1 /*
   2  * Copyright (c) 2012, 2022, 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
 123  * {@linkplain #equals(Object) equal} as interchangeable and should not
 124  * use instances for synchronization, or unpredictable behavior may
 125  * occur. For example, in a future release, synchronization may fail.
 126  * The {@code equals} method should be used for comparisons.
 127  *
 128  * @implSpec
 129  * This class is immutable and thread-safe.
 130  *
 131  * @since 1.8
 132  */
 133 @jdk.internal.ValueBased
 134 public final class Duration
 135         implements TemporalAmount, Comparable<Duration>, Serializable {
 136 
 137     /**
 138      * Constant for a duration of zero.
 139      */
 140     public static final Duration ZERO = new Duration(0, 0);
 141     /**
 142      * Serialization version.
 143      */
 144     @java.io.Serial
 145     private static final long serialVersionUID = 3078945930695997490L;
 146     /**
 147      * Constant for nanos per second.
 148      */
 149     private static final BigInteger BI_NANOS_PER_SECOND = BigInteger.valueOf(NANOS_PER_SECOND);
 150     /**
 151      * The pattern for parsing.
 152      */
 153     private static class Lazy {
 154         static final Pattern PATTERN =
 155             Pattern.compile("([-+]?)P(?:([-+]?[0-9]+)D)?" +
 156                     "(T(?:([-+]?[0-9]+)H)?(?:([-+]?[0-9]+)M)?(?:([-+]?[0-9]+)(?:[.,]([0-9]{0,9}))?S)?)?",
 157                     Pattern.CASE_INSENSITIVE);
 158     }
 159 
 160     /**
 161      * The number of seconds in the duration.
 162      */
 163     private final long seconds;
 164     /**
 165      * The number of nanoseconds in the duration, expressed as a fraction of the
 166      * number of seconds. This is always positive, and never exceeds 999,999,999.
 167      */
 168     private final int nanos;
 169 
 170     //-----------------------------------------------------------------------
 171     /**
 172      * Obtains a {@code Duration} representing a number of standard 24 hour days.
 173      * <p>
 174      * The seconds are calculated based on the standard definition of a day,
 175      * where each day is 86400 seconds which implies a 24 hour day.
 176      * The nanosecond in second field is set to zero.
 177      *
 178      * @param days  the number of days, positive or negative
 179      * @return a {@code Duration}, not null
 180      * @throws ArithmeticException if the input days exceeds the capacity of {@code Duration}
 181      */
 182     public static Duration ofDays(long days) {
 183         return create(Math.multiplyExact(days, SECONDS_PER_DAY), 0);
 184     }
 185 
 186     /**
 187      * Obtains a {@code Duration} representing a number of standard hours.
 188      * <p>
 189      * The seconds are calculated based on the standard definition of an hour,
 190      * where each hour is 3600 seconds.
 191      * The nanosecond in second field is set to zero.
 192      *
 193      * @param hours  the number of hours, positive or negative
 194      * @return a {@code Duration}, not null
 195      * @throws ArithmeticException if the input hours exceeds the capacity of {@code Duration}
 196      */
 197     public static Duration ofHours(long hours) {
 198         return create(Math.multiplyExact(hours, SECONDS_PER_HOUR), 0);
 199     }
 200 
 201     /**
 202      * Obtains a {@code Duration} representing a number of standard minutes.
 203      * <p>
 204      * The seconds are calculated based on the standard definition of a minute,
 205      * where each minute is 60 seconds.
 206      * The nanosecond in second field is set to zero.
 207      *
 208      * @param minutes  the number of minutes, positive or negative
 209      * @return a {@code Duration}, not null
 210      * @throws ArithmeticException if the input minutes exceeds the capacity of {@code Duration}
 211      */
 212     public static Duration ofMinutes(long minutes) {
 213         return create(Math.multiplyExact(minutes, SECONDS_PER_MINUTE), 0);
 214     }
 215 
 216     //-----------------------------------------------------------------------
 217     /**
 218      * Obtains a {@code Duration} representing a number of seconds.
 219      * <p>
 220      * The nanosecond in second field is set to zero.
 221      *
 222      * @param seconds  the number of seconds, positive or negative
 223      * @return a {@code Duration}, not null
 224      */
 225     public static Duration ofSeconds(long seconds) {
 226         return create(seconds, 0);
 227     }
 228 
 229     /**
 230      * Obtains a {@code Duration} representing a number of seconds and an
 231      * adjustment in nanoseconds.
 232      * <p>
 233      * This method allows an arbitrary number of nanoseconds to be passed in.
 234      * The factory will alter the values of the second and nanosecond in order
 235      * to ensure that the stored nanosecond is in the range 0 to 999,999,999.
 236      * For example, the following will result in exactly the same duration:
 237      * <pre>
 238      *  Duration.ofSeconds(3, 1);
 239      *  Duration.ofSeconds(4, -999_999_999);
 240      *  Duration.ofSeconds(2, 1000_000_001);
 241      * </pre>
 242      *
 243      * @param seconds  the number of seconds, positive or negative
 244      * @param nanoAdjustment  the nanosecond adjustment to the number of seconds, positive or negative
 245      * @return a {@code Duration}, not null
 246      * @throws ArithmeticException if the adjustment causes the seconds to exceed the capacity of {@code Duration}
 247      */
 248     public static Duration ofSeconds(long seconds, long nanoAdjustment) {
 249         long secs = Math.addExact(seconds, Math.floorDiv(nanoAdjustment, NANOS_PER_SECOND));
 250         int nos = (int) Math.floorMod(nanoAdjustment, NANOS_PER_SECOND);
 251         return create(secs, nos);
 252     }
 253 
 254     //-----------------------------------------------------------------------
 255     /**
 256      * Obtains a {@code Duration} representing a number of milliseconds.
 257      * <p>
 258      * The seconds and nanoseconds are extracted from the specified milliseconds.
 259      *
 260      * @param millis  the number of milliseconds, positive or negative
 261      * @return a {@code Duration}, not null
 262      */
 263     public static Duration ofMillis(long millis) {
 264         long secs = millis / 1000;
 265         int mos = (int) (millis % 1000);
 266         if (mos < 0) {
 267             mos += 1000;
 268             secs--;
 269         }
 270         return create(secs, mos * 1000_000);
 271     }
 272 
 273     //-----------------------------------------------------------------------
 274     /**
 275      * Obtains a {@code Duration} representing a number of nanoseconds.
 276      * <p>
 277      * The seconds and nanoseconds are extracted from the specified nanoseconds.
 278      *
 279      * @param nanos  the number of nanoseconds, positive or negative
 280      * @return a {@code Duration}, not null
 281      */
 282     public static Duration ofNanos(long nanos) {
 283         long secs = nanos / NANOS_PER_SECOND;
 284         int nos = (int) (nanos % NANOS_PER_SECOND);
 285         if (nos < 0) {
 286             nos += (int) NANOS_PER_SECOND;
 287             secs--;
 288         }
 289         return create(secs, nos);
 290     }
 291 
 292     //-----------------------------------------------------------------------
 293     /**
 294      * Obtains a {@code Duration} representing an amount in the specified unit.
 295      * <p>
 296      * The parameters represent the two parts of a phrase like '6 Hours'. For example:
 297      * <pre>
 298      *  Duration.of(3, SECONDS);
 299      *  Duration.of(465, HOURS);
 300      * </pre>
 301      * Only a subset of units are accepted by this method.
 302      * The unit must either have an {@linkplain TemporalUnit#isDurationEstimated() exact duration} or
 303      * be {@link ChronoUnit#DAYS} which is treated as 24 hours. Other units throw an exception.
 304      *
 305      * @param amount  the amount of the duration, measured in terms of the unit, positive or negative
 306      * @param unit  the unit that the duration is measured in, must have an exact duration, not null
 307      * @return a {@code Duration}, not null
 308      * @throws DateTimeException if the period unit has an estimated duration
 309      * @throws ArithmeticException if a numeric overflow occurs
 310      */
 311     public static Duration of(long amount, TemporalUnit unit) {
 312         return ZERO.plus(amount, unit);
 313     }
 314 
 315     //-----------------------------------------------------------------------
 316     /**
 317      * Obtains an instance of {@code Duration} from a temporal amount.
 318      * <p>
 319      * This obtains a duration based on the specified amount.
 320      * A {@code TemporalAmount} represents an  amount of time, which may be
 321      * date-based or time-based, which this factory extracts to a duration.
 322      * <p>
 323      * The conversion loops around the set of units from the amount and uses
 324      * the {@linkplain TemporalUnit#getDuration() duration} of the unit to
 325      * calculate the total {@code Duration}.
 326      * Only a subset of units are accepted by this method. The unit must either
 327      * have an {@linkplain TemporalUnit#isDurationEstimated() exact duration}
 328      * or be {@link ChronoUnit#DAYS} which is treated as 24 hours.
 329      * If any other units are found then an exception is thrown.
 330      *
 331      * @param amount  the temporal amount to convert, not null
 332      * @return the equivalent duration, not null
 333      * @throws DateTimeException if unable to convert to a {@code Duration}
 334      * @throws ArithmeticException if numeric overflow occurs
 335      */
 336     public static Duration from(TemporalAmount amount) {
 337         Objects.requireNonNull(amount, "amount");
 338         Duration duration = ZERO;
 339         for (TemporalUnit unit : amount.getUnits()) {
 340             duration = duration.plus(amount.get(unit), unit);
 341         }
 342         return duration;
 343     }
 344 
 345     //-----------------------------------------------------------------------
 346     /**
 347      * Obtains a {@code Duration} from a text string such as {@code PnDTnHnMn.nS}.
 348      * <p>
 349      * This will parse a textual representation of a duration, including the
 350      * string produced by {@code toString()}. The formats accepted are based
 351      * on the ISO-8601 duration format {@code PnDTnHnMn.nS} with days
 352      * considered to be exactly 24 hours.
 353      * <p>
 354      * The string starts with an optional sign, denoted by the ASCII negative
 355      * or positive symbol. If negative, the whole period is negated.
 356      * The ASCII letter "P" is next in upper or lower case.
 357      * There are then four sections, each consisting of a number and a suffix.
 358      * The sections have suffixes in ASCII of "D", "H", "M" and "S" for
 359      * days, hours, minutes and seconds, accepted in upper or lower case.
 360      * The suffixes must occur in order. The ASCII letter "T" must occur before
 361      * the first occurrence, if any, of an hour, minute or second section.
 362      * At least one of the four sections must be present, and if "T" is present
 363      * there must be at least one section after the "T".
 364      * The number part of each section must consist of one or more ASCII digits.
 365      * The number may be prefixed by the ASCII negative or positive symbol.
 366      * The number of days, hours and minutes must parse to a {@code long}.
 367      * The number of seconds must parse to a {@code long} with optional fraction.
 368      * The decimal point may be either a dot or a comma.
 369      * The fractional part may have from zero to 9 digits.
 370      * <p>
 371      * The leading plus/minus sign, and negative values for other units are
 372      * not part of the ISO-8601 standard.
 373      * <p>
 374      * Examples:
 375      * <pre>
 376      *    "PT20.345S" -- parses as "20.345 seconds"
 377      *    "PT15M"     -- parses as "15 minutes" (where a minute is 60 seconds)
 378      *    "PT10H"     -- parses as "10 hours" (where an hour is 3600 seconds)
 379      *    "P2D"       -- parses as "2 days" (where a day is 24 hours or 86400 seconds)
 380      *    "P2DT3H4M"  -- parses as "2 days, 3 hours and 4 minutes"
 381      *    "PT-6H3M"    -- parses as "-6 hours and +3 minutes"
 382      *    "-PT6H3M"    -- parses as "-6 hours and -3 minutes"
 383      *    "-PT-6H+3M"  -- parses as "+6 hours and -3 minutes"
 384      * </pre>
 385      *
 386      * @param text  the text to parse, not null
 387      * @return the parsed duration, not null
 388      * @throws DateTimeParseException if the text cannot be parsed to a duration
 389      */
 390     public static Duration parse(CharSequence text) {
 391         Objects.requireNonNull(text, "text");
 392         Matcher matcher = Lazy.PATTERN.matcher(text);
 393         if (matcher.matches()) {
 394             // check for letter T but no time sections
 395             if (!charMatch(text, matcher.start(3), matcher.end(3), 'T')) {
 396                 boolean negate = charMatch(text, matcher.start(1), matcher.end(1), '-');
 397 
 398                 int dayStart = matcher.start(2), dayEnd = matcher.end(2);
 399                 int hourStart = matcher.start(4), hourEnd = matcher.end(4);
 400                 int minuteStart = matcher.start(5), minuteEnd = matcher.end(5);
 401                 int secondStart = matcher.start(6), secondEnd = matcher.end(6);
 402                 int fractionStart = matcher.start(7), fractionEnd = matcher.end(7);
 403 
 404                 if (dayStart >= 0 || hourStart >= 0 || minuteStart >= 0 || secondStart >= 0) {
 405                     long daysAsSecs = parseNumber(text, dayStart, dayEnd, SECONDS_PER_DAY, "days");
 406                     long hoursAsSecs = parseNumber(text, hourStart, hourEnd, SECONDS_PER_HOUR, "hours");
 407                     long minsAsSecs = parseNumber(text, minuteStart, minuteEnd, SECONDS_PER_MINUTE, "minutes");
 408                     long seconds = parseNumber(text, secondStart, secondEnd, 1, "seconds");
 409                     boolean negativeSecs = secondStart >= 0 && text.charAt(secondStart) == '-';
 410                     int nanos = parseFraction(text, fractionStart, fractionEnd, negativeSecs ? -1 : 1);
 411                     try {
 412                         return create(negate, daysAsSecs, hoursAsSecs, minsAsSecs, seconds, nanos);
 413                     } catch (ArithmeticException ex) {
 414                         throw new DateTimeParseException("Text cannot be parsed to a Duration: overflow", text, 0, ex);
 415                     }
 416                 }
 417             }
 418         }
 419         throw new DateTimeParseException("Text cannot be parsed to a Duration", text, 0);
 420     }
 421 
 422     private static boolean charMatch(CharSequence text, int start, int end, char c) {
 423         return (start >= 0 && end == start + 1 && text.charAt(start) == c);
 424     }
 425 
 426     private static long parseNumber(CharSequence text, int start, int end, int multiplier, String errorText) {
 427         // regex limits to [-+]?[0-9]+
 428         if (start < 0 || end < 0) {
 429             return 0;
 430         }
 431         try {
 432             long val = Long.parseLong(text, start, end, 10);
 433             return Math.multiplyExact(val, multiplier);
 434         } catch (NumberFormatException | ArithmeticException ex) {
 435             throw new DateTimeParseException("Text cannot be parsed to a Duration: " + errorText, text, 0, ex);
 436         }
 437     }
 438 
 439     private static int parseFraction(CharSequence text, int start, int end, int negate) {
 440         // regex limits to [0-9]{0,9}
 441         if (start < 0 || end < 0 || end - start == 0) {
 442             return 0;
 443         }
 444         try {
 445             int fraction = Integer.parseInt(text, start, end, 10);
 446 
 447             // for number strings smaller than 9 digits, interpret as if there
 448             // were trailing zeros
 449             for (int i = end - start; i < 9; i++) {
 450                 fraction *= 10;
 451             }
 452             return fraction * negate;
 453         } catch (NumberFormatException | ArithmeticException ex) {
 454             throw new DateTimeParseException("Text cannot be parsed to a Duration: fraction", text, 0, ex);
 455         }
 456     }
 457 
 458     private static Duration create(boolean negate, long daysAsSecs, long hoursAsSecs, long minsAsSecs, long secs, int nanos) {
 459         long seconds = Math.addExact(daysAsSecs, Math.addExact(hoursAsSecs, Math.addExact(minsAsSecs, secs)));
 460         if (negate) {
 461             return ofSeconds(seconds, nanos).negated();
 462         }
 463         return ofSeconds(seconds, nanos);
 464     }
 465 
 466     //-----------------------------------------------------------------------
 467     /**
 468      * Obtains a {@code Duration} representing the duration between two temporal objects.
 469      * <p>
 470      * This calculates the duration between two temporal objects. If the objects
 471      * are of different types, then the duration is calculated based on the type
 472      * of the first object. For example, if the first argument is a {@code LocalTime}
 473      * then the second argument is converted to a {@code LocalTime}.
 474      * <p>
 475      * The specified temporal objects must support the {@link ChronoUnit#SECONDS SECONDS} unit.
 476      * For full accuracy, either the {@link ChronoUnit#NANOS NANOS} unit or the
 477      * {@link ChronoField#NANO_OF_SECOND NANO_OF_SECOND} field should be supported.
 478      * <p>
 479      * The result of this method can be a negative period if the end is before the start.
 480      * To guarantee to obtain a positive duration call {@link #abs()} on the result.
 481      *
 482      * @param startInclusive  the start instant, inclusive, not null
 483      * @param endExclusive  the end instant, exclusive, not null
 484      * @return a {@code Duration}, not null
 485      * @throws DateTimeException if the seconds between the temporals cannot be obtained
 486      * @throws ArithmeticException if the calculation exceeds the capacity of {@code Duration}
 487      */
 488     public static Duration between(Temporal startInclusive, Temporal endExclusive) {
 489         try {
 490             return ofNanos(startInclusive.until(endExclusive, NANOS));
 491         } catch (DateTimeException | ArithmeticException ex) {
 492             long secs = startInclusive.until(endExclusive, SECONDS);
 493             long nanos;
 494             try {
 495                 nanos = endExclusive.getLong(NANO_OF_SECOND) - startInclusive.getLong(NANO_OF_SECOND);
 496                 if (secs > 0 && nanos < 0) {
 497                     secs++;
 498                 } else if (secs < 0 && nanos > 0) {
 499                     secs--;
 500                 }
 501             } catch (DateTimeException ex2) {
 502                 nanos = 0;
 503             }
 504             return ofSeconds(secs, nanos);
 505         }
 506     }
 507 
 508     //-----------------------------------------------------------------------
 509     /**
 510      * Obtains an instance of {@code Duration} using seconds and nanoseconds.
 511      *
 512      * @param seconds  the length of the duration in seconds, positive or negative
 513      * @param nanoAdjustment  the nanosecond adjustment within the second, from 0 to 999,999,999
 514      */
 515     private static Duration create(long seconds, int nanoAdjustment) {
 516         if ((seconds | nanoAdjustment) == 0) {
 517             return ZERO;
 518         }
 519         return new Duration(seconds, nanoAdjustment);
 520     }
 521 
 522     /**
 523      * Constructs an instance of {@code Duration} using seconds and nanoseconds.
 524      *
 525      * @param seconds  the length of the duration in seconds, positive or negative
 526      * @param nanos  the nanoseconds within the second, from 0 to 999,999,999
 527      */
 528     private Duration(long seconds, int nanos) {
 529         this.seconds = seconds;
 530         this.nanos = nanos;
 531     }
 532 
 533     //-----------------------------------------------------------------------
 534     /**
 535      * Gets the value of the requested unit.
 536      * <p>
 537      * This returns a value for each of the two supported units,
 538      * {@link ChronoUnit#SECONDS SECONDS} and {@link ChronoUnit#NANOS NANOS}.
 539      * All other units throw an exception.
 540      *
 541      * @param unit the {@code TemporalUnit} for which to return the value
 542      * @return the long value of the unit
 543      * @throws DateTimeException if the unit is not supported
 544      * @throws UnsupportedTemporalTypeException if the unit is not supported
 545      */
 546     @Override
 547     public long get(TemporalUnit unit) {
 548         if (unit == SECONDS) {
 549             return seconds;
 550         } else if (unit == NANOS) {
 551             return nanos;
 552         } else {
 553             throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
 554         }
 555     }
 556 
 557     /**
 558      * Gets the set of units supported by this duration.
 559      * <p>
 560      * The supported units are {@link ChronoUnit#SECONDS SECONDS},
 561      * and {@link ChronoUnit#NANOS NANOS}.
 562      * They are returned in the order seconds, nanos.
 563      * <p>
 564      * This set can be used in conjunction with {@link #get(TemporalUnit)}
 565      * to access the entire state of the duration.
 566      *
 567      * @return a list containing the seconds and nanos units, not null
 568      */
 569     @Override
 570     public List<TemporalUnit> getUnits() {
 571         return DurationUnits.UNITS;
 572     }
 573 
 574     /**
 575      * Private class to delay initialization of this list until needed.
 576      * The circular dependency between Duration and ChronoUnit prevents
 577      * the simple initialization in Duration.
 578      */
 579     private static class DurationUnits {
 580         static final List<TemporalUnit> UNITS = List.of(SECONDS, NANOS);
 581     }
 582 
 583     //-----------------------------------------------------------------------
 584     /**
 585      * Checks if this duration is positive, excluding zero.
 586      * <p>
 587      * A {@code Duration} represents a directed distance between two points on
 588      * the time-line and can therefore be positive, zero or negative.
 589      * This method checks whether the length is greater than zero.
 590      *
 591      * @return true if this duration has a total length greater than zero
 592      * @since 18
 593      */
 594     public boolean isPositive() {
 595         return (seconds | nanos) > 0;
 596     }
 597 
 598     /**
 599      * Checks if this duration is zero length.
 600      * <p>
 601      * A {@code Duration} represents a directed distance between two points on
 602      * the time-line and can therefore be positive, zero or negative.
 603      * This method checks whether the length is zero.
 604      *
 605      * @return true if this duration has a total length equal to zero
 606      */
 607     public boolean isZero() {
 608         return (seconds | nanos) == 0;
 609     }
 610 
 611     /**
 612      * Checks if this duration is negative, excluding zero.
 613      * <p>
 614      * A {@code Duration} represents a directed distance between two points on
 615      * the time-line and can therefore be positive, zero or negative.
 616      * This method checks whether the length is less than zero.
 617      *
 618      * @return true if this duration has a total length less than zero
 619      */
 620     public boolean isNegative() {
 621         return seconds < 0;
 622     }
 623 
 624     //-----------------------------------------------------------------------
 625     /**
 626      * Gets the number of seconds in this duration.
 627      * <p>
 628      * The length of the duration is stored using two fields - seconds and nanoseconds.
 629      * The nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to
 630      * the length in seconds.
 631      * The total duration is defined by calling this method and {@link #getNano()}.
 632      * <p>
 633      * A {@code Duration} represents a directed distance between two points on the time-line.
 634      * A negative duration is expressed by the negative sign of the seconds part.
 635      * A duration of -1 nanosecond is stored as -1 seconds plus 999,999,999 nanoseconds.
 636      *
 637      * @return the whole seconds part of the length of the duration, positive or negative
 638      */
 639     public long getSeconds() {
 640         return seconds;
 641     }
 642 
 643     /**
 644      * Gets the number of nanoseconds within the second in this duration.
 645      * <p>
 646      * The length of the duration is stored using two fields - seconds and nanoseconds.
 647      * The nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to
 648      * the length in seconds.
 649      * The total duration is defined by calling this method and {@link #getSeconds()}.
 650      * <p>
 651      * A {@code Duration} represents a directed distance between two points on the time-line.
 652      * A negative duration is expressed by the negative sign of the seconds part.
 653      * A duration of -1 nanosecond is stored as -1 seconds plus 999,999,999 nanoseconds.
 654      *
 655      * @return the nanoseconds within the second part of the length of the duration, from 0 to 999,999,999
 656      */
 657     public int getNano() {
 658         return nanos;
 659     }
 660 
 661     //-----------------------------------------------------------------------
 662     /**
 663      * Returns a copy of this duration with the specified amount of seconds.
 664      * <p>
 665      * This returns a duration with the specified seconds, retaining the
 666      * nano-of-second part of this duration.
 667      * <p>
 668      * This instance is immutable and unaffected by this method call.
 669      *
 670      * @param seconds  the seconds to represent, may be negative
 671      * @return a {@code Duration} based on this period with the requested seconds, not null
 672      */
 673     public Duration withSeconds(long seconds) {
 674         return create(seconds, nanos);
 675     }
 676 
 677     /**
 678      * Returns a copy of this duration with the specified nano-of-second.
 679      * <p>
 680      * This returns a duration with the specified nano-of-second, retaining the
 681      * seconds part of this duration.
 682      * <p>
 683      * This instance is immutable and unaffected by this method call.
 684      *
 685      * @param nanoOfSecond  the nano-of-second to represent, from 0 to 999,999,999
 686      * @return a {@code Duration} based on this period with the requested nano-of-second, not null
 687      * @throws DateTimeException if the nano-of-second is invalid
 688      */
 689     public Duration withNanos(int nanoOfSecond) {
 690         NANO_OF_SECOND.checkValidIntValue(nanoOfSecond);
 691         return create(seconds, nanoOfSecond);
 692     }
 693 
 694     //-----------------------------------------------------------------------
 695     /**
 696      * Returns a copy of this duration with the specified duration added.
 697      * <p>
 698      * This instance is immutable and unaffected by this method call.
 699      *
 700      * @param duration  the duration to add, positive or negative, not null
 701      * @return a {@code Duration} based on this duration with the specified duration added, not null
 702      * @throws ArithmeticException if numeric overflow occurs
 703      */
 704     public Duration plus(Duration duration) {
 705         return plus(duration.getSeconds(), duration.getNano());
 706      }
 707 
 708     /**
 709      * Returns a copy of this duration with the specified duration added.
 710      * <p>
 711      * The duration amount is measured in terms of the specified unit.
 712      * Only a subset of units are accepted by this method.
 713      * The unit must either have an {@linkplain TemporalUnit#isDurationEstimated() exact duration} or
 714      * be {@link ChronoUnit#DAYS} which is treated as 24 hours. Other units throw an exception.
 715      * <p>
 716      * This instance is immutable and unaffected by this method call.
 717      *
 718      * @param amountToAdd  the amount to add, measured in terms of the unit, positive or negative
 719      * @param unit  the unit that the amount is measured in, must have an exact duration, not null
 720      * @return a {@code Duration} based on this duration with the specified duration added, not null
 721      * @throws UnsupportedTemporalTypeException if the unit is not supported
 722      * @throws ArithmeticException if numeric overflow occurs
 723      */
 724     public Duration plus(long amountToAdd, TemporalUnit unit) {
 725         Objects.requireNonNull(unit, "unit");
 726         if (unit == DAYS) {
 727             return plus(Math.multiplyExact(amountToAdd, SECONDS_PER_DAY), 0);
 728         }
 729         if (unit.isDurationEstimated()) {
 730             throw new UnsupportedTemporalTypeException("Unit must not have an estimated duration");
 731         }
 732         if (amountToAdd == 0) {
 733             return this;
 734         }
 735         if (unit instanceof ChronoUnit chronoUnit) {
 736             return switch (chronoUnit) {
 737                 case NANOS -> plusNanos(amountToAdd);
 738                 case MICROS -> plusSeconds((amountToAdd / (1000_000L * 1000)) * 1000).plusNanos((amountToAdd % (1000_000L * 1000)) * 1000);
 739                 case MILLIS -> plusMillis(amountToAdd);
 740                 case SECONDS -> plusSeconds(amountToAdd);
 741                 default -> plusSeconds(Math.multiplyExact(unit.getDuration().seconds, amountToAdd));
 742             };
 743         }
 744         Duration duration = unit.getDuration().multipliedBy(amountToAdd);
 745         return plusSeconds(duration.getSeconds()).plusNanos(duration.getNano());
 746     }
 747 
 748     //-----------------------------------------------------------------------
 749     /**
 750      * Returns a copy of this duration with the specified duration in standard 24 hour days added.
 751      * <p>
 752      * The number of days is multiplied by 86400 to obtain the number of seconds to add.
 753      * This is based on the standard definition of a day as 24 hours.
 754      * <p>
 755      * This instance is immutable and unaffected by this method call.
 756      *
 757      * @param daysToAdd  the days to add, positive or negative
 758      * @return a {@code Duration} based on this duration with the specified days added, not null
 759      * @throws ArithmeticException if numeric overflow occurs
 760      */
 761     public Duration plusDays(long daysToAdd) {
 762         return plus(Math.multiplyExact(daysToAdd, SECONDS_PER_DAY), 0);
 763     }
 764 
 765     /**
 766      * Returns a copy of this duration with the specified duration in hours added.
 767      * <p>
 768      * This instance is immutable and unaffected by this method call.
 769      *
 770      * @param hoursToAdd  the hours to add, positive or negative
 771      * @return a {@code Duration} based on this duration with the specified hours added, not null
 772      * @throws ArithmeticException if numeric overflow occurs
 773      */
 774     public Duration plusHours(long hoursToAdd) {
 775         return plus(Math.multiplyExact(hoursToAdd, SECONDS_PER_HOUR), 0);
 776     }
 777 
 778     /**
 779      * Returns a copy of this duration with the specified duration in minutes added.
 780      * <p>
 781      * This instance is immutable and unaffected by this method call.
 782      *
 783      * @param minutesToAdd  the minutes to add, positive or negative
 784      * @return a {@code Duration} based on this duration with the specified minutes added, not null
 785      * @throws ArithmeticException if numeric overflow occurs
 786      */
 787     public Duration plusMinutes(long minutesToAdd) {
 788         return plus(Math.multiplyExact(minutesToAdd, SECONDS_PER_MINUTE), 0);
 789     }
 790 
 791     /**
 792      * Returns a copy of this duration with the specified duration in seconds added.
 793      * <p>
 794      * This instance is immutable and unaffected by this method call.
 795      *
 796      * @param secondsToAdd  the seconds to add, positive or negative
 797      * @return a {@code Duration} based on this duration with the specified seconds added, not null
 798      * @throws ArithmeticException if numeric overflow occurs
 799      */
 800     public Duration plusSeconds(long secondsToAdd) {
 801         return plus(secondsToAdd, 0);
 802     }
 803 
 804     /**
 805      * Returns a copy of this duration with the specified duration in milliseconds added.
 806      * <p>
 807      * This instance is immutable and unaffected by this method call.
 808      *
 809      * @param millisToAdd  the milliseconds to add, positive or negative
 810      * @return a {@code Duration} based on this duration with the specified milliseconds added, not null
 811      * @throws ArithmeticException if numeric overflow occurs
 812      */
 813     public Duration plusMillis(long millisToAdd) {
 814         return plus(millisToAdd / 1000, (millisToAdd % 1000) * 1000_000);
 815     }
 816 
 817     /**
 818      * Returns a copy of this duration with the specified duration in nanoseconds added.
 819      * <p>
 820      * This instance is immutable and unaffected by this method call.
 821      *
 822      * @param nanosToAdd  the nanoseconds to add, positive or negative
 823      * @return a {@code Duration} based on this duration with the specified nanoseconds added, not null
 824      * @throws ArithmeticException if numeric overflow occurs
 825      */
 826     public Duration plusNanos(long nanosToAdd) {
 827         return plus(0, nanosToAdd);
 828     }
 829 
 830     /**
 831      * Returns a copy of this duration with the specified duration added.
 832      * <p>
 833      * This instance is immutable and unaffected by this method call.
 834      *
 835      * @param secondsToAdd  the seconds to add, positive or negative
 836      * @param nanosToAdd  the nanos to add, positive or negative
 837      * @return a {@code Duration} based on this duration with the specified seconds added, not null
 838      * @throws ArithmeticException if numeric overflow occurs
 839      */
 840     private Duration plus(long secondsToAdd, long nanosToAdd) {
 841         if ((secondsToAdd | nanosToAdd) == 0) {
 842             return this;
 843         }
 844         long epochSec = Math.addExact(seconds, secondsToAdd);
 845         epochSec = Math.addExact(epochSec, nanosToAdd / NANOS_PER_SECOND);
 846         nanosToAdd = nanosToAdd % NANOS_PER_SECOND;
 847         long nanoAdjustment = nanos + nanosToAdd;  // safe int+NANOS_PER_SECOND
 848         return ofSeconds(epochSec, nanoAdjustment);
 849     }
 850 
 851     //-----------------------------------------------------------------------
 852     /**
 853      * Returns a copy of this duration with the specified duration subtracted.
 854      * <p>
 855      * This instance is immutable and unaffected by this method call.
 856      *
 857      * @param duration  the duration to subtract, positive or negative, not null
 858      * @return a {@code Duration} based on this duration with the specified duration subtracted, not null
 859      * @throws ArithmeticException if numeric overflow occurs
 860      */
 861     public Duration minus(Duration duration) {
 862         long secsToSubtract = duration.getSeconds();
 863         int nanosToSubtract = duration.getNano();
 864         if (secsToSubtract == Long.MIN_VALUE) {
 865             return plus(Long.MAX_VALUE, -nanosToSubtract).plus(1, 0);
 866         }
 867         return plus(-secsToSubtract, -nanosToSubtract);
 868      }
 869 
 870     /**
 871      * Returns a copy of this duration with the specified duration subtracted.
 872      * <p>
 873      * The duration amount is measured in terms of the specified unit.
 874      * Only a subset of units are accepted by this method.
 875      * The unit must either have an {@linkplain TemporalUnit#isDurationEstimated() exact duration} or
 876      * be {@link ChronoUnit#DAYS} which is treated as 24 hours. Other units throw an exception.
 877      * <p>
 878      * This instance is immutable and unaffected by this method call.
 879      *
 880      * @param amountToSubtract  the amount to subtract, measured in terms of the unit, positive or negative
 881      * @param unit  the unit that the amount is measured in, must have an exact duration, not null
 882      * @return a {@code Duration} based on this duration with the specified duration subtracted, not null
 883      * @throws ArithmeticException if numeric overflow occurs
 884      */
 885     public Duration minus(long amountToSubtract, TemporalUnit unit) {
 886         return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
 887     }
 888 
 889     //-----------------------------------------------------------------------
 890     /**
 891      * Returns a copy of this duration with the specified duration in standard 24 hour days subtracted.
 892      * <p>
 893      * The number of days is multiplied by 86400 to obtain the number of seconds to subtract.
 894      * This is based on the standard definition of a day as 24 hours.
 895      * <p>
 896      * This instance is immutable and unaffected by this method call.
 897      *
 898      * @param daysToSubtract  the days to subtract, positive or negative
 899      * @return a {@code Duration} based on this duration with the specified days subtracted, not null
 900      * @throws ArithmeticException if numeric overflow occurs
 901      */
 902     public Duration minusDays(long daysToSubtract) {
 903         return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract));
 904     }
 905 
 906     /**
 907      * Returns a copy of this duration with the specified duration in hours subtracted.
 908      * <p>
 909      * The number of hours is multiplied by 3600 to obtain the number of seconds to subtract.
 910      * <p>
 911      * This instance is immutable and unaffected by this method call.
 912      *
 913      * @param hoursToSubtract  the hours to subtract, positive or negative
 914      * @return a {@code Duration} based on this duration with the specified hours subtracted, not null
 915      * @throws ArithmeticException if numeric overflow occurs
 916      */
 917     public Duration minusHours(long hoursToSubtract) {
 918         return (hoursToSubtract == Long.MIN_VALUE ? plusHours(Long.MAX_VALUE).plusHours(1) : plusHours(-hoursToSubtract));
 919     }
 920 
 921     /**
 922      * Returns a copy of this duration with the specified duration in minutes subtracted.
 923      * <p>
 924      * The number of hours is multiplied by 60 to obtain the number of seconds to subtract.
 925      * <p>
 926      * This instance is immutable and unaffected by this method call.
 927      *
 928      * @param minutesToSubtract  the minutes to subtract, positive or negative
 929      * @return a {@code Duration} based on this duration with the specified minutes subtracted, not null
 930      * @throws ArithmeticException if numeric overflow occurs
 931      */
 932     public Duration minusMinutes(long minutesToSubtract) {
 933         return (minutesToSubtract == Long.MIN_VALUE ? plusMinutes(Long.MAX_VALUE).plusMinutes(1) : plusMinutes(-minutesToSubtract));
 934     }
 935 
 936     /**
 937      * Returns a copy of this duration with the specified duration in seconds subtracted.
 938      * <p>
 939      * This instance is immutable and unaffected by this method call.
 940      *
 941      * @param secondsToSubtract  the seconds to subtract, positive or negative
 942      * @return a {@code Duration} based on this duration with the specified seconds subtracted, not null
 943      * @throws ArithmeticException if numeric overflow occurs
 944      */
 945     public Duration minusSeconds(long secondsToSubtract) {
 946         return (secondsToSubtract == Long.MIN_VALUE ? plusSeconds(Long.MAX_VALUE).plusSeconds(1) : plusSeconds(-secondsToSubtract));
 947     }
 948 
 949     /**
 950      * Returns a copy of this duration with the specified duration in milliseconds subtracted.
 951      * <p>
 952      * This instance is immutable and unaffected by this method call.
 953      *
 954      * @param millisToSubtract  the milliseconds to subtract, positive or negative
 955      * @return a {@code Duration} based on this duration with the specified milliseconds subtracted, not null
 956      * @throws ArithmeticException if numeric overflow occurs
 957      */
 958     public Duration minusMillis(long millisToSubtract) {
 959         return (millisToSubtract == Long.MIN_VALUE ? plusMillis(Long.MAX_VALUE).plusMillis(1) : plusMillis(-millisToSubtract));
 960     }
 961 
 962     /**
 963      * Returns a copy of this duration with the specified duration in nanoseconds subtracted.
 964      * <p>
 965      * This instance is immutable and unaffected by this method call.
 966      *
 967      * @param nanosToSubtract  the nanoseconds to subtract, positive or negative
 968      * @return a {@code Duration} based on this duration with the specified nanoseconds subtracted, not null
 969      * @throws ArithmeticException if numeric overflow occurs
 970      */
 971     public Duration minusNanos(long nanosToSubtract) {
 972         return (nanosToSubtract == Long.MIN_VALUE ? plusNanos(Long.MAX_VALUE).plusNanos(1) : plusNanos(-nanosToSubtract));
 973     }
 974 
 975     //-----------------------------------------------------------------------
 976     /**
 977      * Returns a copy of this duration multiplied by the scalar.
 978      * <p>
 979      * This instance is immutable and unaffected by this method call.
 980      *
 981      * @param multiplicand  the value to multiply the duration by, positive or negative
 982      * @return a {@code Duration} based on this duration multiplied by the specified scalar, not null
 983      * @throws ArithmeticException if numeric overflow occurs
 984      */
 985     public Duration multipliedBy(long multiplicand) {
 986         if (multiplicand == 0) {
 987             return ZERO;
 988         }
 989         if (multiplicand == 1) {
 990             return this;
 991         }
 992         return create(toBigDecimalSeconds().multiply(BigDecimal.valueOf(multiplicand)));
 993      }
 994 
 995     /**
 996      * Returns a copy of this duration divided by the specified value.
 997      * <p>
 998      * This instance is immutable and unaffected by this method call.
 999      *
1000      * @param divisor  the value to divide the duration by, positive or negative, not zero
1001      * @return a {@code Duration} based on this duration divided by the specified divisor, not null
1002      * @throws ArithmeticException if the divisor is zero or if numeric overflow occurs
1003      */
1004     public Duration dividedBy(long divisor) {
1005         if (divisor == 0) {
1006             throw new ArithmeticException("Cannot divide by zero");
1007         }
1008         if (divisor == 1) {
1009             return this;
1010         }
1011         return create(toBigDecimalSeconds().divide(BigDecimal.valueOf(divisor), RoundingMode.DOWN));
1012      }
1013 
1014     /**
1015      * Returns number of whole times a specified Duration occurs within this Duration.
1016      * <p>
1017      * This instance is immutable and unaffected by this method call.
1018      *
1019      * @param divisor the value to divide the duration by, positive or negative, not null
1020      * @return number of whole times, rounded toward zero, a specified
1021      *         {@code Duration} occurs within this Duration, may be negative
1022      * @throws ArithmeticException if the divisor is zero, or if numeric overflow occurs
1023      * @since 9
1024      */
1025     public long dividedBy(Duration divisor) {
1026         Objects.requireNonNull(divisor, "divisor");
1027         BigDecimal dividendBigD = toBigDecimalSeconds();
1028         BigDecimal divisorBigD = divisor.toBigDecimalSeconds();
1029         return dividendBigD.divideToIntegralValue(divisorBigD).longValueExact();
1030     }
1031 
1032     /**
1033      * Converts this duration to the total length in seconds and
1034      * fractional nanoseconds expressed as a {@code BigDecimal}.
1035      *
1036      * @return the total length of the duration in seconds, with a scale of 9, not null
1037      */
1038     private BigDecimal toBigDecimalSeconds() {
1039         return BigDecimal.valueOf(seconds).add(BigDecimal.valueOf(nanos, 9));
1040     }
1041 
1042     /**
1043      * Creates an instance of {@code Duration} from a number of seconds.
1044      *
1045      * @param seconds  the number of seconds, up to scale 9, positive or negative
1046      * @return a {@code Duration}, not null
1047      * @throws ArithmeticException if numeric overflow occurs
1048      */
1049     private static Duration create(BigDecimal seconds) {
1050         BigInteger nanos = seconds.movePointRight(9).toBigIntegerExact();
1051         BigInteger[] divRem = nanos.divideAndRemainder(BI_NANOS_PER_SECOND);
1052         if (divRem[0].bitLength() > 63) {
1053             throw new ArithmeticException("Exceeds capacity of Duration: " + nanos);
1054         }
1055         return ofSeconds(divRem[0].longValue(), divRem[1].intValue());
1056     }
1057 
1058     //-----------------------------------------------------------------------
1059     /**
1060      * Returns a copy of this duration with the length negated.
1061      * <p>
1062      * This method swaps the sign of the total length of this duration.
1063      * For example, {@code PT1.3S} will be returned as {@code PT-1.3S}.
1064      * <p>
1065      * This instance is immutable and unaffected by this method call.
1066      *
1067      * @return a {@code Duration} based on this duration with the amount negated, not null
1068      * @throws ArithmeticException if numeric overflow occurs
1069      */
1070     public Duration negated() {
1071         return multipliedBy(-1);
1072     }
1073 
1074     /**
1075      * Returns a copy of this duration with a positive length.
1076      * <p>
1077      * This method returns a positive duration by effectively removing the sign from any negative total length.
1078      * For example, {@code PT-1.3S} will be returned as {@code PT1.3S}.
1079      * <p>
1080      * This instance is immutable and unaffected by this method call.
1081      *
1082      * @return a {@code Duration} based on this duration with an absolute length, not null
1083      * @throws ArithmeticException if numeric overflow occurs
1084      */
1085     public Duration abs() {
1086         return isNegative() ? negated() : this;
1087     }
1088 
1089     //-------------------------------------------------------------------------
1090     /**
1091      * Adds this duration to the specified temporal object.
1092      * <p>
1093      * This returns a temporal object of the same observable type as the input
1094      * with this duration added.
1095      * <p>
1096      * In most cases, it is clearer to reverse the calling pattern by using
1097      * {@link Temporal#plus(TemporalAmount)}.
1098      * <pre>
1099      *   // these two lines are equivalent, but the second approach is recommended
1100      *   dateTime = thisDuration.addTo(dateTime);
1101      *   dateTime = dateTime.plus(thisDuration);
1102      * </pre>
1103      * <p>
1104      * The calculation will add the seconds, then nanos.
1105      * Only non-zero amounts will be added.
1106      * <p>
1107      * This instance is immutable and unaffected by this method call.
1108      *
1109      * @param temporal  the temporal object to adjust, not null
1110      * @return an object of the same type with the adjustment made, not null
1111      * @throws DateTimeException if unable to add
1112      * @throws ArithmeticException if numeric overflow occurs
1113      */
1114     @Override
1115     public Temporal addTo(Temporal temporal) {
1116         if (seconds != 0) {
1117             temporal = temporal.plus(seconds, SECONDS);
1118         }
1119         if (nanos != 0) {
1120             temporal = temporal.plus(nanos, NANOS);
1121         }
1122         return temporal;
1123     }
1124 
1125     /**
1126      * Subtracts this duration from the specified temporal object.
1127      * <p>
1128      * This returns a temporal object of the same observable type as the input
1129      * with this duration subtracted.
1130      * <p>
1131      * In most cases, it is clearer to reverse the calling pattern by using
1132      * {@link Temporal#minus(TemporalAmount)}.
1133      * <pre>
1134      *   // these two lines are equivalent, but the second approach is recommended
1135      *   dateTime = thisDuration.subtractFrom(dateTime);
1136      *   dateTime = dateTime.minus(thisDuration);
1137      * </pre>
1138      * <p>
1139      * The calculation will subtract the seconds, then nanos.
1140      * Only non-zero amounts will be added.
1141      * <p>
1142      * This instance is immutable and unaffected by this method call.
1143      *
1144      * @param temporal  the temporal object to adjust, not null
1145      * @return an object of the same type with the adjustment made, not null
1146      * @throws DateTimeException if unable to subtract
1147      * @throws ArithmeticException if numeric overflow occurs
1148      */
1149     @Override
1150     public Temporal subtractFrom(Temporal temporal) {
1151         if (seconds != 0) {
1152             temporal = temporal.minus(seconds, SECONDS);
1153         }
1154         if (nanos != 0) {
1155             temporal = temporal.minus(nanos, NANOS);
1156         }
1157         return temporal;
1158     }
1159 
1160     //-----------------------------------------------------------------------
1161     /**
1162      * Gets the number of days in this duration.
1163      * <p>
1164      * This returns the total number of days in the duration by dividing the
1165      * number of seconds by 86400.
1166      * This is based on the standard definition of a day as 24 hours.
1167      * <p>
1168      * This instance is immutable and unaffected by this method call.
1169      *
1170      * @return the number of days in the duration, may be negative
1171      */
1172     public long toDays() {
1173         return seconds / SECONDS_PER_DAY;
1174     }
1175 
1176     /**
1177      * Gets the number of hours in this duration.
1178      * <p>
1179      * This returns the total number of hours in the duration by dividing the
1180      * number of seconds by 3600.
1181      * <p>
1182      * This instance is immutable and unaffected by this method call.
1183      *
1184      * @return the number of hours in the duration, may be negative
1185      */
1186     public long toHours() {
1187         return seconds / SECONDS_PER_HOUR;
1188     }
1189 
1190     /**
1191      * Gets the number of minutes in this duration.
1192      * <p>
1193      * This returns the total number of minutes in the duration by dividing the
1194      * number of seconds by 60.
1195      * <p>
1196      * This instance is immutable and unaffected by this method call.
1197      *
1198      * @return the number of minutes in the duration, may be negative
1199      */
1200     public long toMinutes() {
1201         return seconds / SECONDS_PER_MINUTE;
1202     }
1203 
1204     /**
1205      * Gets the number of seconds in this duration.
1206      * <p>
1207      * This returns the total number of whole seconds in the duration.
1208      * <p>
1209      * This instance is immutable and unaffected by this method call.
1210      *
1211      * @return the whole seconds part of the length of the duration, positive or negative
1212      * @since 9
1213      */
1214     public long toSeconds() {
1215         return seconds;
1216     }
1217 
1218     /**
1219      * Converts this duration to the total length in milliseconds.
1220      * <p>
1221      * If this duration is too large to fit in a {@code long} milliseconds, then an
1222      * exception is thrown.
1223      * <p>
1224      * If this duration has greater than millisecond precision, then the conversion
1225      * will drop any excess precision information as though the amount in nanoseconds
1226      * was subject to integer division by one million.
1227      *
1228      * @return the total length of the duration in milliseconds
1229      * @throws ArithmeticException if numeric overflow occurs
1230      */
1231     public long toMillis() {
1232         long tempSeconds = seconds;
1233         long tempNanos = nanos;
1234         if (tempSeconds < 0) {
1235             // change the seconds and nano value to
1236             // handle Long.MIN_VALUE case
1237             tempSeconds = tempSeconds + 1;
1238             tempNanos = tempNanos - NANOS_PER_SECOND;
1239         }
1240         long millis = Math.multiplyExact(tempSeconds, 1000);
1241         millis = Math.addExact(millis, tempNanos / NANOS_PER_MILLI);
1242         return millis;
1243     }
1244 
1245     /**
1246      * Converts this duration to the total length in nanoseconds expressed as a {@code long}.
1247      * <p>
1248      * If this duration is too large to fit in a {@code long} nanoseconds, then an
1249      * exception is thrown.
1250      *
1251      * @return the total length of the duration in nanoseconds
1252      * @throws ArithmeticException if numeric overflow occurs
1253      */
1254     public long toNanos() {
1255         long tempSeconds = seconds;
1256         long tempNanos = nanos;
1257         if (tempSeconds < 0) {
1258             // change the seconds and nano value to
1259             // handle Long.MIN_VALUE case
1260             tempSeconds = tempSeconds + 1;
1261             tempNanos = tempNanos - NANOS_PER_SECOND;
1262         }
1263         long totalNanos = Math.multiplyExact(tempSeconds, NANOS_PER_SECOND);
1264         totalNanos = Math.addExact(totalNanos, tempNanos);
1265         return totalNanos;
1266     }
1267 
1268     /**
1269      * Extracts the number of days in the duration.
1270      * <p>
1271      * This returns the total number of days in the duration by dividing the
1272      * number of seconds by 86400.
1273      * This is based on the standard definition of a day as 24 hours.
1274      * <p>
1275      * This instance is immutable and unaffected by this method call.
1276      * @apiNote
1277      * This method behaves exactly the same way as {@link #toDays()}.
1278      *
1279      * @return the number of days in the duration, may be negative
1280      * @since 9
1281      */
1282     public long toDaysPart(){
1283         return seconds / SECONDS_PER_DAY;
1284     }
1285 
1286     /**
1287      * Extracts the number of hours part in the duration.
1288      * <p>
1289      * This returns the number of remaining hours when dividing {@link #toHours}
1290      * by hours in a day.
1291      * This is based on the standard definition of a day as 24 hours.
1292      * <p>
1293      * This instance is immutable and unaffected by this method call.
1294      *
1295      * @return the number of hours part in the duration, may be negative
1296      * @since 9
1297      */
1298     public int toHoursPart(){
1299         return (int) (toHours() % 24);
1300     }
1301 
1302     /**
1303      * Extracts the number of minutes part in the duration.
1304      * <p>
1305      * This returns the number of remaining minutes when dividing {@link #toMinutes}
1306      * by minutes in an hour.
1307      * This is based on the standard definition of an hour as 60 minutes.
1308      * <p>
1309      * This instance is immutable and unaffected by this method call.
1310      *
1311      * @return the number of minutes parts in the duration, may be negative
1312      * @since 9
1313      */
1314     public int toMinutesPart(){
1315         return (int) (toMinutes() % MINUTES_PER_HOUR);
1316     }
1317 
1318     /**
1319      * Extracts the number of seconds part in the duration.
1320      * <p>
1321      * This returns the remaining seconds when dividing {@link #toSeconds}
1322      * by seconds in a minute.
1323      * This is based on the standard definition of a minute as 60 seconds.
1324      * <p>
1325      * This instance is immutable and unaffected by this method call.
1326      *
1327      * @return the number of seconds parts in the duration, may be negative
1328      * @since 9
1329      */
1330     public int toSecondsPart(){
1331         return (int) (seconds % SECONDS_PER_MINUTE);
1332     }
1333 
1334     /**
1335      * Extracts the number of milliseconds part of the duration.
1336      * <p>
1337      * This returns the milliseconds part by dividing the number of nanoseconds by 1,000,000.
1338      * The length of the duration is stored using two fields - seconds and nanoseconds.
1339      * The nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to
1340      * the length in seconds.
1341      * The total duration is defined by calling {@link #getNano()} and {@link #getSeconds()}.
1342      * <p>
1343      * This instance is immutable and unaffected by this method call.
1344      *
1345      * @return the number of milliseconds part of the duration.
1346      * @since 9
1347      */
1348     public int toMillisPart(){
1349         return nanos / 1000_000;
1350     }
1351 
1352     /**
1353      * Get the nanoseconds part within seconds of the duration.
1354      * <p>
1355      * The length of the duration is stored using two fields - seconds and nanoseconds.
1356      * The nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to
1357      * the length in seconds.
1358      * The total duration is defined by calling {@link #getNano()} and {@link #getSeconds()}.
1359      * <p>
1360      * This instance is immutable and unaffected by this method call.
1361      *
1362      * @return the nanoseconds within the second part of the length of the duration, from 0 to 999,999,999
1363      * @since 9
1364      */
1365     public int toNanosPart(){
1366         return nanos;
1367     }
1368 
1369 
1370     //-----------------------------------------------------------------------
1371     /**
1372      * Returns a copy of this {@code Duration} truncated to the specified unit.
1373      * <p>
1374      * Truncating the duration returns a copy of the original with conceptual fields
1375      * smaller than the specified unit set to zero.
1376      * For example, truncating with the {@link ChronoUnit#MINUTES MINUTES} unit will
1377      * round down towards zero to the nearest minute, setting the seconds and
1378      * nanoseconds to zero.
1379      * <p>
1380      * The unit must have a {@linkplain TemporalUnit#getDuration() duration}
1381      * that divides into the length of a standard day without remainder.
1382      * This includes all
1383      * {@linkplain ChronoUnit#isTimeBased() time-based units on {@code ChronoUnit}}
1384      * and {@link ChronoUnit#DAYS DAYS}. Other ChronoUnits throw an exception.
1385      * <p>
1386      * This instance is immutable and unaffected by this method call.
1387      *
1388      * @param unit the unit to truncate to, not null
1389      * @return a {@code Duration} based on this duration with the time truncated, not null
1390      * @throws DateTimeException if the unit is invalid for truncation
1391      * @throws UnsupportedTemporalTypeException if the unit is not supported
1392      * @since 9
1393      */
1394     public Duration truncatedTo(TemporalUnit unit) {
1395         Objects.requireNonNull(unit, "unit");
1396         if (unit == ChronoUnit.SECONDS && (seconds >= 0 || nanos == 0)) {
1397             return new Duration(seconds, 0);
1398         } else if (unit == ChronoUnit.NANOS) {
1399             return this;
1400         }
1401         Duration unitDur = unit.getDuration();
1402         if (unitDur.getSeconds() > LocalTime.SECONDS_PER_DAY) {
1403             throw new UnsupportedTemporalTypeException("Unit is too large to be used for truncation");
1404         }
1405         long dur = unitDur.toNanos();
1406         if ((LocalTime.NANOS_PER_DAY % dur) != 0) {
1407             throw new UnsupportedTemporalTypeException("Unit must divide into a standard day without remainder");
1408         }
1409         long nod = (seconds % LocalTime.SECONDS_PER_DAY) * LocalTime.NANOS_PER_SECOND + nanos;
1410         long result = (nod / dur) * dur;
1411         return plusNanos(result - nod);
1412     }
1413 
1414     //-----------------------------------------------------------------------
1415     /**
1416      * Compares this duration to the specified {@code Duration}.
1417      * <p>
1418      * The comparison is based on the total length of the durations.
1419      * It is "consistent with equals", as defined by {@link Comparable}.
1420      *
1421      * @param otherDuration the other duration to compare to, not null
1422      * @return the comparator value, negative if less, positive if greater
1423      */
1424     @Override
1425     public int compareTo(Duration otherDuration) {
1426         int cmp = Long.compare(seconds, otherDuration.seconds);
1427         if (cmp != 0) {
1428             return cmp;
1429         }
1430         return nanos - otherDuration.nanos;
1431     }
1432 
1433     //-----------------------------------------------------------------------
1434     /**
1435      * Checks if this duration is equal to the specified {@code Duration}.
1436      * <p>
1437      * The comparison is based on the total length of the durations.
1438      *
1439      * @param other the other duration, null returns false
1440      * @return true if the other duration is equal to this one
1441      */
1442     @Override
1443     public boolean equals(Object other) {
1444         if (this == other) {
1445             return true;
1446         }
1447         return (other instanceof Duration otherDuration)
1448                 && this.seconds == otherDuration.seconds
1449                 && this.nanos == otherDuration.nanos;
1450     }
1451 
1452     /**
1453      * A hash code for this duration.
1454      *
1455      * @return a suitable hash code
1456      */
1457     @Override
1458     public int hashCode() {
1459         return ((int) (seconds ^ (seconds >>> 32))) + (51 * nanos);
1460     }
1461 
1462     //-----------------------------------------------------------------------
1463     /**
1464      * A string representation of this duration using ISO-8601 seconds
1465      * based representation, such as {@code PT8H6M12.345S}.
1466      * <p>
1467      * The format of the returned string will be {@code PTnHnMnS}, where n is
1468      * the relevant hours, minutes or seconds part of the duration.
1469      * Any fractional seconds are placed after a decimal point in the seconds section.
1470      * If a section has a zero value, it is omitted.
1471      * The hours, minutes and seconds will all have the same sign.
1472      * <p>
1473      * Examples:
1474      * <pre>
1475      *    "20.345 seconds"                 -- "PT20.345S
1476      *    "15 minutes" (15 * 60 seconds)   -- "PT15M"
1477      *    "10 hours" (10 * 3600 seconds)   -- "PT10H"
1478      *    "2 days" (2 * 86400 seconds)     -- "PT48H"
1479      * </pre>
1480      * Note that multiples of 24 hours are not output as days to avoid confusion
1481      * with {@code Period}.
1482      *
1483      * @return an ISO-8601 representation of this duration, not null
1484      */
1485     @Override
1486     public String toString() {
1487         if (this == ZERO) {
1488             return "PT0S";
1489         }
1490         long effectiveTotalSecs = seconds;
1491         if (seconds < 0 && nanos > 0) {
1492             effectiveTotalSecs++;
1493         }
1494         long hours = effectiveTotalSecs / SECONDS_PER_HOUR;
1495         int minutes = (int) ((effectiveTotalSecs % SECONDS_PER_HOUR) / SECONDS_PER_MINUTE);
1496         int secs = (int) (effectiveTotalSecs % SECONDS_PER_MINUTE);
1497         StringBuilder buf = new StringBuilder(24);
1498         buf.append("PT");
1499         if (hours != 0) {
1500             buf.append(hours).append('H');
1501         }
1502         if (minutes != 0) {
1503             buf.append(minutes).append('M');
1504         }
1505         if (secs == 0 && nanos == 0 && buf.length() > 2) {
1506             return buf.toString();
1507         }
1508         if (seconds < 0 && nanos > 0) {
1509             if (secs == 0) {
1510                 buf.append("-0");
1511             } else {
1512                 buf.append(secs);
1513             }
1514         } else {
1515             buf.append(secs);
1516         }
1517         if (nanos > 0) {
1518             int pos = buf.length();
1519             if (seconds < 0) {
1520                 buf.append(2 * NANOS_PER_SECOND - nanos);
1521             } else {
1522                 buf.append(nanos + NANOS_PER_SECOND);
1523             }
1524             while (buf.charAt(buf.length() - 1) == '0') {
1525                 buf.setLength(buf.length() - 1);
1526             }
1527             buf.setCharAt(pos, '.');
1528         }
1529         buf.append('S');
1530         return buf.toString();
1531     }
1532 
1533     //-----------------------------------------------------------------------
1534     /**
1535      * Writes the object using a
1536      * <a href="{@docRoot}/serialized-form.html#java.time.Ser">dedicated serialized form</a>.
1537      * @serialData
1538      * <pre>
1539      *  out.writeByte(1);  // identifies a Duration
1540      *  out.writeLong(seconds);
1541      *  out.writeInt(nanos);
1542      * </pre>
1543      *
1544      * @return the instance of {@code Ser}, not null
1545      */
1546     @java.io.Serial
1547     private Object writeReplace() {
1548         return new Ser(Ser.DURATION_TYPE, this);
1549     }
1550 
1551     /**
1552      * Defend against malicious streams.
1553      *
1554      * @param s the stream to read
1555      * @throws InvalidObjectException always
1556      */
1557     @java.io.Serial
1558     private void readObject(ObjectInputStream s) throws InvalidObjectException {
1559         throw new InvalidObjectException("Deserialization via serialization delegate");
1560     }
1561 
1562     void writeExternal(DataOutput out) throws IOException {
1563         out.writeLong(seconds);
1564         out.writeInt(nanos);
1565     }
1566 
1567     static Duration readExternal(DataInput in) throws IOException {
1568         long seconds = in.readLong();
1569         int nanos = in.readInt();
1570         return Duration.ofSeconds(seconds, nanos);
1571     }
1572 
1573 }