java/11 : java.base/java/time/zone/ZoneRules.java

ZoneRules
https://openjdk.java.net/
GPLv2 + Classpath Exception
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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * Copyright (c) 2009-2012, Stephen Colebourne & Michael Nascimento Santos
 *
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package java.time.zone;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.Year;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

The rules defining how the zone offset varies for a single time-zone.
 The rules model all the historic and future transitions for a time-zone. ZoneOffsetTransition is used for known transitions, typically historic. ZoneOffsetTransitionRule is used for future transitions that are based on the result of an algorithm. 
 The rules are loaded via ZoneRulesProvider using a ZoneId. The same rules may be shared internally between multiple zone IDs. 
 Serializing an instance of ZoneRules will store the entire set of rules. It does not store the zone ID as it is not part of the state of this object. 

A rule implementation may or may not store full information about historic
and future transitions, and the information stored is only as accurate as
that supplied to the implementation by the rules provider.
Applications should treat the data provided as representing the best information
available to the implementation of this rule.
Implementation Requirements: 
This class is immutable and thread-safe.
Since: 1.8/**
 * The rules defining how the zone offset varies for a single time-zone.
 * <p>
 * The rules model all the historic and future transitions for a time-zone.
 * {@link ZoneOffsetTransition} is used for known transitions, typically historic.
 * {@link ZoneOffsetTransitionRule} is used for future transitions that are based
 * on the result of an algorithm.
 * <p>
 * The rules are loaded via {@link ZoneRulesProvider} using a {@link ZoneId}.
 * The same rules may be shared internally between multiple zone IDs.
 * <p>
 * Serializing an instance of {@code ZoneRules} will store the entire set of rules.
 * It does not store the zone ID as it is not part of the state of this object.
 * <p>
 * A rule implementation may or may not store full information about historic
 * and future transitions, and the information stored is only as accurate as
 * that supplied to the implementation by the rules provider.
 * Applications should treat the data provided as representing the best information
 * available to the implementation of this rule.
 *
 * @implSpec
 * This class is immutable and thread-safe.
 *
 * @since 1.8
 */
public final class ZoneRules implements Serializable {

    Serialization version.
/**
     * Serialization version.
     */
    private static final long serialVersionUID = 3044319355680032515L;
    The last year to have its transitions cached.
/**
     * The last year to have its transitions cached.
     */
    private static final int LAST_CACHED_YEAR = 2100;

    The transitions between standard offsets (epoch seconds), sorted.
/**
     * The transitions between standard offsets (epoch seconds), sorted.
     */
    private final long[] standardTransitions;
    The standard offsets.
/**
     * The standard offsets.
     */
    private final ZoneOffset[] standardOffsets;
    The transitions between instants (epoch seconds), sorted.
/**
     * The transitions between instants (epoch seconds), sorted.
     */
    private final long[] savingsInstantTransitions;
    The transitions between local date-times, sorted.
This is a paired array, where the first entry is the start of the transition
and the second entry is the end of the transition.
/**
     * The transitions between local date-times, sorted.
     * This is a paired array, where the first entry is the start of the transition
     * and the second entry is the end of the transition.
     */
    private final LocalDateTime[] savingsLocalTransitions;
    The wall offsets.
/**
     * The wall offsets.
     */
    private final ZoneOffset[] wallOffsets;
    The last rule.
/**
     * The last rule.
     */
    private final ZoneOffsetTransitionRule[] lastRules;
    The map of recent transitions.
/**
     * The map of recent transitions.
     */
    private final transient ConcurrentMap<Integer, ZoneOffsetTransition[]> lastRulesCache =
                new ConcurrentHashMap<Integer, ZoneOffsetTransition[]>();
    The zero-length long array.
/**
     * The zero-length long array.
     */
    private static final long[] EMPTY_LONG_ARRAY = new long[0];
    The zero-length lastrules array.
/**
     * The zero-length lastrules array.
     */
    private static final ZoneOffsetTransitionRule[] EMPTY_LASTRULES =
        new ZoneOffsetTransitionRule[0];
    The zero-length ldt array.
/**
     * The zero-length ldt array.
     */
    private static final LocalDateTime[] EMPTY_LDT_ARRAY = new LocalDateTime[0];

    Obtains an instance of a ZoneRules.
Params: baseStandardOffset –  the standard offset to use before legal rules were set, not null
baseWallOffset –  the wall offset to use before legal rules were set, not null
standardOffsetTransitionList –  the list of changes to the standard offset, not null
transitionList –  the list of transitions, not null
lastRules –  the recurring last rules, size 16 or less, not null
Returns: the zone rules, not null/**
     * Obtains an instance of a ZoneRules.
     *
     * @param baseStandardOffset  the standard offset to use before legal rules were set, not null
     * @param baseWallOffset  the wall offset to use before legal rules were set, not null
     * @param standardOffsetTransitionList  the list of changes to the standard offset, not null
     * @param transitionList  the list of transitions, not null
     * @param lastRules  the recurring last rules, size 16 or less, not null
     * @return the zone rules, not null
     */
    public static ZoneRules of(ZoneOffset baseStandardOffset,
                               ZoneOffset baseWallOffset,
                               List<ZoneOffsetTransition> standardOffsetTransitionList,
                               List<ZoneOffsetTransition> transitionList,
                               List<ZoneOffsetTransitionRule> lastRules) {
        Objects.requireNonNull(baseStandardOffset, "baseStandardOffset");
        Objects.requireNonNull(baseWallOffset, "baseWallOffset");
        Objects.requireNonNull(standardOffsetTransitionList, "standardOffsetTransitionList");
        Objects.requireNonNull(transitionList, "transitionList");
        Objects.requireNonNull(lastRules, "lastRules");
        return new ZoneRules(baseStandardOffset, baseWallOffset,
                             standardOffsetTransitionList, transitionList, lastRules);
    }

    Obtains an instance of ZoneRules that has fixed zone rules.
Params: offset –  the offset this fixed zone rules is based on, not null
See Also: isFixedOffset()
Returns: the zone rules, not null/**
     * Obtains an instance of ZoneRules that has fixed zone rules.
     *
     * @param offset  the offset this fixed zone rules is based on, not null
     * @return the zone rules, not null
     * @see #isFixedOffset()
     */
    public static ZoneRules of(ZoneOffset offset) {
        Objects.requireNonNull(offset, "offset");
        return new ZoneRules(offset);
    }

    Creates an instance.
Params: baseStandardOffset –  the standard offset to use before legal rules were set, not null
baseWallOffset –  the wall offset to use before legal rules were set, not null
standardOffsetTransitionList –  the list of changes to the standard offset, not null
transitionList –  the list of transitions, not null
lastRules –  the recurring last rules, size 16 or less, not null/**
     * Creates an instance.
     *
     * @param baseStandardOffset  the standard offset to use before legal rules were set, not null
     * @param baseWallOffset  the wall offset to use before legal rules were set, not null
     * @param standardOffsetTransitionList  the list of changes to the standard offset, not null
     * @param transitionList  the list of transitions, not null
     * @param lastRules  the recurring last rules, size 16 or less, not null
     */
    ZoneRules(ZoneOffset baseStandardOffset,
              ZoneOffset baseWallOffset,
              List<ZoneOffsetTransition> standardOffsetTransitionList,
              List<ZoneOffsetTransition> transitionList,
              List<ZoneOffsetTransitionRule> lastRules) {
        super();

        // convert standard transitions

        this.standardTransitions = new long[standardOffsetTransitionList.size()];

        this.standardOffsets = new ZoneOffset[standardOffsetTransitionList.size() + 1];
        this.standardOffsets[0] = baseStandardOffset;
        for (int i = 0; i < standardOffsetTransitionList.size(); i++) {
            this.standardTransitions[i] = standardOffsetTransitionList.get(i).toEpochSecond();
            this.standardOffsets[i + 1] = standardOffsetTransitionList.get(i).getOffsetAfter();
        }

        // convert savings transitions to locals
        List<LocalDateTime> localTransitionList = new ArrayList<>();
        List<ZoneOffset> localTransitionOffsetList = new ArrayList<>();
        localTransitionOffsetList.add(baseWallOffset);
        for (ZoneOffsetTransition trans : transitionList) {
            if (trans.isGap()) {
                localTransitionList.add(trans.getDateTimeBefore());
                localTransitionList.add(trans.getDateTimeAfter());
            } else {
                localTransitionList.add(trans.getDateTimeAfter());
                localTransitionList.add(trans.getDateTimeBefore());
            }
            localTransitionOffsetList.add(trans.getOffsetAfter());
        }
        this.savingsLocalTransitions = localTransitionList.toArray(new LocalDateTime[localTransitionList.size()]);
        this.wallOffsets = localTransitionOffsetList.toArray(new ZoneOffset[localTransitionOffsetList.size()]);

        // convert savings transitions to instants
        this.savingsInstantTransitions = new long[transitionList.size()];
        for (int i = 0; i < transitionList.size(); i++) {
            this.savingsInstantTransitions[i] = transitionList.get(i).toEpochSecond();
        }

        // last rules
        if (lastRules.size() > 16) {
            throw new IllegalArgumentException("Too many transition rules");
        }
        this.lastRules = lastRules.toArray(new ZoneOffsetTransitionRule[lastRules.size()]);
    }

    Constructor.
Params: standardTransitions –  the standard transitions, not null
standardOffsets –  the standard offsets, not null
savingsInstantTransitions –  the standard transitions, not null
wallOffsets –  the wall offsets, not null
lastRules –  the recurring last rules, size 15 or less, not null/**
     * Constructor.
     *
     * @param standardTransitions  the standard transitions, not null
     * @param standardOffsets  the standard offsets, not null
     * @param savingsInstantTransitions  the standard transitions, not null
     * @param wallOffsets  the wall offsets, not null
     * @param lastRules  the recurring last rules, size 15 or less, not null
     */
    private ZoneRules(long[] standardTransitions,
                      ZoneOffset[] standardOffsets,
                      long[] savingsInstantTransitions,
                      ZoneOffset[] wallOffsets,
                      ZoneOffsetTransitionRule[] lastRules) {
        super();

        this.standardTransitions = standardTransitions;
        this.standardOffsets = standardOffsets;
        this.savingsInstantTransitions = savingsInstantTransitions;
        this.wallOffsets = wallOffsets;
        this.lastRules = lastRules;

        if (savingsInstantTransitions.length == 0) {
            this.savingsLocalTransitions = EMPTY_LDT_ARRAY;
        } else {
            // convert savings transitions to locals
            List<LocalDateTime> localTransitionList = new ArrayList<>();
            for (int i = 0; i < savingsInstantTransitions.length; i++) {
                ZoneOffset before = wallOffsets[i];
                ZoneOffset after = wallOffsets[i + 1];
                ZoneOffsetTransition trans = new ZoneOffsetTransition(savingsInstantTransitions[i], before, after);
                if (trans.isGap()) {
                    localTransitionList.add(trans.getDateTimeBefore());
                    localTransitionList.add(trans.getDateTimeAfter());
                } else {
                    localTransitionList.add(trans.getDateTimeAfter());
                    localTransitionList.add(trans.getDateTimeBefore());
               }
            }
            this.savingsLocalTransitions = localTransitionList.toArray(new LocalDateTime[localTransitionList.size()]);
        }
    }

    Creates an instance of ZoneRules that has fixed zone rules.
Params: offset –  the offset this fixed zone rules is based on, not null
See Also: isFixedOffset()/**
     * Creates an instance of ZoneRules that has fixed zone rules.
     *
     * @param offset  the offset this fixed zone rules is based on, not null
     * @see #isFixedOffset()
     */
    private ZoneRules(ZoneOffset offset) {
        this.standardOffsets = new ZoneOffset[1];
        this.standardOffsets[0] = offset;
        this.standardTransitions = EMPTY_LONG_ARRAY;
        this.savingsInstantTransitions = EMPTY_LONG_ARRAY;
        this.savingsLocalTransitions = EMPTY_LDT_ARRAY;
        this.wallOffsets = standardOffsets;
        this.lastRules = EMPTY_LASTRULES;
    }

    Defend against malicious streams.
Params: s – the stream to read
Throws: InvalidObjectException – always/**
     * Defend against malicious streams.
     *
     * @param s the stream to read
     * @throws InvalidObjectException always
     */
    private void readObject(ObjectInputStream s) throws InvalidObjectException {
        throw new InvalidObjectException("Deserialization via serialization delegate");
    }

    Writes the object using a
dedicated serialized form.
@serialData 

  out.writeByte(1);  // identifies a ZoneRules
  out.writeInt(standardTransitions.length);
  for (long trans : standardTransitions) {
      Ser.writeEpochSec(trans, out);
  }
  for (ZoneOffset offset : standardOffsets) {
      Ser.writeOffset(offset, out);
  }
  out.writeInt(savingsInstantTransitions.length);
  for (long trans : savingsInstantTransitions) {
      Ser.writeEpochSec(trans, out);
  }
  for (ZoneOffset offset : wallOffsets) {
      Ser.writeOffset(offset, out);
  }
  out.writeByte(lastRules.length);
  for (ZoneOffsetTransitionRule rule : lastRules) {
      rule.writeExternal(out);
  }
 

Epoch second values used for offsets are encoded in a variable
length form to make the common cases put fewer bytes in the stream.

 static void writeEpochSec(long epochSec, DataOutput out) throws IOException {
    if (epochSec >= -4575744000L && epochSec < 10413792000L && epochSec % 900 == 0) {  // quarter hours between 1825 and 2300
        int store = (int) ((epochSec + 4575744000L) / 900);
        out.writeByte((store >>> 16) & 255);
        out.writeByte((store >>> 8) & 255);
        out.writeByte(store & 255);
     } else {
         out.writeByte(255);
         out.writeLong(epochSec);
     }
 }
 

ZoneOffset values are encoded in a variable length form so the
common cases put fewer bytes in the stream.

 static void writeOffset(ZoneOffset offset, DataOutput out) throws IOException {
    final int offsetSecs = offset.getTotalSeconds();
    int offsetByte = offsetSecs % 900 == 0 ? offsetSecs / 900 : 127;  // compress to -72 to +72
    out.writeByte(offsetByte);
    if (offsetByte == 127) {
        out.writeInt(offsetSecs);
    }
 }
 
Returns: the replacing object, not null/**
     * Writes the object using a
     * <a href="../../../serialized-form.html#java.time.zone.Ser">dedicated serialized form</a>.
     * @serialData
     * <pre style="font-size:1.0em">{@code
     *
     *   out.writeByte(1);  // identifies a ZoneRules
     *   out.writeInt(standardTransitions.length);
     *   for (long trans : standardTransitions) {
     *       Ser.writeEpochSec(trans, out);
     *   }
     *   for (ZoneOffset offset : standardOffsets) {
     *       Ser.writeOffset(offset, out);
     *   }
     *   out.writeInt(savingsInstantTransitions.length);
     *   for (long trans : savingsInstantTransitions) {
     *       Ser.writeEpochSec(trans, out);
     *   }
     *   for (ZoneOffset offset : wallOffsets) {
     *       Ser.writeOffset(offset, out);
     *   }
     *   out.writeByte(lastRules.length);
     *   for (ZoneOffsetTransitionRule rule : lastRules) {
     *       rule.writeExternal(out);
     *   }
     * }
     * </pre>
     * <p>
     * Epoch second values used for offsets are encoded in a variable
     * length form to make the common cases put fewer bytes in the stream.
     * <pre style="font-size:1.0em">{@code
     *
     *  static void writeEpochSec(long epochSec, DataOutput out) throws IOException {
     *     if (epochSec >= -4575744000L && epochSec < 10413792000L && epochSec % 900 == 0) {  // quarter hours between 1825 and 2300
     *         int store = (int) ((epochSec + 4575744000L) / 900);
     *         out.writeByte((store >>> 16) & 255);
     *         out.writeByte((store >>> 8) & 255);
     *         out.writeByte(store & 255);
     *      } else {
     *          out.writeByte(255);
     *          out.writeLong(epochSec);
     *      }
     *  }
     * }
     * </pre>
     * <p>
     * ZoneOffset values are encoded in a variable length form so the
     * common cases put fewer bytes in the stream.
     * <pre style="font-size:1.0em">{@code
     *
     *  static void writeOffset(ZoneOffset offset, DataOutput out) throws IOException {
     *     final int offsetSecs = offset.getTotalSeconds();
     *     int offsetByte = offsetSecs % 900 == 0 ? offsetSecs / 900 : 127;  // compress to -72 to +72
     *     out.writeByte(offsetByte);
     *     if (offsetByte == 127) {
     *         out.writeInt(offsetSecs);
     *     }
     * }
     *}
     * </pre>
     * @return the replacing object, not null
     */
    private Object writeReplace() {
        return new Ser(Ser.ZRULES, this);
    }

    Writes the state to the stream.
Params: out –  the output stream, not null
Throws: IOException – if an error occurs/**
     * Writes the state to the stream.
     *
     * @param out  the output stream, not null
     * @throws IOException if an error occurs
     */
    void writeExternal(DataOutput out) throws IOException {
        out.writeInt(standardTransitions.length);
        for (long trans : standardTransitions) {
            Ser.writeEpochSec(trans, out);
        }
        for (ZoneOffset offset : standardOffsets) {
            Ser.writeOffset(offset, out);
        }
        out.writeInt(savingsInstantTransitions.length);
        for (long trans : savingsInstantTransitions) {
            Ser.writeEpochSec(trans, out);
        }
        for (ZoneOffset offset : wallOffsets) {
            Ser.writeOffset(offset, out);
        }
        out.writeByte(lastRules.length);
        for (ZoneOffsetTransitionRule rule : lastRules) {
            rule.writeExternal(out);
        }
    }

    Reads the state from the stream.
Params: in –  the input stream, not null
Throws: IOException – if an error occurs
Returns: the created object, not null/**
     * Reads the state from the stream.
     *
     * @param in  the input stream, not null
     * @return the created object, not null
     * @throws IOException if an error occurs
     */
    static ZoneRules readExternal(DataInput in) throws IOException, ClassNotFoundException {
        int stdSize = in.readInt();
        long[] stdTrans = (stdSize == 0) ? EMPTY_LONG_ARRAY
                                         : new long[stdSize];
        for (int i = 0; i < stdSize; i++) {
            stdTrans[i] = Ser.readEpochSec(in);
        }
        ZoneOffset[] stdOffsets = new ZoneOffset[stdSize + 1];
        for (int i = 0; i < stdOffsets.length; i++) {
            stdOffsets[i] = Ser.readOffset(in);
        }
        int savSize = in.readInt();
        long[] savTrans = (savSize == 0) ? EMPTY_LONG_ARRAY
                                         : new long[savSize];
        for (int i = 0; i < savSize; i++) {
            savTrans[i] = Ser.readEpochSec(in);
        }
        ZoneOffset[] savOffsets = new ZoneOffset[savSize + 1];
        for (int i = 0; i < savOffsets.length; i++) {
            savOffsets[i] = Ser.readOffset(in);
        }
        int ruleSize = in.readByte();
        ZoneOffsetTransitionRule[] rules = (ruleSize == 0) ?
            EMPTY_LASTRULES : new ZoneOffsetTransitionRule[ruleSize];
        for (int i = 0; i < ruleSize; i++) {
            rules[i] = ZoneOffsetTransitionRule.readExternal(in);
        }
        return new ZoneRules(stdTrans, stdOffsets, savTrans, savOffsets, rules);
    }

    Checks of the zone rules are fixed, such that the offset never varies.
Returns: true if the time-zone is fixed and the offset never changes/**
     * Checks of the zone rules are fixed, such that the offset never varies.
     *
     * @return true if the time-zone is fixed and the offset never changes
     */
    public boolean isFixedOffset() {
        return savingsInstantTransitions.length == 0;
    }

    Gets the offset applicable at the specified instant in these rules.

The mapping from an instant to an offset is simple, there is only
one valid offset for each instant.
This method returns that offset.
Params: instant –  the instant to find the offset for, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the offset, not null/**
     * Gets the offset applicable at the specified instant in these rules.
     * <p>
     * The mapping from an instant to an offset is simple, there is only
     * one valid offset for each instant.
     * This method returns that offset.
     *
     * @param instant  the instant to find the offset for, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the offset, not null
     */
    public ZoneOffset getOffset(Instant instant) {
        if (savingsInstantTransitions.length == 0) {
            return standardOffsets[0];
        }
        long epochSec = instant.getEpochSecond();
        // check if using last rules
        if (lastRules.length > 0 &&
                epochSec > savingsInstantTransitions[savingsInstantTransitions.length - 1]) {
            int year = findYear(epochSec, wallOffsets[wallOffsets.length - 1]);
            ZoneOffsetTransition[] transArray = findTransitionArray(year);
            ZoneOffsetTransition trans = null;
            for (int i = 0; i < transArray.length; i++) {
                trans = transArray[i];
                if (epochSec < trans.toEpochSecond()) {
                    return trans.getOffsetBefore();
                }
            }
            return trans.getOffsetAfter();
        }

        // using historic rules
        int index  = Arrays.binarySearch(savingsInstantTransitions, epochSec);
        if (index < 0) {
            // switch negative insert position to start of matched range
            index = -index - 2;
        }
        return wallOffsets[index + 1];
    }

    Gets a suitable offset for the specified local date-time in these rules.

The mapping from a local date-time to an offset is not straightforward.
There are three cases:

Normal, with one valid offset. For the vast majority of the year, the normal
 case applies, where there is a single valid offset for the local date-time.
Gap, with zero valid offsets. This is when clocks jump forward typically
 due to the spring daylight savings change from "winter" to "summer".
 In a gap there are local date-time values with no valid offset.
Overlap, with two valid offsets. This is when clocks are set back typically
 due to the autumn daylight savings change from "summer" to "winter".
 In an overlap there are local date-time values with two valid offsets.

Thus, for any given local date-time there can be zero, one or two valid offsets.
This method returns the single offset in the Normal case, and in the Gap or Overlap
case it returns the offset before the transition.
 Since, in the case of Gap and Overlap, the offset returned is a "best" value, rather than the "correct" value, it should be treated with care. Applications that care about the correct offset should use a combination of this method, getValidOffsets(LocalDateTime) and getTransition(LocalDateTime). 
Params: localDateTime –  the local date-time to query, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the best available offset for the local date-time, not null/**
     * Gets a suitable offset for the specified local date-time in these rules.
     * <p>
     * The mapping from a local date-time to an offset is not straightforward.
     * There are three cases:
     * <ul>
     * <li>Normal, with one valid offset. For the vast majority of the year, the normal
     *  case applies, where there is a single valid offset for the local date-time.</li>
     * <li>Gap, with zero valid offsets. This is when clocks jump forward typically
     *  due to the spring daylight savings change from "winter" to "summer".
     *  In a gap there are local date-time values with no valid offset.</li>
     * <li>Overlap, with two valid offsets. This is when clocks are set back typically
     *  due to the autumn daylight savings change from "summer" to "winter".
     *  In an overlap there are local date-time values with two valid offsets.</li>
     * </ul>
     * Thus, for any given local date-time there can be zero, one or two valid offsets.
     * This method returns the single offset in the Normal case, and in the Gap or Overlap
     * case it returns the offset before the transition.
     * <p>
     * Since, in the case of Gap and Overlap, the offset returned is a "best" value, rather
     * than the "correct" value, it should be treated with care. Applications that care
     * about the correct offset should use a combination of this method,
     * {@link #getValidOffsets(LocalDateTime)} and {@link #getTransition(LocalDateTime)}.
     *
     * @param localDateTime  the local date-time to query, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the best available offset for the local date-time, not null
     */
    public ZoneOffset getOffset(LocalDateTime localDateTime) {
        Object info = getOffsetInfo(localDateTime);
        if (info instanceof ZoneOffsetTransition) {
            return ((ZoneOffsetTransition) info).getOffsetBefore();
        }
        return (ZoneOffset) info;
    }

    Gets the offset applicable at the specified local date-time in these rules.

The mapping from a local date-time to an offset is not straightforward.
There are three cases:

Normal, with one valid offset. For the vast majority of the year, the normal
 case applies, where there is a single valid offset for the local date-time.
Gap, with zero valid offsets. This is when clocks jump forward typically
 due to the spring daylight savings change from "winter" to "summer".
 In a gap there are local date-time values with no valid offset.
Overlap, with two valid offsets. This is when clocks are set back typically
 due to the autumn daylight savings change from "summer" to "winter".
 In an overlap there are local date-time values with two valid offsets.

Thus, for any given local date-time there can be zero, one or two valid offsets.
This method returns that list of valid offsets, which is a list of size 0, 1 or 2.
In the case where there are two offsets, the earlier offset is returned at index 0
and the later offset at index 1.
 There are various ways to handle the conversion from a LocalDateTime. One technique, using this method, would be: 
 List<ZoneOffset> validOffsets = rules.getOffset(localDT);
 if (validOffsets.size() == 1) {
   // Normal case: only one valid offset
   zoneOffset = validOffsets.get(0);
 } else {
   // Gap or Overlap: determine what to do from transition (which will be non-null)
   ZoneOffsetTransition trans = rules.getTransition(localDT);
 }


In theory, it is possible for there to be more than two valid offsets.
This would happen if clocks to be put back more than once in quick succession.
This has never happened in the history of time-zones and thus has no special handling.
However, if it were to happen, then the list would return more than 2 entries.
Params: localDateTime –  the local date-time to query for valid offsets, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the list of valid offsets, may be immutable, not null/**
     * Gets the offset applicable at the specified local date-time in these rules.
     * <p>
     * The mapping from a local date-time to an offset is not straightforward.
     * There are three cases:
     * <ul>
     * <li>Normal, with one valid offset. For the vast majority of the year, the normal
     *  case applies, where there is a single valid offset for the local date-time.</li>
     * <li>Gap, with zero valid offsets. This is when clocks jump forward typically
     *  due to the spring daylight savings change from "winter" to "summer".
     *  In a gap there are local date-time values with no valid offset.</li>
     * <li>Overlap, with two valid offsets. This is when clocks are set back typically
     *  due to the autumn daylight savings change from "summer" to "winter".
     *  In an overlap there are local date-time values with two valid offsets.</li>
     * </ul>
     * Thus, for any given local date-time there can be zero, one or two valid offsets.
     * This method returns that list of valid offsets, which is a list of size 0, 1 or 2.
     * In the case where there are two offsets, the earlier offset is returned at index 0
     * and the later offset at index 1.
     * <p>
     * There are various ways to handle the conversion from a {@code LocalDateTime}.
     * One technique, using this method, would be:
     * <pre>
     *  List&lt;ZoneOffset&gt; validOffsets = rules.getOffset(localDT);
     *  if (validOffsets.size() == 1) {
     *    // Normal case: only one valid offset
     *    zoneOffset = validOffsets.get(0);
     *  } else {
     *    // Gap or Overlap: determine what to do from transition (which will be non-null)
     *    ZoneOffsetTransition trans = rules.getTransition(localDT);
     *  }
     * </pre>
     * <p>
     * In theory, it is possible for there to be more than two valid offsets.
     * This would happen if clocks to be put back more than once in quick succession.
     * This has never happened in the history of time-zones and thus has no special handling.
     * However, if it were to happen, then the list would return more than 2 entries.
     *
     * @param localDateTime  the local date-time to query for valid offsets, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the list of valid offsets, may be immutable, not null
     */
    public List<ZoneOffset> getValidOffsets(LocalDateTime localDateTime) {
        // should probably be optimized
        Object info = getOffsetInfo(localDateTime);
        if (info instanceof ZoneOffsetTransition) {
            return ((ZoneOffsetTransition) info).getValidOffsets();
        }
        return Collections.singletonList((ZoneOffset) info);
    }

    Gets the offset transition applicable at the specified local date-time in these rules.

The mapping from a local date-time to an offset is not straightforward.
There are three cases:

Normal, with one valid offset. For the vast majority of the year, the normal
 case applies, where there is a single valid offset for the local date-time.
Gap, with zero valid offsets. This is when clocks jump forward typically
 due to the spring daylight savings change from "winter" to "summer".
 In a gap there are local date-time values with no valid offset.
Overlap, with two valid offsets. This is when clocks are set back typically
 due to the autumn daylight savings change from "summer" to "winter".
 In an overlap there are local date-time values with two valid offsets.

A transition is used to model the cases of a Gap or Overlap.
The Normal case will return null.
 There are various ways to handle the conversion from a LocalDateTime. One technique, using this method, would be: 
 ZoneOffsetTransition trans = rules.getTransition(localDT);
 if (trans != null) {
   // Gap or Overlap: determine what to do from transition
 } else {
   // Normal case: only one valid offset
   zoneOffset = rule.getOffset(localDT);
 }

Params: localDateTime –  the local date-time to query for offset transition, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the offset transition, null if the local date-time is not in transition/**
     * Gets the offset transition applicable at the specified local date-time in these rules.
     * <p>
     * The mapping from a local date-time to an offset is not straightforward.
     * There are three cases:
     * <ul>
     * <li>Normal, with one valid offset. For the vast majority of the year, the normal
     *  case applies, where there is a single valid offset for the local date-time.</li>
     * <li>Gap, with zero valid offsets. This is when clocks jump forward typically
     *  due to the spring daylight savings change from "winter" to "summer".
     *  In a gap there are local date-time values with no valid offset.</li>
     * <li>Overlap, with two valid offsets. This is when clocks are set back typically
     *  due to the autumn daylight savings change from "summer" to "winter".
     *  In an overlap there are local date-time values with two valid offsets.</li>
     * </ul>
     * A transition is used to model the cases of a Gap or Overlap.
     * The Normal case will return null.
     * <p>
     * There are various ways to handle the conversion from a {@code LocalDateTime}.
     * One technique, using this method, would be:
     * <pre>
     *  ZoneOffsetTransition trans = rules.getTransition(localDT);
     *  if (trans != null) {
     *    // Gap or Overlap: determine what to do from transition
     *  } else {
     *    // Normal case: only one valid offset
     *    zoneOffset = rule.getOffset(localDT);
     *  }
     * </pre>
     *
     * @param localDateTime  the local date-time to query for offset transition, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the offset transition, null if the local date-time is not in transition
     */
    public ZoneOffsetTransition getTransition(LocalDateTime localDateTime) {
        Object info = getOffsetInfo(localDateTime);
        return (info instanceof ZoneOffsetTransition ? (ZoneOffsetTransition) info : null);
    }

    private Object getOffsetInfo(LocalDateTime dt) {
        if (savingsInstantTransitions.length == 0) {
            return standardOffsets[0];
        }
        // check if using last rules
        if (lastRules.length > 0 &&
                dt.isAfter(savingsLocalTransitions[savingsLocalTransitions.length - 1])) {
            ZoneOffsetTransition[] transArray = findTransitionArray(dt.getYear());
            Object info = null;
            for (ZoneOffsetTransition trans : transArray) {
                info = findOffsetInfo(dt, trans);
                if (info instanceof ZoneOffsetTransition || info.equals(trans.getOffsetBefore())) {
                    return info;
                }
            }
            return info;
        }

        // using historic rules
        int index  = Arrays.binarySearch(savingsLocalTransitions, dt);
        if (index == -1) {
            // before first transition
            return wallOffsets[0];
        }
        if (index < 0) {
            // switch negative insert position to start of matched range
            index = -index - 2;
        } else if (index < savingsLocalTransitions.length - 1 &&
                savingsLocalTransitions[index].equals(savingsLocalTransitions[index + 1])) {
            // handle overlap immediately following gap
            index++;
        }
        if ((index & 1) == 0) {
            // gap or overlap
            LocalDateTime dtBefore = savingsLocalTransitions[index];
            LocalDateTime dtAfter = savingsLocalTransitions[index + 1];
            ZoneOffset offsetBefore = wallOffsets[index / 2];
            ZoneOffset offsetAfter = wallOffsets[index / 2 + 1];
            if (offsetAfter.getTotalSeconds() > offsetBefore.getTotalSeconds()) {
                // gap
                return new ZoneOffsetTransition(dtBefore, offsetBefore, offsetAfter);
            } else {
                // overlap
                return new ZoneOffsetTransition(dtAfter, offsetBefore, offsetAfter);
            }
        } else {
            // normal (neither gap or overlap)
            return wallOffsets[index / 2 + 1];
        }
    }

    Finds the offset info for a local date-time and transition.
Params: dt –  the date-time, not null
trans –  the transition, not null
Returns: the offset info, not null/**
     * Finds the offset info for a local date-time and transition.
     *
     * @param dt  the date-time, not null
     * @param trans  the transition, not null
     * @return the offset info, not null
     */
    private Object findOffsetInfo(LocalDateTime dt, ZoneOffsetTransition trans) {
        LocalDateTime localTransition = trans.getDateTimeBefore();
        if (trans.isGap()) {
            if (dt.isBefore(localTransition)) {
                return trans.getOffsetBefore();
            }
            if (dt.isBefore(trans.getDateTimeAfter())) {
                return trans;
            } else {
                return trans.getOffsetAfter();
            }
        } else {
            if (dt.isBefore(localTransition) == false) {
                return trans.getOffsetAfter();
            }
            if (dt.isBefore(trans.getDateTimeAfter())) {
                return trans.getOffsetBefore();
            } else {
                return trans;
            }
        }
    }

    Finds the appropriate transition array for the given year.
Params: year –  the year, not null
Returns: the transition array, not null/**
     * Finds the appropriate transition array for the given year.
     *
     * @param year  the year, not null
     * @return the transition array, not null
     */
    private ZoneOffsetTransition[] findTransitionArray(int year) {
        Integer yearObj = year;  // should use Year class, but this saves a class load
        ZoneOffsetTransition[] transArray = lastRulesCache.get(yearObj);
        if (transArray != null) {
            return transArray;
        }
        ZoneOffsetTransitionRule[] ruleArray = lastRules;
        transArray  = new ZoneOffsetTransition[ruleArray.length];
        for (int i = 0; i < ruleArray.length; i++) {
            transArray[i] = ruleArray[i].createTransition(year);
        }
        if (year < LAST_CACHED_YEAR) {
            lastRulesCache.putIfAbsent(yearObj, transArray);
        }
        return transArray;
    }

    Gets the standard offset for the specified instant in this zone.

This provides access to historic information on how the standard offset
has changed over time.
The standard offset is the offset before any daylight saving time is applied.
This is typically the offset applicable during winter.
Params: instant –  the instant to find the offset information for, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the standard offset, not null/**
     * Gets the standard offset for the specified instant in this zone.
     * <p>
     * This provides access to historic information on how the standard offset
     * has changed over time.
     * The standard offset is the offset before any daylight saving time is applied.
     * This is typically the offset applicable during winter.
     *
     * @param instant  the instant to find the offset information for, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the standard offset, not null
     */
    public ZoneOffset getStandardOffset(Instant instant) {
        if (savingsInstantTransitions.length == 0) {
            return standardOffsets[0];
        }
        long epochSec = instant.getEpochSecond();
        int index  = Arrays.binarySearch(standardTransitions, epochSec);
        if (index < 0) {
            // switch negative insert position to start of matched range
            index = -index - 2;
        }
        return standardOffsets[index + 1];
    }

    Gets the amount of daylight savings in use for the specified instant in this zone.

This provides access to historic information on how the amount of daylight
savings has changed over time.
This is the difference between the standard offset and the actual offset.
Typically the amount is zero during winter and one hour during summer.
Time-zones are second-based, so the nanosecond part of the duration will be zero.
 This default implementation calculates the duration from the actual and standard offsets. 
Params: instant –  the instant to find the daylight savings for, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the difference between the standard and actual offset, not null/**
     * Gets the amount of daylight savings in use for the specified instant in this zone.
     * <p>
     * This provides access to historic information on how the amount of daylight
     * savings has changed over time.
     * This is the difference between the standard offset and the actual offset.
     * Typically the amount is zero during winter and one hour during summer.
     * Time-zones are second-based, so the nanosecond part of the duration will be zero.
     * <p>
     * This default implementation calculates the duration from the
     * {@link #getOffset(java.time.Instant) actual} and
     * {@link #getStandardOffset(java.time.Instant) standard} offsets.
     *
     * @param instant  the instant to find the daylight savings for, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the difference between the standard and actual offset, not null
     */
    public Duration getDaylightSavings(Instant instant) {
        if (savingsInstantTransitions.length == 0) {
            return Duration.ZERO;
        }
        ZoneOffset standardOffset = getStandardOffset(instant);
        ZoneOffset actualOffset = getOffset(instant);
        return Duration.ofSeconds(actualOffset.getTotalSeconds() - standardOffset.getTotalSeconds());
    }

    Checks if the specified instant is in daylight savings.

This checks if the standard offset and the actual offset are the same
for the specified instant.
If they are not, it is assumed that daylight savings is in operation.
 This default implementation compares the actual and standard offsets. 
Params: instant –  the instant to find the offset information for, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the standard offset, not null/**
     * Checks if the specified instant is in daylight savings.
     * <p>
     * This checks if the standard offset and the actual offset are the same
     * for the specified instant.
     * If they are not, it is assumed that daylight savings is in operation.
     * <p>
     * This default implementation compares the {@link #getOffset(java.time.Instant) actual}
     * and {@link #getStandardOffset(java.time.Instant) standard} offsets.
     *
     * @param instant  the instant to find the offset information for, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the standard offset, not null
     */
    public boolean isDaylightSavings(Instant instant) {
        return (getStandardOffset(instant).equals(getOffset(instant)) == false);
    }

    Checks if the offset date-time is valid for these rules.

To be valid, the local date-time must not be in a gap and the offset
must match one of the valid offsets.
 This default implementation checks if getValidOffsets(LocalDateTime) contains the specified offset. 
Params: localDateTime –  the date-time to check, not null, but null
 may be ignored if the rules have a single offset for all instants
offset –  the offset to check, null returns false
Returns: true if the offset date-time is valid for these rules/**
     * Checks if the offset date-time is valid for these rules.
     * <p>
     * To be valid, the local date-time must not be in a gap and the offset
     * must match one of the valid offsets.
     * <p>
     * This default implementation checks if {@link #getValidOffsets(java.time.LocalDateTime)}
     * contains the specified offset.
     *
     * @param localDateTime  the date-time to check, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @param offset  the offset to check, null returns false
     * @return true if the offset date-time is valid for these rules
     */
    public boolean isValidOffset(LocalDateTime localDateTime, ZoneOffset offset) {
        return getValidOffsets(localDateTime).contains(offset);
    }

    Gets the next transition after the specified instant.

This returns details of the next transition after the specified instant.
For example, if the instant represents a point where "Summer" daylight savings time
applies, then the method will return the transition to the next "Winter" time.
Params: instant –  the instant to get the next transition after, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the next transition after the specified instant, null if this is after the last transition/**
     * Gets the next transition after the specified instant.
     * <p>
     * This returns details of the next transition after the specified instant.
     * For example, if the instant represents a point where "Summer" daylight savings time
     * applies, then the method will return the transition to the next "Winter" time.
     *
     * @param instant  the instant to get the next transition after, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the next transition after the specified instant, null if this is after the last transition
     */
    public ZoneOffsetTransition nextTransition(Instant instant) {
        if (savingsInstantTransitions.length == 0) {
            return null;
        }
        long epochSec = instant.getEpochSecond();
        // check if using last rules
        if (epochSec >= savingsInstantTransitions[savingsInstantTransitions.length - 1]) {
            if (lastRules.length == 0) {
                return null;
            }
            // search year the instant is in
            int year = findYear(epochSec, wallOffsets[wallOffsets.length - 1]);
            ZoneOffsetTransition[] transArray = findTransitionArray(year);
            for (ZoneOffsetTransition trans : transArray) {
                if (epochSec < trans.toEpochSecond()) {
                    return trans;
                }
            }
            // use first from following year
            if (year < Year.MAX_VALUE) {
                transArray = findTransitionArray(year + 1);
                return transArray[0];
            }
            return null;
        }

        // using historic rules
        int index  = Arrays.binarySearch(savingsInstantTransitions, epochSec);
        if (index < 0) {
            index = -index - 1;  // switched value is the next transition
        } else {
            index += 1;  // exact match, so need to add one to get the next
        }
        return new ZoneOffsetTransition(savingsInstantTransitions[index], wallOffsets[index], wallOffsets[index + 1]);
    }

    Gets the previous transition before the specified instant.

This returns details of the previous transition before the specified instant.
For example, if the instant represents a point where "summer" daylight saving time
applies, then the method will return the transition from the previous "winter" time.
Params: instant –  the instant to get the previous transition after, not null, but null
 may be ignored if the rules have a single offset for all instants
Returns: the previous transition before the specified instant, null if this is before the first transition/**
     * Gets the previous transition before the specified instant.
     * <p>
     * This returns details of the previous transition before the specified instant.
     * For example, if the instant represents a point where "summer" daylight saving time
     * applies, then the method will return the transition from the previous "winter" time.
     *
     * @param instant  the instant to get the previous transition after, not null, but null
     *  may be ignored if the rules have a single offset for all instants
     * @return the previous transition before the specified instant, null if this is before the first transition
     */
    public ZoneOffsetTransition previousTransition(Instant instant) {
        if (savingsInstantTransitions.length == 0) {
            return null;
        }
        long epochSec = instant.getEpochSecond();
        if (instant.getNano() > 0 && epochSec < Long.MAX_VALUE) {
            epochSec += 1;  // allow rest of method to only use seconds
        }

        // check if using last rules
        long lastHistoric = savingsInstantTransitions[savingsInstantTransitions.length - 1];
        if (lastRules.length > 0 && epochSec > lastHistoric) {
            // search year the instant is in
            ZoneOffset lastHistoricOffset = wallOffsets[wallOffsets.length - 1];
            int year = findYear(epochSec, lastHistoricOffset);
            ZoneOffsetTransition[] transArray = findTransitionArray(year);
            for (int i = transArray.length - 1; i >= 0; i--) {
                if (epochSec > transArray[i].toEpochSecond()) {
                    return transArray[i];
                }
            }
            // use last from preceding year
            int lastHistoricYear = findYear(lastHistoric, lastHistoricOffset);
            if (--year > lastHistoricYear) {
                transArray = findTransitionArray(year);
                return transArray[transArray.length - 1];
            }
            // drop through
        }

        // using historic rules
        int index  = Arrays.binarySearch(savingsInstantTransitions, epochSec);
        if (index < 0) {
            index = -index - 1;
        }
        if (index <= 0) {
            return null;
        }
        return new ZoneOffsetTransition(savingsInstantTransitions[index - 1], wallOffsets[index - 1], wallOffsets[index]);
    }

    private int findYear(long epochSecond, ZoneOffset offset) {
        // inline for performance
        long localSecond = epochSecond + offset.getTotalSeconds();
        long localEpochDay = Math.floorDiv(localSecond, 86400);
        return LocalDate.ofEpochDay(localEpochDay).getYear();
    }

    Gets the complete list of fully defined transitions.
 The complete set of transitions for this rules instance is defined by this method and getTransitionRules(). This method returns those transitions that have been fully defined. These are typically historical, but may be in the future. 

The list will be empty for fixed offset rules and for any time-zone where there has
only ever been a single offset. The list will also be empty if the transition rules are unknown.
Returns: an immutable list of fully defined transitions, not null/**
     * Gets the complete list of fully defined transitions.
     * <p>
     * The complete set of transitions for this rules instance is defined by this method
     * and {@link #getTransitionRules()}. This method returns those transitions that have
     * been fully defined. These are typically historical, but may be in the future.
     * <p>
     * The list will be empty for fixed offset rules and for any time-zone where there has
     * only ever been a single offset. The list will also be empty if the transition rules are unknown.
     *
     * @return an immutable list of fully defined transitions, not null
     */
    public List<ZoneOffsetTransition> getTransitions() {
        List<ZoneOffsetTransition> list = new ArrayList<>();
        for (int i = 0; i < savingsInstantTransitions.length; i++) {
            list.add(new ZoneOffsetTransition(savingsInstantTransitions[i], wallOffsets[i], wallOffsets[i + 1]));
        }
        return Collections.unmodifiableList(list);
    }

    Gets the list of transition rules for years beyond those defined in the transition list.
 The complete set of transitions for this rules instance is defined by this method and getTransitions(). This method returns instances of ZoneOffsetTransitionRule that define an algorithm for when transitions will occur. 
 For any given ZoneRules, this list contains the transition rules for years beyond those years that have been fully defined. These rules typically refer to future daylight saving time rule changes. 

If the zone defines daylight savings into the future, then the list will normally
be of size two and hold information about entering and exiting daylight savings.
If the zone does not have daylight savings, or information about future changes
is uncertain, then the list will be empty.

The list will be empty for fixed offset rules and for any time-zone where there is no
daylight saving time. The list will also be empty if the transition rules are unknown.
Returns: an immutable list of transition rules, not null/**
     * Gets the list of transition rules for years beyond those defined in the transition list.
     * <p>
     * The complete set of transitions for this rules instance is defined by this method
     * and {@link #getTransitions()}. This method returns instances of {@link ZoneOffsetTransitionRule}
     * that define an algorithm for when transitions will occur.
     * <p>
     * For any given {@code ZoneRules}, this list contains the transition rules for years
     * beyond those years that have been fully defined. These rules typically refer to future
     * daylight saving time rule changes.
     * <p>
     * If the zone defines daylight savings into the future, then the list will normally
     * be of size two and hold information about entering and exiting daylight savings.
     * If the zone does not have daylight savings, or information about future changes
     * is uncertain, then the list will be empty.
     * <p>
     * The list will be empty for fixed offset rules and for any time-zone where there is no
     * daylight saving time. The list will also be empty if the transition rules are unknown.
     *
     * @return an immutable list of transition rules, not null
     */
    public List<ZoneOffsetTransitionRule> getTransitionRules() {
        return List.of(lastRules);
    }

    Checks if this set of rules equals another.

Two rule sets are equal if they will always result in the same output
for any given input instant or local date-time.
Rules from two different groups may return false even if they are in fact the same.

This definition should result in implementations comparing their entire state.
Params: otherRules –  the other rules, null returns false
Returns: true if this rules is the same as that specified/**
     * Checks if this set of rules equals another.
     * <p>
     * Two rule sets are equal if they will always result in the same output
     * for any given input instant or local date-time.
     * Rules from two different groups may return false even if they are in fact the same.
     * <p>
     * This definition should result in implementations comparing their entire state.
     *
     * @param otherRules  the other rules, null returns false
     * @return true if this rules is the same as that specified
     */
    @Override
    public boolean equals(Object otherRules) {
        if (this == otherRules) {
           return true;
        }
        if (otherRules instanceof ZoneRules) {
            ZoneRules other = (ZoneRules) otherRules;
            return Arrays.equals(standardTransitions, other.standardTransitions) &&
                    Arrays.equals(standardOffsets, other.standardOffsets) &&
                    Arrays.equals(savingsInstantTransitions, other.savingsInstantTransitions) &&
                    Arrays.equals(wallOffsets, other.wallOffsets) &&
                    Arrays.equals(lastRules, other.lastRules);
        }
        return false;
    }

    Returns a suitable hash code given the definition of #equals. 
Returns: the hash code/**
     * Returns a suitable hash code given the definition of {@code #equals}.
     *
     * @return the hash code
     */
    @Override
    public int hashCode() {
        return Arrays.hashCode(standardTransitions) ^
                Arrays.hashCode(standardOffsets) ^
                Arrays.hashCode(savingsInstantTransitions) ^
                Arrays.hashCode(wallOffsets) ^
                Arrays.hashCode(lastRules);
    }

    Returns a string describing this object.
Returns: a string for debugging, not null/**
     * Returns a string describing this object.
     *
     * @return a string for debugging, not null
     */
    @Override
    public String toString() {
        return "ZoneRules[currentStandardOffset=" + standardOffsets[standardOffsets.length - 1] + "]";
    }

}
Implementation Requirements:	This class is immutable and thread-safe.
Since:	1.8
Params:	baseStandardOffset – the standard offset to use before legal rules were set, not null baseWallOffset – the wall offset to use before legal rules were set, not null standardOffsetTransitionList – the list of changes to the standard offset, not null transitionList – the list of transitions, not null lastRules – the recurring last rules, size 16 or less, not null
Returns:	the zone rules, not null
Params:	offset – the offset this fixed zone rules is based on, not null
See Also:	isFixedOffset()
Returns:	the zone rules, not null
Params:	s – the stream to read
Throws:	InvalidObjectException – always
Params:	out – the output stream, not null
Throws:	IOException – if an error occurs
Params:	in – the input stream, not null
Throws:	IOException – if an error occurs
Returns:	the created object, not null
Params:	instant – the instant to find the offset for, not null, but null may be ignored if the rules have a single offset for all instants
Returns:	the offset, not null
Params:	localDateTime – the local date-time to query, not null, but null may be ignored if the rules have a single offset for all instants
Returns:	the best available offset for the local date-time, not null
Params:	dt – the date-time, not null trans – the transition, not null
Returns:	the offset info, not null
Params:	year – the year, not null
Returns:	the transition array, not null
Params:	instant – the instant to find the daylight savings for, not null, but null may be ignored if the rules have a single offset for all instants
Returns:	the difference between the standard and actual offset, not null
Params:	localDateTime – the date-time to check, not null, but null may be ignored if the rules have a single offset for all instants offset – the offset to check, null returns false
Returns:	true if the offset date-time is valid for these rules
Params:	instant – the instant to get the next transition after, not null, but null may be ignored if the rules have a single offset for all instants
Returns:	the next transition after the specified instant, null if this is after the last transition
Params:	instant – the instant to get the previous transition after, not null, but null may be ignored if the rules have a single offset for all instants
Returns:	the previous transition before the specified instant, null if this is before the first transition
Params:	otherRules – the other rules, null returns false
Returns:	true if this rules is the same as that specified
/

java/ 11/ java.base/java/time/zone/ZoneRules.java
