Java Reference
In-Depth Information
parameter represents calendar-specific eras, such as
B.C.
and
A.D.
in the Gregorian calendar.
24.4.3.
GregorianCalendar
and
SimpleTimeZone
The
GregorianCalendar
class is a concrete subclass of
Calendar
that re-
flects
UTC
(Coordinated Universal Time), although it cannot always do so
exactly. Imprecise behavior is inherited from the time mechanisms of
units and ranges. Here are the ranges for
GregorianCalendar
:
[2]
Almost all modern systems assume that one day is 24*60*60 seconds. In
UTC
, about once a year
an extra second, called a
leap second,
is added to a day to account for the wobble of the Earth. Most
computer clocks are not accurate enough to reflect this distinction, so neither is the
Date
class. Some
computer standards are defined in
GMT
, which is the "civil" name for the standard;
UT
is the scientific
name for the same standard. The distinction between
UTC
and
UT
is that
UT
is based on an atomic clock
and
UTC
is based on astronomical observations. For almost all practical purposes, this is an invisibly
fine hair to split. See "
Further Reading
" on page
755
for references.
1292278994
YEAR
011
MONTH
Day of the month, 131
DATE
HOUR_OF_DAY
023
059
MINUTE
059
SECOND
