TimeZone represents a time zone offset, and also figures out daylight
* savings.
*
*
* Typically, you get a TimeZone using getDefault
* which creates a TimeZone based on the time zone where the program
* is running. For example, for a program running in Japan, getDefault
* creates a TimeZone object based on Japanese Standard Time.
*
*
* You can also get a TimeZone using getTimeZone
* along with a time zone ID. For instance, the time zone ID for the
* U.S. Pacific Time zone is "America/Los_Angeles". So, you can get a
* U.S. Pacific Time TimeZone object with:
*
* TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");
* getAvailableIDs method to iterate through
* all the supported time zone IDs. You can then choose a
* supported ID to get a TimeZone.
* If the time zone you want is not represented by one of the
* supported IDs, then a custom time zone ID can be specified to
* produce a TimeZone. The syntax of a custom time zone ID is:
*
* * * Hours must be between 0 to 23 and Minutes must be * between 00 to 59. For example, "GMT+10" and "GMT+0010" mean ten * hours and ten minutes ahead of GMT, respectively. ** CustomID: *GMTSign Hours:Minutes *GMTSign Hours Minutes *GMTSign Hours * Sign: one of *+ -* Hours: * Digit * Digit Digit * Minutes: * Digit Digit * Digit: one of *0 1 2 3 4 5 6 7 8 9*
* The format is locale independent and digits must be taken from the
* Basic Latin block of the Unicode standard. No daylight saving time
* transition schedule can be specified with a custom time zone ID. If
* the specified string doesn't match the syntax, "GMT"
* is used.
*
* When creating a TimeZone, the specified custom time
* zone ID is normalized in the following syntax:
*
* For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00". * ** NormalizedCustomID: *GMTSign TwoDigitHours:Minutes * Sign: one of *+ -* TwoDigitHours: * Digit Digit * Minutes: * Digit Digit * Digit: one of *0 1 2 3 4 5 6 7 8 9*
getDisplayName() indicating
* a short name, such as "PST."
* @see #LONG
* @since 1.2
*/
public static final int SHORT = 0;
/**
* A style specifier for getDisplayName() indicating
* a long name, such as "Pacific Standard Time."
* @see #SHORT
* @since 1.2
*/
public static final int LONG = 1;
// Use a preload holder to allow compile-time initialization of TimeZone and dependents.
private static class NoImagePreloadHolder {
public static final Pattern CUSTOM_ZONE_ID_PATTERN = Pattern.compile("^GMT[-+](\\d{1,2})(:?(\\d\\d))?$");
}
// Proclaim serialization compatibility with JDK 1.1
static final long serialVersionUID = 3581463369166924961L;
private static final TimeZone GMT = new SimpleTimeZone(0, "GMT");
private static final TimeZone UTC = new SimpleTimeZone(0, "UTC");
/**
* Gets the time zone offset, for current date, modified in case of
* daylight savings. This is the offset to add to UTC to get local time.
*
* This method returns a historically correct offset if an
* underlying TimeZone implementation subclass
* supports historical Daylight Saving Time schedule and GMT
* offset changes.
*
* @param era the era of the given date.
* @param year the year in the given date.
* @param month the month in the given date.
* Month is 0-based. e.g., 0 for January.
* @param day the day-in-month of the given date.
* @param dayOfWeek the day-of-week of the given date.
* @param milliseconds the milliseconds in day in standard
* local time.
*
* @return the offset in milliseconds to add to GMT to get local time.
*
* @see Calendar#ZONE_OFFSET
* @see Calendar#DST_OFFSET
*/
public abstract int getOffset(int era, int year, int month, int day,
int dayOfWeek, int milliseconds);
/**
* Returns the offset of this time zone from UTC at the specified
* date. If Daylight Saving Time is in effect at the specified
* date, the offset value is adjusted with the amount of daylight
* saving.
*
* This method returns a historically correct offset value if an * underlying TimeZone implementation subclass supports historical * Daylight Saving Time schedule and GMT offset changes. * * @param date the date represented in milliseconds since January 1, 1970 00:00:00 GMT * @return the amount of time in milliseconds to add to UTC to get local time. * * @see Calendar#ZONE_OFFSET * @see Calendar#DST_OFFSET * @since 1.4 */ public int getOffset(long date) { if (inDaylightTime(new Date(date))) { return getRawOffset() + getDSTSavings(); } return getRawOffset(); } /** * Gets the raw GMT offset and the amount of daylight saving of this * time zone at the given time. * @param date the milliseconds (since January 1, 1970, * 00:00:00.000 GMT) at which the time zone offset and daylight * saving amount are found * @param offset an array of int where the raw GMT offset * (offset[0]) and daylight saving amount (offset[1]) are stored, * or null if those values are not needed. The method assumes that * the length of the given array is two or larger. * @return the total amount of the raw GMT offset and daylight * saving at the specified date. * * @see Calendar#ZONE_OFFSET * @see Calendar#DST_OFFSET */ int getOffsets(long date, int[] offsets) { int rawoffset = getRawOffset(); int dstoffset = 0; if (inDaylightTime(new Date(date))) { dstoffset = getDSTSavings(); } if (offsets != null) { offsets[0] = rawoffset; offsets[1] = dstoffset; } return rawoffset + dstoffset; } /** * Sets the base time zone offset to GMT. * This is the offset to add to UTC to get local time. *
* If an underlying TimeZone implementation subclass
* supports historical GMT offset changes, the specified GMT
* offset is set as the latest GMT offset and the difference from
* the known latest GMT offset value is used to adjust all
* historical GMT offset values.
*
* @param offsetMillis the given base time zone offset to GMT.
*/
abstract public void setRawOffset(int offsetMillis);
/**
* Returns the amount of time in milliseconds to add to UTC to get
* standard time in this time zone. Because this value is not
* affected by daylight saving time, it is called raw
* offset.
*
* If an underlying TimeZone implementation subclass
* supports historical GMT offset changes, the method returns the
* raw offset value of the current date. In Honolulu, for example,
* its raw offset changed from GMT-10:30 to GMT-10:00 in 1947, and
* this method always returns -36000000 milliseconds (i.e., -10
* hours).
*
* @return the amount of raw offset time in milliseconds to add to UTC.
* @see Calendar#ZONE_OFFSET
*/
public abstract int getRawOffset();
/**
* Gets the ID of this time zone.
* @return the ID of this time zone.
*/
public String getID()
{
return ID;
}
/**
* Sets the time zone ID. This does not change any other data in
* the time zone object.
* @param ID the new time zone ID.
*/
public void setID(String ID)
{
if (ID == null) {
throw new NullPointerException();
}
this.ID = ID;
}
/**
* Returns a long standard time name of this {@code TimeZone} suitable for
* presentation to the user in the default locale.
*
*
This method is equivalent to: *
* * @return the human-readable name of this time zone in the default locale. * @since 1.2 * @see #getDisplayName(boolean, int, Locale) * @see Locale#getDefault(Locale.Category) * @see Locale.Category */ public final String getDisplayName() { return getDisplayName(false, LONG, Locale.getDefault(Locale.Category.DISPLAY)); } /** * Returns a long standard time name of this {@code TimeZone} suitable for * presentation to the user in the specified {@code locale}. * ** getDisplayName(false, {@link #LONG}, * Locale.getDefault({@link Locale.Category#DISPLAY})) *
This method is equivalent to: *
* * @param locale the locale in which to supply the display name. * @return the human-readable name of this time zone in the given locale. * @exception NullPointerException if {@code locale} is {@code null}. * @since 1.2 * @see #getDisplayName(boolean, int, Locale) */ public final String getDisplayName(Locale locale) { return getDisplayName(false, LONG, locale); } /** * Returns a name in the specified {@code style} of this {@code TimeZone} * suitable for presentation to the user in the default locale. If the * specified {@code daylight} is {@code true}, a Daylight Saving Time name * is returned (even if this {@code TimeZone} doesn't observe Daylight Saving * Time). Otherwise, a Standard Time name is returned. * ** getDisplayName(false, {@link #LONG}, locale) *
This method is equivalent to: *
* * @param daylight {@code true} specifying a Daylight Saving Time name, or * {@code false} specifying a Standard Time name * @param style either {@link #LONG} or {@link #SHORT} * @return the human-readable name of this time zone in the default locale. * @exception IllegalArgumentException if {@code style} is invalid. * @since 1.2 * @see #getDisplayName(boolean, int, Locale) * @see Locale#getDefault(Locale.Category) * @see Locale.Category * @see java.text.DateFormatSymbols#getZoneStrings() */ public final String getDisplayName(boolean daylight, int style) { return getDisplayName(daylight, style, Locale.getDefault(Locale.Category.DISPLAY)); } /** * Returns the {@link #SHORT short} or {@link #LONG long} name of this time * zone with either standard or daylight time, as written in {@code locale}. * If the name is not available, the result is in the format * {@code GMT[+-]hh:mm}. * * @param daylightTime true for daylight time, false for standard time. * @param style either {@link TimeZone#LONG} or {@link TimeZone#SHORT}. * @param locale the display locale. */ public String getDisplayName(boolean daylightTime, int style, Locale locale) { if (style != SHORT && style != LONG) { throw new IllegalArgumentException("Bad style: " + style); } String[][] zoneStrings = TimeZoneNames.getZoneStrings(locale); String result = TimeZoneNames.getDisplayName(zoneStrings, getID(), daylightTime, style); if (result != null) { return result; } // If we get here, it's because icu4c has nothing for us. Most commonly, this is in the // case of short names. For Pacific/Fiji, for example, icu4c has nothing better to offer // than "GMT+12:00". Why do we re-do this work ourselves? Because we have up-to-date // time zone transition data, which icu4c _doesn't_ use --- it uses its own baked-in copy, // which only gets updated when we update icu4c. http://b/7955614 and http://b/8026776. // TODO: should we generate these once, in TimeZoneNames.getDisplayName? Revisit when we // upgrade to icu4c 50 and rewrite the underlying native code. See also the // "element[j] != null" check in SimpleDateFormat.parseTimeZone, and the extra work in // DateFormatSymbols.getZoneStrings. int offsetMillis = getRawOffset(); if (daylightTime) { offsetMillis += getDSTSavings(); } return createGmtOffsetString(true /* includeGmt */, true /* includeMinuteSeparator */, offsetMillis); } /** * Returns a string representation of an offset from UTC. * ** getDisplayName(daylight, style, * Locale.getDefault({@link Locale.Category#DISPLAY})) *
The format is "[GMT](+|-)HH[:]MM". The output is not localized. * * @param includeGmt true to include "GMT", false to exclude * @param includeMinuteSeparator true to include the separator between hours and minutes, false * to exclude. * @param offsetMillis the offset from UTC * * @hide used internally by SimpleDateFormat */ public static String createGmtOffsetString(boolean includeGmt, boolean includeMinuteSeparator, int offsetMillis) { int offsetMinutes = offsetMillis / 60000; char sign = '+'; if (offsetMinutes < 0) { sign = '-'; offsetMinutes = -offsetMinutes; } StringBuilder builder = new StringBuilder(9); if (includeGmt) { builder.append("GMT"); } builder.append(sign); appendNumber(builder, 2, offsetMinutes / 60); if (includeMinuteSeparator) { builder.append(':'); } appendNumber(builder, 2, offsetMinutes % 60); return builder.toString(); } private static void appendNumber(StringBuilder builder, int count, int value) { String string = Integer.toString(value); for (int i = 0; i < count - string.length(); i++) { builder.append('0'); } builder.append(string); } /** * Returns the amount of time to be added to local standard time * to get local wall clock time. * *
The default implementation returns 3600000 milliseconds * (i.e., one hour) if a call to {@link #useDaylightTime()} * returns {@code true}. Otherwise, 0 (zero) is returned. * *
If an underlying {@code TimeZone} implementation subclass * supports historical and future Daylight Saving Time schedule * changes, this method returns the amount of saving time of the * last known Daylight Saving Time rule that can be a future * prediction. * *
If the amount of saving time at any given time stamp is * required, construct a {@link Calendar} with this {@code * TimeZone} and the time stamp, and call {@link Calendar#get(int) * Calendar.get}{@code (}{@link Calendar#DST_OFFSET}{@code )}. * * @return the amount of saving time in milliseconds * @since 1.4 * @see #inDaylightTime(Date) * @see #getOffset(long) * @see #getOffset(int,int,int,int,int,int) * @see Calendar#ZONE_OFFSET */ public int getDSTSavings() { if (useDaylightTime()) { return 3600000; } return 0; } /** * Queries if this {@code TimeZone} uses Daylight Saving Time. * *
If an underlying {@code TimeZone} implementation subclass * supports historical and future Daylight Saving Time schedule * changes, this method refers to the last known Daylight Saving Time * rule that can be a future prediction and may not be the same as * the current rule. Consider calling {@link #observesDaylightTime()} * if the current rule should also be taken into account. * * @return {@code true} if this {@code TimeZone} uses Daylight Saving Time, * {@code false}, otherwise. * @see #inDaylightTime(Date) * @see Calendar#DST_OFFSET */ public abstract boolean useDaylightTime(); /** * Returns {@code true} if this {@code TimeZone} is currently in * Daylight Saving Time, or if a transition from Standard Time to * Daylight Saving Time occurs at any future time. * *
The default implementation returns {@code true} if
* {@code useDaylightTime()} or {@code inDaylightTime(new Date())}
* returns {@code true}.
*
* @return {@code true} if this {@code TimeZone} is currently in
* Daylight Saving Time, or if a transition from Standard Time to
* Daylight Saving Time occurs at any future time; {@code false}
* otherwise.
* @since 1.7
* @see #useDaylightTime()
* @see #inDaylightTime(Date)
* @see Calendar#DST_OFFSET
*/
public boolean observesDaylightTime() {
return useDaylightTime() || inDaylightTime(new Date());
}
/**
* Queries if the given {@code date} is in Daylight Saving Time in
* this time zone.
*
* @param date the given Date.
* @return {@code true} if the given date is in Daylight Saving Time,
* {@code false}, otherwise.
*/
abstract public boolean inDaylightTime(Date date);
/**
* Gets the TimeZone for the given ID.
*
* @param id the ID for a TimeZone, either an abbreviation
* such as "PST", a full name such as "America/Los_Angeles", or a custom
* ID such as "GMT-8:00". Note that the support of abbreviations is
* for JDK 1.1.x compatibility only and full names should be used.
*
* @return the specified TimeZone, or the GMT zone if the given ID
* cannot be understood.
*/
// Android changed param s/ID/id
public static synchronized TimeZone getTimeZone(String id) {
if (id == null) {
throw new NullPointerException("id == null");
}
// Special cases? These can clone an existing instance.
if (id.length() == 3) {
if (id.equals("GMT")) {
return (TimeZone) GMT.clone();
}
if (id.equals("UTC")) {
return (TimeZone) UTC.clone();
}
}
// In the database?
TimeZone zone = null;
try {
zone = ZoneInfoDB.getInstance().makeTimeZone(id);
} catch (IOException ignored) {
}
// Custom time zone?
if (zone == null && id.length() > 3 && id.startsWith("GMT")) {
zone = getCustomTimeZone(id);
}
// We never return null; on failure we return the equivalent of "GMT".
return (zone != null) ? zone : (TimeZone) GMT.clone();
}
/**
* Returns a new SimpleTimeZone for an ID of the form "GMT[+|-]hh[[:]mm]", or null.
*/
private static TimeZone getCustomTimeZone(String id) {
Matcher m = NoImagePreloadHolder.CUSTOM_ZONE_ID_PATTERN.matcher(id);
if (!m.matches()) {
return null;
}
int hour;
int minute = 0;
try {
hour = Integer.parseInt(m.group(1));
if (m.group(3) != null) {
minute = Integer.parseInt(m.group(3));
}
} catch (NumberFormatException impossible) {
throw new AssertionError(impossible);
}
if (hour < 0 || hour > 23 || minute < 0 || minute > 59) {
return null;
}
char sign = id.charAt(3);
int raw = (hour * 3600000) + (minute * 60000);
if (sign == '-') {
raw = -raw;
}
String cleanId = String.format(Locale.ROOT, "GMT%c%02d:%02d", sign, hour, minute);
return new SimpleTimeZone(raw, cleanId);
}
/**
* Gets the available IDs according to the given time zone offset in milliseconds.
*
* @param rawOffset the given time zone GMT offset in milliseconds.
* @return an array of IDs, where the time zone for that ID has
* the specified GMT offset. For example, "America/Phoenix" and "America/Denver"
* both have GMT-07:00, but differ in daylight saving behavior.
* @see #getRawOffset()
*/
public static synchronized String[] getAvailableIDs(int rawOffset) {
return ZoneInfoDB.getInstance().getAvailableIDs(rawOffset);
}
/**
* Gets all the available IDs supported.
* @return an array of IDs.
*/
public static synchronized String[] getAvailableIDs() {
return ZoneInfoDB.getInstance().getAvailableIDs();
}
/**
* Gets the platform defined TimeZone ID.
**/
private static native String getSystemTimeZoneID(String javaHome,
String country);
/**
* Gets the custom time zone ID based on the GMT offset of the
* platform. (e.g., "GMT+08:00")
*/
private static native String getSystemGMTOffsetID();
/**
* Gets the default TimeZone for this host.
* The source of the default TimeZone
* may vary with implementation.
* @return a default TimeZone.
* @see #setDefault
*/
public static TimeZone getDefault() {
return (TimeZone) getDefaultRef().clone();
}
/**
* Returns the reference to the default TimeZone object. This
* method doesn't create a clone.
*/
static synchronized TimeZone getDefaultRef() {
if (defaultTimeZone == null) {
TimezoneGetter tzGetter = TimezoneGetter.getInstance();
String zoneName = (tzGetter != null) ? tzGetter.getId() : null;
if (zoneName != null) {
zoneName = zoneName.trim();
}
if (zoneName == null || zoneName.isEmpty()) {
try {
// On the host, we can find the configured timezone here.
zoneName = IoUtils.readFileAsString("/etc/timezone");
} catch (IOException ex) {
// "vogar --mode device" can end up here.
// TODO: give libcore access to Android system properties and read "persist.sys.timezone".
zoneName = "GMT";
}
}
defaultTimeZone = TimeZone.getTimeZone(zoneName);
}
return defaultTimeZone;
}
private static boolean hasPermission() {
boolean hasPermission = true;
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
try {
sm.checkPermission(new PropertyPermission
("user.timezone", "write"));
} catch (SecurityException e) {
hasPermission = false;
}
}
return hasPermission;
}
/**
* Sets the TimeZone that is
* returned by the getDefault method. If zone
* is null, reset the default to the value it had originally when the
* VM first started.
* @param timeZone the new default time zone
* @see #getDefault
*/
// Android changed s/zone/timeZone
public synchronized static void setDefault(TimeZone timeZone)
{
if (hasPermission()) {
defaultTimeZone = timeZone != null ? (TimeZone) timeZone.clone() : null;
android.icu.util.TimeZone.clearCachedDefault();
}
}
/**
* Returns true if this zone has the same rule and offset as another zone.
* That is, if this zone differs only in ID, if at all. Returns false
* if the other zone is null.
* @param other the TimeZone object to be compared with
* @return true if the other zone is not null and is the same as this one,
* with the possible exception of the ID
* @since 1.2
*/
public boolean hasSameRules(TimeZone other) {
return other != null && getRawOffset() == other.getRawOffset() &&
useDaylightTime() == other.useDaylightTime();
}
/**
* Creates a copy of this TimeZone.
*
* @return a clone of this TimeZone
*/
public Object clone()
{
try {
TimeZone other = (TimeZone) super.clone();
other.ID = ID;
return other;
} catch (CloneNotSupportedException e) {
throw new InternalError();
}
}
/**
* The null constant as a TimeZone.
*/
static final TimeZone NO_TIMEZONE = null;
// =======================privates===============================
/**
* The string identifier of this TimeZone. This is a
* programmatic identifier used internally to look up TimeZone
* objects from the system table and also to map them to their localized
* display names. ID values are unique in the system
* table but may not be for dynamically created zones.
* @serial
*/
private String ID;
private static volatile TimeZone defaultTimeZone;
}