TimeZone, SimpleTimeZone - java.util

TimeZone

Another time-related class is TimeZone. The abstract TimeZone class allows you to work with time zone offsets from Greenwich mean time (GMT), also referred to as Coordinated Universal Time (UTC). It also computes daylight saving time. TimeZone only supplies the default constructor.

A sampling of methods defined by TimeZone is given in Table 19-6.

SimpleTimeZone

The SimpleTimeZone class is a convenient subclass of TimeZone. It implements TimeZone's abstract methods and allows you to work with time zones for a Gregorian calendar. It also computes daylight saving time.

SimpleTimeZone defines four constructors. One is SimpleTimeZone(int timeDelta, String tzName)

This constructor creates a SimpleTimeZone object. The offset relative to Greenwich mean time (GMT) is timeDelta. The time zone is named tzName.

The second SimpleTimeZone constructor is

SimpleTimeZone(int timeDelta, String tzId, int dstMonth0, int dstDayInMonth0, int dstDay0, int time0,

int dstMonth1, int dstDayInMonth1, int dstDay1, int time1)

Here, the offset relative to GMT is specified in timeDelta. The time zone name is passed in tzId. The start of daylight saving time is indicated by the parameters dstMonth0, dstDayInMonth0, dstDay0, and time0. The end of daylight saving time is indicated by the parameters dstMonth1, dstDayInMonth1, dstDay1, and time1.

The third SimpleTimeZone constructor is

SimpleTimeZone(int timeDelta, String tzId, int dstMonth0, int dstDayInMonth0, int dstDay0, int time0, int dstMonth1, int dstDayInMonth1,

int dstDay1, int time1, int dstDelta)

Here, dstDelta is the number of milliseconds saved during daylight saving time. The fourth SimpleTimeZone constructor is:

SimpleTimeZone(int timeDelta, String tzId, int dstMonth0, int dstDayInMonth0, int dstDay0, int time0,

int time0mode, int dstMonth1, int dstDayInMonth1, int dstDay1, int time1, int time1mode, int dstDelta)

Here, time0mode specifies the mode of the starting time, and time1mode specifies the mode of the ending time. Valid mode values include:

The time mode indicates how the time values are interpreted. The default mode used by the other constructors is WALL_TIME.