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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) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
 *
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package java.time;

import static java.time.LocalTime.MINUTES_PER_HOUR;
import static java.time.LocalTime.SECONDS_PER_HOUR;
import static java.time.LocalTime.SECONDS_PER_MINUTE;
import static java.time.temporal.ChronoField.OFFSET_SECONDS;

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.temporal.ChronoField;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalQuery;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.time.zone.ZoneRules;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

A time-zone offset from Greenwich/UTC, such as +02:00. 

A time-zone offset is the amount of time that a time-zone differs from Greenwich/UTC.
This is usually a fixed number of hours and minutes.
 Different parts of the world have different time-zone offsets. The rules for how offsets vary by place and time of year are captured in the ZoneId class. 
 For example, Paris is one hour ahead of Greenwich/UTC in winter and two hours ahead in summer. The ZoneId instance for Paris will reference two ZoneOffset instances - a +01:00 instance for winter, and a +02:00 instance for summer. 

In 2008, time-zone offsets around the world extended from -12:00 to +14:00.
To prevent any problems with that range being extended, yet still provide
validation, the range of offsets is restricted to -18:00 to 18:00 inclusive.

This class is designed for use with the ISO calendar system.
The fields of hours, minutes and seconds make assumptions that are valid for the
standard ISO definitions of those fields. This class may be used with other
calendar systems providing the definition of the time fields matches those
of the ISO calendar system.
 Instances of ZoneOffset must be compared using equals. Implementations may choose to cache certain common offsets, however applications must not rely on such caching. 

This is a value-based class; use of identity-sensitive operations (including reference equality (==), identity hash code, or synchronization) on instances of ZoneOffset may have unpredictable results and should be avoided. The equals method should be used for comparisons. 
Implementation Requirements:

This class is immutable and thread-safe.
Since:
1.8/**
 * A time-zone offset from Greenwich/UTC, such as {@code +02:00}.
 * <p>
 * A time-zone offset is the amount of time that a time-zone differs from Greenwich/UTC.
 * This is usually a fixed number of hours and minutes.
 * <p>
 * Different parts of the world have different time-zone offsets.
 * The rules for how offsets vary by place and time of year are captured in the
 * {@link ZoneId} class.
 * <p>
 * For example, Paris is one hour ahead of Greenwich/UTC in winter and two hours
 * ahead in summer. The {@code ZoneId} instance for Paris will reference two
 * {@code ZoneOffset} instances - a {@code +01:00} instance for winter,
 * and a {@code +02:00} instance for summer.
 * <p>
 * In 2008, time-zone offsets around the world extended from -12:00 to +14:00.
 * To prevent any problems with that range being extended, yet still provide
 * validation, the range of offsets is restricted to -18:00 to 18:00 inclusive.
 * <p>
 * This class is designed for use with the ISO calendar system.
 * The fields of hours, minutes and seconds make assumptions that are valid for the
 * standard ISO definitions of those fields. This class may be used with other
 * calendar systems providing the definition of the time fields matches those
 * of the ISO calendar system.
 * <p>
 * Instances of {@code ZoneOffset} must be compared using {@link #equals}.
 * Implementations may choose to cache certain common offsets, however
 * applications must not rely on such caching.
 *
 * <p>
 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
 * class; use of identity-sensitive operations (including reference equality
 * ({@code ==}), identity hash code, or synchronization) on instances of
 * {@code ZoneOffset} may have unpredictable results and should be avoided.
 * The {@code equals} method should be used for comparisons.
 *
 * @implSpec
 * This class is immutable and thread-safe.
 *
 * @since 1.8
 */
public final class ZoneOffset
        extends ZoneId
        implements TemporalAccessor, TemporalAdjuster, Comparable<ZoneOffset>, Serializable {

    
Cache of time-zone offset by offset in seconds. /** Cache of time-zone offset by offset in seconds. */
    private static final ConcurrentMap<Integer, ZoneOffset> SECONDS_CACHE = new ConcurrentHashMap<>(16, 0.75f, 4);
    
Cache of time-zone offset by ID. /** Cache of time-zone offset by ID. */
    private static final ConcurrentMap<String, ZoneOffset> ID_CACHE = new ConcurrentHashMap<>(16, 0.75f, 4);

    
The abs maximum seconds.
/**
     * The abs maximum seconds.
     */
    private static final int MAX_SECONDS = 18 * SECONDS_PER_HOUR;
    
Serialization version.
/**
     * Serialization version.
     */
    private static final long serialVersionUID = 2357656521762053153L;

    
The time-zone offset for UTC, with an ID of 'Z'.
/**
     * The time-zone offset for UTC, with an ID of 'Z'.
     */
    public static final ZoneOffset UTC = ZoneOffset.ofTotalSeconds(0);
    
Constant for the minimum supported offset.
/**
     * Constant for the minimum supported offset.
     */
    public static final ZoneOffset MIN = ZoneOffset.ofTotalSeconds(-MAX_SECONDS);
    
Constant for the maximum supported offset.
/**
     * Constant for the maximum supported offset.
     */
    public static final ZoneOffset MAX = ZoneOffset.ofTotalSeconds(MAX_SECONDS);

    
The total offset in seconds.
/**
     * The total offset in seconds.
     */
    private final int totalSeconds;
    
The string form of the time-zone offset.
/**
     * The string form of the time-zone offset.
     */
    private final transient String id;

    //-----------------------------------------------------------------------
    
Obtains an instance of ZoneOffset using the ID. 
 This method parses the string ID of a ZoneOffset to return an instance. The parsing accepts all the formats generated by getId(), plus some additional formats: 

Z - for UTC 
+h 
+hh 
+hh:mm 
-hh:mm 
+hhmm 
-hhmm 
+hh:mm:ss 
-hh:mm:ss 
+hhmmss 
-hhmmss 
Note that ± means either the plus or minus symbol.
 The ID of the returned offset will be normalized to one of the formats described by getId(). 

The maximum supported range is from +18:00 to -18:00 inclusive.
Params:
offsetId –  the offset ID, not null
Throws:
DateTimeException – if the offset ID is invalid
Returns:
the zone-offset, not null/**
     * Obtains an instance of {@code ZoneOffset} using the ID.
     * <p>
     * This method parses the string ID of a {@code ZoneOffset} to
     * return an instance. The parsing accepts all the formats generated by
     * {@link #getId()}, plus some additional formats:
     * <ul>
     * <li>{@code Z} - for UTC
     * <li>{@code +h}
     * <li>{@code +hh}
     * <li>{@code +hh:mm}
     * <li>{@code -hh:mm}
     * <li>{@code +hhmm}
     * <li>{@code -hhmm}
     * <li>{@code +hh:mm:ss}
     * <li>{@code -hh:mm:ss}
     * <li>{@code +hhmmss}
     * <li>{@code -hhmmss}
     * </ul>
     * Note that &plusmn; means either the plus or minus symbol.
     * <p>
     * The ID of the returned offset will be normalized to one of the formats
     * described by {@link #getId()}.
     * <p>
     * The maximum supported range is from +18:00 to -18:00 inclusive.
     *
     * @param offsetId  the offset ID, not null
     * @return the zone-offset, not null
     * @throws DateTimeException if the offset ID is invalid
     */
    @SuppressWarnings("fallthrough")
    public static ZoneOffset of(String offsetId) {
        Objects.requireNonNull(offsetId, "offsetId");
        // "Z" is always in the cache
        ZoneOffset offset = ID_CACHE.get(offsetId);
        if (offset != null) {
            return offset;
        }

        // parse - +h, +hh, +hhmm, +hh:mm, +hhmmss, +hh:mm:ss
        final int hours, minutes, seconds;
        switch (offsetId.length()) {
            case 2:
                offsetId = offsetId.charAt(0) + "0" + offsetId.charAt(1);  // fallthru
            case 3:
                hours = parseNumber(offsetId, 1, false);
                minutes = 0;
                seconds = 0;
                break;
            case 5:
                hours = parseNumber(offsetId, 1, false);
                minutes = parseNumber(offsetId, 3, false);
                seconds = 0;
                break;
            case 6:
                hours = parseNumber(offsetId, 1, false);
                minutes = parseNumber(offsetId, 4, true);
                seconds = 0;
                break;
            case 7:
                hours = parseNumber(offsetId, 1, false);
                minutes = parseNumber(offsetId, 3, false);
                seconds = parseNumber(offsetId, 5, false);
                break;
            case 9:
                hours = parseNumber(offsetId, 1, false);
                minutes = parseNumber(offsetId, 4, true);
                seconds = parseNumber(offsetId, 7, true);
                break;
            default:
                throw new DateTimeException("Invalid ID for ZoneOffset, invalid format: " + offsetId);
        }
        char first = offsetId.charAt(0);
        if (first != '+' && first != '-') {
            throw new DateTimeException("Invalid ID for ZoneOffset, plus/minus not found when expected: " + offsetId);
        }
        if (first == '-') {
            return ofHoursMinutesSeconds(-hours, -minutes, -seconds);
        } else {
            return ofHoursMinutesSeconds(hours, minutes, seconds);
        }
    }

    
Parse a two digit zero-prefixed number.
Params:
offsetId –  the offset ID, not null
pos –  the position to parse, valid
precededByColon –  should this number be prefixed by a precededByColon
Returns:
the parsed number, from 0 to 99/**
     * Parse a two digit zero-prefixed number.
     *
     * @param offsetId  the offset ID, not null
     * @param pos  the position to parse, valid
     * @param precededByColon  should this number be prefixed by a precededByColon
     * @return the parsed number, from 0 to 99
     */
    private static int parseNumber(CharSequence offsetId, int pos, boolean precededByColon) {
        if (precededByColon && offsetId.charAt(pos - 1) != ':') {
            throw new DateTimeException("Invalid ID for ZoneOffset, colon not found when expected: " + offsetId);
        }
        char ch1 = offsetId.charAt(pos);
        char ch2 = offsetId.charAt(pos + 1);
        if (ch1 < '0' || ch1 > '9' || ch2 < '0' || ch2 > '9') {
            throw new DateTimeException("Invalid ID for ZoneOffset, non numeric characters found: " + offsetId);
        }
        return (ch1 - 48) * 10 + (ch2 - 48);
    }

    //-----------------------------------------------------------------------
    
Obtains an instance of ZoneOffset using an offset in hours. 
Params:
hours –  the time-zone offset in hours, from -18 to +18
Throws:
DateTimeException – if the offset is not in the required range
Returns:
the zone-offset, not null/**
     * Obtains an instance of {@code ZoneOffset} using an offset in hours.
     *
     * @param hours  the time-zone offset in hours, from -18 to +18
     * @return the zone-offset, not null
     * @throws DateTimeException if the offset is not in the required range
     */
    public static ZoneOffset ofHours(int hours) {
        return ofHoursMinutesSeconds(hours, 0, 0);
    }

    
Obtains an instance of ZoneOffset using an offset in hours and minutes. 

The sign of the hours and minutes components must match.
Thus, if the hours is negative, the minutes must be negative or zero.
If the hours is zero, the minutes may be positive, negative or zero.
Params:
hours –  the time-zone offset in hours, from -18 to +18
minutes –  the time-zone offset in minutes, from 0 to ±59, sign matches hours
Throws:
DateTimeException – if the offset is not in the required range
Returns:
the zone-offset, not null/**
     * Obtains an instance of {@code ZoneOffset} using an offset in
     * hours and minutes.
     * <p>
     * The sign of the hours and minutes components must match.
     * Thus, if the hours is negative, the minutes must be negative or zero.
     * If the hours is zero, the minutes may be positive, negative or zero.
     *
     * @param hours  the time-zone offset in hours, from -18 to +18
     * @param minutes  the time-zone offset in minutes, from 0 to &plusmn;59, sign matches hours
     * @return the zone-offset, not null
     * @throws DateTimeException if the offset is not in the required range
     */
    public static ZoneOffset ofHoursMinutes(int hours, int minutes) {
        return ofHoursMinutesSeconds(hours, minutes, 0);
    }

    
Obtains an instance of ZoneOffset using an offset in hours, minutes and seconds. 

The sign of the hours, minutes and seconds components must match.
Thus, if the hours is negative, the minutes and seconds must be negative or zero.
Params:
hours –  the time-zone offset in hours, from -18 to +18
minutes –  the time-zone offset in minutes, from 0 to ±59, sign matches hours and seconds
seconds –  the time-zone offset in seconds, from 0 to ±59, sign matches hours and minutes
Throws:
DateTimeException – if the offset is not in the required range
Returns:
the zone-offset, not null/**
     * Obtains an instance of {@code ZoneOffset} using an offset in
     * hours, minutes and seconds.
     * <p>
     * The sign of the hours, minutes and seconds components must match.
     * Thus, if the hours is negative, the minutes and seconds must be negative or zero.
     *
     * @param hours  the time-zone offset in hours, from -18 to +18
     * @param minutes  the time-zone offset in minutes, from 0 to &plusmn;59, sign matches hours and seconds
     * @param seconds  the time-zone offset in seconds, from 0 to &plusmn;59, sign matches hours and minutes
     * @return the zone-offset, not null
     * @throws DateTimeException if the offset is not in the required range
     */
    public static ZoneOffset ofHoursMinutesSeconds(int hours, int minutes, int seconds) {
        validate(hours, minutes, seconds);
        int totalSeconds = totalSeconds(hours, minutes, seconds);
        return ofTotalSeconds(totalSeconds);
    }

    //-----------------------------------------------------------------------
    
Obtains an instance of ZoneOffset from a temporal object. 
 This obtains an offset based on the specified temporal. A TemporalAccessor represents an arbitrary set of date and time information, which this factory converts to an instance of ZoneOffset. 
 A TemporalAccessor represents some form of date and time information. This factory converts the arbitrary temporal object to an instance of ZoneOffset. 
 The conversion uses the TemporalQueries.offset() query, which relies on extracting the OFFSET_SECONDS field. 
 This method matches the signature of the functional interface TemporalQuery allowing it to be used as a query via method reference, ZoneOffset::from. 
Params:
temporal –  the temporal object to convert, not null
Throws:
DateTimeException – if unable to convert to an ZoneOffset
Returns:
the zone-offset, not null/**
     * Obtains an instance of {@code ZoneOffset} from a temporal object.
     * <p>
     * This obtains an offset based on the specified temporal.
     * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
     * which this factory converts to an instance of {@code ZoneOffset}.
     * <p>
     * A {@code TemporalAccessor} represents some form of date and time information.
     * This factory converts the arbitrary temporal object to an instance of {@code ZoneOffset}.
     * <p>
     * The conversion uses the {@link TemporalQueries#offset()} query, which relies
     * on extracting the {@link ChronoField#OFFSET_SECONDS OFFSET_SECONDS} field.
     * <p>
     * This method matches the signature of the functional interface {@link TemporalQuery}
     * allowing it to be used as a query via method reference, {@code ZoneOffset::from}.
     *
     * @param temporal  the temporal object to convert, not null
     * @return the zone-offset, not null
     * @throws DateTimeException if unable to convert to an {@code ZoneOffset}
     */
    public static ZoneOffset from(TemporalAccessor temporal) {
        Objects.requireNonNull(temporal, "temporal");
        ZoneOffset offset = temporal.query(TemporalQueries.offset());
        if (offset == null) {
            throw new DateTimeException("Unable to obtain ZoneOffset from TemporalAccessor: " +
                    temporal + " of type " + temporal.getClass().getName());
        }
        return offset;
    }

    //-----------------------------------------------------------------------
    
Validates the offset fields.
Params:
hours –  the time-zone offset in hours, from -18 to +18
minutes –  the time-zone offset in minutes, from 0 to ±59
seconds –  the time-zone offset in seconds, from 0 to ±59
Throws:
DateTimeException – if the offset is not in the required range/**
     * Validates the offset fields.
     *
     * @param hours  the time-zone offset in hours, from -18 to +18
     * @param minutes  the time-zone offset in minutes, from 0 to &plusmn;59
     * @param seconds  the time-zone offset in seconds, from 0 to &plusmn;59
     * @throws DateTimeException if the offset is not in the required range
     */
    private static void validate(int hours, int minutes, int seconds) {
        if (hours < -18 || hours > 18) {
            throw new DateTimeException("Zone offset hours not in valid range: value " + hours +
                    " is not in the range -18 to 18");
        }
        if (hours > 0) {
            if (minutes < 0 || seconds < 0) {
                throw new DateTimeException("Zone offset minutes and seconds must be positive because hours is positive");
            }
        } else if (hours < 0) {
            if (minutes > 0 || seconds > 0) {
                throw new DateTimeException("Zone offset minutes and seconds must be negative because hours is negative");
            }
        } else if ((minutes > 0 && seconds < 0) || (minutes < 0 && seconds > 0)) {
            throw new DateTimeException("Zone offset minutes and seconds must have the same sign");
        }
        if (minutes < -59 || minutes > 59) {
            throw new DateTimeException("Zone offset minutes not in valid range: value " +
                    minutes + " is not in the range -59 to 59");
        }
        if (seconds < -59 || seconds > 59) {
            throw new DateTimeException("Zone offset seconds not in valid range: value " +
                    seconds + " is not in the range -59 to 59");
        }
        if (Math.abs(hours) == 18 && (minutes | seconds) != 0) {
            throw new DateTimeException("Zone offset not in valid range: -18:00 to +18:00");
        }
    }

    
Calculates the total offset in seconds.
Params:
hours –  the time-zone offset in hours, from -18 to +18
minutes –  the time-zone offset in minutes, from 0 to ±59, sign matches hours and seconds
seconds –  the time-zone offset in seconds, from 0 to ±59, sign matches hours and minutes
Returns:
the total in seconds/**
     * Calculates the total offset in seconds.
     *
     * @param hours  the time-zone offset in hours, from -18 to +18
     * @param minutes  the time-zone offset in minutes, from 0 to &plusmn;59, sign matches hours and seconds
     * @param seconds  the time-zone offset in seconds, from 0 to &plusmn;59, sign matches hours and minutes
     * @return the total in seconds
     */
    private static int totalSeconds(int hours, int minutes, int seconds) {
        return hours * SECONDS_PER_HOUR + minutes * SECONDS_PER_MINUTE + seconds;
    }

    //-----------------------------------------------------------------------
    
Obtains an instance of ZoneOffset specifying the total offset in seconds 
 The offset must be in the range -18:00 to +18:00, which corresponds to -64800 to +64800. 
Params:
totalSeconds –  the total time-zone offset in seconds, from -64800 to +64800
Throws:
DateTimeException – if the offset is not in the required range
Returns:
the ZoneOffset, not null/**
     * Obtains an instance of {@code ZoneOffset} specifying the total offset in seconds
     * <p>
     * The offset must be in the range {@code -18:00} to {@code +18:00}, which corresponds to -64800 to +64800.
     *
     * @param totalSeconds  the total time-zone offset in seconds, from -64800 to +64800
     * @return the ZoneOffset, not null
     * @throws DateTimeException if the offset is not in the required range
     */
    public static ZoneOffset ofTotalSeconds(int totalSeconds) {
        if (totalSeconds < -MAX_SECONDS || totalSeconds > MAX_SECONDS) {
            throw new DateTimeException("Zone offset not in valid range: -18:00 to +18:00");
        }
        if (totalSeconds % (15 * SECONDS_PER_MINUTE) == 0) {
            Integer totalSecs = totalSeconds;
            ZoneOffset result = SECONDS_CACHE.get(totalSecs);
            if (result == null) {
                result = new ZoneOffset(totalSeconds);
                SECONDS_CACHE.putIfAbsent(totalSecs, result);
                result = SECONDS_CACHE.get(totalSecs);
                ID_CACHE.putIfAbsent(result.getId(), result);
            }
            return result;
        } else {
            return new ZoneOffset(totalSeconds);
        }
    }

    //-----------------------------------------------------------------------
    
Constructor.
Params:
totalSeconds –  the total time-zone offset in seconds, from -64800 to +64800/**
     * Constructor.
     *
     * @param totalSeconds  the total time-zone offset in seconds, from -64800 to +64800
     */
    private ZoneOffset(int totalSeconds) {
        super();
        this.totalSeconds = totalSeconds;
        id = buildId(totalSeconds);
    }

    private static String buildId(int totalSeconds) {
        if (totalSeconds == 0) {
            return "Z";
        } else {
            int absTotalSeconds = Math.abs(totalSeconds);
            StringBuilder buf = new StringBuilder();
            int absHours = absTotalSeconds / SECONDS_PER_HOUR;
            int absMinutes = (absTotalSeconds / SECONDS_PER_MINUTE) % MINUTES_PER_HOUR;
            buf.append(totalSeconds < 0 ? "-" : "+")
                .append(absHours < 10 ? "0" : "").append(absHours)
                .append(absMinutes < 10 ? ":0" : ":").append(absMinutes);
            int absSeconds = absTotalSeconds % SECONDS_PER_MINUTE;
            if (absSeconds != 0) {
                buf.append(absSeconds < 10 ? ":0" : ":").append(absSeconds);
            }
            return buf.toString();
        }
    }

    //-----------------------------------------------------------------------
    
Gets the total zone offset in seconds.

This is the primary way to access the offset amount.
It returns the total of the hours, minutes and seconds fields as a
single offset that can be added to a time.
Returns:
the total zone offset amount in seconds/**
     * Gets the total zone offset in seconds.
     * <p>
     * This is the primary way to access the offset amount.
     * It returns the total of the hours, minutes and seconds fields as a
     * single offset that can be added to a time.
     *
     * @return the total zone offset amount in seconds
     */
    public int getTotalSeconds() {
        return totalSeconds;
    }

    
Gets the normalized zone offset ID.

The ID is minor variation to the standard ISO-8601 formatted string
for the offset. There are three formats:

Z - for UTC (ISO-8601) 
+hh:mm or -hh:mm - if the seconds are zero (ISO-8601) 
+hh:mm:ss or -hh:mm:ss - if the seconds are non-zero (not ISO-8601) 
Returns:
the zone offset ID, not null/**
     * Gets the normalized zone offset ID.
     * <p>
     * The ID is minor variation to the standard ISO-8601 formatted string
     * for the offset. There are three formats:
     * <ul>
     * <li>{@code Z} - for UTC (ISO-8601)
     * <li>{@code +hh:mm} or {@code -hh:mm} - if the seconds are zero (ISO-8601)
     * <li>{@code +hh:mm:ss} or {@code -hh:mm:ss} - if the seconds are non-zero (not ISO-8601)
     * </ul>
     *
     * @return the zone offset ID, not null
     */
    @Override
    public String getId() {
        return id;
    }

    
Gets the associated time-zone rules.

The rules will always return this offset when queried.
The implementation class is immutable, thread-safe and serializable.
Returns:
the rules, not null/**
     * Gets the associated time-zone rules.
     * <p>
     * The rules will always return this offset when queried.
     * The implementation class is immutable, thread-safe and serializable.
     *
     * @return the rules, not null
     */
    @Override
    public ZoneRules getRules() {
        return ZoneRules.of(this);
    }

    //-----------------------------------------------------------------------
    
Checks if the specified field is supported.
 This checks if this offset can be queried for the specified field. If false, then calling the range and get methods will throw an exception. 
 If the field is a ChronoField then the query is implemented here. The OFFSET_SECONDS field returns true. All other ChronoField instances will return false. 
 If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.isSupportedBy(TemporalAccessor) passing this as the argument. Whether the field is supported is determined by the field. 
Params:
field –  the field to check, null returns false
Returns:
true if the field is supported on this offset, false if not/**
     * Checks if the specified field is supported.
     * <p>
     * This checks if this offset can be queried for the specified field.
     * If false, then calling the {@link #range(TemporalField) range} and
     * {@link #get(TemporalField) get} methods will throw an exception.
     * <p>
     * If the field is a {@link ChronoField} then the query is implemented here.
     * The {@code OFFSET_SECONDS} field returns true.
     * All other {@code ChronoField} instances will return false.
     * <p>
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
     * passing {@code this} as the argument.
     * Whether the field is supported is determined by the field.
     *
     * @param field  the field to check, null returns false
     * @return true if the field is supported on this offset, false if not
     */
    @Override
    public boolean isSupported(TemporalField field) {
        if (field instanceof ChronoField) {
            return field == OFFSET_SECONDS;
        }
        return field != null && field.isSupportedBy(this);
    }

    
Gets the range of valid values for the specified field.

The range object expresses the minimum and maximum valid values for a field.
This offset is used to enhance the accuracy of the returned range.
If it is not possible to return the range, because the field is not supported
or for some other reason, an exception is thrown.
 If the field is a ChronoField then the query is implemented here. The supported fields will return appropriate range instances. All other ChronoField instances will throw an UnsupportedTemporalTypeException. 
 If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.rangeRefinedBy(TemporalAccessor) passing this as the argument. Whether the range can be obtained is determined by the field. 
Params:
field –  the field to query the range for, not null
Throws:
DateTimeException – if the range for the field cannot be obtained
UnsupportedTemporalTypeException – if the field is not supported
Returns:
the range of valid values for the field, not null/**
     * Gets the range of valid values for the specified field.
     * <p>
     * The range object expresses the minimum and maximum valid values for a field.
     * This offset is used to enhance the accuracy of the returned range.
     * If it is not possible to return the range, because the field is not supported
     * or for some other reason, an exception is thrown.
     * <p>
     * If the field is a {@link ChronoField} then the query is implemented here.
     * The {@link #isSupported(TemporalField) supported fields} will return
     * appropriate range instances.
     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     * <p>
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
     * passing {@code this} as the argument.
     * Whether the range can be obtained is determined by the field.
     *
     * @param field  the field to query the range for, not null
     * @return the range of valid values for the field, not null
     * @throws DateTimeException if the range for the field cannot be obtained
     * @throws UnsupportedTemporalTypeException if the field is not supported
     */
    @Override  // override for Javadoc
    public ValueRange range(TemporalField field) {
        return TemporalAccessor.super.range(field);
    }

    
Gets the value of the specified field from this offset as an int. 

This queries this offset for the value of the specified field.
The returned value will always be within the valid range of values for the field.
If it is not possible to return the value, because the field is not supported
or for some other reason, an exception is thrown.
 If the field is a ChronoField then the query is implemented here. The OFFSET_SECONDS field returns the value of the offset. All other ChronoField instances will throw an UnsupportedTemporalTypeException. 
 If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.getFrom(TemporalAccessor) passing this as the argument. Whether the value can be obtained, and what the value represents, is determined by the field. 
Params:
field –  the field to get, not null
Throws:
DateTimeException – if a value for the field cannot be obtained or
        the value is outside the range of valid values for the field
UnsupportedTemporalTypeException – if the field is not supported or the range of values exceeds an int
ArithmeticException – if numeric overflow occurs
Returns:
the value for the field/**
     * Gets the value of the specified field from this offset as an {@code int}.
     * <p>
     * This queries this offset for the value of the specified field.
     * The returned value will always be within the valid range of values for the field.
     * If it is not possible to return the value, because the field is not supported
     * or for some other reason, an exception is thrown.
     * <p>
     * If the field is a {@link ChronoField} then the query is implemented here.
     * The {@code OFFSET_SECONDS} field returns the value of the offset.
     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     * <p>
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
     * passing {@code this} as the argument. Whether the value can be obtained,
     * and what the value represents, is determined by the field.
     *
     * @param field  the field to get, not null
     * @return the value for the field
     * @throws DateTimeException if a value for the field cannot be obtained or
     *         the value is outside the range of valid values for the field
     * @throws UnsupportedTemporalTypeException if the field is not supported or
     *         the range of values exceeds an {@code int}
     * @throws ArithmeticException if numeric overflow occurs
     */
    @Override  // override for Javadoc and performance
    public int get(TemporalField field) {
        if (field == OFFSET_SECONDS) {
            return totalSeconds;
        } else if (field instanceof ChronoField) {
            throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        }
        return range(field).checkValidIntValue(getLong(field), field);
    }

    
Gets the value of the specified field from this offset as a long. 

This queries this offset for the value of the specified field.
If it is not possible to return the value, because the field is not supported
or for some other reason, an exception is thrown.
 If the field is a ChronoField then the query is implemented here. The OFFSET_SECONDS field returns the value of the offset. All other ChronoField instances will throw an UnsupportedTemporalTypeException. 
 If the field is not a ChronoField, then the result of this method is obtained by invoking TemporalField.getFrom(TemporalAccessor) passing this as the argument. Whether the value can be obtained, and what the value represents, is determined by the field. 
Params:
field –  the field to get, not null
Throws:
DateTimeException – if a value for the field cannot be obtained
UnsupportedTemporalTypeException – if the field is not supported
ArithmeticException – if numeric overflow occurs
Returns:
the value for the field/**
     * Gets the value of the specified field from this offset as a {@code long}.
     * <p>
     * This queries this offset for the value of the specified field.
     * If it is not possible to return the value, because the field is not supported
     * or for some other reason, an exception is thrown.
     * <p>
     * If the field is a {@link ChronoField} then the query is implemented here.
     * The {@code OFFSET_SECONDS} field returns the value of the offset.
     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     * <p>
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
     * passing {@code this} as the argument. Whether the value can be obtained,
     * and what the value represents, is determined by the field.
     *
     * @param field  the field to get, not null
     * @return the value for the field
     * @throws DateTimeException if a value for the field cannot be obtained
     * @throws UnsupportedTemporalTypeException if the field is not supported
     * @throws ArithmeticException if numeric overflow occurs
     */
    @Override
    public long getLong(TemporalField field) {
        if (field == OFFSET_SECONDS) {
            return totalSeconds;
        } else if (field instanceof ChronoField) {
            throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        }
        return field.getFrom(this);
    }

    //-----------------------------------------------------------------------
    
Queries this offset using the specified query.
 This queries this offset using the specified query strategy object. The TemporalQuery object defines the logic to be used to obtain the result. Read the documentation of the query to understand what the result of this method will be. 
 The result of this method is obtained by invoking the TemporalQuery.queryFrom(TemporalAccessor) method on the specified query passing this as the argument. 
Params:
query –  the query to invoke, not null
Type parameters:
<R> – the type of the result
Throws:
DateTimeException – if unable to query (defined by the query)
ArithmeticException – if numeric overflow occurs (defined by the query)
Returns:
the query result, null may be returned (defined by the query)/**
     * Queries this offset using the specified query.
     * <p>
     * This queries this offset using the specified query strategy object.
     * The {@code TemporalQuery} object defines the logic to be used to
     * obtain the result. Read the documentation of the query to understand
     * what the result of this method will be.
     * <p>
     * The result of this method is obtained by invoking the
     * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
     * specified query passing {@code this} as the argument.
     *
     * @param <R> the type of the result
     * @param query  the query to invoke, not null
     * @return the query result, null may be returned (defined by the query)
     * @throws DateTimeException if unable to query (defined by the query)
     * @throws ArithmeticException if numeric overflow occurs (defined by the query)
     */
    @SuppressWarnings("unchecked")
    @Override
    public <R> R query(TemporalQuery<R> query) {
        if (query == TemporalQueries.offset() || query == TemporalQueries.zone()) {
            return (R) this;
        }
        return TemporalAccessor.super.query(query);
    }

    
Adjusts the specified temporal object to have the same offset as this object.

This returns a temporal object of the same observable type as the input
with the offset changed to be the same as this.
 The adjustment is equivalent to using Temporal.with(TemporalField, long) passing ChronoField.OFFSET_SECONDS as the field. 
 In most cases, it is clearer to reverse the calling pattern by using Temporal.with(TemporalAdjuster): 
  // these two lines are equivalent, but the second approach is recommended
  temporal = thisOffset.adjustInto(temporal);
  temporal = temporal.with(thisOffset);


This instance is immutable and unaffected by this method call.
Params:
temporal –  the target object to be adjusted, not null
Throws:
DateTimeException – if unable to make the adjustment
ArithmeticException – if numeric overflow occurs
Returns:
the adjusted object, not null/**
     * Adjusts the specified temporal object to have the same offset as this object.
     * <p>
     * This returns a temporal object of the same observable type as the input
     * with the offset changed to be the same as this.
     * <p>
     * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
     * passing {@link ChronoField#OFFSET_SECONDS} as the field.
     * <p>
     * In most cases, it is clearer to reverse the calling pattern by using
     * {@link Temporal#with(TemporalAdjuster)}:
     * <pre>
     *   // these two lines are equivalent, but the second approach is recommended
     *   temporal = thisOffset.adjustInto(temporal);
     *   temporal = temporal.with(thisOffset);
     * </pre>
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param temporal  the target object to be adjusted, not null
     * @return the adjusted object, not null
     * @throws DateTimeException if unable to make the adjustment
     * @throws ArithmeticException if numeric overflow occurs
     */
    @Override
    public Temporal adjustInto(Temporal temporal) {
        return temporal.with(OFFSET_SECONDS, totalSeconds);
    }

    //-----------------------------------------------------------------------
    
Compares this offset to another offset in descending order.
 The offsets are compared in the order that they occur for the same time of day around the world. Thus, an offset of +10:00 comes before an offset of +09:00 and so on down to -18:00. 
 The comparison is "consistent with equals", as defined by Comparable. 
Params:
other –  the other date to compare to, not null
Throws:
NullPointerException – if other is null
Returns:
the comparator value, negative if less, positive if greater/**
     * Compares this offset to another offset in descending order.
     * <p>
     * The offsets are compared in the order that they occur for the same time
     * of day around the world. Thus, an offset of {@code +10:00} comes before an
     * offset of {@code +09:00} and so on down to {@code -18:00}.
     * <p>
     * The comparison is "consistent with equals", as defined by {@link Comparable}.
     *
     * @param other  the other date to compare to, not null
     * @return the comparator value, negative if less, positive if greater
     * @throws NullPointerException if {@code other} is null
     */
    @Override
    public int compareTo(ZoneOffset other) {
        // abs(totalSeconds) <= MAX_SECONDS, so no overflow can happen here
        return other.totalSeconds - totalSeconds;
    }

    //-----------------------------------------------------------------------
    
Checks if this offset is equal to another offset.

The comparison is based on the amount of the offset in seconds.
This is equivalent to a comparison by ID.
Params:
obj –  the object to check, null returns false
Returns:
true if this is equal to the other offset/**
     * Checks if this offset is equal to another offset.
     * <p>
     * The comparison is based on the amount of the offset in seconds.
     * This is equivalent to a comparison by ID.
     *
     * @param obj  the object to check, null returns false
     * @return true if this is equal to the other offset
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
           return true;
        }
        if (obj instanceof ZoneOffset) {
            return totalSeconds == ((ZoneOffset) obj).totalSeconds;
        }
        return false;
    }

    
A hash code for this offset.
Returns:
a suitable hash code/**
     * A hash code for this offset.
     *
     * @return a suitable hash code
     */
    @Override
    public int hashCode() {
        return totalSeconds;
    }

    //-----------------------------------------------------------------------
    
Outputs this offset as a String, using the normalized ID. 
Returns:
a string representation of this offset, not null/**
     * Outputs this offset as a {@code String}, using the normalized ID.
     *
     * @return a string representation of this offset, not null
     */
    @Override
    public String toString() {
        return id;
    }

    // -----------------------------------------------------------------------
    
Writes the object using a
dedicated serialized form.
@serialData

 out.writeByte(8);                  // identifies a ZoneOffset
 int offsetByte = totalSeconds % 900 == 0 ? totalSeconds / 900 : 127;
 out.writeByte(offsetByte);
 if (offsetByte == 127) {
     out.writeInt(totalSeconds);
 }
Returns:
the instance of Ser, not null/**
     * Writes the object using a
     * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
     * @serialData
     * <pre>
     *  out.writeByte(8);                  // identifies a ZoneOffset
     *  int offsetByte = totalSeconds % 900 == 0 ? totalSeconds / 900 : 127;
     *  out.writeByte(offsetByte);
     *  if (offsetByte == 127) {
     *      out.writeInt(totalSeconds);
     *  }
     * </pre>
     *
     * @return the instance of {@code Ser}, not null
     */
    private Object writeReplace() {
        return new Ser(Ser.ZONE_OFFSET_TYPE, this);
    }

    
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");
    }

    @Override
    void write(DataOutput out) throws IOException {
        out.writeByte(Ser.ZONE_OFFSET_TYPE);
        writeExternal(out);
    }

    void writeExternal(DataOutput out) throws IOException {
        final int offsetSecs = totalSeconds;
        int offsetByte = offsetSecs % 900 == 0 ? offsetSecs / 900 : 127;  // compress to -72 to +72
        out.writeByte(offsetByte);
        if (offsetByte == 127) {
            out.writeInt(offsetSecs);
        }
    }

    static ZoneOffset readExternal(DataInput in) throws IOException {
        int offsetByte = in.readByte();
        return (offsetByte == 127 ? ZoneOffset.ofTotalSeconds(in.readInt()) : ZoneOffset.ofTotalSeconds(offsetByte * 900));
    }

}