java.util

Class SimpleTimeZone

public class SimpleTimeZone extends TimeZone

This class represents a simple time zone offset and handles daylight savings. It can only handle one daylight savings rule, so it can't represent historical changes. This object is tightly bound to the Gregorian calendar. It assumes a regular seven days week, and the month lengths are that of the Gregorian Calendar. It can only handle daylight savings for years lying in the AD era.

Field Summary
static int	STANDARD_TIME Constant to indicate that start and end times are specified in standard time, without adjusting for daylight savings.
static int	UTC_TIME Constant to indicate that start and end times are specified in UTC.
static int	WALL_TIME Constant to indicate that start and end times are specified in wall time, adjusting for daylight savings.

Constructor Summary
	SimpleTimeZone(int rawOffset, String id) Create a `SimpleTimeZone` with the given time offset from GMT and without daylight savings.
	SimpleTimeZone(int rawOffset, String id, int startMonth, int startDayOfWeekInMonth, int startDayOfWeek, int startTime, int endMonth, int endDayOfWeekInMonth, int endDayOfWeek, int endTime) Create a `SimpleTimeZone` with the given time offset from GMT and with daylight savings.
	SimpleTimeZone(int rawOffset, String id, int startMonth, int startDayOfWeekInMonth, int startDayOfWeek, int startTime, int endMonth, int endDayOfWeekInMonth, int endDayOfWeek, int endTime, int dstSavings) This constructs a new SimpleTimeZone that supports a daylight savings rule.
	SimpleTimeZone(int rawOffset, String id, int startMonth, int startDayOfWeekInMonth, int startDayOfWeek, int startTime, int startTimeMode, int endMonth, int endDayOfWeekInMonth, int endDayOfWeek, int endTime, int endTimeMode, int dstSavings) This constructs a new SimpleTimeZone that supports a daylight savings rule.

Method Summary
boolean	equals(Object o)
int	getDSTSavings() Gets the daylight savings offset.
int	getOffset(int era, int year, int month, int day, int dayOfWeek, int millis) Gets the time zone offset, for current date, modified in case of daylight savings.
int	getRawOffset() Returns the time zone offset to GMT in milliseconds, ignoring day light savings.
int	hashCode() Generates the hashCode for the SimpleDateFormat object.
boolean	hasSameRules(TimeZone other) Test if the other time zone uses the same rule and only possibly differs in ID.
boolean	inDaylightTime(Date date) Determines if the given date is in daylight savings time.
void	setDSTSavings(int dstSavings) Sets the daylight savings offset.
void	setEndRule(int month, int day, int dayOfWeek, int time) Sets the daylight savings end rule.
void	setEndRule(int month, int day, int dayOfWeek, int time, boolean after) Sets the daylight savings end rule.
void	setEndRule(int month, int day, int time) Sets the daylight savings end rule.
void	setRawOffset(int rawOffset) Sets the standard time zone offset to GMT.
void	setStartRule(int month, int day, int dayOfWeek, int time) Sets the daylight savings start rule.
void	setStartRule(int month, int day, int dayOfWeek, int time, boolean after) Sets the daylight savings start rule.
void	setStartRule(int month, int day, int time) Sets the daylight savings start rule.
void	setStartYear(int year) Sets the first year, where daylight savings applies.
String	toString() Returns a string representation of this SimpleTimeZone object.
boolean	useDaylightTime() Returns if this time zone uses daylight savings time.

Field Detail

STANDARD_TIME

public static final int STANDARD_TIME

Constant to indicate that start and end times are specified in standard time, without adjusting for daylight savings.

UTC_TIME

public static final int UTC_TIME

Constant to indicate that start and end times are specified in UTC.

WALL_TIME

public static final int WALL_TIME

Constant to indicate that start and end times are specified in wall time, adjusting for daylight savings. This is the default.

Constructor Detail

SimpleTimeZone

public SimpleTimeZone(int rawOffset, String id)

Create a SimpleTimeZone with the given time offset from GMT and without daylight savings.

Parameters: rawOffset the time offset from GMT in milliseconds. id The identifier of this time zone.

SimpleTimeZone

public SimpleTimeZone(int rawOffset, String id, int startMonth, int startDayOfWeekInMonth, int startDayOfWeek, int startTime, int endMonth, int endDayOfWeekInMonth, int endDayOfWeek, int endTime)

Create a SimpleTimeZone with the given time offset from GMT and with daylight savings. The start/end parameters can have different meaning (replace WEEKDAY with a real day of week). Only the first two meanings were supported by earlier versions of jdk.

day > 0, dayOfWeek = Calendar.WEEKDAY: The start/end of daylight savings is on the day-th WEEKDAY in the given month.
day < 0, dayOfWeek = Calendar.WEEKDAY: The start/end of daylight savings is on the -day-th WEEKDAY counted from the end of the month.
day > 0, dayOfWeek = 0: The start/end of daylight is on the day-th day of the month.
day > 0, dayOfWeek = -Calendar.WEEKDAY: The start/end of daylight is on the first WEEKDAY on or after the day-th day of the month. You must make sure that this day lies in the same month.
day < 0, dayOfWeek = -Calendar.WEEKDAY: The start/end of daylight is on the first WEEKDAY on or before the -day-th day of the month. You must make sure that this day lies in the same month.

If you give a non existing month, a day that is zero, or too big, or a dayOfWeek that is too big, the result is undefined. The start rule must have a different month than the end rule. This restriction shouldn't hurt for all possible time zones.

Parameters: rawOffset The time offset from GMT in milliseconds. id The identifier of this time zone. startMonth The start month of daylight savings; use the constants in Calendar. startDayOfWeekInMonth A day in month or a day of week number, as described above. startDayOfWeek The start rule day of week; see above. startTime A time in millis in standard time. endMonth The end month of daylight savings; use the constants in Calendar. endDayOfWeekInMonth A day in month or a day of week number, as described above. endDayOfWeek The end rule day of week; see above. endTime A time in millis in standard time.

Throws: IllegalArgumentException if parameters are invalid or out of range.

SimpleTimeZone

public SimpleTimeZone(int rawOffset, String id, int startMonth, int startDayOfWeekInMonth, int startDayOfWeek, int startTime, int endMonth, int endDayOfWeekInMonth, int endDayOfWeek, int endTime, int dstSavings)

This constructs a new SimpleTimeZone that supports a daylight savings rule. The parameter are the same as for the constructor above, except there is the additional dstSavaings parameter.

Parameters: dstSavings the amount of savings for daylight savings time in milliseconds. This must be positive.

Since: 1.2

SimpleTimeZone

public SimpleTimeZone(int rawOffset, String id, int startMonth, int startDayOfWeekInMonth, int startDayOfWeek, int startTime, int startTimeMode, int endMonth, int endDayOfWeekInMonth, int endDayOfWeek, int endTime, int endTimeMode, int dstSavings)

This constructs a new SimpleTimeZone that supports a daylight savings rule. The parameter are the same as for the constructor above, except there are the additional startTimeMode, endTimeMode, and dstSavings parameters.

Parameters: startTimeMode the mode that start times are specified in. One of WALL_TIME, STANDARD_TIME, or UTC_TIME. endTimeMode the mode that end times are specified in. One of WALL_TIME, STANDARD_TIME, or UTC_TIME. dstSavings the amount of savings for daylight savings time in milliseconds. This must be positive.

Throws: IllegalArgumentException if parameters are invalid or out of range.

Since: 1.4

Method Detail

equals

public boolean equals(Object o)

getDSTSavings

public int getDSTSavings()

Gets the daylight savings offset. This is a positive offset in milliseconds with respect to standard time. Typically this is one hour, but for some time zones this may be half an our.

Returns: the daylight savings offset in milliseconds.

Since: 1.2

getOffset

public int getOffset(int era, int year, int month, int day, int dayOfWeek, int millis)

Gets the time zone offset, for current date, modified in case of daylight savings. This is the offset to add to UTC to get the local time. In the standard JDK the results given by this method may result in inaccurate results at the end of February or the beginning of March. To avoid this, you should use Calendar instead:

offset = cal.get(Calendar.ZONE_OFFSET)
 + cal.get(Calendar.DST_OFFSET);

This version doesn't suffer this inaccuracy. The arguments don't follow the approach for setting start and end rules. The day must be a positive number and dayOfWeek must be a positive value from Calendar. dayOfWeek is redundant, but must match the other values or an inaccurate result may be returned.

Parameters: era the era of the given date year the year of the given date month the month of the given date, 0 for January. day the day of month dayOfWeek the day of week; this must match the other fields. millis the millis in the day (in local standard time)

Returns: the time zone offset in milliseconds.

Throws: IllegalArgumentException if arguments are incorrect.

getRawOffset

public int getRawOffset()

Returns the time zone offset to GMT in milliseconds, ignoring day light savings.

Returns: the time zone offset.

hashCode

public int hashCode()

Generates the hashCode for the SimpleDateFormat object. It is the rawOffset, possibly, if useDaylightSavings is true, xored with startYear, startMonth, startDayOfWeekInMonth, ..., endTime.

hasSameRules

public boolean hasSameRules(TimeZone other)

Test if the other time zone uses the same rule and only possibly differs in ID. This implementation for this particular class will return true if the other object is a SimpleTimeZone, the raw offsets and useDaylight are identical and if useDaylight is true, also the start and end datas are identical.

Returns: true if this zone uses the same rule.

inDaylightTime

public boolean inDaylightTime(Date date)

Determines if the given date is in daylight savings time.

Returns: true, if it is in daylight savings time, false otherwise.

setDSTSavings

public void setDSTSavings(int dstSavings)

Sets the daylight savings offset. This is a positive offset in milliseconds with respect to standard time.

Parameters: dstSavings the daylight savings offset in milliseconds.

Since: 1.2

setEndRule

public void setEndRule(int month, int day, int dayOfWeek, int time)

Sets the daylight savings end rule. You must also set the start rule with setStartRule or the result of getOffset is undefined. For the parameters see the ten-argument constructor above.

Parameters: month The end month of daylight savings. day A day in month, or a day of week in month. dayOfWeek A day of week, when daylight savings ends. time A time in millis in standard time.

See Also: SimpleTimeZone

setEndRule

public void setEndRule(int month, int day, int dayOfWeek, int time, boolean after)

Sets the daylight savings end rule. You must also set the start rule with setStartRule or the result of getOffset is undefined. For the parameters see the ten-argument constructor above. Note that this API isn't incredibly well specified. It appears that the after flag must override the parameters, since normally, the day and dayofweek can select this. I.e., if day < 0 and dayOfWeek < 0, on or before mode is chosen. But if after == true, this implementation overrides the signs of the other arguments. And if dayOfWeek == 0, it falls back to the behavior in the other APIs. I guess this should be checked against Sun's implementation.

Parameters: month The end month of daylight savings. day A day in month, or a day of week in month. dayOfWeek A day of week, when daylight savings ends. time A time in millis in standard time. after If true, day and dayOfWeek specify first day of week on or after day, else first day of week on or before.

Since: 1.2

See Also: SimpleTimeZone

setEndRule

public void setEndRule(int month, int day, int time)

Sets the daylight savings end rule. You must also set the start rule with setStartRule or the result of getOffset is undefined. For the parameters see the ten-argument constructor above.

Parameters: month The end month of daylight savings. day A day in month, or a day of week in month. time A time in millis in standard time.

See Also: SimpleTimeZone

setRawOffset

public void setRawOffset(int rawOffset)

Sets the standard time zone offset to GMT.

Parameters: rawOffset The time offset from GMT in milliseconds.

setStartRule

public void setStartRule(int month, int day, int dayOfWeek, int time)

Sets the daylight savings start rule. You must also set the end rule with setEndRule or the result of getOffset is undefined. For the parameters see the ten-argument constructor above.

Parameters: month The month where daylight savings start, zero based. You should use the constants in Calendar. day A day of month or day of week in month. dayOfWeek The day of week where daylight savings start. time The time in milliseconds standard time where daylight savings start.

Throws: IllegalArgumentException if parameters are out of range.

See Also: SimpleTimeZone

setStartRule

public void setStartRule(int month, int day, int dayOfWeek, int time, boolean after)

Sets the daylight savings start rule. You must also set the end rule with setEndRule or the result of getOffset is undefined. For the parameters see the ten-argument constructor above. Note that this API isn't incredibly well specified. It appears that the after flag must override the parameters, since normally, the day and dayofweek can select this. I.e., if day < 0 and dayOfWeek < 0, on or before mode is chosen. But if after == true, this implementation overrides the signs of the other arguments. And if dayOfWeek == 0, it falls back to the behavior in the other APIs. I guess this should be checked against Sun's implementation.

Since: 1.2

See Also: SimpleTimeZone

setStartRule

public void setStartRule(int month, int day, int time)

Sets the daylight savings start rule. You must also set the end rule with setEndRule or the result of getOffset is undefined. For the parameters see the ten-argument constructor above.

Parameters: month The month where daylight savings start, zero based. You should use the constants in Calendar. day A day of month or day of week in month. time The time in milliseconds standard time where daylight savings start.

Since: 1.2

See Also: SimpleTimeZone

setStartYear

public void setStartYear(int year)

Sets the first year, where daylight savings applies. The daylight savings rule never apply for years in the BC era. Note that this is gregorian calendar specific.

Parameters: year the start year.

toString

public String toString()

Returns a string representation of this SimpleTimeZone object.

Returns: a string representation of this SimpleTimeZone object.

useDaylightTime

public boolean useDaylightTime()

Returns if this time zone uses daylight savings time.

Returns: true, if we use daylight savings time, false otherwise.