Module java.base
Package java.time.zone

Class ZoneOffsetTransition

java.lang.Object
java.time.zone.ZoneOffsetTransition
All Implemented Interfaces:
Serializable, Comparable<ZoneOffsetTransition>
public final class ZoneOffsetTransition extends Object implements Comparable<ZoneOffsetTransition>, Serializable
A transition between two offsets caused by a discontinuity in the local time-line.

A transition between two offsets is normally the result of a daylight savings cutover. The discontinuity is normally a gap in spring and an overlap in autumn. ZoneOffsetTransition models the transition between the two offsets.

Gaps occur where there are local date-times that simply do not exist. An example would be when the offset changes from +03:00 to +04:00. This might be described as 'the clocks will move forward one hour tonight at 1am'.

Overlaps occur where there are local date-times that exist twice. An example would be when the offset changes from +04:00 to +03:00. This might be described as 'the clocks will move back one hour tonight at 2am'.

Implementation Requirements:
This class is immutable and thread-safe.
Since:
1.8
See Also:
Serialized Form

  • Method Details

    • of

      public static ZoneOffsetTransition of​(LocalDateTime transition, ZoneOffset offsetBefore, ZoneOffset offsetAfter)
      Obtains an instance defining a transition between two offsets.

      Applications should normally obtain an instance from ZoneRules. This factory is only intended for use when creating ZoneRules.

      Parameters:
      transition - the transition date-time at the transition, which never actually occurs, expressed local to the before offset, not null
      offsetBefore - the offset before the transition, not null
      offsetAfter - the offset at and after the transition, not null
      Returns:
      the transition, not null
      Throws:
      IllegalArgumentException - if offsetBefore and offsetAfter are equal, or transition.getNano() returns non-zero value

    • getInstant

      public Instant getInstant()
      Gets the transition instant.

      This is the instant of the discontinuity, which is defined as the first instant that the 'after' offset applies.

      The methods getInstant(), getDateTimeBefore() and getDateTimeAfter() all represent the same instant.

      Returns:
      the transition instant, not null

    • toEpochSecond

      public long toEpochSecond()
      Gets the transition instant as an epoch second.
      Returns:
      the transition epoch second

    • getDateTimeBefore

      public LocalDateTime getDateTimeBefore()
      Gets the local transition date-time, as would be expressed with the 'before' offset.

      This is the date-time where the discontinuity begins expressed with the 'before' offset. At this instant, the 'after' offset is actually used, therefore the combination of this date-time and the 'before' offset will never occur.

      The combination of the 'before' date-time and offset represents the same instant as the 'after' date-time and offset.

      Returns:
      the transition date-time expressed with the before offset, not null

    • getDateTimeAfter

      public LocalDateTime getDateTimeAfter()
      Gets the local transition date-time, as would be expressed with the 'after' offset.

      This is the first date-time after the discontinuity, when the new offset applies.

      The combination of the 'before' date-time and offset represents the same instant as the 'after' date-time and offset.

      Returns:
      the transition date-time expressed with the after offset, not null

    • getOffsetBefore

      public ZoneOffset getOffsetBefore()
      Gets the offset before the transition.

      This is the offset in use before the instant of the transition.

      Returns:
      the offset before the transition, not null

    • getOffsetAfter

      public ZoneOffset getOffsetAfter()
      Gets the offset after the transition.

      This is the offset in use on and after the instant of the transition.

      Returns:
      the offset after the transition, not null

    • getDuration

      public Duration getDuration()
      Gets the duration of the transition.

      In most cases, the transition duration is one hour, however this is not always the case. The duration will be positive for a gap and negative for an overlap. Time-zones are second-based, so the nanosecond part of the duration will be zero.

      Returns:
      the duration of the transition, positive for gaps, negative for overlaps

    • isGap

      public boolean isGap()
      Does this transition represent a gap in the local time-line.

      Gaps occur where there are local date-times that simply do not exist. An example would be when the offset changes from +01:00 to +02:00. This might be described as 'the clocks will move forward one hour tonight at 1am'.

      Returns:
      true if this transition is a gap, false if it is an overlap

    • isOverlap

      public boolean isOverlap()
      Does this transition represent an overlap in the local time-line.

      Overlaps occur where there are local date-times that exist twice. An example would be when the offset changes from +02:00 to +01:00. This might be described as 'the clocks will move back one hour tonight at 2am'.

      Returns:
      true if this transition is an overlap, false if it is a gap

    • isValidOffset

      public boolean isValidOffset​(ZoneOffset offset)
      Checks if the specified offset is valid during this transition.

      This checks to see if the given offset will be valid at some point in the transition. A gap will always return false. An overlap will return true if the offset is either the before or after offset.

      Parameters:
      offset - the offset to check, null returns false
      Returns:
      true if the offset is valid during the transition

    • compareTo

      public int compareTo​(ZoneOffsetTransition transition)
      Compares this transition to another based on the transition instant.

      This compares the instants of each transition. The offsets are ignored, making this order inconsistent with equals.

      Specified by:
      compareTo in interface Comparable<ZoneOffsetTransition>
      Parameters:
      transition - the transition to compare to, not null
      Returns:
      the comparator value, negative if less, positive if greater

    • equals

      public boolean equals​(Object other)
      Checks if this object equals another.

      The entire state of the object is compared.

      Overrides:
      equals in class Object
      Parameters:
      other - the other object to compare to, null returns false
      Returns:
      true if equal
      See Also:
      Object.hashCode(), HashMap

    • hashCode

      public int hashCode()
      Returns a suitable hash code.
      Overrides:
      hashCode in class Object
      Returns:
      the hash code
      See Also:
      Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

    • toString

      public String toString()
      Returns a string describing this object.
      Overrides:
      toString in class Object
      Returns:
      a string for debugging, not null