Class java.util.Date
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Class java.util.Date
java.lang.Object
|
+----java.util.Date
- public class Date
- extends Object
A wrapper for a date. This class lets you manipulate
dates in a system independent way. To print today's
date use:
Date d = new Date();
System.out.println("today = " + d);
To find out what day corresponds to a particular date:
Date d = new Date(63, 0, 16); // January 16, 1963
System.out.println("Day of the week: " + d.getDay());
The date can be set and examined
according to the local time zone into the
year, month, day, hour, minute and second.
While the API is intended to reflect UTC, Coordinated Universal Time,
it doesn't do so exactly. This inexact behavior is inherited from
the time system of the underlying OS. All modern OS's that I (jag)
am aware of assume that 1 day = 24*60*60 seconds. In UTC, about once
a year there is an extra second, called a "leap second" added to
a day to account for the wobble of the earth. Most computer clocks
are not accurate enough to be able to reflect this distinction.
Some computer standards are defined in GMT, which is equivalent
to UT, Universal Time. 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 the first is based on an atomic clock and
the second is based on astronomical observations, which for all
practical purposes is an invisibly fine hair to split.
An interesting source of further information is the
US Naval Observatory, particularly the
Directorate of Time
and their definitions of
Systems of Time.
-
Date()
- Creates today's date/time.
-
Date(long)
- Creates a date.
-
Date(int, int, int)
- Creates a date.
-
Date(int, int, int, int, int)
- Creates a date.
-
Date(int, int, int, int, int, int)
- Creates a date.
-
Date(String)
- Creates a date from a string according to the syntax
accepted by parse().
-
UTC(int, int, int, int, int, int)
- Calculates a UTC value from YMDHMS.
-
after(Date)
- Checks whether this date comes after the specified date.
-
before(Date)
- Checks whether this date comes before the specified date.
-
equals(Object)
- Compares this object against the specified object.
-
getDate()
- Returns the day of the month.
-
getDay()
- Returns the day of the week.
-
getHours()
- Returns the hour.
-
getMinutes()
- Returns the minute.
-
getMonth()
- Returns the month.
-
getSeconds()
- Returns the second.
-
getTime()
- Returns the time in milliseconds since the epoch.
-
getTimezoneOffset()
- Return the time zone offset in minutes for the current locale that is appropriate
for this time.
-
getYear()
- Returns the year after 1900.
-
hashCode()
- Computes a hashCode.
-
parse(String)
- Given a string representing a time, parse it and return the time value.
-
setDate(int)
- Sets the date.
-
setHours(int)
- Sets the hours.
-
setMinutes(int)
- Sets the minutes.
-
setMonth(int)
- Sets the month.
-
setSeconds(int)
- Sets the seconds.
-
setTime(long)
- Sets the time.
-
setYear(int)
- Sets the year.
-
toGMTString()
- Converts a date to a String, using the Internet GMT conventions.
-
toLocaleString()
- Converts a date to a String, using the locale conventions.
-
toString()
- Converts a date to a String, using the UNIX ctime conventions.
Date
public Date()
- Creates today's date/time.
Date
public Date(long date)
- Creates a date.
The fields are normalized before the Date object is created.
The argument does not have to be in the correct range. For
example, the 32nd of January is correctly interpreted as the
1st of February. You can use this to figure out what day a
particular date falls on.
- Parameters:
- date - the value of the argument to be created
Date
public Date(int year,
int month,
int date)
- Creates a date.
The fields are normalized before the Date object is created.
The arguments do not have to be in the correct range. For example,
the 32nd of January is correctly interpreted as the 1st of February.
You can use this to figure out what day a particular date falls on.
- Parameters:
- year - a year after 1900
- month - a month between 0-11
- date - day of the month between 1-31
Date
public Date(int year,
int month,
int date,
int hrs,
int min)
- Creates a date.
The fields are normalized before the Date object is created.
The arguments do not have to be in the correct range. For example,
the 32nd of January is correctly interpreted as the 1st of February.
You can use this to figure out what day a particular date falls on.
- Parameters:
- year - a year after 1900
- month - a month between 0-11
- date - day of the month between 1-31
- hrs - hours between 0-23
- min - minutes between 0-59
Date
public Date(int year,
int month,
int date,
int hrs,
int min,
int sec)
- Creates a date. The fields are normalized before the Date object is
created. The arguments do not have to be in the correct range. For
example, the 32nd of January is correctly interpreted as the 1st of
February. You can use this to figure out what day a particular date
falls on.
- Parameters:
- year - a year after 1900
- month - a month between 0-11
- date - day of the month between 1-31
- hrs - hours between 0-23
- min - minutes between 0-59
- sec - seconds between 0-59
Date
public Date(String s)
- Creates a date from a string according to the syntax
accepted by parse().
UTC
public static long UTC(int year,
int month,
int date,
int hrs,
int min,
int sec)
- Calculates a UTC value from YMDHMS. Interpretes
the parameters in UTC, not in the local time zone.
- Parameters:
- year - a year after 1900
- month - a month between 0-11
- date - day of the month between 1-31
- hrs - hours between 0-23
- min - minutes between 0-59
- sec - seconds between 0-59
parse
public static long parse(String s)
- Given a string representing a time, parse it and return the time value.
It accepts many syntaxes, but most importantly, in accepts the IETF
standard date syntax: "Sat, 12 Aug 1995 13:30:00 GMT". It understands
the continental US time zone abbreviations, but for general use, a
timezone 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.
getYear
public int getYear()
- Returns the year after 1900.
setYear
public void setYear(int year)
- Sets the year.
- Parameters:
- year - the year value
getMonth
public int getMonth()
- Returns the month. This method assigns months with the
values 0-11, with January beginning at value 0.
setMonth
public void setMonth(int month)
- Sets the month.
- Parameters:
- month - the month value (0-11)
getDate
public int getDate()
- Returns the day of the month. This method assigns days
with the values of 1 to 31.
setDate
public void setDate(int date)
- Sets the date.
- Parameters:
- date - the day value
getDay
public int getDay()
- Returns the day of the week. This method assigns days
of the week with the values 0-6, with 0 being Sunday.
getHours
public int getHours()
- Returns the hour. This method assigns the value of the
hours of the day to range from 0 to 23, with midnight equal
to 0.
setHours
public void setHours(int hours)
- Sets the hours.
- Parameters:
- hours - the hour value
getMinutes
public int getMinutes()
- Returns the minute. This method assigns the minutes of an
hour to be any value from 0 to 59.
setMinutes
public void setMinutes(int minutes)
- Sets the minutes.
- Parameters:
- minutes - the value of the minutes
getSeconds
public int getSeconds()
- Returns the second. This method assigns the seconds of
a minute to values of 0-59.
setSeconds
public void setSeconds(int seconds)
- Sets the seconds.
- Parameters:
- seconds - the second value
getTime
public long getTime()
- Returns the time in milliseconds since the epoch.
setTime
public void setTime(long time)
- Sets the time.
- Parameters:
- time - The new time value in milliseconds since the epoch.
before
public boolean before(Date when)
- Checks whether this date comes before the specified date.
- Parameters:
- when - the date to compare
- Returns:
- true if the original date comes before the specified
one; false otherwise.
after
public boolean after(Date when)
- Checks whether this date comes after the specified date.
- Parameters:
- when - the date to compare
- Returns:
- true if the original date comes after the specified
one; false otherwise.
equals
public boolean equals(Object obj)
- Compares this object against the specified object.
- Parameters:
- obj - the object to compare with
- Returns:
- true if the objects are the same; false otherwise.
- Overrides:
- equals in class Object
hashCode
public int hashCode()
- Computes a hashCode.
- Overrides:
- hashCode in class Object
toString
public String toString()
- Converts a date to a String, using the UNIX ctime conventions.
- Overrides:
- toString in class Object
toLocaleString
public String toLocaleString()
- Converts a date to a String, using the locale conventions.
toGMTString
public String toGMTString()
- Converts a date to a String, using the Internet GMT conventions.
getTimezoneOffset
public int getTimezoneOffset()
- Return the time zone offset in minutes for the current locale that is appropriate
for this time. This value would be a constant except for
daylight savings time.
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