The class
Date represents a specific instant
in time, with millisecond precision.
Prior to JDK 1.1, the class Date had two additional
functions. It allowed the interpretation of dates as year, month, day, hour,
minute, and second values. It also allowed the formatting and parsing
of date strings. Unfortunately, the API for these functions was not
amenable to internationalization. As of JDK 1.1, the
Calendar class should be used to convert between dates and time
fields and the DateFormat class should be used to format and
parse date strings.
The corresponding methods in Date are deprecated.
Although the Date class is intended to reflect
coordinated universal time (UTC), it may not do so exactly,
depending on the host environment of the Java Virtual Machine.
Nearly all modern operating systems assume that 1 day =
24 × 60 × 60 = 86400 seconds
in all cases. In UTC, however, about once every year or two there
is an extra second, called a "leap second." The leap
second is always added as the last second of the day, and always
on December 31 or June 30. For example, the last minute of the
year 1995 was 61 seconds long, thanks to an added leap second.
Most computer clocks are not accurate enough to be able to reflect
the leap-second distinction.
Some computer standards are defined in terms of Greenwich mean
time (GMT), which is equivalent to universal time (UT). GMT is
the "civil" name for the standard; UT is the
"scientific" name for the same standard. The
distinction between UTC and UT is that UTC is based on an atomic
clock and UT is based on astronomical observations, which for all
practical purposes is an invisibly fine hair to split. Because the
earth's rotation is not uniform (it slows down and speeds up
in complicated ways), UT does not always flow uniformly. Leap
seconds are introduced as needed into UTC so as to keep UTC within
0.9 seconds of UT1, which is a version of UT with certain
corrections applied. There are other time and date systems as
well; for example, the time scale used by the satellite-based
global positioning system (GPS) is synchronized to UTC but is
not adjusted for leap seconds. An interesting source of
further information is the U.S. Naval Observatory, particularly
the Directorate of Time at:
http://tycho.usno.navy.mil
and their definitions of "Systems of Time" at:
http://tycho.usno.navy.mil/systime.html
In all methods of class Date that accept or return
year, month, date, hours, minutes, and seconds values, the
following representations are used:
- A year y is represented by the integer
y
- 1900.
- A month is represented by an integer from 0 to 11; 0 is January,
1 is February, and so forth; thus 11 is December.
- A date (day of month) is represented by an integer from 1 to 31
in the usual manner.
- An hour is represented by an integer from 0 to 23. Thus, the hour
from midnight to 1 a.m. is hour 0, and the hour from noon to 1
p.m. is hour 12.
- A minute is represented by an integer from 0 to 59 in the usual manner.
- A second is represented by an integer from 0 to 61; the values 60 and
61 occur only for leap seconds and even then only in Java
implementations that actually track leap seconds correctly. Because
of the manner in which leap seconds are currently introduced, it is
extremely unlikely that two leap seconds will occur in the same
minute, but this specification follows the date and time conventions
for ISO C.
In all cases, arguments given to methods for these purposes need
not fall within the indicated ranges; for example, a date may be
specified as January 32 and is interpreted as meaning February 1.
Allocates a
Date object and initializes it so that
it represents the time at which it was allocated, measured to the
nearest millisecond.
Allocates a
Date object and initializes it to
represent the specified number of milliseconds since the
standard base time known as "the epoch", namely January 1,
1970, 00:00:00 GMT.
Allocates a
Date object and initializes it so that
it represents midnight, local time, at the beginning of the day
specified by the
year,
month, and
date arguments.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(year + 1900, month, date)
or GregorianCalendar(year + 1900, month, date). - Parameters:
year the year minus 1900.month the month between 0-11.date the day of the month between 1-31.- See also:
Calendar
public Date(int year, int month, int date) { this(year, month, date, 0, 0, 0);
Allocates a
Date object and initializes it so that
it represents the instant at the start of the minute specified by
the
year,
month,
date,
hrs, and
min arguments, in the local
time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(year + 1900, month, date,
hrs, min) or GregorianCalendar(year + 1900,
month, date, hrs, min). - Parameters:
year the year minus 1900.month the month between 0-11.date the day of the month between 1-31.hrs the hours between 0-23.min the minutes between 0-59.- See also:
Calendar
public Date(int year, int month, int date, int hrs, int min) { this(year, month, date, hrs, min, 0);
Allocates a
Date object and initializes it so that
it represents the instant at the start of the second specified
by the
year,
month,
date,
hrs,
min, and
sec arguments,
in the local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(year + 1900, month, date,
hrs, min, sec) or GregorianCalendar(year + 1900,
month, date, hrs, min, sec). - Parameters:
year the year minus 1900.month the month between 0-11.date the day of the month between 1-31.hrs the hours between 0-23.min the minutes between 0-59.sec the seconds between 0-59.- See also:
Calendar
public Date(int year, int month, int date, int hrs, int min, int sec) { month = CalendarUtils.mod(month, 12);
Allocates a
Date object and initializes it so that
it represents the date and time indicated by the string
s, which is interpreted as if by the
parse(java.lang.String) method.
Return a copy of this object.
Determines the date and time based on the arguments. The
arguments are interpreted as a year, month, day of the month,
hour of the day, minute within the hour, and second within the
minute, exactly as for the
Date constructor with six
arguments, except that the arguments are interpreted relative
to UTC rather than to the local time zone. The time indicated is
returned represented as the distance, measured in milliseconds,
of that time from the epoch (00:00:00 GMT on January 1, 1970).
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(year + 1900, month, date,
hrs, min, sec) or GregorianCalendar(year + 1900,
month, date, hrs, min, sec), using a UTC
TimeZone, followed by Calendar.getTime().getTime(). - Parameters:
year the year minus 1900.month the month between 0-11.date the day of the month between 1-31.hrs the hours between 0-23.min the minutes between 0-59.sec the seconds between 0-59.- Returns:
- the number of milliseconds since January 1, 1970, 00:00:00 GMT for
the date and time specified by the arguments.
- See also:
Calendar
public static long UTC(int year, int month, int date,
int hrs, int min, int sec) { month = CalendarUtils.mod(month, 12);
Attempts to interpret the string
s as a representation
of a date and time. If the attempt is successful, the time
indicated is returned represented as the distance, measured in
milliseconds, of that time from the epoch (00:00:00 GMT on
January 1, 1970). If the attempt fails, an
IllegalArgumentException is thrown.
It accepts many syntaxes; in particular, it recognizes the IETF
standard date syntax: "Sat, 12 Aug 1995 13:30:00 GMT". It also
understands the continental U.S. time-zone abbreviations, but for
general use, a time-zone offset should be used: "Sat, 12 Aug 1995
13:30:00 GMT+0430" (4 hours, 30 minutes west of the Greenwich
meridian). If no time zone is specified, the local time zone is
assumed. GMT and UTC are considered equivalent.
The string s is processed from left to right, looking for
data of interest. Any material in s that is within the
ASCII parenthesis characters ( and ) is ignored.
Parentheses may be nested. Otherwise, the only characters permitted
within s are these ASCII characters:
abcdefghijklmnopqrstuvwxyz
ABCDEFGHIJKLMNOPQRSTUVWXYZ
0123456789,+-:/
and whitespace characters.
A consecutive sequence of decimal digits is treated as a decimal
number:
- If a number is preceded by + or - and a year
has already been recognized, then the number is a time-zone
offset. If the number is less than 24, it is an offset measured
in hours. Otherwise, it is regarded as an offset in minutes,
expressed in 24-hour time format without punctuation. A
preceding - means a westward offset. Time zone offsets
are always relative to UTC (Greenwich). Thus, for example,
-5 occurring in the string would mean "five hours west
of Greenwich" and +0430 would mean "four hours and
thirty minutes east of Greenwich." It is permitted for the
string to specify GMT, UT, or UTC
redundantly-for example, GMT-5 or utc+0430.
- The number is regarded as a year number if one of the
following conditions is true:
- The number is equal to or greater than 70 and followed by a
space, comma, slash, or end of string
- The number is less than 70, and both a month and a day of
the month have already been recognized
If the recognized year number is less than 100, it is
interpreted as an abbreviated year relative to a century of
which dates are within 80 years before and 19 years after
the time when the Date class is initialized.
After adjusting the year number, 1900 is subtracted from
it. For example, if the current year is 1999 then years in
the range 19 to 99 are assumed to mean 1919 to 1999, while
years from 0 to 18 are assumed to mean 2000 to 2018. Note
that this is slightly different from the interpretation of
years less than 100 that is used in java.text.SimpleDateFormat - If the number is followed by a colon, it is regarded as an hour,
unless an hour has already been recognized, in which case it is
regarded as a minute.
- If the number is followed by a slash, it is regarded as a month
(it is decreased by 1 to produce a number in the range 0
to 11), unless a month has already been recognized, in
which case it is regarded as a day of the month.
- If the number is followed by whitespace, a comma, a hyphen, or
end of string, then if an hour has been recognized but not a
minute, it is regarded as a minute; otherwise, if a minute has
been recognized but not a second, it is regarded as a second;
otherwise, it is regarded as a day of the month.
A consecutive sequence of letters is regarded as a word and treated
as follows:
- A word that matches AM, ignoring case, is ignored (but
the parse fails if an hour has not been recognized or is less
than 1 or greater than 12).
- A word that matches PM, ignoring case, adds 12
to the hour (but the parse fails if an hour has not been
recognized or is less than 1 or greater than 12).
- Any word that matches any prefix of SUNDAY, MONDAY, TUESDAY,
WEDNESDAY, THURSDAY, FRIDAY, or SATURDAY, ignoring
case, is ignored. For example, sat, Friday, TUE, and
Thurs are ignored.
- Otherwise, any word that matches any prefix of JANUARY,
FEBRUARY, MARCH, APRIL, MAY, JUNE, JULY, AUGUST, SEPTEMBER,
OCTOBER, NOVEMBER, or DECEMBER, ignoring case, and
considering them in the order given here, is recognized as
specifying a month and is converted to a number (0 to
11). For example, aug, Sept, april, and
NOV are recognized as months. So is Ma, which
is recognized as MARCH, not MAY.
- Any word that matches GMT, UT, or UTC, ignoring
case, is treated as referring to UTC.
- Any word that matches EST, CST, MST, or PST,
ignoring case, is recognized as referring to the time zone in
North America that is five, six, seven, or eight hours west of
Greenwich, respectively. Any word that matches EDT, CDT,
MDT, or PDT, ignoring case, is recognized as
referring to the same time zone, respectively, during daylight
saving time.
Once the entire string s has been scanned, it is converted to a time
result in one of two ways. If a time zone or time-zone offset has been
recognized, then the year, month, day of month, hour, minute, and
second are interpreted in UTC and then the time-zone offset is
applied. Otherwise, the year, month, day of month, hour, minute, and
second are interpreted in the local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
DateFormat.parse(String s). - Parameters:
s a string to be parsed as a date.- Returns:
- the number of milliseconds since January 1, 1970, 00:00:00 GMT
represented by the string argument.
- See also:
java.text.DateFormat
if (c <= ' ' || c == ',')
if ('0' <= c && c <= '9') { while (i < limit && '0' <= (c = s.charAt(i)) && c <= '9') { n = n % 100 + n / 100 * 60;
if (tzoffset != 0 && tzoffset != -1)
else if (c <= ' ' || c == ',' || c == '/' || i >= limit)
else if (i < limit && c != ',' && c > ' ' && c != '-')
else if (hour >= 0 && min < 0)
else if (min >= 0 && sec < 0)
} else if (c == '/' || c == ':' || c == '+' || c == '-')
if (!('A' <= c && c <= 'Z' || 'a' <= c && c <= 'z')) if (hour > 12 || hour < 1)
} else if (action == 14) { if (hour > 12 || hour < 1)
} else if (action <= 13) { mon = (byte) (action - 2);
tzoffset = action - 10000;
synchronized (Date.class) { ldate.setDate(year, mon + 1, mday);
udate.setDate(year, mon + 1, mday);
return cal.getTime(udate) + tzoffset * (60 * 1000);
"monday", "tuesday", "wednesday", "thursday", "friday",
"january", "february", "march", "april", "may", "june",
"july", "august", "september", "october", "november", "december",
"gmt", "ut", "utc", "est", "edt", "cst", "cdt",
"mst", "mdt", "pst", "pdt"
private final static int ttb[] = { 14, 1, 0, 0, 0, 0, 0, 0, 0,
2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
10000 + 0, 10000 + 0, 10000 + 0,
10000 + 5 * 60, 10000 + 4 * 60,
10000 + 6 * 60, 10000 + 5 * 60,
10000 + 7 * 60, 10000 + 6 * 60,
10000 + 8 * 60, 10000 + 7 * 60
Returns a value that is the result of subtracting 1900 from the
year that contains or begins with the instant in time represented
by this
Date object, as interpreted in the local
time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.get(Calendar.YEAR) - 1900. - Returns:
- the year represented by this date, minus 1900.
- See also:
Calendar
Sets the year of this
Date object to be the specified
value plus 1900. This
Date object is modified so
that it represents a point in time within the specified year,
with the month, date, hour, minute, and second the same as
before, as interpreted in the local time zone. (Of course, if
the date was February 29, for example, and the year is set to a
non-leap year, then the new date will be treated as if it were
on March 1.)
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(Calendar.YEAR, year + 1900). - Parameters:
year the year value.- See also:
Calendar
Returns a number representing the month that contains or begins
with the instant in time represented by this
Date object.
The value returned is between
0 and
11,
with the value
0 representing January.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.get(Calendar.MONTH). - Returns:
- the month represented by this date.
- See also:
Calendar
Sets the month of this date to the specified value. This
Date object is modified so that it represents a point
in time within the specified month, with the year, date, hour,
minute, and second the same as before, as interpreted in the
local time zone. If the date was October 31, for example, and
the month is set to June, then the new date will be treated as
if it were on July 1, because June has only 30 days.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(Calendar.MONTH, int month). - Parameters:
month the month value between 0-11.- See also:
Calendar
month = CalendarUtils.mod(month, 12);
Returns the day of the month represented by this
Date object.
The value returned is between
1 and
31
representing the day of the month that contains or begins with the
instant in time represented by this
Date object, as
interpreted in the local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.get(Calendar.DAY_OF_MONTH). - Returns:
- the day of the month represented by this date.
- See also:
Calendar
Sets the day of the month of this
Date object to the
specified value. This
Date object is modified so that
it represents a point in time within the specified day of the
month, with the year, month, hour, minute, and second the same
as before, as interpreted in the local time zone. If the date
was April 30, for example, and the date is set to 31, then it
will be treated as if it were on May 1, because April has only
30 days.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(Calendar.DAY_OF_MONTH, int date). - Parameters:
date the day of the month value between 1-31.- See also:
Calendar
Returns the day of the week represented by this date. The
returned value (
0 = Sunday,
1 = Monday,
2 = Tuesday,
3 = Wednesday,
4 =
Thursday,
5 = Friday,
6 = Saturday)
represents the day of the week that contains or begins with
the instant in time represented by this
Date object,
as interpreted in the local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.get(Calendar.DAY_OF_WEEK). - Returns:
- the day of the week represented by this date.
- See also:
Calendar
Returns the hour represented by this
Date object. The
returned value is a number (
0 through
23)
representing the hour within the day that contains or begins
with the instant in time represented by this
Date
object, as interpreted in the local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.get(Calendar.HOUR_OF_DAY). - Returns:
- the hour represented by this date.
- See also:
Calendar
Sets the hour of this
Date object to the specified value.
This
Date object is modified so that it represents a point
in time within the specified hour of the day, with the year, month,
date, minute, and second the same as before, as interpreted in the
local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(Calendar.HOUR_OF_DAY, int hours). - Parameters:
hours the hour value.- See also:
Calendar
Returns the number of minutes past the hour represented by this date,
as interpreted in the local time zone.
The value returned is between
0 and
59.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.get(Calendar.MINUTE). - Returns:
- the number of minutes past the hour represented by this date.
- See also:
Calendar
Sets the minutes of this
Date object to the specified value.
This
Date object is modified so that it represents a point
in time within the specified minute of the hour, with the year, month,
date, hour, and second the same as before, as interpreted in the
local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(Calendar.MINUTE, int minutes). - Parameters:
minutes the value of the minutes.- See also:
Calendar
Returns the number of seconds past the minute represented by this date.
The value returned is between
0 and
61. The
values
60 and
61 can only occur on those
Java Virtual Machines that take leap seconds into account.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.get(Calendar.SECOND). - Returns:
- the number of seconds past the minute represented by this date.
- See also:
Calendar
Sets the seconds of this
Date to the specified value.
This
Date object is modified so that it represents a
point in time within the specified second of the minute, with
the year, month, date, hour, and minute the same as before, as
interpreted in the local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
Calendar.set(Calendar.SECOND, int seconds). - Parameters:
seconds the seconds value.- See also:
Calendar
Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT
represented by this
Date object.
- Returns:
- the number of milliseconds since January 1, 1970, 00:00:00 GMT
represented by this date.
Sets this
Date object to represent a point in time that is
time milliseconds after January 1, 1970 00:00:00 GMT.
- Parameters:
time the number of milliseconds.
Tests if this date is before the specified date.
- Parameters:
when a date.- Returns:
true if and only if the instant of time
represented by this Date object is strictly
earlier than the instant represented by when;
false otherwise.- Throws:
java.lang.NullPointerException if when is null.
Tests if this date is after the specified date.
- Parameters:
when a date.- Returns:
true if and only if the instant represented
by this Date object is strictly later than the
instant represented by when;
false otherwise.- Throws:
java.lang.NullPointerException if when is null.
Compares two dates for equality.
The result is
true if and only if the argument is
not
null and is a
Date object that
represents the same point in time, to the millisecond, as this object.
Thus, two Date objects are equal if and only if the
getTime method returns the same long
value for both.
- Parameters:
obj the object to compare with.- Returns:
true if the objects are the same;
false otherwise.- See also:
getTime()
Returns the millisecond value of this
Date object
without affecting its internal state.
if (date.cdate == null) { Compares two Dates for ordering.
- Parameters:
anotherDate the Date to be compared.- Returns:
- the value
0 if the argument Date is equal to
this Date; a value less than 0 if this Date
is before the Date argument; and a value greater than
0 if this Date is after the Date argument. - Throws:
java.lang.NullPointerException if anotherDate is null.- Since:
- 1.2
return (thisTime<anotherTime ? -1 : (thisTime==anotherTime ? 0 : 1));
Returns a hash code value for this object. The result is the
exclusive OR of the two halves of the primitive
long
value returned by the
getTime()
method. That is, the hash code is the value of the expression:
(int)(this.getTime()^(this.getTime() >>> 32))
- Returns:
- a hash code value for this object.
return (int) ht ^ (int) (ht >> 32);
Converts this
Date object to a
String
of the form:
dow mon dd hh:mm:ss zzz yyyy
where:
- dow is the day of the week (Sun, Mon, Tue, Wed,
Thu, Fri, Sat).
- mon is the month (Jan, Feb, Mar, Apr, May, Jun,
Jul, Aug, Sep, Oct, Nov, Dec).
- dd is the day of the month (01 through
31), as two decimal digits.
- hh is the hour of the day (00 through
23), as two decimal digits.
- mm is the minute within the hour (00 through
59), as two decimal digits.
- ss is the second within the minute (00 through
61, as two decimal digits.
- zzz is the time zone (and may reflect daylight saving
time). Standard time zone abbreviations include those
recognized by the method parse. If time zone
information is not available, then zzz is empty -
that is, it consists of no characters at all.
- yyyy is the year, as four decimal digits.
Converts the given name to its 3-letter abbreviation (e.g.,
"monday" -> "Mon") and stored the abbreviation in the given
StringBuilder.
Creates a string representation of this
Date object in an
implementation-dependent form. The intent is that the form should
be familiar to the user of the Java application, wherever it may
happen to be running. The intent is comparable to that of the
"
%c" format supported by the
strftime()
function of ISO C.
return formatter.format(this);
Creates a string representation of this
Date object of
the form:
d mon yyyy hh:mm:ss GMT
where:
- d is the day of the month (1 through 31),
as one or two decimal digits.
- mon is the month (Jan, Feb, Mar, Apr, May, Jun, Jul,
Aug, Sep, Oct, Nov, Dec).
- yyyy is the year, as four decimal digits.
- hh is the hour of the day (00 through 23),
as two decimal digits.
- mm is the minute within the hour (00 through
59), as two decimal digits.
- ss is the second within the minute (00 through
61), as two decimal digits.
- GMT is exactly the ASCII letters "GMT" to indicate
Greenwich Mean Time.
The result does not depend on the local time zone.
- Deprecated:
- As of JDK version 1.1,
replaced by
DateFormat.format(Date date), using a
GMT TimeZone. - Returns:
- a string representation of this date, using the Internet GMT
conventions.
- See also:
java.text.DateFormattoString()toLocaleString()
Returns the offset, measured in minutes, for the local time zone
relative to UTC that is appropriate for the time represented by
this
Date object.
For example, in Massachusetts, five time zones west of Greenwich:
new Date(96, 1, 14).getTimezoneOffset() returns 300
because on February 14, 1996, standard time (Eastern Standard Time)
is in use, which is offset five hours from UTC; but:
new Date(96, 5, 1).getTimezoneOffset() returns 240
because on June 1, 1996, daylight saving time (Eastern Daylight Time)
is in use, which is offset only four hours from UTC.
This method produces the same result as if it computed:
(this.getTime() - UTC(this.getYear(),
this.getMonth(),
this.getDate(),
this.getHours(),
this.getMinutes(),
this.getSeconds())) / (60 * 1000)
return -zoneOffset/60000;
if (y == 1582 || y > 280000000 || y < -280000000) { gc.set(gc.MILLISECOND, ms);
gc.set(y, m-1, d, hh, mm, ss);
Returns the Gregorian or Julian calendar system to use with the
given date. Use Gregorian from October 15, 1582.
- Parameters:
year normalized calendar year (not -1900)- Returns:
- the CalendarSystem to use for the specified date
Save the state of this object to a stream (i.e., serialize it).
- SerialData:
- The value returned by
getTime()
is emitted (long). This represents the offset from
January 1, 1970, 00:00:00 GMT in milliseconds.
Reconstitute this object from a stream (i.e., deserialize it).
