SimpleTimeZone

public class SimpleTimeZone extends TimeZone

SimpleTimeZone is a concrete subclass of TimeZone that represents a time zone for use with a Gregorian calendar. The class holds an offset from GMT, called raw offset, and start and end rules for a daylight saving time schedule. Since it only holds single values for each, it cannot handle historical changes in the offset from GMT and the daylight saving schedule, except that the setStartYear method can specify the year when the daylight saving time schedule starts in effect.

To construct a SimpleTimeZone with a daylight saving time schedule, the schedule can be described with a set of rules, start-rule and end-rule. A day when daylight saving time starts or ends is specified by a combination of month, day-of-month, and day-of-week values. The month value is represented by a Calendar MONTH field value, such as MARCH. The day-of-week value is represented by a Calendar DAY_OF_WEEK value, such as SUNDAY. The meanings of value combinations are as follows.

  • Exact day of month
    To specify an exact day of month, set the month and day-of-month to an exact value, and day-of-week to zero. For example, to specify March 1, set the month to MARCH, day-of-month to 1, and day-of-week to 0.
  • Day of week on or after day of month
    To specify a day of week on or after an exact day of month, set the month to an exact month value, day-of-month to the day on or after which the rule is applied, and day-of-week to a negative DAY_OF_WEEK field value. For example, to specify the second Sunday of April, set month to APRIL, day-of-month to 8, and day-of-week to -SUNDAY.
  • Day of week on or before day of month
    To specify a day of the week on or before an exact day of the month, set day-of-month and day-of-week to a negative value. For example, to specify the last Wednesday on or before the 21st of March, set month to MARCH, day-of-month is -21 and day-of-week is -WEDNESDAY.
  • Last day-of-week of month
    To specify, the last day-of-week of the month, set day-of-week to a DAY_OF_WEEK value and day-of-month to -1. For example, to specify the last Sunday of October, set month to OCTOBER, day-of-week to SUNDAY and day-of-month to -1.
The time of the day at which daylight saving time starts or ends is specified by a millisecond value within the day. There are three kinds of modes to specify the time: WALL_TIME, STANDARD_TIME and UTC_TIME. For example, if daylight saving time ends at 2:00 am in the wall clock time, it can be specified by 7200000 milliseconds in the WALL_TIME mode. In this case, the wall clock time for an end-rule means the same thing as the daylight time.

The following are examples of parameters for constructing time zone objects.


      // Base GMT offset: -8:00
      // DST starts:      at 2:00am in standard time
      //                  on the first Sunday in April
      // DST ends:        at 2:00am in daylight time
      //                  on the last Sunday in October
      // Save:            1 hour
      SimpleTimeZone(-28800000,
                     "America/Los_Angeles",
                     Calendar.APRIL, 1, -Calendar.SUNDAY,
                     7200000,
                     Calendar.OCTOBER, -1, Calendar.SUNDAY,
                     7200000,
                     3600000)

      // Base GMT offset: +1:00
      // DST starts:      at 1:00am in UTC time
      //                  on the last Sunday in March
      // DST ends:        at 1:00am in UTC time
      //                  on the last Sunday in October
      // Save:            1 hour
      SimpleTimeZone(3600000,
                     "Europe/Paris",
                     Calendar.MARCH, -1, Calendar.SUNDAY,
                     3600000, SimpleTimeZone.UTC_TIME,
                     Calendar.OCTOBER, -1, Calendar.SUNDAY,
                     3600000, SimpleTimeZone.UTC_TIME,
                     3600000)
 
These parameter rules are also applicable to the set rule methods, such as setStartRule.

Constant Summary

int STANDARD_TIME Constant for a mode of start or end time specified as standard time.
int UTC_TIME Constant for a mode of start or end time specified as UTC.
int WALL_TIME Constant for a mode of start or end time specified as wall clock time.

Inherited Constant Summary

Public Constructor Summary

SimpleTimeZone(int rawOffset, String ID)
Constructs a SimpleTimeZone with the given base time zone offset from GMT and time zone ID with no daylight saving time schedule.
SimpleTimeZone(int rawOffset, String ID, int startMonth, int startDay, int startDayOfWeek, int startTime, int endMonth, int endDay, int endDayOfWeek, int endTime)
Constructs a SimpleTimeZone with the given base time zone offset from GMT, time zone ID, and rules for starting and ending the daylight time.
SimpleTimeZone(int rawOffset, String ID, int startMonth, int startDay, int startDayOfWeek, int startTime, int endMonth, int endDay, int endDayOfWeek, int endTime, int dstSavings)
Constructs a SimpleTimeZone with the given base time zone offset from GMT, time zone ID, and rules for starting and ending the daylight time.
SimpleTimeZone(int rawOffset, String ID, int startMonth, int startDay, int startDayOfWeek, int startTime, int startTimeMode, int endMonth, int endDay, int endDayOfWeek, int endTime, int endTimeMode, int dstSavings)
Constructs a SimpleTimeZone with the given base time zone offset from GMT, time zone ID, and rules for starting and ending the daylight time.

Public Method Summary

Object
clone()
Returns a clone of this SimpleTimeZone instance.
boolean
equals(Object obj)
Compares the equality of two SimpleTimeZone objects.
int
getDSTSavings()
Returns the amount of time in milliseconds that the clock is advanced during daylight saving time.
int
getOffset(long date)
Returns the offset of this time zone from UTC at the given time.
int
getOffset(int era, int year, int month, int day, int dayOfWeek, int millis)
Returns the difference in milliseconds between local time and UTC, taking into account both the raw offset and the effect of daylight saving, for the specified date and time.
int
getRawOffset()
Gets the GMT offset for this time zone.
boolean
hasSameRules(TimeZone other)
Returns true if this zone has the same rules and offset as another zone.
synchronized int
hashCode()
Generates the hash code for the SimpleDateFormat object.
boolean
inDaylightTime(Date date)
Queries if the given date is in daylight saving time.
boolean
observesDaylightTime()
Returns true if this SimpleTimeZone observes Daylight Saving Time.
void
setDSTSavings(int millisSavedDuringDST)
Sets the amount of time in milliseconds that the clock is advanced during daylight saving time.
void
setEndRule(int endMonth, int endDay, int endDayOfWeek, int endTime, boolean after)
Sets the daylight saving time end rule to a weekday before or after the given date within a month, e.g., the first Monday on or after the 8th.
void
setEndRule(int endMonth, int endDay, int endDayOfWeek, int endTime)
Sets the daylight saving time end rule.
void
setEndRule(int endMonth, int endDay, int endTime)
Sets the daylight saving time end rule to a fixed date within a month.
void
setRawOffset(int offsetMillis)
Sets the base time zone offset to GMT.
void
setStartRule(int startMonth, int startDay, int startDayOfWeek, int startTime)
Sets the daylight saving time start rule.
void
setStartRule(int startMonth, int startDay, int startTime)
Sets the daylight saving time start rule to a fixed date within a month.
void
setStartRule(int startMonth, int startDay, int startDayOfWeek, int startTime, boolean after)
Sets the daylight saving time start rule to a weekday before or after the given date within a month, e.g., the first Monday on or after the 8th.
void
setStartYear(int year)
Sets the daylight saving time starting year.
String
toString()
Returns a string representation of this time zone.
boolean
useDaylightTime()
Queries if this time zone uses daylight saving time.

Inherited Method Summary

Constants

public static final int STANDARD_TIME

Constant for a mode of start or end time specified as standard time.

Constant Value: 1

public static final int UTC_TIME

Constant for a mode of start or end time specified as UTC. European Union rules are specified as UTC time, for example.

Constant Value: 2

public static final int WALL_TIME

Constant for a mode of start or end time specified as wall clock time. Wall clock time is standard time for the onset rule, and daylight time for the end rule.

Constant Value: 0

Public Constructors

public SimpleTimeZone (int rawOffset, String ID)

Constructs a SimpleTimeZone with the given base time zone offset from GMT and time zone ID with no daylight saving time schedule.

Parameters
rawOffset The base time zone offset in milliseconds to GMT.
ID The time zone name that is given to this instance.

public SimpleTimeZone (int rawOffset, String ID, int startMonth, int startDay, int startDayOfWeek, int startTime, int endMonth, int endDay, int endDayOfWeek, int endTime)

Constructs a SimpleTimeZone with the given base time zone offset from GMT, time zone ID, and rules for starting and ending the daylight time. Both startTime and endTime are specified to be represented in the wall clock time. The amount of daylight saving is assumed to be 3600000 milliseconds (i.e., one hour). This constructor is equivalent to:


     SimpleTimeZone(rawOffset,
                    ID,
                    startMonth,
                    startDay,
                    startDayOfWeek,
                    startTime,
                    SimpleTimeZone.WALL_TIME,
                    endMonth,
                    endDay,
                    endDayOfWeek,
                    endTime,
                    SimpleTimeZone.WALL_TIME,
                    3600000)
 

Parameters
rawOffset The given base time zone offset from GMT.
ID The time zone ID which is given to this object.
startMonth The daylight saving time starting month. Month is a MONTH field value (0-based. e.g., 0 for January).
startDay The day of the month on which the daylight saving time starts. See the class description for the special cases of this parameter.
startDayOfWeek The daylight saving time starting day-of-week. See the class description for the special cases of this parameter.
startTime The daylight saving time starting time in local wall clock time (in milliseconds within the day), which is local standard time in this case.
endMonth The daylight saving time ending month. Month is a MONTH field value (0-based. e.g., 9 for October).
endDay The day of the month on which the daylight saving time ends. See the class description for the special cases of this parameter.
endDayOfWeek The daylight saving time ending day-of-week. See the class description for the special cases of this parameter.
endTime The daylight saving ending time in local wall clock time, (in milliseconds within the day) which is local daylight time in this case.
Throws
IllegalArgumentException if the month, day, dayOfWeek, or time parameters are out of range for the start or end rule

public SimpleTimeZone (int rawOffset, String ID, int startMonth, int startDay, int startDayOfWeek, int startTime, int endMonth, int endDay, int endDayOfWeek, int endTime, int dstSavings)

Constructs a SimpleTimeZone with the given base time zone offset from GMT, time zone ID, and rules for starting and ending the daylight time. Both startTime and endTime are assumed to be represented in the wall clock time. This constructor is equivalent to:


     SimpleTimeZone(rawOffset,
                    ID,
                    startMonth,
                    startDay,
                    startDayOfWeek,
                    startTime,
                    SimpleTimeZone.WALL_TIME,
                    endMonth,
                    endDay,
                    endDayOfWeek,
                    endTime,
                    SimpleTimeZone.WALL_TIME,
                    dstSavings)
 

Parameters
rawOffset The given base time zone offset from GMT.
ID The time zone ID which is given to this object.
startMonth The daylight saving time starting month. Month is a MONTH field value (0-based. e.g., 0 for January).
startDay The day of the month on which the daylight saving time starts. See the class description for the special cases of this parameter.
startDayOfWeek The daylight saving time starting day-of-week. See the class description for the special cases of this parameter.
startTime The daylight saving time starting time in local wall clock time, which is local standard time in this case.
endMonth The daylight saving time ending month. Month is a MONTH field value (0-based. e.g., 9 for October).
endDay The day of the month on which the daylight saving time ends. See the class description for the special cases of this parameter.
endDayOfWeek The daylight saving time ending day-of-week. See the class description for the special cases of this parameter.
endTime The daylight saving ending time in local wall clock time, which is local daylight time in this case.
dstSavings The amount of time in milliseconds saved during daylight saving time.
Throws
IllegalArgumentException if the month, day, dayOfWeek, or time parameters are out of range for the start or end rule

public SimpleTimeZone (int rawOffset, String ID, int startMonth, int startDay, int startDayOfWeek, int startTime, int startTimeMode, int endMonth, int endDay, int endDayOfWeek, int endTime, int endTimeMode, int dstSavings)

Constructs a SimpleTimeZone with the given base time zone offset from GMT, time zone ID, and rules for starting and ending the daylight time. This constructor takes the full set of the start and end rules parameters, including modes of startTime and endTime. The mode specifies either wall time or standard time or UTC time.

Parameters
rawOffset The given base time zone offset from GMT.
ID The time zone ID which is given to this object.
startMonth The daylight saving time starting month. Month is a MONTH field value (0-based. e.g., 0 for January).
startDay The day of the month on which the daylight saving time starts. See the class description for the special cases of this parameter.
startDayOfWeek The daylight saving time starting day-of-week. See the class description for the special cases of this parameter.
startTime The daylight saving time starting time in the time mode specified by startTimeMode.
startTimeMode The mode of the start time specified by startTime.
endMonth The daylight saving time ending month. Month is a MONTH field value (0-based. e.g., 9 for October).
endDay The day of the month on which the daylight saving time ends. See the class description for the special cases of this parameter.
endDayOfWeek The daylight saving time ending day-of-week. See the class description for the special cases of this parameter.
endTime The daylight saving ending time in time time mode specified by endTimeMode.
endTimeMode The mode of the end time specified by endTime
dstSavings The amount of time in milliseconds saved during daylight saving time.
Throws
IllegalArgumentException if the month, day, dayOfWeek, time more, or time parameters are out of range for the start or end rule, or if a time mode value is invalid.

Public Methods

public Object clone ()

Returns a clone of this SimpleTimeZone instance.

Returns
  • a clone of this instance.

public boolean equals (Object obj)

Compares the equality of two SimpleTimeZone objects.

Parameters
obj The SimpleTimeZone object to be compared with.
Returns
  • True if the given obj is the same as this SimpleTimeZone object; false otherwise.

public int getDSTSavings ()

Returns the amount of time in milliseconds that the clock is advanced during daylight saving time.

Returns
  • the number of milliseconds the time is advanced with respect to standard time when the daylight saving rules are in effect, or 0 (zero) if this time zone doesn't observe daylight saving time.

public int getOffset (long date)

Returns the offset of this time zone from UTC at the given time. If daylight saving time is in effect at the given time, the offset value is adjusted with the amount of daylight saving.

Parameters
date the time at which the time zone offset is found
Returns
  • the amount of time in milliseconds to add to UTC to get local time.

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

Returns the difference in milliseconds between local time and UTC, taking into account both the raw offset and the effect of daylight saving, for the specified date and time. This method assumes that the start and end month are distinct. It also uses a default GregorianCalendar object as its underlying calendar, such as for determining leap years. Do not use the result of this method with a calendar other than a default GregorianCalendar.

Note: In general, clients should use Calendar.get(ZONE_OFFSET) + Calendar.get(DST_OFFSET) instead of calling this method.

Parameters
era The era of the given date.
year The year in the given date.
month The month in the given date. Month is 0-based. e.g., 0 for January.
day The day-in-month of the given date.
dayOfWeek The day-of-week of the given date.
millis The milliseconds in day in standard local time.
Returns
  • The milliseconds to add to UTC to get local time.
Throws
IllegalArgumentException the era, month, day, dayOfWeek, or millis parameters are out of range

public int getRawOffset ()

Gets the GMT offset for this time zone.

Returns
  • the GMT offset value in milliseconds

public boolean hasSameRules (TimeZone other)

Returns true if this zone has the same rules and offset as another zone.

Parameters
other the TimeZone object to be compared with
Returns
  • true if the given zone is a SimpleTimeZone and has the same rules and offset as this one

public synchronized int hashCode ()

Generates the hash code for the SimpleDateFormat object.

Returns
  • the hash code for this object

public boolean inDaylightTime (Date date)

Queries if the given date is in daylight saving time.

Parameters
date the given Date.
Returns
  • true if daylight saving time is in effective at the given date; false otherwise.

public boolean observesDaylightTime ()

Returns true if this SimpleTimeZone observes Daylight Saving Time. This method is equivalent to useDaylightTime().

Returns
  • true if this SimpleTimeZone observes Daylight Saving Time; false otherwise.

public void setDSTSavings (int millisSavedDuringDST)

Sets the amount of time in milliseconds that the clock is advanced during daylight saving time.

Parameters
millisSavedDuringDST the number of milliseconds the time is advanced with respect to standard time when the daylight saving time rules are in effect. A positive number, typically one hour (3600000).
See Also

public void setEndRule (int endMonth, int endDay, int endDayOfWeek, int endTime, boolean after)

Sets the daylight saving time end rule to a weekday before or after the given date within a month, e.g., the first Monday on or after the 8th.

Parameters
endMonth The daylight saving time ending month. Month is a MONTH field value (0-based. e.g., 9 for October).
endDay The day of the month on which the daylight saving time ends.
endDayOfWeek The daylight saving time ending day-of-week.
endTime The daylight saving ending time in local wall clock time, (in milliseconds within the day) which is local daylight time in this case.
after If true, this rule selects the first endDayOfWeek on or after endDay. If false, this rule selects the last endDayOfWeek on or before endDay of the month.
Throws
IllegalArgumentException the endMonth, endDay, endDayOfWeek, or endTime parameters are out of range

public void setEndRule (int endMonth, int endDay, int endDayOfWeek, int endTime)

Sets the daylight saving time end rule. For example, if daylight saving time ends on the last Sunday in October at 2 am in wall clock time, you can set the end rule by calling: setEndRule(Calendar.OCTOBER, -1, Calendar.SUNDAY, 2*60*60*1000);

Parameters
endMonth The daylight saving time ending month. Month is a MONTH field value (0-based. e.g., 9 for October).
endDay The day of the month on which the daylight saving time ends. See the class description for the special cases of this parameter.
endDayOfWeek The daylight saving time ending day-of-week. See the class description for the special cases of this parameter.
endTime The daylight saving ending time in local wall clock time, (in milliseconds within the day) which is local daylight time in this case.
Throws
IllegalArgumentException if the endMonth, endDay, endDayOfWeek, or endTime parameters are out of range

public void setEndRule (int endMonth, int endDay, int endTime)

Sets the daylight saving time end rule to a fixed date within a month. This method is equivalent to:

setEndRule(endMonth, endDay, 0, endTime)

Parameters
endMonth The daylight saving time ending month. Month is a MONTH field value (0-based. e.g., 9 for October).
endDay The day of the month on which the daylight saving time ends.
endTime The daylight saving ending time in local wall clock time, (in milliseconds within the day) which is local daylight time in this case.
Throws
IllegalArgumentException the endMonth, endDay, or endTime parameters are out of range

public void setRawOffset (int offsetMillis)

Sets the base time zone offset to GMT. This is the offset to add to UTC to get local time.

Parameters
offsetMillis the given base time zone offset to GMT.
See Also

public void setStartRule (int startMonth, int startDay, int startDayOfWeek, int startTime)

Sets the daylight saving time start rule. For example, if daylight saving time starts on the first Sunday in April at 2 am in local wall clock time, you can set the start rule by calling:

setStartRule(Calendar.APRIL, 1, Calendar.SUNDAY, 2*60*60*1000);

Parameters
startMonth The daylight saving time starting month. Month is a MONTH field value (0-based. e.g., 0 for January).
startDay The day of the month on which the daylight saving time starts. See the class description for the special cases of this parameter.
startDayOfWeek The daylight saving time starting day-of-week. See the class description for the special cases of this parameter.
startTime The daylight saving time starting time in local wall clock time, which is local standard time in this case.
Throws
IllegalArgumentException if the startMonth, startDay, startDayOfWeek, or startTime parameters are out of range

public void setStartRule (int startMonth, int startDay, int startTime)

Sets the daylight saving time start rule to a fixed date within a month. This method is equivalent to:

setStartRule(startMonth, startDay, 0, startTime)

Parameters
startMonth The daylight saving time starting month. Month is a MONTH field value (0-based. e.g., 0 for January).
startDay The day of the month on which the daylight saving time starts.
startTime The daylight saving time starting time in local wall clock time, which is local standard time in this case. See the class description for the special cases of this parameter.
Throws
IllegalArgumentException if the startMonth, startDayOfMonth, or startTime parameters are out of range

public void setStartRule (int startMonth, int startDay, int startDayOfWeek, int startTime, boolean after)

Sets the daylight saving time start rule to a weekday before or after the given date within a month, e.g., the first Monday on or after the 8th.

Parameters
startMonth The daylight saving time starting month. Month is a MONTH field value (0-based. e.g., 0 for January).
startDay The day of the month on which the daylight saving time starts.
startDayOfWeek The daylight saving time starting day-of-week.
startTime The daylight saving time starting time in local wall clock time, which is local standard time in this case.
after If true, this rule selects the first dayOfWeek on or after dayOfMonth. If false, this rule selects the last dayOfWeek on or before dayOfMonth.
Throws
IllegalArgumentException if the startMonth, startDay, startDayOfWeek, or startTime parameters are out of range

public void setStartYear (int year)

Sets the daylight saving time starting year.

Parameters
year The daylight saving starting year.

public String toString ()

Returns a string representation of this time zone.

Returns
  • a string representation of this time zone.

public boolean useDaylightTime ()

Queries if this time zone uses daylight saving time.

Returns
  • true if this time zone uses daylight saving time; false otherwise.