/**
* {@icu} Returns the array of <code>TimeZoneRule</code> which represents the rule of this time
* zone object near the specified date. Some applications are not capable to handle historic time
* zone rule changes. Also some applications can only handle certain type of rule definitions.
* This method returns either a single <code>InitialTimeZoneRule</code> if this time zone does not
* have any daylight saving time within 1 year from the specified time, or a pair of <code>
* AnnualTimeZoneRule</code> whose rule type is <code>DateTimeRule.DOW</code> for date and <code>
* DateTimeRule.WALL_TIME</code> for time with a single <code>InitialTimeZoneRule</code>
* representing the initial time, when this time zone observes daylight saving time near the
* specified date. Thus, the result may be only valid for dates around the specified date.
*
* @param date The date to be used for <code>TimeZoneRule</code> extraction.
* @return The array of <code>TimeZoneRule</code>, either a single <code>InitialTimeZoneRule
* </code> object, or a pair of <code>AnnualTimeZoneRule</code> with a single <code>
* InitialTimeZoneRule</code>. The first element in the array is always a <code>
* InitialTimeZoneRule</code>.
* @stable ICU 3.8
*/
public TimeZoneRule[] getSimpleTimeZoneRulesNear(long date) {
AnnualTimeZoneRule[] annualRules = null;
TimeZoneRule initialRule = null;
// Get the next transition
TimeZoneTransition tr = getNextTransition(date, false);
if (tr != null) {
String initialName = tr.getFrom().getName();
int initialRaw = tr.getFrom().getRawOffset();
int initialDst = tr.getFrom().getDSTSavings();
// Check if the next transition is either DST->STD or STD->DST and
// within roughly 1 year from the specified date
long nextTransitionTime = tr.getTime();
if (((tr.getFrom().getDSTSavings() == 0 && tr.getTo().getDSTSavings() != 0)
|| (tr.getFrom().getDSTSavings() != 0 && tr.getTo().getDSTSavings() == 0))
&& date + MILLIS_PER_YEAR > nextTransitionTime) {
annualRules = new AnnualTimeZoneRule[2];
// Get local wall time for the transition time
int dtfields[] =
Grego.timeToFields(
nextTransitionTime + tr.getFrom().getRawOffset() + tr.getFrom().getDSTSavings(),
null);
int weekInMonth = Grego.getDayOfWeekInMonth(dtfields[0], dtfields[1], dtfields[2]);
// Create DOW rule
DateTimeRule dtr =
new DateTimeRule(
dtfields[1], weekInMonth, dtfields[3], dtfields[5], DateTimeRule.WALL_TIME);
AnnualTimeZoneRule secondRule = null;
// Note: SimpleTimeZone does not support raw offset change.
// So we always use raw offset of the given time for the rule,
// even raw offset is changed. This will result that the result
// zone to return wrong offset after the transition.
// When we encounter such case, we do not inspect next next
// transition for another rule.
annualRules[0] =
new AnnualTimeZoneRule(
tr.getTo().getName(),
initialRaw,
tr.getTo().getDSTSavings(),
dtr,
dtfields[0],
AnnualTimeZoneRule.MAX_YEAR);
if (tr.getTo().getRawOffset() == initialRaw) {
// Get the next next transition
tr = getNextTransition(nextTransitionTime, false);
if (tr != null) {
// Check if the next next transition is either DST->STD or STD->DST
// and within roughly 1 year from the next transition
if (((tr.getFrom().getDSTSavings() == 0 && tr.getTo().getDSTSavings() != 0)
|| (tr.getFrom().getDSTSavings() != 0 && tr.getTo().getDSTSavings() == 0))
&& nextTransitionTime + MILLIS_PER_YEAR > tr.getTime()) {
// Generate another DOW rule
dtfields =
Grego.timeToFields(
tr.getTime() + tr.getFrom().getRawOffset() + tr.getFrom().getDSTSavings(),
dtfields);
weekInMonth = Grego.getDayOfWeekInMonth(dtfields[0], dtfields[1], dtfields[2]);
dtr =
new DateTimeRule(
dtfields[1], weekInMonth, dtfields[3], dtfields[5], DateTimeRule.WALL_TIME);
secondRule =
new AnnualTimeZoneRule(
tr.getTo().getName(),
tr.getTo().getRawOffset(),
tr.getTo().getDSTSavings(),
dtr,
dtfields[0] - 1,
AnnualTimeZoneRule.MAX_YEAR);
// Make sure this rule can be applied to the specified date
Date d =
secondRule.getPreviousStart(
date, tr.getFrom().getRawOffset(), tr.getFrom().getDSTSavings(), true);
if (d != null
&& d.getTime() <= date
&& initialRaw == tr.getTo().getRawOffset()
&& initialDst == tr.getTo().getDSTSavings()) {
// We can use this rule as the second transition rule
annualRules[1] = secondRule;
}
}
}
}
if (annualRules[1] == null) {
// Try previous transition
tr = getPreviousTransition(date, true);
if (tr != null) {
// Check if the previous transition is either DST->STD or STD->DST.
// The actual transition time does not matter here.
if ((tr.getFrom().getDSTSavings() == 0 && tr.getTo().getDSTSavings() != 0)
|| (tr.getFrom().getDSTSavings() != 0 && tr.getTo().getDSTSavings() == 0)) {
// Generate another DOW rule
dtfields =
Grego.timeToFields(
tr.getTime() + tr.getFrom().getRawOffset() + tr.getFrom().getDSTSavings(),
dtfields);
weekInMonth = Grego.getDayOfWeekInMonth(dtfields[0], dtfields[1], dtfields[2]);
dtr =
new DateTimeRule(
dtfields[1], weekInMonth, dtfields[3], dtfields[5], DateTimeRule.WALL_TIME);
// second rule raw/dst offsets should match raw/dst offsets
// at the given time
secondRule =
new AnnualTimeZoneRule(
tr.getTo().getName(),
initialRaw,
initialDst,
dtr,
annualRules[0].getStartYear() - 1,
AnnualTimeZoneRule.MAX_YEAR);
// Check if this rule start after the first rule after the
// specified date
Date d =
secondRule.getNextStart(
date, tr.getFrom().getRawOffset(), tr.getFrom().getDSTSavings(), false);
if (d.getTime() > nextTransitionTime) {
// We can use this rule as the second transition rule
annualRules[1] = secondRule;
}
}
}
}
if (annualRules[1] == null) {
// Cannot generate a good pair of AnnualTimeZoneRule
annualRules = null;
} else {
// The initial rule should represent the rule before the previous transition
initialName = annualRules[0].getName();
initialRaw = annualRules[0].getRawOffset();
initialDst = annualRules[0].getDSTSavings();
}
}
initialRule = new InitialTimeZoneRule(initialName, initialRaw, initialDst);
} else {
// Try the previous one
tr = getPreviousTransition(date, true);
if (tr != null) {
initialRule =
new InitialTimeZoneRule(
tr.getTo().getName(), tr.getTo().getRawOffset(), tr.getTo().getDSTSavings());
} else {
// No transitions in the past. Just use the current offsets
int[] offsets = new int[2];
getOffset(date, false, offsets);
initialRule = new InitialTimeZoneRule(getID(), offsets[0], offsets[1]);
}
}
TimeZoneRule[] result = null;
if (annualRules == null) {
result = new TimeZoneRule[1];
result[0] = initialRule;
} else {
result = new TimeZoneRule[3];
result[0] = initialRule;
result[1] = annualRules[0];
result[2] = annualRules[1];
}
return result;
}
