Java tutorial
/* * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * 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 * * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * * Neither the name of JSR-310 nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ 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. * <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. */ private static final long serialVersionUID = 3044319355680032515L; /** * The last year to have its transitions cached. */ private static final int LAST_CACHED_YEAR = 2100; /** * The transitions between standard offsets (epoch seconds), sorted. */ private final long[] standardTransitions; /** * The standard offsets. */ private final ZoneOffset[] standardOffsets; /** * 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. */ private final LocalDateTime[] savingsLocalTransitions; /** * The wall offsets. */ private final ZoneOffset[] wallOffsets; /** * The last rule. */ private final ZoneOffsetTransitionRule[] lastRules; /** * The map of recent transitions. */ private final transient ConcurrentMap<Integer, ZoneOffsetTransition[]> lastRulesCache = new ConcurrentHashMap<Integer, ZoneOffsetTransition[]>(); /** * The zero-length long array. */ private static final long[] EMPTY_LONG_ARRAY = new long[0]; /** * The zero-length lastrules array. */ private static final ZoneOffsetTransitionRule[] EMPTY_LASTRULES = new ZoneOffsetTransitionRule[0]; /** * The zero-length ldt array. */ private static final LocalDateTime[] EMPTY_LDT_ARRAY = new LocalDateTime[0]; /** * 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. * * @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. * * @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. * * @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. * * @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. * * @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 * <a href="{@docRoot}/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. * * @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. * * @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. * * @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. * <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. * <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. * <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<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); * } * </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. * <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. * * @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. * * @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. * <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. * <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. * <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. * <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. * <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. * <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. * <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. * <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. * <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 {@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. * * @return a string for debugging, not null */ @Override public String toString() { return "ZoneRules[currentStandardOffset=" + standardOffsets[standardOffsets.length - 1] + "]"; } }