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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.
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61  */
62 package java.time.chrono;
63 
64 import static java.time.temporal.ChronoField.INSTANT_SECONDS;
65 import static java.time.temporal.ChronoField.OFFSET_SECONDS;
66 import static java.time.temporal.ChronoUnit.FOREVER;
67 import static java.time.temporal.ChronoUnit.NANOS;
68 
69 import java.time.DateTimeException;
70 import java.time.Instant;
71 import java.time.LocalTime;
72 import java.time.ZoneId;
73 import java.time.ZoneOffset;
74 import java.time.ZonedDateTime;
75 import java.time.format.DateTimeFormatter;
76 import java.time.temporal.ChronoField;
77 import java.time.temporal.ChronoUnit;
78 import java.time.temporal.Temporal;
79 import java.time.temporal.TemporalAccessor;
80 import java.time.temporal.TemporalAdjuster;
81 import java.time.temporal.TemporalAmount;
82 import java.time.temporal.TemporalField;
83 import java.time.temporal.TemporalQueries;
84 import java.time.temporal.TemporalQuery;
85 import java.time.temporal.TemporalUnit;
86 import java.time.temporal.UnsupportedTemporalTypeException;
87 import java.time.temporal.ValueRange;
88 import java.util.Comparator;
89 import java.util.Objects;
90 
91 /**
92  * A date-time with a time-zone in an arbitrary chronology,
93  * intended for advanced globalization use cases.
94  * <p>
95  * <b>Most applications should declare method signatures, fields and variables
96  * as {@link ZonedDateTime}, not this interface.</b>
97  * <p>
98  * A {@code ChronoZonedDateTime} is the abstract representation of an offset date-time
99  * where the {@code Chronology chronology}, or calendar system, is pluggable.
100  * The date-time is defined in terms of fields expressed by {@link TemporalField},
101  * where most common implementations are defined in {@link ChronoField}.
102  * The chronology defines how the calendar system operates and the meaning of
103  * the standard fields.
104  *
105  * <h3>When to use this interface</h3>
106  * The design of the API encourages the use of {@code ZonedDateTime} rather than this
107  * interface, even in the case where the application needs to deal with multiple
108  * calendar systems. The rationale for this is explored in detail in {@link ChronoLocalDate}.
109  * <p>
110  * Ensure that the discussion in {@code ChronoLocalDate} has been read and understood
111  * before using this interface.
112  *
113  * @implSpec
114  * This interface must be implemented with care to ensure other classes operate correctly.
115  * All implementations that can be instantiated must be final, immutable and thread-safe.
116  * Subclasses should be Serializable wherever possible.
117  *
118  * @param <D> the concrete type for the date of this date-time
119  * @since 1.8
120  */
121 public interface ChronoZonedDateTime<D extends ChronoLocalDate>
122         extends Temporal, Comparable<ChronoZonedDateTime<?>> {
123 
124     /**
125      * Gets a comparator that compares {@code ChronoZonedDateTime} in
126      * time-line order ignoring the chronology.
127      * <p>
128      * This comparator differs from the comparison in {@link #compareTo} in that it
129      * only compares the underlying instant and not the chronology.
130      * This allows dates in different calendar systems to be compared based
131      * on the position of the date-time on the instant time-line.
132      * The underlying comparison is equivalent to comparing the epoch-second and nano-of-second.
133      *
134      * @return a comparator that compares in time-line order ignoring the chronology
135      * @see #isAfter
136      * @see #isBefore
137      * @see #isEqual
138      */
timeLineOrder()139     static Comparator<ChronoZonedDateTime<?>> timeLineOrder() {
140         return AbstractChronology.INSTANT_ORDER;
141     }
142 
143     //-----------------------------------------------------------------------
144     /**
145      * Obtains an instance of {@code ChronoZonedDateTime} from a temporal object.
146      * <p>
147      * This creates a zoned date-time based on the specified temporal.
148      * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
149      * which this factory converts to an instance of {@code ChronoZonedDateTime}.
150      * <p>
151      * The conversion extracts and combines the chronology, date, time and zone
152      * from the temporal object. The behavior is equivalent to using
153      * {@link Chronology#zonedDateTime(TemporalAccessor)} with the extracted chronology.
154      * Implementations are permitted to perform optimizations such as accessing
155      * those fields that are equivalent to the relevant objects.
156      * <p>
157      * This method matches the signature of the functional interface {@link TemporalQuery}
158      * allowing it to be used as a query via method reference, {@code ChronoZonedDateTime::from}.
159      *
160      * @param temporal  the temporal object to convert, not null
161      * @return the date-time, not null
162      * @throws DateTimeException if unable to convert to a {@code ChronoZonedDateTime}
163      * @see Chronology#zonedDateTime(TemporalAccessor)
164      */
from(TemporalAccessor temporal)165     static ChronoZonedDateTime<?> from(TemporalAccessor temporal) {
166         if (temporal instanceof ChronoZonedDateTime) {
167             return (ChronoZonedDateTime<?>) temporal;
168         }
169         Objects.requireNonNull(temporal, "temporal");
170         Chronology chrono = temporal.query(TemporalQueries.chronology());
171         if (chrono == null) {
172             throw new DateTimeException("Unable to obtain ChronoZonedDateTime from TemporalAccessor: " + temporal.getClass());
173         }
174         return chrono.zonedDateTime(temporal);
175     }
176 
177     //-----------------------------------------------------------------------
178     @Override
range(TemporalField field)179     default ValueRange range(TemporalField field) {
180         if (field instanceof ChronoField) {
181             if (field == INSTANT_SECONDS || field == OFFSET_SECONDS) {
182                 return field.range();
183             }
184             return toLocalDateTime().range(field);
185         }
186         return field.rangeRefinedBy(this);
187     }
188 
189     @Override
get(TemporalField field)190     default int get(TemporalField field) {
191         if (field instanceof ChronoField) {
192             switch ((ChronoField) field) {
193                 case INSTANT_SECONDS:
194                     throw new UnsupportedTemporalTypeException("Invalid field 'InstantSeconds' for get() method, use getLong() instead");
195                 case OFFSET_SECONDS:
196                     return getOffset().getTotalSeconds();
197             }
198             return toLocalDateTime().get(field);
199         }
200         return Temporal.super.get(field);
201     }
202 
203     @Override
getLong(TemporalField field)204     default long getLong(TemporalField field) {
205         if (field instanceof ChronoField) {
206             switch ((ChronoField) field) {
207                 case INSTANT_SECONDS: return toEpochSecond();
208                 case OFFSET_SECONDS: return getOffset().getTotalSeconds();
209             }
210             return toLocalDateTime().getLong(field);
211         }
212         return field.getFrom(this);
213     }
214 
215     /**
216      * Gets the local date part of this date-time.
217      * <p>
218      * This returns a local date with the same year, month and day
219      * as this date-time.
220      *
221      * @return the date part of this date-time, not null
222      */
toLocalDate()223     default D toLocalDate() {
224         return toLocalDateTime().toLocalDate();
225     }
226 
227     /**
228      * Gets the local time part of this date-time.
229      * <p>
230      * This returns a local time with the same hour, minute, second and
231      * nanosecond as this date-time.
232      *
233      * @return the time part of this date-time, not null
234      */
toLocalTime()235     default LocalTime toLocalTime() {
236         return toLocalDateTime().toLocalTime();
237     }
238 
239     /**
240      * Gets the local date-time part of this date-time.
241      * <p>
242      * This returns a local date with the same year, month and day
243      * as this date-time.
244      *
245      * @return the local date-time part of this date-time, not null
246      */
toLocalDateTime()247     ChronoLocalDateTime<D> toLocalDateTime();
248 
249     /**
250      * Gets the chronology of this date-time.
251      * <p>
252      * The {@code Chronology} represents the calendar system in use.
253      * The era and other fields in {@link ChronoField} are defined by the chronology.
254      *
255      * @return the chronology, not null
256      */
getChronology()257     default Chronology getChronology() {
258         return toLocalDate().getChronology();
259     }
260 
261     /**
262      * Gets the zone offset, such as '+01:00'.
263      * <p>
264      * This is the offset of the local date-time from UTC/Greenwich.
265      *
266      * @return the zone offset, not null
267      */
getOffset()268     ZoneOffset getOffset();
269 
270     /**
271      * Gets the zone ID, such as 'Europe/Paris'.
272      * <p>
273      * This returns the stored time-zone id used to determine the time-zone rules.
274      *
275      * @return the zone ID, not null
276      */
getZone()277     ZoneId getZone();
278 
279     //-----------------------------------------------------------------------
280     /**
281      * Returns a copy of this date-time changing the zone offset to the
282      * earlier of the two valid offsets at a local time-line overlap.
283      * <p>
284      * This method only has any effect when the local time-line overlaps, such as
285      * at an autumn daylight savings cutover. In this scenario, there are two
286      * valid offsets for the local date-time. Calling this method will return
287      * a zoned date-time with the earlier of the two selected.
288      * <p>
289      * If this method is called when it is not an overlap, {@code this}
290      * is returned.
291      * <p>
292      * This instance is immutable and unaffected by this method call.
293      *
294      * @return a {@code ChronoZonedDateTime} based on this date-time with the earlier offset, not null
295      * @throws DateTimeException if no rules can be found for the zone
296      * @throws DateTimeException if no rules are valid for this date-time
297      */
withEarlierOffsetAtOverlap()298     ChronoZonedDateTime<D> withEarlierOffsetAtOverlap();
299 
300     /**
301      * Returns a copy of this date-time changing the zone offset to the
302      * later of the two valid offsets at a local time-line overlap.
303      * <p>
304      * This method only has any effect when the local time-line overlaps, such as
305      * at an autumn daylight savings cutover. In this scenario, there are two
306      * valid offsets for the local date-time. Calling this method will return
307      * a zoned date-time with the later of the two selected.
308      * <p>
309      * If this method is called when it is not an overlap, {@code this}
310      * is returned.
311      * <p>
312      * This instance is immutable and unaffected by this method call.
313      *
314      * @return a {@code ChronoZonedDateTime} based on this date-time with the later offset, not null
315      * @throws DateTimeException if no rules can be found for the zone
316      * @throws DateTimeException if no rules are valid for this date-time
317      */
withLaterOffsetAtOverlap()318     ChronoZonedDateTime<D> withLaterOffsetAtOverlap();
319 
320     /**
321      * Returns a copy of this date-time with a different time-zone,
322      * retaining the local date-time if possible.
323      * <p>
324      * This method changes the time-zone and retains the local date-time.
325      * The local date-time is only changed if it is invalid for the new zone.
326      * <p>
327      * To change the zone and adjust the local date-time,
328      * use {@link #withZoneSameInstant(ZoneId)}.
329      * <p>
330      * This instance is immutable and unaffected by this method call.
331      *
332      * @param zone  the time-zone to change to, not null
333      * @return a {@code ChronoZonedDateTime} based on this date-time with the requested zone, not null
334      */
withZoneSameLocal(ZoneId zone)335     ChronoZonedDateTime<D> withZoneSameLocal(ZoneId zone);
336 
337     /**
338      * Returns a copy of this date-time with a different time-zone,
339      * retaining the instant.
340      * <p>
341      * This method changes the time-zone and retains the instant.
342      * This normally results in a change to the local date-time.
343      * <p>
344      * This method is based on retaining the same instant, thus gaps and overlaps
345      * in the local time-line have no effect on the result.
346      * <p>
347      * To change the offset while keeping the local time,
348      * use {@link #withZoneSameLocal(ZoneId)}.
349      *
350      * @param zone  the time-zone to change to, not null
351      * @return a {@code ChronoZonedDateTime} based on this date-time with the requested zone, not null
352      * @throws DateTimeException if the result exceeds the supported date range
353      */
withZoneSameInstant(ZoneId zone)354     ChronoZonedDateTime<D> withZoneSameInstant(ZoneId zone);
355 
356     /**
357      * Checks if the specified field is supported.
358      * <p>
359      * This checks if the specified field can be queried on this date-time.
360      * If false, then calling the {@link #range(TemporalField) range},
361      * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
362      * methods will throw an exception.
363      * <p>
364      * The set of supported fields is defined by the chronology and normally includes
365      * all {@code ChronoField} fields.
366      * <p>
367      * If the field is not a {@code ChronoField}, then the result of this method
368      * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
369      * passing {@code this} as the argument.
370      * Whether the field is supported is determined by the field.
371      *
372      * @param field  the field to check, null returns false
373      * @return true if the field can be queried, false if not
374      */
375     @Override
isSupported(TemporalField field)376     boolean isSupported(TemporalField field);
377 
378     /**
379      * Checks if the specified unit is supported.
380      * <p>
381      * This checks if the specified unit can be added to or subtracted from this date-time.
382      * If false, then calling the {@link #plus(long, TemporalUnit)} and
383      * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
384      * <p>
385      * The set of supported units is defined by the chronology and normally includes
386      * all {@code ChronoUnit} units except {@code FOREVER}.
387      * <p>
388      * If the unit is not a {@code ChronoUnit}, then the result of this method
389      * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
390      * passing {@code this} as the argument.
391      * Whether the unit is supported is determined by the unit.
392      *
393      * @param unit  the unit to check, null returns false
394      * @return true if the unit can be added/subtracted, false if not
395      */
396     @Override
isSupported(TemporalUnit unit)397     default boolean isSupported(TemporalUnit unit) {
398         if (unit instanceof ChronoUnit) {
399             return unit != FOREVER;
400         }
401         return unit != null && unit.isSupportedBy(this);
402     }
403 
404     //-----------------------------------------------------------------------
405     // override for covariant return type
406     /**
407      * {@inheritDoc}
408      * @throws DateTimeException {@inheritDoc}
409      * @throws ArithmeticException {@inheritDoc}
410      */
411     @Override
with(TemporalAdjuster adjuster)412     default ChronoZonedDateTime<D> with(TemporalAdjuster adjuster) {
413         return ChronoZonedDateTimeImpl.ensureValid(getChronology(), Temporal.super.with(adjuster));
414     }
415 
416     /**
417      * {@inheritDoc}
418      * @throws DateTimeException {@inheritDoc}
419      * @throws ArithmeticException {@inheritDoc}
420      */
421     @Override
with(TemporalField field, long newValue)422     ChronoZonedDateTime<D> with(TemporalField field, long newValue);
423 
424     /**
425      * {@inheritDoc}
426      * @throws DateTimeException {@inheritDoc}
427      * @throws ArithmeticException {@inheritDoc}
428      */
429     @Override
plus(TemporalAmount amount)430     default ChronoZonedDateTime<D> plus(TemporalAmount amount) {
431         return ChronoZonedDateTimeImpl.ensureValid(getChronology(), Temporal.super.plus(amount));
432     }
433 
434     /**
435      * {@inheritDoc}
436      * @throws DateTimeException {@inheritDoc}
437      * @throws ArithmeticException {@inheritDoc}
438      */
439     @Override
plus(long amountToAdd, TemporalUnit unit)440     ChronoZonedDateTime<D> plus(long amountToAdd, TemporalUnit unit);
441 
442     /**
443      * {@inheritDoc}
444      * @throws DateTimeException {@inheritDoc}
445      * @throws ArithmeticException {@inheritDoc}
446      */
447     @Override
minus(TemporalAmount amount)448     default ChronoZonedDateTime<D> minus(TemporalAmount amount) {
449         return ChronoZonedDateTimeImpl.ensureValid(getChronology(), Temporal.super.minus(amount));
450     }
451 
452     /**
453      * {@inheritDoc}
454      * @throws DateTimeException {@inheritDoc}
455      * @throws ArithmeticException {@inheritDoc}
456      */
457     @Override
minus(long amountToSubtract, TemporalUnit unit)458     default ChronoZonedDateTime<D> minus(long amountToSubtract, TemporalUnit unit) {
459         return ChronoZonedDateTimeImpl.ensureValid(getChronology(), Temporal.super.minus(amountToSubtract, unit));
460     }
461 
462     //-----------------------------------------------------------------------
463     /**
464      * Queries this date-time using the specified query.
465      * <p>
466      * This queries this date-time using the specified query strategy object.
467      * The {@code TemporalQuery} object defines the logic to be used to
468      * obtain the result. Read the documentation of the query to understand
469      * what the result of this method will be.
470      * <p>
471      * The result of this method is obtained by invoking the
472      * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
473      * specified query passing {@code this} as the argument.
474      *
475      * @param <R> the type of the result
476      * @param query  the query to invoke, not null
477      * @return the query result, null may be returned (defined by the query)
478      * @throws DateTimeException if unable to query (defined by the query)
479      * @throws ArithmeticException if numeric overflow occurs (defined by the query)
480      */
481     @SuppressWarnings("unchecked")
482     @Override
query(TemporalQuery<R> query)483     default <R> R query(TemporalQuery<R> query) {
484         if (query == TemporalQueries.zone() || query == TemporalQueries.zoneId()) {
485             return (R) getZone();
486         } else if (query == TemporalQueries.offset()) {
487             return (R) getOffset();
488         } else if (query == TemporalQueries.localTime()) {
489             return (R) toLocalTime();
490         } else if (query == TemporalQueries.chronology()) {
491             return (R) getChronology();
492         } else if (query == TemporalQueries.precision()) {
493             return (R) NANOS;
494         }
495         // inline TemporalAccessor.super.query(query) as an optimization
496         // non-JDK classes are not permitted to make this optimization
497         return query.queryFrom(this);
498     }
499 
500     /**
501      * Formats this date-time using the specified formatter.
502      * <p>
503      * This date-time will be passed to the formatter to produce a string.
504      * <p>
505      * The default implementation must behave as follows:
506      * <pre>
507      *  return formatter.format(this);
508      * </pre>
509      *
510      * @param formatter  the formatter to use, not null
511      * @return the formatted date-time string, not null
512      * @throws DateTimeException if an error occurs during printing
513      */
format(DateTimeFormatter formatter)514     default String format(DateTimeFormatter formatter) {
515         Objects.requireNonNull(formatter, "formatter");
516         return formatter.format(this);
517     }
518 
519     //-----------------------------------------------------------------------
520     /**
521      * Converts this date-time to an {@code Instant}.
522      * <p>
523      * This returns an {@code Instant} representing the same point on the
524      * time-line as this date-time. The calculation combines the
525      * {@linkplain #toLocalDateTime() local date-time} and
526      * {@linkplain #getOffset() offset}.
527      *
528      * @return an {@code Instant} representing the same instant, not null
529      */
toInstant()530     default Instant toInstant() {
531         return Instant.ofEpochSecond(toEpochSecond(), toLocalTime().getNano());
532     }
533 
534     /**
535      * Converts this date-time to the number of seconds from the epoch
536      * of 1970-01-01T00:00:00Z.
537      * <p>
538      * This uses the {@linkplain #toLocalDateTime() local date-time} and
539      * {@linkplain #getOffset() offset} to calculate the epoch-second value,
540      * which is the number of elapsed seconds from 1970-01-01T00:00:00Z.
541      * Instants on the time-line after the epoch are positive, earlier are negative.
542      *
543      * @return the number of seconds from the epoch of 1970-01-01T00:00:00Z
544      */
toEpochSecond()545     default long toEpochSecond() {
546         long epochDay = toLocalDate().toEpochDay();
547         long secs = epochDay * 86400 + toLocalTime().toSecondOfDay();
548         secs -= getOffset().getTotalSeconds();
549         return secs;
550     }
551 
552     //-----------------------------------------------------------------------
553     /**
554      * Compares this date-time to another date-time, including the chronology.
555      * <p>
556      * The comparison is based first on the instant, then on the local date-time,
557      * then on the zone ID, then on the chronology.
558      * It is "consistent with equals", as defined by {@link Comparable}.
559      * <p>
560      * If all the date-time objects being compared are in the same chronology, then the
561      * additional chronology stage is not required.
562      * <p>
563      * This default implementation performs the comparison defined above.
564      *
565      * @param other  the other date-time to compare to, not null
566      * @return the comparator value, negative if less, positive if greater
567      */
568     @Override
compareTo(ChronoZonedDateTime<?> other)569     default int compareTo(ChronoZonedDateTime<?> other) {
570         int cmp = Long.compare(toEpochSecond(), other.toEpochSecond());
571         if (cmp == 0) {
572             cmp = toLocalTime().getNano() - other.toLocalTime().getNano();
573             if (cmp == 0) {
574                 cmp = toLocalDateTime().compareTo(other.toLocalDateTime());
575                 if (cmp == 0) {
576                     cmp = getZone().getId().compareTo(other.getZone().getId());
577                     if (cmp == 0) {
578                         cmp = getChronology().compareTo(other.getChronology());
579                     }
580                 }
581             }
582         }
583         return cmp;
584     }
585 
586     /**
587      * Checks if the instant of this date-time is before that of the specified date-time.
588      * <p>
589      * This method differs from the comparison in {@link #compareTo} in that it
590      * only compares the instant of the date-time. This is equivalent to using
591      * {@code dateTime1.toInstant().isBefore(dateTime2.toInstant());}.
592      * <p>
593      * This default implementation performs the comparison based on the epoch-second
594      * and nano-of-second.
595      *
596      * @param other  the other date-time to compare to, not null
597      * @return true if this point is before the specified date-time
598      */
isBefore(ChronoZonedDateTime<?> other)599     default boolean isBefore(ChronoZonedDateTime<?> other) {
600         long thisEpochSec = toEpochSecond();
601         long otherEpochSec = other.toEpochSecond();
602         return thisEpochSec < otherEpochSec ||
603             (thisEpochSec == otherEpochSec && toLocalTime().getNano() < other.toLocalTime().getNano());
604     }
605 
606     /**
607      * Checks if the instant of this date-time is after that of the specified date-time.
608      * <p>
609      * This method differs from the comparison in {@link #compareTo} in that it
610      * only compares the instant of the date-time. This is equivalent to using
611      * {@code dateTime1.toInstant().isAfter(dateTime2.toInstant());}.
612      * <p>
613      * This default implementation performs the comparison based on the epoch-second
614      * and nano-of-second.
615      *
616      * @param other  the other date-time to compare to, not null
617      * @return true if this is after the specified date-time
618      */
isAfter(ChronoZonedDateTime<?> other)619     default boolean isAfter(ChronoZonedDateTime<?> other) {
620         long thisEpochSec = toEpochSecond();
621         long otherEpochSec = other.toEpochSecond();
622         return thisEpochSec > otherEpochSec ||
623             (thisEpochSec == otherEpochSec && toLocalTime().getNano() > other.toLocalTime().getNano());
624     }
625 
626     /**
627      * Checks if the instant of this date-time is equal to that of the specified date-time.
628      * <p>
629      * This method differs from the comparison in {@link #compareTo} and {@link #equals}
630      * in that it only compares the instant of the date-time. This is equivalent to using
631      * {@code dateTime1.toInstant().equals(dateTime2.toInstant());}.
632      * <p>
633      * This default implementation performs the comparison based on the epoch-second
634      * and nano-of-second.
635      *
636      * @param other  the other date-time to compare to, not null
637      * @return true if the instant equals the instant of the specified date-time
638      */
isEqual(ChronoZonedDateTime<?> other)639     default boolean isEqual(ChronoZonedDateTime<?> other) {
640         return toEpochSecond() == other.toEpochSecond() &&
641                 toLocalTime().getNano() == other.toLocalTime().getNano();
642     }
643 
644     //-----------------------------------------------------------------------
645     /**
646      * Checks if this date-time is equal to another date-time.
647      * <p>
648      * The comparison is based on the offset date-time and the zone.
649      * To compare for the same instant on the time-line, use {@link #compareTo}.
650      * Only objects of type {@code ChronoZonedDateTime} are compared, other types return false.
651      *
652      * @param obj  the object to check, null returns false
653      * @return true if this is equal to the other date-time
654      */
655     @Override
equals(Object obj)656     boolean equals(Object obj);
657 
658     /**
659      * A hash code for this date-time.
660      *
661      * @return a suitable hash code
662      */
663     @Override
hashCode()664     int hashCode();
665 
666     //-----------------------------------------------------------------------
667     /**
668      * Outputs this date-time as a {@code String}.
669      * <p>
670      * The output will include the full zoned date-time.
671      *
672      * @return a string representation of this date-time, not null
673      */
674     @Override
toString()675     String toString();
676 
677 }
678