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