Java compact1, compact2, compact3 java.time.temporal Class TemporalQueries（JDK8）

Method Detail

• zoneId

  public static TemporalQuery<ZoneId> zoneId()

  A strict query for the ZoneId.

  This queries a TemporalAccessor for the zone. The zone is only returned if the date-time conceptually contains a ZoneId. It will not be returned if the date-time only conceptually has an ZoneOffset. Thus a ZonedDateTime will return the result of getZone(), but an OffsetDateTime will return null.

  In most cases, applications should use zone() as this query is too strict.

  The result from JDK classes implementing TemporalAccessor is as follows:
  LocalDate returns null
  LocalTime returns null
  LocalDateTime returns null
  ZonedDateTime returns the associated zone
  OffsetTime returns null
  OffsetDateTime returns null
  ChronoLocalDate returns null
  ChronoLocalDateTime returns null
  ChronoZonedDateTime returns the associated zone
  Era returns null
  DayOfWeek returns null
  Month returns null
  Year returns null
  YearMonth returns null
  MonthDay returns null
  ZoneOffset returns null
  Instant returns null
  

  Returns:

  a query that can obtain the zone ID of a temporal, not null

• chronology

  public static TemporalQuery<Chronology> chronology()

  A query for the Chronology.

  This queries a TemporalAccessor for the chronology. If the target TemporalAccessor represents a date, or part of a date, then it should return the chronology that the date is expressed in. As a result of this definition, objects only representing time, such as LocalTime, will return null.

  The result from JDK classes implementing TemporalAccessor is as follows:
  LocalDate returns IsoChronology.INSTANCE
LocalTime returns null (does not represent a date)
  LocalDateTime returns IsoChronology.INSTANCE
ZonedDateTime returns IsoChronology.INSTANCE
OffsetTime returns null (does not represent a date)
  OffsetDateTime returns IsoChronology.INSTANCE
ChronoLocalDate returns the associated chronology
  ChronoLocalDateTime returns the associated chronology
  ChronoZonedDateTime returns the associated chronology
  Era returns the associated chronology
  DayOfWeek returns null (shared across chronologies)
  Month returns IsoChronology.INSTANCE
Year returns IsoChronology.INSTANCE
YearMonth returns IsoChronology.INSTANCE
MonthDay returns null IsoChronology.INSTANCE
ZoneOffset returns null (does not represent a date)
  Instant returns null (does not represent a date)
  

  The method Chronology.from(TemporalAccessor) can be used as a TemporalQuery via a method reference, Chronology::from. That method is equivalent to this query, except that it throws an exception if a chronology cannot be obtained.

  Returns:

  a query that can obtain the chronology of a temporal, not null

• precision

  public static TemporalQuery<TemporalUnit> precision()

  A query for the smallest supported unit.

  This queries a TemporalAccessor for the time precision. If the target TemporalAccessor represents a consistent or complete date-time, date or time then this must return the smallest precision actually supported. Note that fields such as NANO_OF_DAY and NANO_OF_SECOND are defined to always return ignoring the precision, thus this is the only way to find the actual smallest supported unit. For example, were GregorianCalendar to implement TemporalAccessor it would return a precision of MILLIS.

  The result from JDK classes implementing TemporalAccessor is as follows:
  LocalDate returns DAYS
LocalTime returns NANOS
LocalDateTime returns NANOS
ZonedDateTime returns NANOS
OffsetTime returns NANOS
OffsetDateTime returns NANOS
ChronoLocalDate returns DAYS
ChronoLocalDateTime returns NANOS
ChronoZonedDateTime returns NANOS
Era returns ERAS
DayOfWeek returns DAYS
Month returns MONTHS
Year returns YEARS
YearMonth returns MONTHS
MonthDay returns null (does not represent a complete date or time)
  ZoneOffset returns null (does not represent a date or time)
  Instant returns NANOS
  

  Returns:

  a query that can obtain the precision of a temporal, not null

• zone

  public static TemporalQuery<ZoneId> zone()

  A lenient query for the ZoneId, falling back to the ZoneOffset.

  This queries a TemporalAccessor for the zone. It first tries to obtain the zone, using zoneId(). If that is not found it tries to obtain the offset(). Thus a ZonedDateTime will return the result of getZone(), while an OffsetDateTime will return the result of getOffset().

  In most cases, applications should use this query rather than #zoneId().

  The method ZoneId.from(TemporalAccessor) can be used as a TemporalQuery via a method reference, ZoneId::from. That method is equivalent to this query, except that it throws an exception if a zone cannot be obtained.

  Returns:

  a query that can obtain the zone ID or offset of a temporal, not null

• offset

  public static TemporalQuery<ZoneOffset> offset()

  A query for ZoneOffset returning null if not found.

  This returns a TemporalQuery that can be used to query a temporal object for the offset. The query will return null if the temporal object cannot supply an offset.

  The query implementation examines the OFFSET_SECONDS field and uses it to create a ZoneOffset.

  The method ZoneOffset.from(TemporalAccessor) can be used as a TemporalQuery via a method reference, ZoneOffset::from. This query and ZoneOffset::from will return the same result if the temporal object contains an offset. If the temporal object does not contain an offset, then the method reference will throw an exception, whereas this query will return null.

  Returns:

  a query that can obtain the offset of a temporal, not null

• localDate

  public static TemporalQuery<LocalDate> localDate()

  A query for LocalDate returning null if not found.

  This returns a TemporalQuery that can be used to query a temporal object for the local date. The query will return null if the temporal object cannot supply a local date.

  The query implementation examines the EPOCH_DAY field and uses it to create a LocalDate.

  The method ZoneOffset.from(TemporalAccessor) can be used as a TemporalQuery via a method reference, LocalDate::from. This query and LocalDate::from will return the same result if the temporal object contains a date. If the temporal object does not contain a date, then the method reference will throw an exception, whereas this query will return null.

  Returns:

  a query that can obtain the date of a temporal, not null

• localTime

  public static TemporalQuery<LocalTime> localTime()

  A query for LocalTime returning null if not found.

  This returns a TemporalQuery that can be used to query a temporal object for the local time. The query will return null if the temporal object cannot supply a local time.

  The query implementation examines the NANO_OF_DAY field and uses it to create a LocalTime.

  The method ZoneOffset.from(TemporalAccessor) can be used as a TemporalQuery via a method reference, LocalTime::from. This query and LocalTime::from will return the same result if the temporal object contains a time. If the temporal object does not contain a time, then the method reference will throw an exception, whereas this query will return null.

  Returns:

  a query that can obtain the time of a temporal, not null