Java example source code file (ZoneId.java)
The ZoneId.java Java example source code/*
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/*
* This file is available under and governed by the GNU General Public
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* file:
*
* Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
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package java.time;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.time.format.DateTimeFormatterBuilder;
import java.time.format.TextStyle;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalQuery;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.zone.ZoneRules;
import java.time.zone.ZoneRulesException;
import java.time.zone.ZoneRulesProvider;
import java.util.Collections;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.TimeZone;
/**
* A time-zone ID, such as {@code Europe/Paris}.
* <p>
* A {@code ZoneId} is used to identify the rules used to convert between
* an {@link Instant} and a {@link LocalDateTime}.
* There are two distinct types of ID:
* <ul>
* <li>Fixed offsets - a fully resolved offset from UTC/Greenwich, that uses
* the same offset for all local date-times
* <li>Geographical regions - an area where a specific set of rules for finding
* the offset from UTC/Greenwich apply
* </ul>
* Most fixed offsets are represented by {@link ZoneOffset}.
* Calling {@link #normalized()} on any {@code ZoneId} will ensure that a
* fixed offset ID will be represented as a {@code ZoneOffset}.
* <p>
* The actual rules, describing when and how the offset changes, are defined by {@link ZoneRules}.
* This class is simply an ID used to obtain the underlying rules.
* This approach is taken because rules are defined by governments and change
* frequently, whereas the ID is stable.
* <p>
* The distinction has other effects. Serializing the {@code ZoneId} will only send
* the ID, whereas serializing the rules sends the entire data set.
* Similarly, a comparison of two IDs only examines the ID, whereas
* a comparison of two rules examines the entire data set.
*
* <h3>Time-zone IDs
* The ID is unique within the system.
* There are three types of ID.
* <p>
* The simplest type of ID is that from {@code ZoneOffset}.
* This consists of 'Z' and IDs starting with '+' or '-'.
* <p>
* The next type of ID are offset-style IDs with some form of prefix,
* such as 'GMT+2' or 'UTC+01:00'.
* The recognised prefixes are 'UTC', 'GMT' and 'UT'.
* The offset is the suffix and will be normalized during creation.
* These IDs can be normalized to a {@code ZoneOffset} using {@code normalized()}.
* <p>
* The third type of ID are region-based IDs. A region-based ID must be of
* two or more characters, and not start with 'UTC', 'GMT', 'UT' '+' or '-'.
* Region-based IDs are defined by configuration, see {@link ZoneRulesProvider}.
* The configuration focuses on providing the lookup from the ID to the
* underlying {@code ZoneRules}.
* <p>
* Time-zone rules are defined by governments and change frequently.
* There are a number of organizations, known here as groups, that monitor
* time-zone changes and collate them.
* The default group is the IANA Time Zone Database (TZDB).
* Other organizations include IATA (the airline industry body) and Microsoft.
* <p>
* Each group defines its own format for the region ID it provides.
* The TZDB group defines IDs such as 'Europe/London' or 'America/New_York'.
* TZDB IDs take precedence over other groups.
* <p>
* It is strongly recommended that the group name is included in all IDs supplied by
* groups other than TZDB to avoid conflicts. For example, IATA airline time-zone
* region IDs are typically the same as the three letter airport code.
* However, the airport of Utrecht has the code 'UTC', which is obviously a conflict.
* The recommended format for region IDs from groups other than TZDB is 'group~region'.
* Thus if IATA data were defined, Utrecht airport would be 'IATA~UTC'.
*
* <h3>Serialization
* This class can be serialized and stores the string zone ID in the external form.
* The {@code ZoneOffset} subclass uses a dedicated format that only stores the
* offset from UTC/Greenwich.
* <p>
* A {@code ZoneId} can be deserialized in a Java Runtime where the ID is unknown.
* For example, if a server-side Java Runtime has been updated with a new zone ID, but
* the client-side Java Runtime has not been updated. In this case, the {@code ZoneId}
* object will exist, and can be queried using {@code getId}, {@code equals},
* {@code hashCode}, {@code toString}, {@code getDisplayName} and {@code normalized}.
* However, any call to {@code getRules} will fail with {@code ZoneRulesException}.
* This approach is designed to allow a {@link ZonedDateTime} to be loaded and
* queried, but not modified, on a Java Runtime with incomplete time-zone information.
*
* <p>
* This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based
* class; use of identity-sensitive operations (including reference equality
* ({@code ==}), identity hash code, or synchronization) on instances of
* {@code ZoneId} may have unpredictable results and should be avoided.
* The {@code equals} method should be used for comparisons.
*
* @implSpec
* This abstract class has two implementations, both of which are immutable and thread-safe.
* One implementation models region-based IDs, the other is {@code ZoneOffset} modelling
* offset-based IDs. This difference is visible in serialization.
*
* @since 1.8
*/
public abstract class ZoneId implements Serializable {
/**
* A map of zone overrides to enable the short time-zone names to be used.
* <p>
* Use of short zone IDs has been deprecated in {@code java.util.TimeZone}.
* This map allows the IDs to continue to be used via the
* {@link #of(String, Map)} factory method.
* <p>
* This map contains a mapping of the IDs that is in line with TZDB 2005r and
* later, where 'EST', 'MST' and 'HST' map to IDs which do not include daylight
* savings.
* <p>
* This maps as follows:
* <ul>
* <li>EST - -05:00
* <li>HST - -10:00
* <li>MST - -07:00
* <li>ACT - Australia/Darwin
* <li>AET - Australia/Sydney
* <li>AGT - America/Argentina/Buenos_Aires
* <li>ART - Africa/Cairo
* <li>AST - America/Anchorage
* <li>BET - America/Sao_Paulo
* <li>BST - Asia/Dhaka
* <li>CAT - Africa/Harare
* <li>CNT - America/St_Johns
* <li>CST - America/Chicago
* <li>CTT - Asia/Shanghai
* <li>EAT - Africa/Addis_Ababa
* <li>ECT - Europe/Paris
* <li>IET - America/Indiana/Indianapolis
* <li>IST - Asia/Kolkata
* <li>JST - Asia/Tokyo
* <li>MIT - Pacific/Apia
* <li>NET - Asia/Yerevan
* <li>NST - Pacific/Auckland
* <li>PLT - Asia/Karachi
* <li>PNT - America/Phoenix
* <li>PRT - America/Puerto_Rico
* <li>PST - America/Los_Angeles
* <li>SST - Pacific/Guadalcanal
* <li>VST - Asia/Ho_Chi_Minh
* </ul>
* The map is unmodifiable.
*/
public static final Map<String, String> SHORT_IDS;
static {
Map<String, String> map = new HashMap<>(64);
map.put("ACT", "Australia/Darwin");
map.put("AET", "Australia/Sydney");
map.put("AGT", "America/Argentina/Buenos_Aires");
map.put("ART", "Africa/Cairo");
map.put("AST", "America/Anchorage");
map.put("BET", "America/Sao_Paulo");
map.put("BST", "Asia/Dhaka");
map.put("CAT", "Africa/Harare");
map.put("CNT", "America/St_Johns");
map.put("CST", "America/Chicago");
map.put("CTT", "Asia/Shanghai");
map.put("EAT", "Africa/Addis_Ababa");
map.put("ECT", "Europe/Paris");
map.put("IET", "America/Indiana/Indianapolis");
map.put("IST", "Asia/Kolkata");
map.put("JST", "Asia/Tokyo");
map.put("MIT", "Pacific/Apia");
map.put("NET", "Asia/Yerevan");
map.put("NST", "Pacific/Auckland");
map.put("PLT", "Asia/Karachi");
map.put("PNT", "America/Phoenix");
map.put("PRT", "America/Puerto_Rico");
map.put("PST", "America/Los_Angeles");
map.put("SST", "Pacific/Guadalcanal");
map.put("VST", "Asia/Ho_Chi_Minh");
map.put("EST", "-05:00");
map.put("MST", "-07:00");
map.put("HST", "-10:00");
SHORT_IDS = Collections.unmodifiableMap(map);
}
/**
* Serialization version.
*/
private static final long serialVersionUID = 8352817235686L;
//-----------------------------------------------------------------------
/**
* Gets the system default time-zone.
* <p>
* This queries {@link TimeZone#getDefault()} to find the default time-zone
* and converts it to a {@code ZoneId}. If the system default time-zone is changed,
* then the result of this method will also change.
*
* @return the zone ID, not null
* @throws DateTimeException if the converted zone ID has an invalid format
* @throws ZoneRulesException if the converted zone region ID cannot be found
*/
public static ZoneId systemDefault() {
return TimeZone.getDefault().toZoneId();
}
/**
* Gets the set of available zone IDs.
* <p>
* This set includes the string form of all available region-based IDs.
* Offset-based zone IDs are not included in the returned set.
* The ID can be passed to {@link #of(String)} to create a {@code ZoneId}.
* <p>
* The set of zone IDs can increase over time, although in a typical application
* the set of IDs is fixed. Each call to this method is thread-safe.
*
* @return a modifiable copy of the set of zone IDs, not null
*/
public static Set<String> getAvailableZoneIds() {
return ZoneRulesProvider.getAvailableZoneIds();
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code ZoneId} using its ID using a map
* of aliases to supplement the standard zone IDs.
* <p>
* Many users of time-zones use short abbreviations, such as PST for
* 'Pacific Standard Time' and PDT for 'Pacific Daylight Time'.
* These abbreviations are not unique, and so cannot be used as IDs.
* This method allows a map of string to time-zone to be setup and reused
* within an application.
*
* @param zoneId the time-zone ID, not null
* @param aliasMap a map of alias zone IDs (typically abbreviations) to real zone IDs, not null
* @return the zone ID, not null
* @throws DateTimeException if the zone ID has an invalid format
* @throws ZoneRulesException if the zone ID is a region ID that cannot be found
*/
public static ZoneId of(String zoneId, Map<String, String> aliasMap) {
Objects.requireNonNull(zoneId, "zoneId");
Objects.requireNonNull(aliasMap, "aliasMap");
String id = aliasMap.get(zoneId);
id = (id != null ? id : zoneId);
return of(id);
}
/**
* Obtains an instance of {@code ZoneId} from an ID ensuring that the
* ID is valid and available for use.
* <p>
* This method parses the ID producing a {@code ZoneId} or {@code ZoneOffset}.
* A {@code ZoneOffset} is returned if the ID is 'Z', or starts with '+' or '-'.
* The result will always be a valid ID for which {@link ZoneRules} can be obtained.
* <p>
* Parsing matches the zone ID step by step as follows.
* <ul>
* <li>If the zone ID equals 'Z', the result is {@code ZoneOffset.UTC}.
* <li>If the zone ID consists of a single letter, the zone ID is invalid
* and {@code DateTimeException} is thrown.
* <li>If the zone ID starts with '+' or '-', the ID is parsed as a
* {@code ZoneOffset} using {@link ZoneOffset#of(String)}.
* <li>If the zone ID equals 'GMT', 'UTC' or 'UT' then the result is a {@code ZoneId}
* with the same ID and rules equivalent to {@code ZoneOffset.UTC}.
* <li>If the zone ID starts with 'UTC+', 'UTC-', 'GMT+', 'GMT-', 'UT+' or 'UT-'
* then the ID is a prefixed offset-based ID. The ID is split in two, with
* a two or three letter prefix and a suffix starting with the sign.
* The suffix is parsed as a {@link ZoneOffset#of(String) ZoneOffset}.
* The result will be a {@code ZoneId} with the specified UTC/GMT/UT prefix
* and the normalized offset ID as per {@link ZoneOffset#getId()}.
* The rules of the returned {@code ZoneId} will be equivalent to the
* parsed {@code ZoneOffset}.
* <li>All other IDs are parsed as region-based zone IDs. Region IDs must
* match the regular expression <code>[A-Za-z][A-Za-z0-9~/._+-]+
* otherwise a {@code DateTimeException} is thrown. If the zone ID is not
* in the configured set of IDs, {@code ZoneRulesException} is thrown.
* The detailed format of the region ID depends on the group supplying the data.
* The default set of data is supplied by the IANA Time Zone Database (TZDB).
* This has region IDs of the form '{area}/{city}', such as 'Europe/Paris' or 'America/New_York'.
* This is compatible with most IDs from {@link java.util.TimeZone}.
* </ul>
*
* @param zoneId the time-zone ID, not null
* @return the zone ID, not null
* @throws DateTimeException if the zone ID has an invalid format
* @throws ZoneRulesException if the zone ID is a region ID that cannot be found
*/
public static ZoneId of(String zoneId) {
return of(zoneId, true);
}
/**
* Obtains an instance of {@code ZoneId} wrapping an offset.
* <p>
* If the prefix is "GMT", "UTC", or "UT" a {@code ZoneId}
* with the prefix and the non-zero offset is returned.
* If the prefix is empty {@code ""} the {@code ZoneOffset} is returned.
*
* @param prefix the time-zone ID, not null
* @param offset the offset, not null
* @return the zone ID, not null
* @throws IllegalArgumentException if the prefix is not one of
* "GMT", "UTC", or "UT", or ""
*/
public static ZoneId ofOffset(String prefix, ZoneOffset offset) {
Objects.requireNonNull(prefix, "prefix");
Objects.requireNonNull(offset, "offset");
if (prefix.length() == 0) {
return offset;
}
if (!prefix.equals("GMT") && !prefix.equals("UTC") && !prefix.equals("UT")) {
throw new IllegalArgumentException("prefix should be GMT, UTC or UT, is: " + prefix);
}
if (offset.getTotalSeconds() != 0) {
prefix = prefix.concat(offset.getId());
}
return new ZoneRegion(prefix, offset.getRules());
}
/**
* Parses the ID, taking a flag to indicate whether {@code ZoneRulesException}
* should be thrown or not, used in deserialization.
*
* @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 ZoneId of(String zoneId, boolean checkAvailable) {
Objects.requireNonNull(zoneId, "zoneId");
if (zoneId.length() <= 1 || zoneId.startsWith("+") || zoneId.startsWith("-")) {
return ZoneOffset.of(zoneId);
} else if (zoneId.startsWith("UTC") || zoneId.startsWith("GMT")) {
return ofWithPrefix(zoneId, 3, checkAvailable);
} else if (zoneId.startsWith("UT")) {
return ofWithPrefix(zoneId, 2, checkAvailable);
}
return ZoneRegion.ofId(zoneId, checkAvailable);
}
/**
* Parse once a prefix is established.
*
* @param zoneId the time-zone ID, not null
* @param prefixLength the length of the prefix, 2 or 3
* @return the zone ID, not null
* @throws DateTimeException if the zone ID has an invalid format
*/
private static ZoneId ofWithPrefix(String zoneId, int prefixLength, boolean checkAvailable) {
String prefix = zoneId.substring(0, prefixLength);
if (zoneId.length() == prefixLength) {
return ofOffset(prefix, ZoneOffset.UTC);
}
if (zoneId.charAt(prefixLength) != '+' && zoneId.charAt(prefixLength) != '-') {
return ZoneRegion.ofId(zoneId, checkAvailable); // drop through to ZoneRulesProvider
}
try {
ZoneOffset offset = ZoneOffset.of(zoneId.substring(prefixLength));
if (offset == ZoneOffset.UTC) {
return ofOffset(prefix, offset);
}
return ofOffset(prefix, offset);
} catch (DateTimeException ex) {
throw new DateTimeException("Invalid ID for offset-based ZoneId: " + zoneId, ex);
}
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code ZoneId} from a temporal object.
* <p>
* This obtains a zone 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 ZoneId}.
* <p>
* A {@code TemporalAccessor} represents some form of date and time information.
* This factory converts the arbitrary temporal object to an instance of {@code ZoneId}.
* <p>
* The conversion will try to obtain the zone in a way that favours region-based
* zones over offset-based zones using {@link TemporalQueries#zone()}.
* <p>
* This method matches the signature of the functional interface {@link TemporalQuery}
* allowing it to be used in queries via method reference, {@code ZoneId::from}.
*
* @param temporal the temporal object to convert, not null
* @return the zone ID, not null
* @throws DateTimeException if unable to convert to a {@code ZoneId}
*/
public static ZoneId from(TemporalAccessor temporal) {
ZoneId obj = temporal.query(TemporalQueries.zone());
if (obj == null) {
throw new DateTimeException("Unable to obtain ZoneId from TemporalAccessor: " +
temporal + " of type " + temporal.getClass().getName());
}
return obj;
}
//-----------------------------------------------------------------------
/**
* Constructor only accessible within the package.
*/
ZoneId() {
if (getClass() != ZoneOffset.class && getClass() != ZoneRegion.class) {
throw new AssertionError("Invalid subclass");
}
}
//-----------------------------------------------------------------------
/**
* Gets the unique time-zone ID.
* <p>
* This ID uniquely defines this object.
* The format of an offset based ID is defined by {@link ZoneOffset#getId()}.
*
* @return the time-zone unique ID, not null
*/
public abstract String getId();
//-----------------------------------------------------------------------
/**
* Gets the textual representation of the zone, such as 'British Time' or
* '+02:00'.
* <p>
* This returns the textual name used to identify the time-zone ID,
* suitable for presentation to the user.
* The parameters control the style of the returned text and the locale.
* <p>
* If no textual mapping is found then the {@link #getId() full ID} is returned.
*
* @param style the length of the text required, not null
* @param locale the locale to use, not null
* @return the text value of the zone, not null
*/
public String getDisplayName(TextStyle style, Locale locale) {
return new DateTimeFormatterBuilder().appendZoneText(style).toFormatter(locale).format(toTemporal());
}
/**
* Converts this zone to a {@code TemporalAccessor}.
* <p>
* A {@code ZoneId} can be fully represented as a {@code TemporalAccessor}.
* However, the interface is not implemented by this class as most of the
* methods on the interface have no meaning to {@code ZoneId}.
* <p>
* The returned temporal has no supported fields, with the query method
* supporting the return of the zone using {@link TemporalQueries#zoneId()}.
*
* @return a temporal equivalent to this zone, not null
*/
private TemporalAccessor toTemporal() {
return new TemporalAccessor() {
@Override
public boolean isSupported(TemporalField field) {
return false;
}
@Override
public long getLong(TemporalField field) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
@SuppressWarnings("unchecked")
@Override
public <R> R query(TemporalQuery
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