1 /*
   2  * Copyright (c) 2012, 2025, 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.MINUTES_PER_HOUR;
  65 import static java.time.LocalTime.NANOS_PER_MILLI;
  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.NANO_OF_SECOND;
  71 import static java.time.temporal.ChronoUnit.DAYS;
  72 import static java.time.temporal.ChronoUnit.NANOS;
  73 import static java.time.temporal.ChronoUnit.SECONDS;
  74 
  75 import java.io.DataInput;
  76 import java.io.DataOutput;
  77 import java.io.IOException;
  78 import java.io.InvalidObjectException;
  79 import java.io.ObjectInputStream;
  80 import java.io.Serializable;
  81 import java.math.BigDecimal;
  82 import java.math.BigInteger;
  83 import java.math.RoundingMode;
  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.TemporalAmount;
  89 import java.time.temporal.TemporalUnit;
  90 import java.time.temporal.UnsupportedTemporalTypeException;
  91 import java.util.List;
  92 import java.util.Objects;
  93 import java.util.regex.Matcher;
  94 import java.util.regex.Pattern;
  95 
  96 /**
  97  * A time-based amount of time, such as '34.5 seconds'.
  98  * <p>
  99  * This class models a quantity or amount of time in terms of seconds and nanoseconds.
 100  * It can be accessed using other duration-based units, such as minutes and hours.
 101  * In addition, the {@link ChronoUnit#DAYS DAYS} unit can be used and is treated as
 102  * exactly equal to 24 hours, thus ignoring daylight savings effects.
 103  * See {@link Period} for the date-based equivalent to this class.
 104  * <p>
 105  * A physical duration could be of infinite length.
 106  * For practicality, the duration is stored with constraints similar to {@link Instant}.
 107  * The duration uses nanosecond resolution with a maximum value of the seconds that can
 108  * be held in a {@code long}. This is greater than the current estimated age of the universe.
 109  * <p>
 110  * The range of a duration requires the storage of a number larger than a {@code long}.
 111  * To achieve this, the class stores a {@code long} representing seconds and an {@code int}
 112  * representing nanosecond-of-second, which will always be between 0 and 999,999,999.
 113  * The model is of a directed duration, meaning that the duration may be negative.
 114  * <p>
 115  * The duration is measured in "seconds", but these are not necessarily identical to
 116  * the scientific "SI second" definition based on atomic clocks.
 117  * This difference only impacts durations measured near a leap-second and should not affect
 118  * most applications.
 119  * See {@link Instant} for a discussion as to the meaning of the second and time-scales.
 120  * <p>
 121  * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
 122  * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
 123  * as interchangeable and should not use instances for synchronization, mutexes, or
 124  * with {@linkplain java.lang.ref.Reference object references}.
 125  *
 126  * <div class="preview-block">
 127  *      <div class="preview-comment">
 128  *          When preview features are enabled, {@code Duration} is a {@linkplain Class#isValue value class}.
 129  *          Use of value class instances for synchronization, mutexes, or with
 130  *          {@linkplain java.lang.ref.Reference object references} result in
 131  *          {@link IdentityException}.
 132  *      </div>
 133  * </div>
 134  *
 135  * @implSpec
 136  * This class is immutable and thread-safe.
 137  *
 138  * @since 1.8
 139  */
 140 @jdk.internal.ValueBased
 141 @jdk.internal.MigratedValueClass
 142 public final class Duration
 143         implements TemporalAmount, Comparable<Duration>, Serializable {
 144 
 145     /**
 146      * Constant for a duration of zero.
 147      */
 148     public static final Duration ZERO = new Duration(0, 0);
 149     /**
 150      * The minimum supported {@code Duration}, which is {@link Long#MIN_VALUE}
 151      * seconds.
 152      *
 153      * @apiNote This constant represents the smallest possible instance of
 154      * {@code Duration}. Since {@code Duration} is directed, the smallest
 155      * possible duration is negative.
 156      *
 157      * The constant is intended to be used as a sentinel value or in tests.
 158      * Care should be taken when performing arithmetic on {@code MIN} as there
 159      * is a high risk that {@link ArithmeticException} or {@link DateTimeException}
 160      * will be thrown.
 161      *
 162      * @since 26
 163      */
 164     public static final Duration MIN = new Duration(Long.MIN_VALUE, 0);
 165     /**
 166      * The maximum supported {@code Duration}, which is {@link Long#MAX_VALUE}
 167      * seconds and {@code 999,999,999} nanoseconds.
 168      *
 169      * @apiNote This constant represents the largest possible instance of
 170      * {@code Duration}.
 171      *
 172      * The constant is intended to be used as a sentinel value or in tests.
 173      * Care should be taken when performing arithmetic on {@code MAX} as there
 174      * is a high risk that {@link ArithmeticException} or {@link DateTimeException}
 175      * will be thrown.
 176      *
 177      * @since 26
 178      */
 179     public static final Duration MAX = new Duration(Long.MAX_VALUE, 999_999_999);
 180     /**
 181      * Serialization version.
 182      */
 183     @java.io.Serial
 184     private static final long serialVersionUID = 3078945930695997490L;
 185     /**
 186      * Constant for nanos per second.
 187      */
 188     private static final BigInteger BI_NANOS_PER_SECOND = BigInteger.valueOf(NANOS_PER_SECOND);
 189     /**
 190      * The pattern for parsing.
 191      */
 192     private static class Lazy {
 193         static final Pattern PATTERN =
 194             Pattern.compile("([-+]?)P(?:([-+]?[0-9]+)D)?" +
 195                     "(T(?:([-+]?[0-9]+)H)?(?:([-+]?[0-9]+)M)?(?:([-+]?[0-9]+)(?:[.,]([0-9]{0,9}))?S)?)?",
 196                     Pattern.CASE_INSENSITIVE);
 197     }
 198 
 199     /**
 200      * @serial The number of seconds in the duration.
 201      */
 202     private final long seconds;
 203     /**
 204      * @serial The number of nanoseconds in the duration, expressed as a fraction of the
 205      * number of seconds. This is always positive, and never exceeds 999,999,999.
 206      */
 207     private final int nanos;
 208 
 209     //-----------------------------------------------------------------------
 210     /**
 211      * Obtains a {@code Duration} representing a number of standard 24 hour days.
 212      * <p>
 213      * The seconds are calculated based on the standard definition of a day,
 214      * where each day is 86,400 seconds which implies a 24 hour day.
 215      * The nanosecond in second field is set to zero.
 216      *
 217      * @param days  the number of days, positive or negative
 218      * @return a {@code Duration}, not null
 219      * @throws ArithmeticException if the input days exceeds the capacity of {@code Duration}
 220      */
 221     public static Duration ofDays(long days) {
 222         return create(Math.multiplyExact(days, SECONDS_PER_DAY), 0);
 223     }
 224 
 225     /**
 226      * Obtains a {@code Duration} representing a number of standard hours.
 227      * <p>
 228      * The seconds are calculated based on the standard definition of an hour,
 229      * where each hour is 3,600 seconds.
 230      * The nanosecond in second field is set to zero.
 231      *
 232      * @param hours  the number of hours, positive or negative
 233      * @return a {@code Duration}, not null
 234      * @throws ArithmeticException if the input hours exceeds the capacity of {@code Duration}
 235      */
 236     public static Duration ofHours(long hours) {
 237         return create(Math.multiplyExact(hours, SECONDS_PER_HOUR), 0);
 238     }
 239 
 240     /**
 241      * Obtains a {@code Duration} representing a number of standard minutes.
 242      * <p>
 243      * The seconds are calculated based on the standard definition of a minute,
 244      * where each minute is 60 seconds.
 245      * The nanosecond in second field is set to zero.
 246      *
 247      * @param minutes  the number of minutes, positive or negative
 248      * @return a {@code Duration}, not null
 249      * @throws ArithmeticException if the input minutes exceeds the capacity of {@code Duration}
 250      */
 251     public static Duration ofMinutes(long minutes) {
 252         return create(Math.multiplyExact(minutes, SECONDS_PER_MINUTE), 0);
 253     }
 254 
 255     //-----------------------------------------------------------------------
 256     /**
 257      * Obtains a {@code Duration} representing a number of seconds.
 258      * <p>
 259      * The nanosecond in second field is set to zero.
 260      *
 261      * @param seconds  the number of seconds, positive or negative
 262      * @return a {@code Duration}, not null
 263      */
 264     public static Duration ofSeconds(long seconds) {
 265         return create(seconds, 0);
 266     }
 267 
 268     /**
 269      * Obtains a {@code Duration} representing a number of seconds and an
 270      * adjustment in nanoseconds.
 271      * <p>
 272      * This method allows an arbitrary number of nanoseconds to be passed in.
 273      * The factory will alter the values of the second and nanosecond in order
 274      * to ensure that the stored nanosecond is in the range 0 to 999,999,999.
 275      * For example, the following will result in exactly the same duration:
 276      * <pre>
 277      *  Duration.ofSeconds(3, 1);
 278      *  Duration.ofSeconds(4, -999_999_999);
 279      *  Duration.ofSeconds(2, 1000_000_001);
 280      * </pre>
 281      *
 282      * @param seconds  the number of seconds, positive or negative
 283      * @param nanoAdjustment  the nanosecond adjustment to the number of seconds, positive or negative
 284      * @return a {@code Duration}, not null
 285      * @throws ArithmeticException if the adjustment causes the seconds to exceed the capacity of {@code Duration}
 286      */
 287     public static Duration ofSeconds(long seconds, long nanoAdjustment) {
 288         long secs = Math.addExact(seconds, Math.floorDiv(nanoAdjustment, NANOS_PER_SECOND));
 289         int nos = (int) Math.floorMod(nanoAdjustment, NANOS_PER_SECOND);
 290         return create(secs, nos);
 291     }
 292 
 293     //-----------------------------------------------------------------------
 294     /**
 295      * Obtains a {@code Duration} representing a number of milliseconds.
 296      * <p>
 297      * The seconds and nanoseconds are extracted from the specified milliseconds.
 298      *
 299      * @param millis  the number of milliseconds, positive or negative
 300      * @return a {@code Duration}, not null
 301      */
 302     public static Duration ofMillis(long millis) {
 303         long secs = millis / 1000;
 304         int mos = (int) (millis % 1000);
 305         if (mos < 0) {
 306             mos += 1000;
 307             secs--;
 308         }
 309         return create(secs, mos * 1000_000);
 310     }
 311 
 312     //-----------------------------------------------------------------------
 313     /**
 314      * Obtains a {@code Duration} representing a number of nanoseconds.
 315      * <p>
 316      * The seconds and nanoseconds are extracted from the specified nanoseconds.
 317      *
 318      * @param nanos  the number of nanoseconds, positive or negative
 319      * @return a {@code Duration}, not null
 320      */
 321     public static Duration ofNanos(long nanos) {
 322         long secs = nanos / NANOS_PER_SECOND;
 323         int nos = (int) (nanos % NANOS_PER_SECOND);
 324         if (nos < 0) {
 325             nos += (int) NANOS_PER_SECOND;
 326             secs--;
 327         }
 328         return create(secs, nos);
 329     }
 330 
 331     //-----------------------------------------------------------------------
 332     /**
 333      * Obtains a {@code Duration} representing an amount in the specified unit.
 334      * <p>
 335      * The parameters represent the two parts of a phrase like '6 Hours'. For example:
 336      * <pre>
 337      *  Duration.of(3, SECONDS);
 338      *  Duration.of(465, HOURS);
 339      * </pre>
 340      * Only a subset of units are accepted by this method.
 341      * The unit must either have an {@linkplain TemporalUnit#isDurationEstimated() exact duration} or
 342      * be {@link ChronoUnit#DAYS} which is treated as 24 hours. Other units throw an exception.
 343      *
 344      * @param amount  the amount of the duration, measured in terms of the unit, positive or negative
 345      * @param unit  the unit that the duration is measured in, must have an exact duration, not null
 346      * @return a {@code Duration}, not null
 347      * @throws DateTimeException if the unit has an estimated duration
 348      * @throws ArithmeticException if a numeric overflow occurs
 349      */
 350     public static Duration of(long amount, TemporalUnit unit) {
 351         return ZERO.plus(amount, unit);
 352     }
 353 
 354     //-----------------------------------------------------------------------
 355     /**
 356      * Obtains an instance of {@code Duration} from a temporal amount.
 357      * <p>
 358      * This obtains a duration based on the specified amount.
 359      * A {@code TemporalAmount} represents an  amount of time, which may be
 360      * date-based or time-based, which this factory extracts to a duration.
 361      * <p>
 362      * The conversion loops around the set of units from the amount and uses
 363      * the {@linkplain TemporalUnit#getDuration() duration} of the unit to
 364      * calculate the total {@code Duration}.
 365      * Only a subset of units are accepted by this method. The unit must either
 366      * have an {@linkplain TemporalUnit#isDurationEstimated() exact duration}
 367      * or be {@link ChronoUnit#DAYS} which is treated as 24 hours.
 368      * If any other units are found then an exception is thrown.
 369      *
 370      * @param amount  the temporal amount to convert, not null
 371      * @return the equivalent duration, not null
 372      * @throws DateTimeException if unable to convert to a {@code Duration}
 373      * @throws ArithmeticException if numeric overflow occurs
 374      */
 375     public static Duration from(TemporalAmount amount) {
 376         Objects.requireNonNull(amount, "amount");
 377         Duration duration = ZERO;
 378         for (TemporalUnit unit : amount.getUnits()) {
 379             duration = duration.plus(amount.get(unit), unit);
 380         }
 381         return duration;
 382     }
 383 
 384     //-----------------------------------------------------------------------
 385     /**
 386      * Obtains a {@code Duration} from a text string such as {@code PnDTnHnMn.nS}.
 387      * <p>
 388      * This will parse a textual representation of a duration, including the
 389      * string produced by {@code toString()}. The formats accepted are based
 390      * on the ISO-8601 duration format {@code PnDTnHnMn.nS} with days
 391      * considered to be exactly 24 hours.
 392      * <p>
 393      * The string starts with an optional sign, denoted by the ASCII negative
 394      * or positive symbol. If negative, the whole duration is negated.
 395      * The ASCII letter "P" is next in upper or lower case.
 396      * There are then four sections, each consisting of a number and a suffix.
 397      * The sections have suffixes in ASCII of "D", "H", "M" and "S" for
 398      * days, hours, minutes and seconds, accepted in upper or lower case.
 399      * The suffixes must occur in order. The ASCII letter "T" must occur before
 400      * the first occurrence, if any, of an hour, minute or second section.
 401      * At least one of the four sections must be present, and if "T" is present
 402      * there must be at least one section after the "T".
 403      * The number part of each section must consist of one or more ASCII digits.
 404      * The number may be prefixed by the ASCII negative or positive symbol.
 405      * The number of days, hours and minutes must parse to a {@code long}.
 406      * The number of seconds must parse to a {@code long} with optional fraction.
 407      * The decimal point may be either a dot or a comma.
 408      * The fractional part may have from zero to 9 digits.
 409      * <p>
 410      * The leading plus/minus sign, and negative values for other units are
 411      * not part of the ISO-8601 standard.
 412      * <p>
 413      * Examples:
 414      * <pre>
 415      *    "PT20.345S" -- parses as "20.345 seconds"
 416      *    "PT15M"     -- parses as "15 minutes" (where a minute is 60 seconds)
 417      *    "PT10H"     -- parses as "10 hours" (where an hour is 3,600 seconds)
 418      *    "P2D"       -- parses as "2 days" (where a day is 24 hours or 86,400 seconds)
 419      *    "P2DT3H4M"  -- parses as "2 days, 3 hours and 4 minutes"
 420      *    "PT-6H3M"    -- parses as "-6 hours and +3 minutes"
 421      *    "-PT6H3M"    -- parses as "-6 hours and -3 minutes"
 422      *    "-PT-6H+3M"  -- parses as "+6 hours and -3 minutes"
 423      * </pre>
 424      *
 425      * @param text  the text to parse, not null
 426      * @return the parsed duration, not null
 427      * @throws DateTimeParseException if the text cannot be parsed to a duration
 428      */
 429     public static Duration parse(CharSequence text) {
 430         Objects.requireNonNull(text, "text");
 431         Matcher matcher = Lazy.PATTERN.matcher(text);
 432         if (matcher.matches()) {
 433             // check for letter T but no time sections
 434             if (!charMatch(text, matcher.start(3), matcher.end(3), 'T')) {
 435                 boolean negate = charMatch(text, matcher.start(1), matcher.end(1), '-');
 436 
 437                 int dayStart = matcher.start(2), dayEnd = matcher.end(2);
 438                 int hourStart = matcher.start(4), hourEnd = matcher.end(4);
 439                 int minuteStart = matcher.start(5), minuteEnd = matcher.end(5);
 440                 int secondStart = matcher.start(6), secondEnd = matcher.end(6);
 441                 int fractionStart = matcher.start(7), fractionEnd = matcher.end(7);
 442 
 443                 if (dayStart >= 0 || hourStart >= 0 || minuteStart >= 0 || secondStart >= 0) {
 444                     long daysAsSecs = parseNumber(text, dayStart, dayEnd, SECONDS_PER_DAY, "days");
 445                     long hoursAsSecs = parseNumber(text, hourStart, hourEnd, SECONDS_PER_HOUR, "hours");
 446                     long minsAsSecs = parseNumber(text, minuteStart, minuteEnd, SECONDS_PER_MINUTE, "minutes");
 447                     long seconds = parseNumber(text, secondStart, secondEnd, 1, "seconds");
 448                     boolean negativeSecs = secondStart >= 0 && text.charAt(secondStart) == '-';
 449                     int nanos = parseFraction(text, fractionStart, fractionEnd, negativeSecs ? -1 : 1);
 450                     try {
 451                         return create(negate, daysAsSecs, hoursAsSecs, minsAsSecs, seconds, nanos);
 452                     } catch (ArithmeticException ex) {
 453                         throw new DateTimeParseException("Text cannot be parsed to a Duration: overflow", text, 0, ex);
 454                     }
 455                 }
 456             }
 457         }
 458         throw new DateTimeParseException("Text cannot be parsed to a Duration", text, 0);
 459     }
 460 
 461     private static boolean charMatch(CharSequence text, int start, int end, char c) {
 462         return (start >= 0 && end == start + 1 && text.charAt(start) == c);
 463     }
 464 
 465     private static long parseNumber(CharSequence text, int start, int end, int multiplier, String errorText) {
 466         // regex limits to [-+]?[0-9]+
 467         if (start < 0 || end < 0) {
 468             return 0;
 469         }
 470         try {
 471             long val = Long.parseLong(text, start, end, 10);
 472             return Math.multiplyExact(val, multiplier);
 473         } catch (NumberFormatException | ArithmeticException ex) {
 474             throw new DateTimeParseException("Text cannot be parsed to a Duration: " + errorText, text, 0, ex);
 475         }
 476     }
 477 
 478     private static int parseFraction(CharSequence text, int start, int end, int negate) {
 479         // regex limits to [0-9]{0,9}
 480         if (start < 0 || end < 0 || end - start == 0) {
 481             return 0;
 482         }
 483         try {
 484             int fraction = Integer.parseInt(text, start, end, 10);
 485 
 486             // for number strings smaller than 9 digits, interpret as if there
 487             // were trailing zeros
 488             for (int i = end - start; i < 9; i++) {
 489                 fraction *= 10;
 490             }
 491             return fraction * negate;
 492         } catch (NumberFormatException | ArithmeticException ex) {
 493             throw new DateTimeParseException("Text cannot be parsed to a Duration: fraction", text, 0, ex);
 494         }
 495     }
 496 
 497     private static Duration create(boolean negate, long daysAsSecs, long hoursAsSecs, long minsAsSecs, long secs, int nanos) {
 498         long seconds = Math.addExact(daysAsSecs, Math.addExact(hoursAsSecs, Math.addExact(minsAsSecs, secs)));
 499         if (negate) {
 500             return ofSeconds(seconds, nanos).negated();
 501         }
 502         return ofSeconds(seconds, nanos);
 503     }
 504 
 505     //-----------------------------------------------------------------------
 506     /**
 507      * Obtains a {@code Duration} representing the duration between two temporal objects.
 508      * <p>
 509      * This calculates the duration between two temporal objects. If the objects
 510      * are of different types, then the duration is calculated based on the type
 511      * of the first object. For example, if the first argument is a {@code LocalTime}
 512      * then the second argument is converted to a {@code LocalTime}.
 513      * <p>
 514      * The specified temporal objects must support the {@link ChronoUnit#SECONDS SECONDS} unit.
 515      * For full accuracy, either the {@link ChronoUnit#NANOS NANOS} unit or the
 516      * {@link ChronoField#NANO_OF_SECOND NANO_OF_SECOND} field should be supported.
 517      * <p>
 518      * The result of this method can be a negative duration if the end is before the start.
 519      * To guarantee a positive duration, call {@link #abs()} on the result.
 520      *
 521      * @param startInclusive  the start instant, inclusive, not null
 522      * @param endExclusive  the end instant, exclusive, not null
 523      * @return a {@code Duration}, not null
 524      * @throws DateTimeException if the seconds between the temporals cannot be obtained
 525      * @throws ArithmeticException if the calculation exceeds the capacity of {@code Duration}
 526      */
 527     public static Duration between(Temporal startInclusive, Temporal endExclusive) {
 528         long secs = startInclusive.until(endExclusive, SECONDS);
 529         if (secs == 0) {
 530             // We don't know which Temporal is earlier, so the adjustment below would not work.
 531             // But we do know that there's no danger of until(NANOS) overflowing in that case.
 532             return ofNanos(startInclusive.until(endExclusive, NANOS));
 533         }
 534         long nanos;
 535         try {
 536             nanos = endExclusive.getLong(NANO_OF_SECOND) - startInclusive.getLong(NANO_OF_SECOND);
 537         } catch (DateTimeException ex2) {
 538             nanos = 0;
 539         }
 540         if (nanos < 0 && secs > 0) {
 541             // ofSeconds will subtract one even though until(SECONDS) already gave the correct
 542             // number of seconds. So compensate. Similarly for the secs < 0 case below.
 543             secs++;
 544         } else if (nanos > 0 && secs < 0) {
 545             secs--;
 546         }
 547         return ofSeconds(secs, nanos);
 548     }
 549 
 550     //-----------------------------------------------------------------------
 551     /**
 552      * Obtains an instance of {@code Duration} using seconds and nanoseconds.
 553      *
 554      * @param seconds  the length of the duration in seconds, positive or negative
 555      * @param nanoAdjustment  the nanosecond adjustment within the second, from 0 to 999,999,999
 556      */
 557     private static Duration create(long seconds, int nanoAdjustment) {
 558         if ((seconds | nanoAdjustment) == 0) {
 559             return ZERO;
 560         }
 561         return new Duration(seconds, nanoAdjustment);
 562     }
 563 
 564     /**
 565      * Constructs an instance of {@code Duration} using seconds and nanoseconds.
 566      *
 567      * @param seconds  the length of the duration in seconds, positive or negative
 568      * @param nanos  the nanoseconds within the second, from 0 to 999,999,999
 569      */
 570     private Duration(long seconds, int nanos) {
 571         this.seconds = seconds;
 572         this.nanos = nanos;
 573     }
 574 
 575     //-----------------------------------------------------------------------
 576     /**
 577      * Gets the value of the requested unit.
 578      * <p>
 579      * This returns a value for each of the two supported units,
 580      * {@link ChronoUnit#SECONDS SECONDS} and {@link ChronoUnit#NANOS NANOS}.
 581      * All other units throw an exception.
 582      *
 583      * @param unit the {@code TemporalUnit} for which to return the value
 584      * @return the long value of the unit
 585      * @throws DateTimeException if the unit is not supported
 586      * @throws UnsupportedTemporalTypeException if the unit is not supported
 587      */
 588     @Override
 589     public long get(TemporalUnit unit) {
 590         if (unit == SECONDS) {
 591             return seconds;
 592         } else if (unit == NANOS) {
 593             return nanos;
 594         } else {
 595             throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
 596         }
 597     }
 598 
 599     /**
 600      * Gets the set of units supported by this duration.
 601      * <p>
 602      * The supported units are {@link ChronoUnit#SECONDS SECONDS},
 603      * and {@link ChronoUnit#NANOS NANOS}.
 604      * They are returned in the order seconds, nanos.
 605      * <p>
 606      * This set can be used in conjunction with {@link #get(TemporalUnit)}
 607      * to access the entire state of the duration.
 608      *
 609      * @return a list containing the seconds and nanos units, not null
 610      */
 611     @Override
 612     public List<TemporalUnit> getUnits() {
 613         return DurationUnits.UNITS;
 614     }
 615 
 616     /**
 617      * Private class to delay initialization of this list until needed.
 618      * The circular dependency between Duration and ChronoUnit prevents
 619      * the simple initialization in Duration.
 620      */
 621     private static class DurationUnits {
 622         static final List<TemporalUnit> UNITS = List.of(SECONDS, NANOS);
 623     }
 624 
 625     //-----------------------------------------------------------------------
 626     /**
 627      * Checks if this duration is positive, excluding zero.
 628      * <p>
 629      * A {@code Duration} represents a directed distance between two points on
 630      * the time-line and can therefore be positive, zero or negative.
 631      * This method checks whether the length is greater than zero.
 632      *
 633      * @return true if this duration has a total length greater than zero
 634      * @since 18
 635      */
 636     public boolean isPositive() {
 637         return (seconds | nanos) > 0;
 638     }
 639 
 640     /**
 641      * Checks if this duration is zero length.
 642      * <p>
 643      * A {@code Duration} represents a directed distance between two points on
 644      * the time-line and can therefore be positive, zero or negative.
 645      * This method checks whether the length is zero.
 646      *
 647      * @return true if this duration has a total length equal to zero
 648      */
 649     public boolean isZero() {
 650         return (seconds | nanos) == 0;
 651     }
 652 
 653     /**
 654      * Checks if this duration is negative, excluding zero.
 655      * <p>
 656      * A {@code Duration} represents a directed distance between two points on
 657      * the time-line and can therefore be positive, zero or negative.
 658      * This method checks whether the length is less than zero.
 659      *
 660      * @return true if this duration has a total length less than zero
 661      */
 662     public boolean isNegative() {
 663         return seconds < 0;
 664     }
 665 
 666     //-----------------------------------------------------------------------
 667     /**
 668      * Gets the number of seconds in this duration.
 669      * <p>
 670      * The length of the duration is stored using two fields - seconds and nanoseconds.
 671      * The nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to
 672      * the length in seconds.
 673      * The total duration is defined by calling this method and {@link #getNano()}.
 674      * <p>
 675      * A {@code Duration} represents a directed distance between two points on the time-line.
 676      * A negative duration is expressed by the negative sign of the seconds part.
 677      * A duration of -1 nanosecond is stored as -1 seconds plus 999,999,999 nanoseconds.
 678      *
 679      * @return the whole seconds part of the length of the duration, positive or negative
 680      */
 681     public long getSeconds() {
 682         return seconds;
 683     }
 684 
 685     /**
 686      * Gets the number of nanoseconds within the second in this duration.
 687      * <p>
 688      * The length of the duration is stored using two fields - seconds and nanoseconds.
 689      * The nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to
 690      * the length in seconds.
 691      * The total duration is defined by calling this method and {@link #getSeconds()}.
 692      * <p>
 693      * A {@code Duration} represents a directed distance between two points on the time-line.
 694      * A negative duration is expressed by the negative sign of the seconds part.
 695      * A duration of -1 nanosecond is stored as -1 seconds plus 999,999,999 nanoseconds.
 696      *
 697      * @return the nanoseconds within the second part of the length of the duration, from 0 to 999,999,999
 698      */
 699     public int getNano() {
 700         return nanos;
 701     }
 702 
 703     //-----------------------------------------------------------------------
 704     /**
 705      * Returns a copy of this duration with the specified amount of seconds.
 706      * <p>
 707      * This returns a duration with the specified seconds, retaining the
 708      * nano-of-second part of this duration.
 709      * <p>
 710      * This instance is immutable and unaffected by this method call.
 711      *
 712      * @param seconds  the seconds to represent, may be negative
 713      * @return a {@code Duration} based on this duration with the requested seconds, not null
 714      */
 715     public Duration withSeconds(long seconds) {
 716         return create(seconds, nanos);
 717     }
 718 
 719     /**
 720      * Returns a copy of this duration with the specified nano-of-second.
 721      * <p>
 722      * This returns a duration with the specified nano-of-second, retaining the
 723      * seconds part of this duration.
 724      * <p>
 725      * This instance is immutable and unaffected by this method call.
 726      *
 727      * @param nanoOfSecond  the nano-of-second to represent, from 0 to 999,999,999
 728      * @return a {@code Duration} based on this duration with the requested nano-of-second, not null
 729      * @throws DateTimeException if the nano-of-second is invalid
 730      */
 731     public Duration withNanos(int nanoOfSecond) {
 732         NANO_OF_SECOND.checkValidIntValue(nanoOfSecond);
 733         return create(seconds, nanoOfSecond);
 734     }
 735 
 736     //-----------------------------------------------------------------------
 737     /**
 738      * Returns a copy of this duration with the specified duration added.
 739      * <p>
 740      * This instance is immutable and unaffected by this method call.
 741      *
 742      * @param duration  the duration to add, positive or negative, not null
 743      * @return a {@code Duration} based on this duration with the specified duration added, not null
 744      * @throws ArithmeticException if numeric overflow occurs
 745      */
 746     public Duration plus(Duration duration) {
 747         return plus(duration.getSeconds(), duration.getNano());
 748      }
 749 
 750     /**
 751      * Returns a copy of this duration with the specified duration added.
 752      * <p>
 753      * The duration amount is measured in terms of the specified unit.
 754      * Only a subset of units are accepted by this method.
 755      * The unit must either have an {@linkplain TemporalUnit#isDurationEstimated() exact duration} or
 756      * be {@link ChronoUnit#DAYS} which is treated as 24 hours. Other units throw an exception.
 757      * <p>
 758      * This instance is immutable and unaffected by this method call.
 759      *
 760      * @param amountToAdd  the amount to add, measured in terms of the unit, positive or negative
 761      * @param unit  the unit that the amount is measured in, must have an exact duration, not null
 762      * @return a {@code Duration} based on this duration with the specified duration added, not null
 763      * @throws UnsupportedTemporalTypeException if the unit is not supported
 764      * @throws ArithmeticException if numeric overflow occurs
 765      */
 766     public Duration plus(long amountToAdd, TemporalUnit unit) {
 767         Objects.requireNonNull(unit, "unit");
 768         if (unit == DAYS) {
 769             return plus(Math.multiplyExact(amountToAdd, SECONDS_PER_DAY), 0);
 770         }
 771         if (unit.isDurationEstimated()) {
 772             throw new UnsupportedTemporalTypeException("Unit must not have an estimated duration");
 773         }
 774         if (amountToAdd == 0) {
 775             return this;
 776         }
 777         if (unit instanceof ChronoUnit chronoUnit) {
 778             return switch (chronoUnit) {
 779                 case NANOS -> plusNanos(amountToAdd);
 780                 case MICROS -> plusSeconds((amountToAdd / (1000_000L * 1000)) * 1000).plusNanos((amountToAdd % (1000_000L * 1000)) * 1000);
 781                 case MILLIS -> plusMillis(amountToAdd);
 782                 case SECONDS -> plusSeconds(amountToAdd);
 783                 default -> plusSeconds(Math.multiplyExact(unit.getDuration().seconds, amountToAdd));
 784             };
 785         }
 786         Duration duration = unit.getDuration().multipliedBy(amountToAdd);
 787         return plusSeconds(duration.getSeconds()).plusNanos(duration.getNano());
 788     }
 789 
 790     //-----------------------------------------------------------------------
 791     /**
 792      * Returns a copy of this duration with the specified duration in standard 24 hour days added.
 793      * <p>
 794      * The number of days is multiplied by 86,400 to obtain the number of seconds to add.
 795      * This is based on the standard definition of a day as 24 hours.
 796      * <p>
 797      * This instance is immutable and unaffected by this method call.
 798      *
 799      * @param daysToAdd  the days to add, positive or negative
 800      * @return a {@code Duration} based on this duration with the specified days added, not null
 801      * @throws ArithmeticException if numeric overflow occurs
 802      */
 803     public Duration plusDays(long daysToAdd) {
 804         return plus(Math.multiplyExact(daysToAdd, SECONDS_PER_DAY), 0);
 805     }
 806 
 807     /**
 808      * Returns a copy of this duration with the specified duration in hours added.
 809      * <p>
 810      * This instance is immutable and unaffected by this method call.
 811      *
 812      * @param hoursToAdd  the hours to add, positive or negative
 813      * @return a {@code Duration} based on this duration with the specified hours added, not null
 814      * @throws ArithmeticException if numeric overflow occurs
 815      */
 816     public Duration plusHours(long hoursToAdd) {
 817         return plus(Math.multiplyExact(hoursToAdd, SECONDS_PER_HOUR), 0);
 818     }
 819 
 820     /**
 821      * Returns a copy of this duration with the specified duration in minutes added.
 822      * <p>
 823      * This instance is immutable and unaffected by this method call.
 824      *
 825      * @param minutesToAdd  the minutes to add, positive or negative
 826      * @return a {@code Duration} based on this duration with the specified minutes added, not null
 827      * @throws ArithmeticException if numeric overflow occurs
 828      */
 829     public Duration plusMinutes(long minutesToAdd) {
 830         return plus(Math.multiplyExact(minutesToAdd, SECONDS_PER_MINUTE), 0);
 831     }
 832 
 833     /**
 834      * Returns a copy of this duration with the specified duration in seconds added.
 835      * <p>
 836      * This instance is immutable and unaffected by this method call.
 837      *
 838      * @param secondsToAdd  the seconds to add, positive or negative
 839      * @return a {@code Duration} based on this duration with the specified seconds added, not null
 840      * @throws ArithmeticException if numeric overflow occurs
 841      */
 842     public Duration plusSeconds(long secondsToAdd) {
 843         return plus(secondsToAdd, 0);
 844     }
 845 
 846     /**
 847      * Returns a copy of this duration with the specified duration in milliseconds added.
 848      * <p>
 849      * This instance is immutable and unaffected by this method call.
 850      *
 851      * @param millisToAdd  the milliseconds to add, positive or negative
 852      * @return a {@code Duration} based on this duration with the specified milliseconds added, not null
 853      * @throws ArithmeticException if numeric overflow occurs
 854      */
 855     public Duration plusMillis(long millisToAdd) {
 856         return plus(millisToAdd / 1000, (millisToAdd % 1000) * 1000_000);
 857     }
 858 
 859     /**
 860      * Returns a copy of this duration with the specified duration in nanoseconds added.
 861      * <p>
 862      * This instance is immutable and unaffected by this method call.
 863      *
 864      * @param nanosToAdd  the nanoseconds to add, positive or negative
 865      * @return a {@code Duration} based on this duration with the specified nanoseconds added, not null
 866      * @throws ArithmeticException if numeric overflow occurs
 867      */
 868     public Duration plusNanos(long nanosToAdd) {
 869         return plus(0, nanosToAdd);
 870     }
 871 
 872     /**
 873      * Returns a copy of this duration with the specified duration added.
 874      * <p>
 875      * This instance is immutable and unaffected by this method call.
 876      *
 877      * @param secondsToAdd  the seconds to add, positive or negative
 878      * @param nanosToAdd  the nanos to add, positive or negative
 879      * @return a {@code Duration} based on this duration with the specified seconds added, not null
 880      * @throws ArithmeticException if numeric overflow occurs
 881      */
 882     private Duration plus(long secondsToAdd, long nanosToAdd) {
 883         if ((secondsToAdd | nanosToAdd) == 0) {
 884             return this;
 885         }
 886         long epochSec = Math.addExact(seconds, secondsToAdd);
 887         epochSec = Math.addExact(epochSec, nanosToAdd / NANOS_PER_SECOND);
 888         nanosToAdd = nanosToAdd % NANOS_PER_SECOND;
 889         long nanoAdjustment = nanos + nanosToAdd;  // safe int+NANOS_PER_SECOND
 890         return ofSeconds(epochSec, nanoAdjustment);
 891     }
 892 
 893     //-----------------------------------------------------------------------
 894     /**
 895      * Returns a copy of this duration with the specified duration subtracted.
 896      * <p>
 897      * This instance is immutable and unaffected by this method call.
 898      *
 899      * @param duration  the duration to subtract, positive or negative, not null
 900      * @return a {@code Duration} based on this duration with the specified duration subtracted, not null
 901      * @throws ArithmeticException if numeric overflow occurs
 902      */
 903     public Duration minus(Duration duration) {
 904         long secsToSubtract = duration.getSeconds();
 905         int nanosToSubtract = duration.getNano();
 906         if (secsToSubtract == Long.MIN_VALUE) {
 907             return plus(Long.MAX_VALUE, -nanosToSubtract).plus(1, 0);
 908         }
 909         return plus(-secsToSubtract, -nanosToSubtract);
 910      }
 911 
 912     /**
 913      * Returns a copy of this duration with the specified duration subtracted.
 914      * <p>
 915      * The duration amount is measured in terms of the specified unit.
 916      * Only a subset of units are accepted by this method.
 917      * The unit must either have an {@linkplain TemporalUnit#isDurationEstimated() exact duration} or
 918      * be {@link ChronoUnit#DAYS} which is treated as 24 hours. Other units throw an exception.
 919      * <p>
 920      * This instance is immutable and unaffected by this method call.
 921      *
 922      * @param amountToSubtract  the amount to subtract, measured in terms of the unit, positive or negative
 923      * @param unit  the unit that the amount is measured in, must have an exact duration, not null
 924      * @return a {@code Duration} based on this duration with the specified duration subtracted, not null
 925      * @throws ArithmeticException if numeric overflow occurs
 926      */
 927     public Duration minus(long amountToSubtract, TemporalUnit unit) {
 928         return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
 929     }
 930 
 931     //-----------------------------------------------------------------------
 932     /**
 933      * Returns a copy of this duration with the specified duration in standard 24 hour days subtracted.
 934      * <p>
 935      * The number of days is multiplied by 86,400 to obtain the number of seconds to subtract.
 936      * This is based on the standard definition of a day as 24 hours.
 937      * <p>
 938      * This instance is immutable and unaffected by this method call.
 939      *
 940      * @param daysToSubtract  the days to subtract, positive or negative
 941      * @return a {@code Duration} based on this duration with the specified days subtracted, not null
 942      * @throws ArithmeticException if numeric overflow occurs
 943      */
 944     public Duration minusDays(long daysToSubtract) {
 945         return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
 946     }
 947 
 948     /**
 949      * Returns a copy of this duration with the specified duration in hours subtracted.
 950      * <p>
 951      * The number of hours is multiplied by 3,600 to obtain the number of seconds to subtract.
 952      * <p>
 953      * This instance is immutable and unaffected by this method call.
 954      *
 955      * @param hoursToSubtract  the hours to subtract, positive or negative
 956      * @return a {@code Duration} based on this duration with the specified hours subtracted, not null
 957      * @throws ArithmeticException if numeric overflow occurs
 958      */
 959     public Duration minusHours(long hoursToSubtract) {
 960         return (hoursToSubtract == Long.MIN_VALUE ? plusHours(Long.MAX_VALUE).plusHours(1) : plusHours(-hoursToSubtract));
 961     }
 962 
 963     /**
 964      * Returns a copy of this duration with the specified duration in minutes subtracted.
 965      * <p>
 966      * The number of minutes is multiplied by 60 to obtain the number of seconds to subtract.
 967      * <p>
 968      * This instance is immutable and unaffected by this method call.
 969      *
 970      * @param minutesToSubtract  the minutes to subtract, positive or negative
 971      * @return a {@code Duration} based on this duration with the specified minutes subtracted, not null
 972      * @throws ArithmeticException if numeric overflow occurs
 973      */
 974     public Duration minusMinutes(long minutesToSubtract) {
 975         return (minutesToSubtract == Long.MIN_VALUE ? plusMinutes(Long.MAX_VALUE).plusMinutes(1) : plusMinutes(-minutesToSubtract));
 976     }
 977 
 978     /**
 979      * Returns a copy of this duration with the specified duration in seconds subtracted.
 980      * <p>
 981      * This instance is immutable and unaffected by this method call.
 982      *
 983      * @param secondsToSubtract  the seconds to subtract, positive or negative
 984      * @return a {@code Duration} based on this duration with the specified seconds subtracted, not null
 985      * @throws ArithmeticException if numeric overflow occurs
 986      */
 987     public Duration minusSeconds(long secondsToSubtract) {
 988         return (secondsToSubtract == Long.MIN_VALUE ? plusSeconds(Long.MAX_VALUE).plusSeconds(1) : plusSeconds(-secondsToSubtract));
 989     }
 990 
 991     /**
 992      * Returns a copy of this duration with the specified duration in milliseconds subtracted.
 993      * <p>
 994      * This instance is immutable and unaffected by this method call.
 995      *
 996      * @param millisToSubtract  the milliseconds to subtract, positive or negative
 997      * @return a {@code Duration} based on this duration with the specified milliseconds subtracted, not null
 998      * @throws ArithmeticException if numeric overflow occurs
 999      */
1000     public Duration minusMillis(long millisToSubtract) {
1001         return (millisToSubtract == Long.MIN_VALUE ? plusMillis(Long.MAX_VALUE).plusMillis(1) : plusMillis(-millisToSubtract));
1002     }
1003 
1004     /**
1005      * Returns a copy of this duration with the specified duration in nanoseconds subtracted.
1006      * <p>
1007      * This instance is immutable and unaffected by this method call.
1008      *
1009      * @param nanosToSubtract  the nanoseconds to subtract, positive or negative
1010      * @return a {@code Duration} based on this duration with the specified nanoseconds subtracted, not null
1011      * @throws ArithmeticException if numeric overflow occurs
1012      */
1013     public Duration minusNanos(long nanosToSubtract) {
1014         return (nanosToSubtract == Long.MIN_VALUE ? plusNanos(Long.MAX_VALUE).plusNanos(1) : plusNanos(-nanosToSubtract));
1015     }
1016 
1017     //-----------------------------------------------------------------------
1018     /**
1019      * Returns a copy of this duration multiplied by the scalar.
1020      * <p>
1021      * This instance is immutable and unaffected by this method call.
1022      *
1023      * @param multiplicand  the value to multiply the duration by, positive or negative
1024      * @return a {@code Duration} based on this duration multiplied by the specified scalar, not null
1025      * @throws ArithmeticException if numeric overflow occurs
1026      */
1027     public Duration multipliedBy(long multiplicand) {
1028         if (multiplicand == 0) {
1029             return ZERO;
1030         }
1031         if (multiplicand == 1) {
1032             return this;
1033         }
1034         return create(toBigDecimalSeconds().multiply(BigDecimal.valueOf(multiplicand)));
1035      }
1036 
1037     /**
1038      * Returns a copy of this duration divided by the specified value.
1039      * <p>
1040      * This instance is immutable and unaffected by this method call.
1041      *
1042      * @param divisor  the value to divide the duration by, positive or negative, not zero
1043      * @return a {@code Duration} based on this duration divided by the specified divisor, not null
1044      * @throws ArithmeticException if the divisor is zero or if numeric overflow occurs
1045      */
1046     public Duration dividedBy(long divisor) {
1047         if (divisor == 0) {
1048             throw new ArithmeticException("Cannot divide by zero");
1049         }
1050         if (divisor == 1) {
1051             return this;
1052         }
1053         return create(toBigDecimalSeconds().divide(BigDecimal.valueOf(divisor), RoundingMode.DOWN));
1054      }
1055 
1056     /**
1057      * Returns number of whole times a specified Duration occurs within this Duration.
1058      * <p>
1059      * This instance is immutable and unaffected by this method call.
1060      *
1061      * @param divisor the value to divide the duration by, positive or negative, not null
1062      * @return number of whole times, rounded toward zero, a specified
1063      *         {@code Duration} occurs within this Duration, may be negative
1064      * @throws ArithmeticException if the divisor is zero, or if numeric overflow occurs
1065      * @since 9
1066      */
1067     public long dividedBy(Duration divisor) {
1068         Objects.requireNonNull(divisor, "divisor");
1069         BigDecimal dividendBigD = toBigDecimalSeconds();
1070         BigDecimal divisorBigD = divisor.toBigDecimalSeconds();
1071         return dividendBigD.divideToIntegralValue(divisorBigD).longValueExact();
1072     }
1073 
1074     /**
1075      * Converts this duration to the total length in seconds and
1076      * fractional nanoseconds expressed as a {@code BigDecimal}.
1077      *
1078      * @return the total length of the duration in seconds, with a scale of 9, not null
1079      */
1080     private BigDecimal toBigDecimalSeconds() {
1081         return BigDecimal.valueOf(seconds).add(BigDecimal.valueOf(nanos, 9));
1082     }
1083 
1084     /**
1085      * Creates an instance of {@code Duration} from a number of seconds.
1086      *
1087      * @param seconds  the number of seconds, up to scale 9, positive or negative
1088      * @return a {@code Duration}, not null
1089      * @throws ArithmeticException if numeric overflow occurs
1090      */
1091     private static Duration create(BigDecimal seconds) {
1092         BigInteger nanos = seconds.movePointRight(9).toBigIntegerExact();
1093         BigInteger[] divRem = nanos.divideAndRemainder(BI_NANOS_PER_SECOND);
1094         if (divRem[0].bitLength() > 63) {
1095             throw new ArithmeticException("Exceeds capacity of Duration: " + nanos);
1096         }
1097         return ofSeconds(divRem[0].longValue(), divRem[1].intValue());
1098     }
1099 
1100     //-----------------------------------------------------------------------
1101     /**
1102      * Returns a copy of this duration with the length negated.
1103      * <p>
1104      * This method swaps the sign of the total length of this duration.
1105      * For example, {@code PT1.3S} will be returned as {@code PT-1.3S}.
1106      * <p>
1107      * This instance is immutable and unaffected by this method call.
1108      *
1109      * @return a {@code Duration} based on this duration with the amount negated, not null
1110      * @throws ArithmeticException if numeric overflow occurs
1111      */
1112     public Duration negated() {
1113         return multipliedBy(-1);
1114     }
1115 
1116     /**
1117      * Returns a copy of this duration with a positive length.
1118      * <p>
1119      * This method returns a positive duration by effectively removing the sign from any negative total length.
1120      * For example, {@code PT-1.3S} will be returned as {@code PT1.3S}.
1121      * <p>
1122      * This instance is immutable and unaffected by this method call.
1123      *
1124      * @return a {@code Duration} based on this duration with an absolute length, not null
1125      * @throws ArithmeticException if numeric overflow occurs
1126      */
1127     public Duration abs() {
1128         return isNegative() ? negated() : this;
1129     }
1130 
1131     //-------------------------------------------------------------------------
1132     /**
1133      * Adds this duration to the specified temporal object.
1134      * <p>
1135      * This returns a temporal object of the same observable type as the input
1136      * with this duration added.
1137      * <p>
1138      * In most cases, it is clearer to reverse the calling pattern by using
1139      * {@link Temporal#plus(TemporalAmount)}.
1140      * <pre>
1141      *   // these two lines are equivalent, but the second approach is recommended
1142      *   dateTime = thisDuration.addTo(dateTime);
1143      *   dateTime = dateTime.plus(thisDuration);
1144      * </pre>
1145      * <p>
1146      * The calculation will add the seconds, then nanos.
1147      * Only non-zero amounts will be added.
1148      * <p>
1149      * This instance is immutable and unaffected by this method call.
1150      *
1151      * @param temporal  the temporal object to adjust, not null
1152      * @return an object of the same type with the adjustment made, not null
1153      * @throws DateTimeException if unable to add
1154      * @throws ArithmeticException if numeric overflow occurs
1155      */
1156     @Override
1157     public Temporal addTo(Temporal temporal) {
1158         if (seconds != 0) {
1159             temporal = temporal.plus(seconds, SECONDS);
1160         }
1161         if (nanos != 0) {
1162             temporal = temporal.plus(nanos, NANOS);
1163         }
1164         return temporal;
1165     }
1166 
1167     /**
1168      * Subtracts this duration from the specified temporal object.
1169      * <p>
1170      * This returns a temporal object of the same observable type as the input
1171      * with this duration subtracted.
1172      * <p>
1173      * In most cases, it is clearer to reverse the calling pattern by using
1174      * {@link Temporal#minus(TemporalAmount)}.
1175      * <pre>
1176      *   // these two lines are equivalent, but the second approach is recommended
1177      *   dateTime = thisDuration.subtractFrom(dateTime);
1178      *   dateTime = dateTime.minus(thisDuration);
1179      * </pre>
1180      * <p>
1181      * The calculation will subtract the seconds, then nanos.
1182      * Only non-zero amounts will be added.
1183      * <p>
1184      * This instance is immutable and unaffected by this method call.
1185      *
1186      * @param temporal  the temporal object to adjust, not null
1187      * @return an object of the same type with the adjustment made, not null
1188      * @throws DateTimeException if unable to subtract
1189      * @throws ArithmeticException if numeric overflow occurs
1190      */
1191     @Override
1192     public Temporal subtractFrom(Temporal temporal) {
1193         if (seconds != 0) {
1194             temporal = temporal.minus(seconds, SECONDS);
1195         }
1196         if (nanos != 0) {
1197             temporal = temporal.minus(nanos, NANOS);
1198         }
1199         return temporal;
1200     }
1201 
1202     //-----------------------------------------------------------------------
1203     /**
1204      * Gets the number of days in this duration.
1205      * <p>
1206      * This returns the total number of days in the duration by dividing the
1207      * number of seconds by 86,400.
1208      * This is based on the standard definition of a day as 24 hours.
1209      * <p>
1210      * This instance is immutable and unaffected by this method call.
1211      *
1212      * @return the number of days in the duration, may be negative
1213      */
1214     public long toDays() {
1215         return seconds / SECONDS_PER_DAY;
1216     }
1217 
1218     /**
1219      * Gets the number of hours in this duration.
1220      * <p>
1221      * This returns the total number of hours in the duration by dividing the
1222      * number of seconds by 3,600.
1223      * <p>
1224      * This instance is immutable and unaffected by this method call.
1225      *
1226      * @return the number of hours in the duration, may be negative
1227      */
1228     public long toHours() {
1229         return seconds / SECONDS_PER_HOUR;
1230     }
1231 
1232     /**
1233      * Gets the number of minutes in this duration.
1234      * <p>
1235      * This returns the total number of minutes in the duration by dividing the
1236      * number of seconds by 60.
1237      * <p>
1238      * This instance is immutable and unaffected by this method call.
1239      *
1240      * @return the number of minutes in the duration, may be negative
1241      */
1242     public long toMinutes() {
1243         return seconds / SECONDS_PER_MINUTE;
1244     }
1245 
1246     /**
1247      * Gets the number of seconds in this duration.
1248      * <p>
1249      * This returns the total number of whole seconds in the duration.
1250      * <p>
1251      * This instance is immutable and unaffected by this method call.
1252      *
1253      * @return the whole seconds part of the length of the duration, positive or negative
1254      * @since 9
1255      */
1256     public long toSeconds() {
1257         return seconds;
1258     }
1259 
1260     /**
1261      * Converts this duration to the total length in milliseconds.
1262      * <p>
1263      * If this duration is too large to fit in a {@code long} milliseconds, then an
1264      * exception is thrown.
1265      * <p>
1266      * If this duration has greater than millisecond precision, then the conversion
1267      * will drop any excess precision information as though the amount in nanoseconds
1268      * was subject to integer division by one million.
1269      *
1270      * @return the total length of the duration in milliseconds
1271      * @throws ArithmeticException if numeric overflow occurs
1272      */
1273     public long toMillis() {
1274         long tempSeconds = seconds;
1275         long tempNanos = nanos;
1276         if (tempSeconds < 0) {
1277             // change the seconds and nano value to
1278             // handle Long.MIN_VALUE case
1279             tempSeconds = tempSeconds + 1;
1280             tempNanos = tempNanos - NANOS_PER_SECOND;
1281         }
1282         long millis = Math.multiplyExact(tempSeconds, 1000);
1283         millis = Math.addExact(millis, tempNanos / NANOS_PER_MILLI);
1284         return millis;
1285     }
1286 
1287     /**
1288      * Converts this duration to the total length in nanoseconds expressed as a {@code long}.
1289      * <p>
1290      * If this duration is too large to fit in a {@code long} nanoseconds, then an
1291      * exception is thrown.
1292      *
1293      * @return the total length of the duration in nanoseconds
1294      * @throws ArithmeticException if numeric overflow occurs
1295      */
1296     public long toNanos() {
1297         long tempSeconds = seconds;
1298         long tempNanos = nanos;
1299         if (tempSeconds < 0) {
1300             // change the seconds and nano value to
1301             // handle Long.MIN_VALUE case
1302             tempSeconds = tempSeconds + 1;
1303             tempNanos = tempNanos - NANOS_PER_SECOND;
1304         }
1305         long totalNanos = Math.multiplyExact(tempSeconds, NANOS_PER_SECOND);
1306         totalNanos = Math.addExact(totalNanos, tempNanos);
1307         return totalNanos;
1308     }
1309 
1310     /**
1311      * Extracts the number of days in the duration.
1312      * <p>
1313      * This returns the total number of days in the duration by dividing the
1314      * number of seconds by 86,400.
1315      * This is based on the standard definition of a day as 24 hours.
1316      * <p>
1317      * This instance is immutable and unaffected by this method call.
1318      * @apiNote
1319      * This method behaves exactly the same way as {@link #toDays()}.
1320      *
1321      * @return the number of days in the duration, may be negative
1322      * @since 9
1323      */
1324     public long toDaysPart(){
1325         return seconds / SECONDS_PER_DAY;
1326     }
1327 
1328     /**
1329      * Extracts the number of hours part in the duration.
1330      * <p>
1331      * This returns the number of remaining hours when dividing {@link #toHours}
1332      * by hours in a day.
1333      * This is based on the standard definition of a day as 24 hours.
1334      * <p>
1335      * This instance is immutable and unaffected by this method call.
1336      *
1337      * @return the number of hours part in the duration, may be negative
1338      * @since 9
1339      */
1340     public int toHoursPart(){
1341         return (int) (toHours() % 24);
1342     }
1343 
1344     /**
1345      * Extracts the number of minutes part in the duration.
1346      * <p>
1347      * This returns the number of remaining minutes when dividing {@link #toMinutes}
1348      * by minutes in an hour.
1349      * This is based on the standard definition of an hour as 60 minutes.
1350      * <p>
1351      * This instance is immutable and unaffected by this method call.
1352      *
1353      * @return the number of minutes parts in the duration, may be negative
1354      * @since 9
1355      */
1356     public int toMinutesPart(){
1357         return (int) (toMinutes() % MINUTES_PER_HOUR);
1358     }
1359 
1360     /**
1361      * Extracts the number of seconds part in the duration.
1362      * <p>
1363      * This returns the remaining seconds when dividing {@link #toSeconds}
1364      * by seconds in a minute.
1365      * This is based on the standard definition of a minute as 60 seconds.
1366      * <p>
1367      * This instance is immutable and unaffected by this method call.
1368      *
1369      * @return the number of seconds parts in the duration, may be negative
1370      * @since 9
1371      */
1372     public int toSecondsPart(){
1373         return (int) (seconds % SECONDS_PER_MINUTE);
1374     }
1375 
1376     /**
1377      * Extracts the number of milliseconds part of the duration.
1378      * <p>
1379      * This returns the milliseconds part by dividing the number of nanoseconds by 1,000,000.
1380      * The length of the duration is stored using two fields - seconds and nanoseconds.
1381      * The nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to
1382      * the length in seconds.
1383      * The total duration is defined by calling {@link #getNano()} and {@link #getSeconds()}.
1384      * <p>
1385      * This instance is immutable and unaffected by this method call.
1386      *
1387      * @return the number of milliseconds part of the duration.
1388      * @since 9
1389      */
1390     public int toMillisPart(){
1391         return nanos / 1000_000;
1392     }
1393 
1394     /**
1395      * Get the nanoseconds part within seconds of the duration.
1396      * <p>
1397      * The length of the duration is stored using two fields - seconds and nanoseconds.
1398      * The nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to
1399      * the length in seconds.
1400      * The total duration is defined by calling {@link #getNano()} and {@link #getSeconds()}.
1401      * <p>
1402      * This instance is immutable and unaffected by this method call.
1403      *
1404      * @return the nanoseconds within the second part of the length of the duration, from 0 to 999,999,999
1405      * @since 9
1406      */
1407     public int toNanosPart(){
1408         return nanos;
1409     }
1410 
1411 
1412     //-----------------------------------------------------------------------
1413     /**
1414      * Returns a copy of this {@code Duration} truncated to the specified unit.
1415      * <p>
1416      * Truncating the duration returns a copy of the original with conceptual fields
1417      * smaller than the specified unit set to zero.
1418      * For example, truncating with the {@link ChronoUnit#MINUTES MINUTES} unit will
1419      * round down towards zero to the nearest minute, setting the seconds and
1420      * nanoseconds to zero.
1421      * <p>
1422      * The unit must have a {@linkplain TemporalUnit#getDuration() duration}
1423      * that divides into the length of a standard day without remainder.
1424      * This includes all
1425      * {@linkplain ChronoUnit#isTimeBased() time-based units on {@code ChronoUnit}}
1426      * and {@link ChronoUnit#DAYS DAYS}. Other ChronoUnits throw an exception.
1427      * <p>
1428      * This instance is immutable and unaffected by this method call.
1429      *
1430      * @param unit the unit to truncate to, not null
1431      * @return a {@code Duration} based on this duration with the time truncated, not null
1432      * @throws DateTimeException if the unit is invalid for truncation
1433      * @throws UnsupportedTemporalTypeException if the unit is not supported
1434      * @since 9
1435      */
1436     public Duration truncatedTo(TemporalUnit unit) {
1437         Objects.requireNonNull(unit, "unit");
1438         if (unit == ChronoUnit.SECONDS && (seconds >= 0 || nanos == 0)) {
1439             return new Duration(seconds, 0);
1440         } else if (unit == ChronoUnit.NANOS) {
1441             return this;
1442         }
1443         Duration unitDur = unit.getDuration();
1444         if (unitDur.getSeconds() > LocalTime.SECONDS_PER_DAY) {
1445             throw new UnsupportedTemporalTypeException("Unit is too large to be used for truncation");
1446         }
1447         long dur = unitDur.toNanos();
1448         if ((LocalTime.NANOS_PER_DAY % dur) != 0) {
1449             throw new UnsupportedTemporalTypeException("Unit must divide into a standard day without remainder");
1450         }
1451         long nod = (seconds % LocalTime.SECONDS_PER_DAY) * LocalTime.NANOS_PER_SECOND + nanos;
1452         long result = (nod / dur) * dur;
1453         return plusNanos(result - nod);
1454     }
1455 
1456     //-----------------------------------------------------------------------
1457     /**
1458      * Compares this duration to the specified {@code Duration}.
1459      * <p>
1460      * The comparison is based on the total length of the durations.
1461      * It is "consistent with equals", as defined by {@link Comparable}.
1462      *
1463      * @param otherDuration the other duration to compare to, not null
1464      * @return the comparator value, that is less than zero if this duration is less than {@code otherDuration},
1465      *          zero if they are equal, greater than zero if this duration is greater than {@code otherDuration}
1466      */
1467     @Override
1468     public int compareTo(Duration otherDuration) {
1469         int cmp = Long.compare(seconds, otherDuration.seconds);
1470         if (cmp != 0) {
1471             return cmp;
1472         }
1473         return nanos - otherDuration.nanos;
1474     }
1475 
1476     //-----------------------------------------------------------------------
1477     /**
1478      * Checks if this duration is equal to the specified {@code Duration}.
1479      * <p>
1480      * The comparison is based on the total length of the durations.
1481      *
1482      * @param other the other duration, null returns false
1483      * @return true if the other duration is equal to this one
1484      */
1485     @Override
1486     public boolean equals(Object other) {
1487         if (this == other) {
1488             return true;
1489         }
1490         return (other instanceof Duration otherDuration)
1491                 && this.seconds == otherDuration.seconds
1492                 && this.nanos == otherDuration.nanos;
1493     }
1494 
1495     /**
1496      * A hash code for this duration.
1497      *
1498      * @return a suitable hash code
1499      */
1500     @Override
1501     public int hashCode() {
1502         return Long.hashCode(seconds) + (51 * nanos);
1503     }
1504 
1505     //-----------------------------------------------------------------------
1506     /**
1507      * A string representation of this duration using ISO-8601 seconds
1508      * based representation, such as {@code PT8H6M12.345S}.
1509      * <p>
1510      * The format of the returned string will be {@code PTnHnMnS}, where n is
1511      * the relevant hours, minutes or seconds part of the duration.
1512      * Any fractional seconds are placed after a decimal point in the seconds section.
1513      * If a section has a zero value, it is omitted.
1514      * The hours, minutes and seconds will all have the same sign.
1515      * <p>
1516      * Examples:
1517      * <pre>
1518      *    "20.345 seconds"                 -- "PT20.345S"
1519      *    "15 minutes" (15 * 60 seconds)   -- "PT15M"
1520      *    "10 hours" (10 * 3,600 seconds)  -- "PT10H"
1521      *    "2 days" (2 * 86,400 seconds)    -- "PT48H"
1522      * </pre>
1523      * Note that multiples of 24 hours are not output as days to avoid confusion
1524      * with {@code Period}.
1525      *
1526      * @return an ISO-8601 representation of this duration, not null
1527      */
1528     @Override
1529     public String toString() {
1530         if (this == ZERO) {
1531             return "PT0S";
1532         }
1533         long effectiveTotalSecs = seconds;
1534         if (seconds < 0 && nanos > 0) {
1535             effectiveTotalSecs++;
1536         }
1537         long hours = effectiveTotalSecs / SECONDS_PER_HOUR;
1538         int minutes = (int) ((effectiveTotalSecs % SECONDS_PER_HOUR) / SECONDS_PER_MINUTE);
1539         int secs = (int) (effectiveTotalSecs % SECONDS_PER_MINUTE);
1540         StringBuilder buf = new StringBuilder(24);
1541         buf.append("PT");
1542         if (hours != 0) {
1543             buf.append(hours).append('H');
1544         }
1545         if (minutes != 0) {
1546             buf.append(minutes).append('M');
1547         }
1548         if (secs == 0 && nanos == 0 && buf.length() > 2) {
1549             return buf.toString();
1550         }
1551         if (seconds < 0 && nanos > 0) {
1552             if (secs == 0) {
1553                 buf.append("-0");
1554             } else {
1555                 buf.append(secs);
1556             }
1557         } else {
1558             buf.append(secs);
1559         }
1560         if (nanos > 0) {
1561             int pos = buf.length();
1562             if (seconds < 0) {
1563                 buf.append(2 * NANOS_PER_SECOND - nanos);
1564             } else {
1565                 buf.append(nanos + NANOS_PER_SECOND);
1566             }
1567             while (buf.charAt(buf.length() - 1) == '0') {
1568                 buf.setLength(buf.length() - 1);
1569             }
1570             buf.setCharAt(pos, '.');
1571         }
1572         buf.append('S');
1573         return buf.toString();
1574     }
1575 
1576     //-----------------------------------------------------------------------
1577     /**
1578      * Writes the object using a
1579      * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1580      * @serialData
1581      * <pre>
1582      *  out.writeByte(1);  // identifies a Duration
1583      *  out.writeLong(seconds);
1584      *  out.writeInt(nanos);
1585      * </pre>
1586      *
1587      * @return the instance of {@code Ser}, not null
1588      */
1589     @java.io.Serial
1590     private Object writeReplace() {
1591         return new Ser(Ser.DURATION_TYPE, this);
1592     }
1593 
1594     /**
1595      * Defend against malicious streams.
1596      *
1597      * @param s the stream to read
1598      * @throws InvalidObjectException always
1599      */
1600     @java.io.Serial
1601     private void readObject(ObjectInputStream s) throws InvalidObjectException {
1602         throw new InvalidObjectException("Deserialization via serialization delegate");
1603     }
1604 
1605     void writeExternal(DataOutput out) throws IOException {
1606         out.writeLong(seconds);
1607         out.writeInt(nanos);
1608     }
1609 
1610     static Duration readExternal(DataInput in) throws IOException {
1611         long seconds = in.readLong();
1612         int nanos = in.readInt();
1613         return Duration.ofSeconds(seconds, nanos);
1614     }
1615 
1616 }