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/*
 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
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package java.time;

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.zone.ZoneRules;
import java.time.zone.ZoneRulesException;
import java.time.zone.ZoneRulesProvider;
import java.util.Objects;


A geographical region where the same time-zone rules apply.


Time-zone information is categorized as a set of rules defining when and
how the offset from UTC/Greenwich changes. These rules are accessed using
identifiers based on geographical regions, such as countries or states.
The most common region classification is the Time Zone Database (TZDB),
which defines regions such as 'Europe/Paris' and 'Asia/Tokyo'.

 The region identifier, modeled by this class, is distinct from the underlying rules, modeled by ZoneRules. The rules are defined by governments and change frequently. By contrast, the region identifier is well-defined and long-lived. This separation also allows rules to be shared between regions if appropriate. 
Implementation Requirements:
This class is immutable and thread-safe.
Since:1.8
/**
 * A geographical region where the same time-zone rules apply.
 * <p>
 * Time-zone information is categorized as a set of rules defining when and
 * how the offset from UTC/Greenwich changes. These rules are accessed using
 * identifiers based on geographical regions, such as countries or states.
 * The most common region classification is the Time Zone Database (TZDB),
 * which defines regions such as 'Europe/Paris' and 'Asia/Tokyo'.
 * <p>
 * The region identifier, modeled by this class, is distinct from the
 * underlying rules, modeled by {@link ZoneRules}.
 * The rules are defined by governments and change frequently.
 * By contrast, the region identifier is well-defined and long-lived.
 * This separation also allows rules to be shared between regions if appropriate.
 *
 * @implSpec
 * This class is immutable and thread-safe.
 *
 * @since 1.8
 */
final class ZoneRegion extends ZoneId implements Serializable {

    
Serialization version.

/**
     * Serialization version.
     */
    private static final long serialVersionUID = 8386373296231747096L;
    
The time-zone ID, not null.

/**
     * The time-zone ID, not null.
     */
    private final String id;
    
The time-zone rules, null if zone ID was loaded leniently.

/**
     * The time-zone rules, null if zone ID was loaded leniently.
     */
    private final transient ZoneRules rules;

    
Obtains an instance of ZoneId from an identifier. 
Params:
  • zoneId –  the time-zone ID, not null
  • checkAvailable –  whether to check if the zone ID is available
Throws:
Returns:the zone ID, not null
/**
     * Obtains an instance of {@code ZoneId} from an identifier.
     *
     * @param zoneId  the time-zone ID, not null
     * @param checkAvailable  whether to check if the zone ID is available
     * @return the zone ID, not null
     * @throws DateTimeException if the ID format is invalid
     * @throws ZoneRulesException if checking availability and the ID cannot be found
     */
    static ZoneRegion ofId(String zoneId, boolean checkAvailable) {
        Objects.requireNonNull(zoneId, "zoneId");
        checkName(zoneId);
        ZoneRules rules = null;
        try {
            // always attempt load for better behavior after deserialization
            rules = ZoneRulesProvider.getRules(zoneId, true);
        } catch (ZoneRulesException ex) {
            if (checkAvailable) {
                throw ex;
            }
        }
        return new ZoneRegion(zoneId, rules);
    }

    
Checks that the given string is a legal ZondId name.

Params:
  • zoneId –  the time-zone ID, not null
Throws:
/**
     * Checks that the given string is a legal ZondId name.
     *
     * @param zoneId  the time-zone ID, not null
     * @throws DateTimeException if the ID format is invalid
     */
    private static void checkName(String zoneId) {
        int n = zoneId.length();
        if (n < 2) {
           throw new DateTimeException("Invalid ID for region-based ZoneId, invalid format: " + zoneId);
        }
        for (int i = 0; i < n; i++) {
            char c = zoneId.charAt(i);
            if (c >= 'a' && c <= 'z') continue;
            if (c >= 'A' && c <= 'Z') continue;
            if (c == '/' && i != 0) continue;
            if (c >= '0' && c <= '9' && i != 0) continue;
            if (c == '~' && i != 0) continue;
            if (c == '.' && i != 0) continue;
            if (c == '_' && i != 0) continue;
            if (c == '+' && i != 0) continue;
            if (c == '-' && i != 0) continue;
            throw new DateTimeException("Invalid ID for region-based ZoneId, invalid format: " + zoneId);
        }
    }

    //-------------------------------------------------------------------------
    
Constructor.

Params:
  • id –  the time-zone ID, not null
  • rules –  the rules, null for lazy lookup
/**
     * Constructor.
     *
     * @param id  the time-zone ID, not null
     * @param rules  the rules, null for lazy lookup
     */
    ZoneRegion(String id, ZoneRules rules) {
        this.id = id;
        this.rules = rules;
    }

    //-----------------------------------------------------------------------
    @Override
    public String getId() {
        return id;
    }

    @Override
    public ZoneRules getRules() {
        // additional query for group provider when null allows for possibility
        // that the provider was updated after the ZoneId was created
        return (rules != null ? rules : ZoneRulesProvider.getRules(id, false));
    }

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

@serialData

 out.writeByte(7);  // identifies a ZoneId (not ZoneOffset)
 out.writeUTF(zoneId);

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(7);  // identifies a ZoneId (not ZoneOffset)
     *  out.writeUTF(zoneId);
     * </pre>
     *
     * @return the instance of {@code Ser}, not null
     */
    private Object writeReplace() {
        return new Ser(Ser.ZONE_REGION_TYPE, this);
    }

    
Defend against malicious streams.

Params:
  • s – the stream to read
Throws:
/**
     * 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_REGION_TYPE);
        writeExternal(out);
    }

    void writeExternal(DataOutput out) throws IOException {
        out.writeUTF(id);
    }

    static ZoneId readExternal(DataInput in) throws IOException {
        String id = in.readUTF();
        return ZoneId.of(id, false);
    }

}