos + nanosToAdd;  // safe int+NANOS_PER_SECOND
 941         return ofEpochSecond(epochSec, nanoAdjustment);
 942     }
 943 
 944     //-----------------------------------------------------------------------
 945     /**
 946      * Returns a copy of this instant with the specified amount subtracted.
 947      * <p>
 948      * This returns an {@code Instant}, based on this one, with the specified amount subtracted.
 949      * The amount is typically {@link Duration} but may be any other type implementing
 950      * the {@link TemporalAmount} interface.
 951      * <p>
 952      * The calculation is delegated to the amount object by calling
 953      * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
 954      * to implement the subtraction in any way it wishes, however it typically
 955      * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
 956      * of the amount implementation to determine if it can be successfully subtracted.
 957      * <p>
 958      * This instance is immutable and unaffected by this method call.
 959      *
 960      * @param amountToSubtract  the amount to subtract, not null
 961      * @return an {@code Instant} based on this instant with the subtraction made, not null
 962      * @throws DateTimeException if the subtraction cannot be made
 963      * @throws ArithmeticException if numeric overflow occurs
 964      */
 965     @Override
 966     public Instant minus(TemporalAmount amountToSubtract) {
 967         return (Instant) amountToSubtract.subtractFrom(this);
 968     }
 969 
 970     /**
 971      * Returns a copy of this instant with the specified amount subtracted.
 972      * <p>
 973      * This returns an {@code Instant}, based on this one, with the amount
 974      * in terms of the unit subtracted. If it is not possible to subtract the amount,
 975      * because the unit is not supported or for some other reason, an exception is thrown.
 976      * <p>
 977      * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
 978      * See that method for a full description of how addition, and thus subtraction, works.
 979      * <p>
 980      * This instance is immutable and unaffected by this method call.
 981      *
 982      * @param amountToSubtract  the amount of the unit to subtract from the result, may be negative
 983      * @param unit  the unit of the amount to subtract, not null
 984      * @return an {@code Instant} based on this instant with the specified amount subtracted, not null
 985      * @throws DateTimeException if the subtraction cannot be made
 986      * @throws UnsupportedTemporalTypeException if the unit is not supported
 987      * @throws ArithmeticException if numeric overflow occurs
 988      */
 989     @Override
 990     public Instant minus(long amountToSubtract, TemporalUnit unit) {
 991         return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
 992     }
 993 
 994     //-----------------------------------------------------------------------
 995     /**
 996      * Returns a copy of this instant with the specified duration in seconds subtracted.
 997      * <p>
 998      * This instance is immutable and unaffected by this method call.
 999      *
1000      * @param secondsToSubtract  the seconds to subtract, positive or negative
1001      * @return an {@code Instant} based on this instant with the specified seconds subtracted, not null
1002      * @throws DateTimeException if the result exceeds the maximum or minimum instant
1003      * @throws ArithmeticException if numeric overflow occurs
1004      */
1005     public Instant minusSeconds(long secondsToSubtract) {
1006         if (secondsToSubtract == Long.MIN_VALUE) {
1007             return plusSeconds(Long.MAX_VALUE).plusSeconds(1);
1008         }
1009         return plusSeconds(-secondsToSubtract);
1010     }
1011 
1012     /**
1013      * Returns a copy of this instant with the specified duration in milliseconds subtracted.
1014      * <p>
1015      * This instance is immutable and unaffected by this method call.
1016      *
1017      * @param millisToSubtract  the milliseconds to subtract, positive or negative
1018      * @return an {@code Instant} based on this instant with the specified milliseconds subtracted, not null
1019      * @throws DateTimeException if the result exceeds the maximum or minimum instant
1020      * @throws ArithmeticException if numeric overflow occurs
1021      */
1022     public Instant minusMillis(long millisToSubtract) {
1023         if (millisToSubtract == Long.MIN_VALUE) {
1024             return plusMillis(Long.MAX_VALUE).plusMillis(1);
1025         }
1026         return plusMillis(-millisToSubtract);
1027     }
1028 
1029     /**
1030      * Returns a copy of this instant with the specified duration in nanoseconds subtracted.
1031      * <p>
1032      * This instance is immutable and unaffected by this method call.
1033      *
1034      * @param nanosToSubtract  the nanoseconds to subtract, positive or negative
1035      * @return an {@code Instant} based on this instant with the specified nanoseconds subtracted, not null
1036      * @throws DateTimeException if the result exceeds the maximum or minimum instant
1037      * @throws ArithmeticException if numeric overflow occurs
1038      */
1039     public Instant minusNanos(long nanosToSubtract) {
1040         if (nanosToSubtract == Long.MIN_VALUE) {
1041             return plusNanos(Long.MAX_VALUE).plusNanos(1);
1042         }
1043         return plusNanos(-nanosToSubtract);
1044     }
1045 
1046     //-------------------------------------------------------------------------
1047     /**
1048      * Queries this instant using the specified query.
1049      * <p>
1050      * This queries this instant using the specified query strategy object.
1051      * The {@code TemporalQuery} object defines the logic to be used to
1052      * obtain the result. Read the documentation of the query to understand
1053      * what the result of this method will be.
1054      * <p>
1055      * The result of this method is obtained by invoking the
1056      * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
1057      * specified query passing {@code this} as the argument.
1058      *
1059      * @param <R> the type of the result
1060      * @param query  the query to invoke, not null
1061      * @return the query result, null may be returned (defined by the query)
1062      * @throws DateTimeException if unable to query (defined by the query)
1063      * @throws ArithmeticException if numeric overflow occurs (defined by the query)
1064      */
1065     @SuppressWarnings("unchecked")
1066     @Override
1067     public <R> R query(TemporalQuery<R> query) {
1068         if (query == TemporalQueries.precision()) {
1069             return (R) NANOS;
1070         }
1071         // inline TemporalAccessor.super.query(query) as an optimization
1072         if (query == TemporalQueries.chronology() || query == TemporalQueries.zoneId() ||
1073                 query == TemporalQueries.zone() || query == TemporalQueries.offset() ||
1074                 query == TemporalQueries.localDate() || query == TemporalQueries.localTime()) {
1075             return null;
1076         }
1077         return query.queryFrom(this);
1078     }
1079 
1080     /**
1081      * Adjusts the specified temporal object to have this instant.
1082      * <p>
1083      * This returns a temporal object of the same observable type as the input
1084      * with the instant changed to be the same as this.
1085      * <p>
1086      * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
1087      * twice, passing {@link ChronoField#INSTANT_SECONDS} and
1088      * {@link ChronoField#NANO_OF_SECOND} as the fields.
1089      * <p>
1090      * In most cases, it is clearer to reverse the calling pattern by using
1091      * {@link Temporal#with(TemporalAdjuster)}:
1092      * <pre>
1093      *   // these two lines are equivalent, but the second approach is recommended
1094      *   temporal = thisInstant.adjustInto(temporal);
1095      *   temporal = temporal.with(thisInstant);
1096      * </pre>
1097      * <p>
1098      * This instance is immutable and unaffected by this method call.
1099      *
1100      * @param temporal  the target object to be adjusted, not null
1101      * @return the adjusted object, not null
1102      * @throws DateTimeException if unable to make the adjustment
1103      * @throws ArithmeticException if numeric overflow occurs
1104      */
1105     @Override
1106     public Temporal adjustInto(Temporal temporal) {
1107         return temporal.with(INSTANT_SECONDS, seconds).with(NANO_OF_SECOND, nanos);
1108     }
1109 
1110     /**
1111      * Calculates the amount of time until another instant in terms of the specified unit.
1112      * <p>
1113      * This calculates the amount of time between two {@code Instant}
1114      * objects in terms of a single {@code TemporalUnit}.
1115      * The start and end points are {@code this} and the specified instant.
1116      * The result will be negative if the end is before the start.
1117      * The calculation returns a whole number, representing the number of
1118      * complete units between the two instants.
1119      * The {@code Temporal} passed to this method is converted to a
1120      * {@code Instant} using {@link #from(TemporalAccessor)}.
1121      * For example, the amount in seconds between two dates can be calculated
1122      * using {@code startInstant.until(endInstant, SECONDS)}.
1123      * <p>
1124      * There are two equivalent ways of using this method.
1125      * The first is to invoke this method.
1126      * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
1127      * <pre>
1128      *   // these two lines are equivalent
1129      *   amount = start.until(end, SECONDS);
1130      *   amount = SECONDS.between(start, end);
1131      * </pre>
1132      * The choice should be made based on which makes the code more readable.
1133      * <p>
1134      * The calculation is implemented in this method for {@link ChronoUnit}.
1135      * The units {@code NANOS}, {@code MICROS}, {@code MILLIS}, {@code SECONDS},
1136      * {@code MINUTES}, {@code HOURS}, {@code HALF_DAYS} and {@code DAYS}
1137      * are supported. Other {@code ChronoUnit} values will throw an exception.
1138      * <p>
1139      * If the unit is not a {@code ChronoUnit}, then the result of this method
1140      * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
1141      * passing {@code this} as the first argument and the converted input temporal
1142      * as the second argument.
1143      * <p>
1144      * This instance is immutable and unaffected by this method call.
1145      *
1146      * @param endExclusive  the end date, exclusive, which is converted to an {@code Instant}, not null
1147      * @param unit  the unit to measure the amount in, not null
1148      * @return the amount of time between this instant and the end instant
1149      * @throws DateTimeException if the amount cannot be calculated, or the end
1150      *  temporal cannot be converted to an {@code Instant}
1151      * @throws UnsupportedTemporalTypeException if the unit is not supported
1152      * @throws ArithmeticException if numeric overflow occurs
1153      */
1154     @Override
1155     public long until(Temporal endExclusive, TemporalUnit unit) {
1156         Instant end = Instant.from(endExclusive);
1157         if (unit instanceof ChronoUnit chronoUnit) {
1158             return switch (chronoUnit) {
1159                 case NANOS     -> nanosUntil(end);
1160                 case MICROS    -> microsUntil(end);
1161                 case MILLIS    -> millisUntil(end);
1162                 case SECONDS   -> secondsUntil(end);
1163                 case MINUTES   -> secondsUntil(end) / SECONDS_PER_MINUTE;
1164                 case HOURS     -> secondsUntil(end) / SECONDS_PER_HOUR;
1165                 case HALF_DAYS -> secondsUntil(end) / (12 * SECONDS_PER_HOUR);
1166                 case DAYS      -> secondsUntil(end) / (SECONDS_PER_DAY);
1167                 default -> throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
1168             };
1169         }
1170         return unit.between(this, end);
1171     }
1172 
1173     /**
1174      * Calculates the {@code Duration} until another {@code Instant}.
1175      * <p>
1176      * The start and end points are {@code this} and the specified instant.
1177      * The result will be negative if the end is before the start. Calling
1178      * this method is equivalent to
1179      * {@link Duration#between(Temporal, Temporal) Duration.between(this,
1180      * endExclusive)}.
1181      * <p>
1182      * This instance is immutable and unaffected by this method call.
1183      *
1184      * @param endExclusive the end {@code Instant}, exclusive, not null
1185      * @return the {@code Duration} from this {@code Instant} until the
1186      *      specified {@code endExclusive} {@code Instant}
1187      * @see Duration#between(Temporal, Temporal)
1188      * @since 23
1189      */
1190     public Duration until(Instant endExclusive) {
1191         Objects.requireNonNull(endExclusive, "endExclusive");
1192         long secsDiff = Math.subtractExact(endExclusive.seconds, seconds);
1193         int nanosDiff = endExclusive.nanos - nanos;
1194         return Duration.ofSeconds(secsDiff, nanosDiff);
1195     }
1196 
1197     private long nanosUntil(Instant end) {
1198         long secsDiff = Math.subtractExact(end.seconds, seconds);
1199         long totalNanos = Math.multiplyExact(secsDiff, NANOS_PER_SECOND);
1200         return Math.addExact(totalNanos, end.nanos - nanos);
1201     }
1202 
1203     private long microsUntil(Instant end) {
1204         long microsDiff = Math.multiplyExact(end.seconds - seconds, MICROS_PER_SECOND);
1205         int nanosDiff = end.nanos - nanos;
1206         if (microsDiff > 0 && nanosDiff < 0) {
1207             return (microsDiff - 1_000_000) + (nanosDiff + 1_000_000_000) / 1_000;
1208         } else if (microsDiff < 0 && nanosDiff > 0) {
1209             return (microsDiff + 1_000_000) + (nanosDiff - 1_000_000_000) / 1_000;
1210         }
1211         return Math.addExact(microsDiff, nanosDiff / 1_000);
1212     }
1213 
1214     private long millisUntil(Instant end) {
1215         long millisDiff = Math.multiplyExact(end.seconds - seconds, MILLIS_PER_SECOND);
1216         int nanosDiff = end.nanos - nanos;
1217         if (millisDiff > 0 && nanosDiff < 0) {
1218             return (millisDiff - 1_000) + (nanosDiff + 1_000_000_000) / 1_000_000;
1219         } else if (millisDiff < 0 && nanosDiff > 0) {
1220             return (millisDiff + 1_000) + (nanosDiff - 1_000_000_000) / 1_000_000;
1221         }
1222         return Math.addExact(millisDiff, nanosDiff / 1_000_000);
1223     }
1224 
1225     private long secondsUntil(Instant end) {
1226         long secsDiff = Math.subtractExact(end.seconds, seconds);
1227         int nanosDiff = end.nanos - nanos;
1228         if (secsDiff > 0 && nanosDiff < 0) {
1229             secsDiff--;
1230         } else if (secsDiff < 0 && nanosDiff > 0) {
1231             secsDiff++;
1232         }
1233         return secsDiff;
1234     }
1235 
1236     //-----------------------------------------------------------------------
1237     /**
1238      * Combines this instant with an offset to create an {@code OffsetDateTime}.
1239      * <p>
1240      * This returns an {@code OffsetDateTime} formed from this instant at the
1241      * specified offset from UTC/Greenwich. An exception will be thrown if the
1242      * instant is too large to fit into an offset date-time.
1243      * <p>
1244      * This method is equivalent to
1245      * {@link OffsetDateTime#ofInstant(Instant, ZoneId) OffsetDateTime.ofInstant(this, offset)}.
1246      *
1247      * @param offset  the offset to combine with, not null
1248      * @return the offset date-time formed from this instant and the specified offset, not null
1249      * @throws DateTimeException if the result exceeds the supported range
1250      */
1251     public OffsetDateTime atOffset(ZoneOffset offset) {
1252         return OffsetDateTime.ofInstant(this, offset);
1253     }
1254 
1255     /**
1256      * Combines this instant with a time-zone to create a {@code ZonedDateTime}.
1257      * <p>
1258      * This returns an {@code ZonedDateTime} formed from this instant at the
1259      * specified time-zone. An exception will be thrown if the instant is too
1260      * large to fit into a zoned date-time.
1261      * <p>
1262      * This method is equivalent to
1263      * {@link ZonedDateTime#ofInstant(Instant, ZoneId) ZonedDateTime.ofInstant(this, zone)}.
1264      *
1265      * @param zone  the zone to combine with, not null
1266      * @return the zoned date-time formed from this instant and the specified zone, not null
1267      * @throws DateTimeException if the result exceeds the supported range
1268      */
1269     public ZonedDateTime atZone(ZoneId zone) {
1270         return ZonedDateTime.ofInstant(this, zone);
1271     }
1272 
1273     //-----------------------------------------------------------------------
1274     /**
1275      * Converts this instant to the number of milliseconds from the epoch
1276      * of 1970-01-01T00:00:00Z.
1277      * <p>
1278      * If this instant represents a point on the time-line too far in the future
1279      * or past to fit in a {@code long} milliseconds, then an exception is thrown.
1280      * <p>
1281      * If this instant has greater than millisecond precision, then the conversion
1282      * will drop any excess precision information as though the amount in nanoseconds
1283      * was subject to integer division by one million.
1284      *
1285      * @return the number of milliseconds since the epoch of 1970-01-01T00:00:00Z
1286      * @throws ArithmeticException if numeric overflow occurs
1287      */
1288     public long toEpochMilli() {
1289         if (seconds < 0 && nanos > 0) {
1290             long millis = Math.multiplyExact(seconds+1, 1000);
1291             long adjustment = nanos / 1000_000 - 1000;
1292             return Math.addExact(millis, adjustment);
1293         } else {
1294             long millis = Math.multiplyExact(seconds, 1000);
1295             return Math.addExact(millis, nanos / 1000_000);
1296         }
1297     }
1298 
1299     //-----------------------------------------------------------------------
1300     /**
1301      * Compares this instant to the specified instant.
1302      * <p>
1303      * The comparison is based on the time-line position of the instants.
1304      * It is "consistent with equals", as defined by {@link Comparable}.
1305      *
1306      * @param otherInstant  the other instant to compare to, not null
1307      * @return the comparator value, that is less than zero if this instant is before {@code otherInstant},
1308      *          zero if they are equal, or greater than zero if this instant is after {@code otherInstant}
1309      * @throws NullPointerException if otherInstant is null
1310      * @see #isBefore
1311      * @see #isAfter
1312      */
1313     @Override
1314     public int compareTo(Instant otherInstant) {
1315         int cmp = Long.compare(seconds, otherInstant.seconds);
1316         if (cmp != 0) {
1317             return cmp;
1318         }
1319         return nanos - otherInstant.nanos;
1320     }
1321 
1322     /**
1323      * Checks if this instant is after the specified instant.
1324      * <p>
1325      * The comparison is based on the time-line position of the instants.
1326      *
1327      * @param otherInstant  the other instant to compare to, not null
1328      * @return true if this instant is after the specified instant
1329      * @throws NullPointerException if otherInstant is null
1330      */
1331     public boolean isAfter(Instant otherInstant) {
1332         return compareTo(otherInstant) > 0;
1333     }
1334 
1335     /**
1336      * Checks if this instant is before the specified instant.
1337      * <p>
1338      * The comparison is based on the time-line position of the instants.
1339      *
1340      * @param otherInstant  the other instant to compare to, not null
1341      * @return true if this instant is before the specified instant
1342      * @throws NullPointerException if otherInstant is null
1343      */
1344     public boolean isBefore(Instant otherInstant) {
1345         return compareTo(otherInstant) < 0;
1346     }
1347 
1348     //-----------------------------------------------------------------------
1349     /**
1350      * Checks if this instant is equal to the specified instant.
1351      * <p>
1352      * The comparison is based on the time-line position of the instants.
1353      *
1354      * @param other  the other instant, null returns false
1355      * @return true if the other instant is equal to this one
1356      */
1357     @Override
1358     public boolean equals(Object other) {
1359         if (this == other) {
1360             return true;
1361         }
1362         return (other instanceof Instant otherInstant)
1363                 && this.seconds == otherInstant.seconds
1364                 && this.nanos == otherInstant.nanos;
1365     }
1366 
1367     /**
1368      * Returns a hash code for this instant.
1369      *
1370      * @return a suitable hash code
1371      */
1372     @Override
1373     public int hashCode() {
1374         return ((int) (seconds ^ (seconds >>> 32))) + 51 * nanos;
1375     }
1376 
1377     //-----------------------------------------------------------------------
1378     /**
1379      * A string representation of this instant using ISO-8601 representation.
1380      * <p>
1381      * The format used is the same as {@link DateTimeFormatter#ISO_INSTANT}.
1382      *
1383      * @return an ISO-8601 representation of this instant, not null
1384      */
1385     @Override
1386     public String toString() {
1387         return DateTimeFormatter.ISO_INSTANT.format(this);
1388     }
1389 
1390     // -----------------------------------------------------------------------
1391     /**
1392      * Writes the object using a
1393      * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1394      * @serialData
1395      * <pre>
1396      *  out.writeByte(2);  // identifies an Instant
1397      *  out.writeLong(seconds);
1398      *  out.writeInt(nanos);
1399      * </pre>
1400      *
1401      * @return the instance of {@code Ser}, not null
1402      */
1403     @java.io.Serial
1404     private Object writeReplace() {
1405         return new Ser(Ser.INSTANT_TYPE, this);
1406     }
1407 
1408     /**
1409      * Defend against malicious streams.
1410      *
1411      * @param s the stream to read
1412      * @throws InvalidObjectException always
1413      */
1414     @java.io.Serial
1415     private void readObject(ObjectInputStream s) throws InvalidObjectException {
1416         throw new InvalidObjectException("Deserialization via serialization delegate");
1417     }
1418 
1419     void writeExternal(DataOutput out) throws IOException {
1420         out.writeLong(seconds);
1421         out.writeInt(nanos);
1422     }
1423 
1424     static Instant readExternal(DataInput in) throws IOException {
1425         long seconds = in.readLong();
1426         int nanos = in.readInt();
1427         return Instant.ofEpochSecond(seconds, nanos);
1428     }
1429 
1430 }