/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.util;
import java.io.IOException;
import java.io.Serializable;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import libcore.icu.TimeZones;
import libcore.util.ZoneInfoDB;
/**
* {@code TimeZone} represents a time zone, primarily used for configuring a {@link Calendar} or
* {@link java.text.SimpleDateFormat} instance.
*
* <p>Most applications will use {@link #getDefault} which returns a {@code TimeZone} based on
* the time zone where the program is running.
*
* <p>You can also get a specific {@code TimeZone} {@link #getTimeZone by Olson ID}.
*
* <p>It is highly unlikely you'll ever want to use anything but the factory methods yourself.
* Let classes like {@link Calendar} and {@link java.text.SimpleDateFormat} do the date
* computations for you.
*
* <p>If you do need to do date computations manually, there are two common cases to take into
* account:
* <ul>
* <li>Somewhere like California, where daylight time is used.
* The {@link #useDaylightTime} method will always return true, and {@link #inDaylightTime}
* must be used to determine whether or not daylight time applies to a given {@code Date}.
* The {@link #getRawOffset} method will return a raw offset of (in this case) -8 hours from UTC,
* which isn't usually very useful. More usefully, the {@link #getOffset} methods return the
* actual offset from UTC <i>for a given point in time</i>; this is the raw offset plus (if the
* point in time is {@link #inDaylightTime in daylight time}) the applicable
* {@link #getDSTSavings DST savings} (usually, but not necessarily, 1 hour).
* <li>Somewhere like Japan, where daylight time is not used.
* The {@link #useDaylightTime} and {@link #inDaylightTime} methods both always return false,
* and the raw and actual offsets will always be the same.
* </ul>
*
* <p>Note the type returned by the factory methods {@link #getDefault} and {@link #getTimeZone} is
* implementation dependent. This may introduce serialization incompatibility issues between
* different implementations, or different versions of Android.
*
* @see Calendar
* @see GregorianCalendar
* @see SimpleDateFormat
*/
public abstract class TimeZone implements Serializable, Cloneable {
private static final long serialVersionUID = 3581463369166924961L;
private static final Pattern CUSTOM_ZONE_ID_PATTERN = Pattern.compile("^GMT[-+](\\d{1,2})(:?(\\d\\d))?$");
/**
* The short display name style, such as {@code PDT}. Requests for this
* style may yield GMT offsets like {@code GMT-08:00}.
*/
public static final int SHORT = 0;
/**
* The long display name style, such as {@code Pacific Daylight Time}.
* Requests for this style may yield GMT offsets like {@code GMT-08:00}.
*/
public static final int LONG = 1;
private static final TimeZone GMT = new SimpleTimeZone(0, "GMT");
private static final TimeZone UTC = new SimpleTimeZone(0, "UTC");
private static TimeZone defaultTimeZone;
private String ID;
public TimeZone() {}
/**
* Returns a new time zone with the same ID, raw offset, and daylight
* savings time rules as this time zone.
*/
@Override public Object clone() {
try {
return super.clone();
} catch (CloneNotSupportedException e) {
throw new AssertionError(e);
}
}
/**
* Returns the system's installed time zone IDs. Any of these IDs can be
* passed to {@link #getTimeZone} to lookup the corresponding time zone
* instance.
*/
public static synchronized String[] getAvailableIDs() {
return ZoneInfoDB.getAvailableIDs();
}
/**
* Returns the IDs of the time zones whose offset from UTC is {@code
* offsetMillis}. Any of these IDs can be passed to {@link #getTimeZone} to
* lookup the corresponding time zone instance.
*
* @return a possibly-empty array.
*/
public static synchronized String[] getAvailableIDs(int offsetMillis) {
return ZoneInfoDB.getAvailableIDs(offsetMillis);
}
/**
* Returns the user's preferred time zone. This may have been overridden for
* this process with {@link #setDefault}.
*
* <p>Since the user's time zone changes dynamically, avoid caching this
* value. Instead, use this method to look it up for each use.
*/
public static synchronized TimeZone getDefault() {
if (defaultTimeZone == null) {
defaultTimeZone = ZoneInfoDB.getSystemDefault();
}
return (TimeZone) defaultTimeZone.clone();
}
/**
* Equivalent to {@code getDisplayName(false, TimeZone.LONG, Locale.getDefault())}.
* <a href="../util/Locale.html#default_locale">Be wary of the default locale</a>.
*/
public final String getDisplayName() {
return getDisplayName(false, LONG, Locale.getDefault());
}
/**
* Equivalent to {@code getDisplayName(false, TimeZone.LONG, locale)}.
*/
public final String getDisplayName(Locale locale) {
return getDisplayName(false, LONG, locale);
}
/**
* Equivalent to {@code getDisplayName(daylightTime, style, Locale.getDefault())}.
* <a href="../util/Locale.html#default_locale">Be wary of the default locale</a>.
*/
public final String getDisplayName(boolean daylightTime, int style) {
return getDisplayName(daylightTime, style, Locale.getDefault());
}
/**
* 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();
}
boolean useDaylight = daylightTime && useDaylightTime();
String[][] zoneStrings = TimeZones.getZoneStrings(locale);
String result = TimeZones.getDisplayName(zoneStrings, getID(), daylightTime, style);
if (result != null) {
return result;
}
// TODO: do we ever get here?
int offset = getRawOffset();
if (useDaylight && this instanceof SimpleTimeZone) {
offset += getDSTSavings();
}
offset /= 60000;
char sign = '+';
if (offset < 0) {
sign = '-';
offset = -offset;
}
StringBuilder builder = new StringBuilder(9);
builder.append("GMT");
builder.append(sign);
appendNumber(builder, 2, offset / 60);
builder.append(':');
appendNumber(builder, 2, offset % 60);
return builder.toString();
}
private 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 ID of this {@code TimeZone}, such as
* {@code America/Los_Angeles}, {@code GMT-08:00} or {@code UTC}.
*/
public String getID() {
return ID;
}
/**
* Returns the latest daylight savings in milliseconds for this time zone, relative
* to this time zone's regular UTC offset (as returned by {@link #getRawOffset}).
*
* <p>This class returns {@code 3600000} (1 hour) for time zones
* that use daylight savings time and {@code 0} for timezones that do not,
* leaving it to subclasses to override this method for other daylight savings
* offsets. (There are time zones, such as {@code Australia/Lord_Howe},
* that use other values.)
*
* <p>Note that this method doesn't tell you whether or not to <i>apply</i> the
* offset: you need to call {@code inDaylightTime} for the specific time
* you're interested in. If this method returns a non-zero offset, that only
* tells you that this {@code TimeZone} sometimes observes daylight savings.
*
* <p>Note also that this method doesn't necessarily return the value you need
* to apply to the time you're working with. This value can and does change over
* time for a given time zone.
*
* <p>It's highly unlikely that you should ever call this method. You
* probably want {@link #getOffset} instead, which tells you the offset
* for a specific point in time, and takes daylight savings into account for you.
*/
public int getDSTSavings() {
return useDaylightTime() ? 3600000 : 0;
}
/**
* Returns the offset in milliseconds from UTC for this time zone at {@code
* time}. The offset includes daylight savings time if the specified
* date is within the daylight savings time period.
*
* @param time the date in milliseconds since January 1, 1970 00:00:00 UTC
*/
public int getOffset(long time) {
if (inDaylightTime(new Date(time))) {
return getRawOffset() + getDSTSavings();
}
return getRawOffset();
}
/**
* Returns this time zone's offset in milliseconds from UTC at the specified
* date and time. The offset includes daylight savings time if the date
* and time is within the daylight savings time period.
*
* <p>This method is intended to be used by {@link Calendar} to compute
* {@link Calendar#DST_OFFSET} and {@link Calendar#ZONE_OFFSET}. Application
* code should have no reason to call this method directly. Each parameter
* is interpreted in the same way as the corresponding {@code Calendar}
* field. Refer to {@link Calendar} for specific definitions of this
* method's parameters.
*/
public abstract int getOffset(int era, int year, int month, int day,
int dayOfWeek, int timeOfDayMillis);
/**
* Returns the offset in milliseconds from UTC of this time zone's standard
* time.
*/
public abstract int getRawOffset();
/**
* Returns a {@code TimeZone} corresponding to the given {@code id}, or {@code GMT}
* for unknown ids.
*
* <p>An ID can be an Olson name of the form <i>Area</i>/<i>Location</i>, such
* as {@code America/Los_Angeles}. The {@link #getAvailableIDs} method returns
* the supported names.
*
* <p>This method can also create a custom {@code TimeZone} given an ID with the following
* syntax: {@code GMT[+|-]hh[[:]mm]}. For example, {@code "GMT+05:00"}, {@code "GMT+0500"},
* {@code "GMT+5:00"}, {@code "GMT+500"}, {@code "GMT+05"}, and {@code "GMT+5"} all return
* an object with a raw offset of +5 hours from UTC, and which does <i>not</i> use daylight
* savings. These are rarely useful, because they don't correspond to time zones actually
* in use by humans.
*
* <p>Other than the special cases "UTC" and "GMT" (which are synonymous in this context,
* both corresponding to UTC), Android does not support the deprecated three-letter time
* zone IDs used in Java 1.1.
*/
public static synchronized TimeZone getTimeZone(String id) {
if (id == null) {
throw new NullPointerException("id == null");
}
// Special cases? These can clone an existing instance.
// TODO: should we just add a cache to ZoneInfoDB instead?
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.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 = 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("GMT%c%02d:%02d", sign, hour, minute);
return new SimpleTimeZone(raw, cleanId);
}
/**
* Returns true if {@code timeZone} has the same rules as this time zone.
*
* <p>The base implementation returns true if both time zones have the same
* raw offset.
*/
public boolean hasSameRules(TimeZone timeZone) {
if (timeZone == null) {
return false;
}
return getRawOffset() == timeZone.getRawOffset();
}
/**
* Returns true if {@code time} is in a daylight savings time period for
* this time zone.
*/
public abstract boolean inDaylightTime(Date time);
/**
* Overrides the default time zone for the current process only.
*
* <p><strong>Warning</strong>: avoid using this method to use a custom time
* zone in your process. This value may be cleared or overwritten at any
* time, which can cause unexpected behavior. Instead, manually supply a
* custom time zone as needed.
*
* @param timeZone a custom time zone, or {@code null} to set the default to
* the user's preferred value.
*/
public static synchronized void setDefault(TimeZone timeZone) {
defaultTimeZone = timeZone != null ? (TimeZone) timeZone.clone() : null;
}
/**
* Sets the ID of this {@code TimeZone}.
*/
public void setID(String id) {
if (id == null) {
throw new NullPointerException("id == null");
}
ID = id;
}
/**
* Sets the offset in milliseconds from UTC of this time zone's standard
* time.
*/
public abstract void setRawOffset(int offsetMillis);
/**
* Returns true if this time zone has a future transition to or from
* daylight savings time.
*
* <p><strong>Warning:</strong> this returns false for time zones like
* {@code Asia/Kuala_Lumpur} that have previously used DST but do not
* currently. A hypothetical country that has never observed daylight
* savings before but plans to start next year would return true.
*
* <p><strong>Warning:</strong> this returns true for time zones that use
* DST, even when it is not active.
*
* <p>Use {@link #inDaylightTime} to find out whether daylight savings is
* in effect at a specific time.
*
* <p>Most applications should not use this method.
*/
public abstract boolean useDaylightTime();
}