java.util
Class 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.

Constructor Summary

Date()
Creates today's date/time.

Date(int year, int month, int date)
Creates a date.

Date(int year, int month, int date, int hrs, int min)
Creates a date.

Date(int year, int month, int date, int hrs, int min, int sec)
Creates a date.

Date(long date)
Creates a date.

Date(String s)
Creates a date from a string according to the syntax accepted by parse().

Method Summary

boolean	after(Date when) Checks whether this date comes after the specified date.
boolean	before(Date when) Checks whether this date comes before the specified date.
boolean	equals(Object obj) Compares this object against the specified object.
int	getDate() Returns the day of the month.
int	getDay() Returns the day of the week.
int	getHours() Returns the hour.
int	getMinutes() Returns the minute.
int	getMonth() Returns the month.
int	getSeconds() Returns the second.
long	getTime() Returns the time in milliseconds since the epoch.
int	getTimezoneOffset() Return the time zone offset in minutes for the current locale that is appropriate for this time.
int	getYear() Returns the year after 1900.
int	hashCode() Computes a hashCode.
static long	parse(String s) Given a string representing a time, parse it and return the time value.
void	setDate(int date) Sets the date.
void	setHours(int hours) Sets the hours.
void	setMinutes(int minutes) Sets the minutes.
void	setMonth(int month) Sets the month.
void	setSeconds(int seconds) Sets the seconds.
void	setTime(long time) Sets the time.
void	setYear(int year) Sets the year.
String	toGMTString() Converts a date to a String, using the Internet GMT conventions.
String	toLocaleString() Converts a date to a String, using the locale conventions.
String	toString() Converts a date to a String, using the UNIX ctime conventions.
static long	UTC(int year, int month, int date, int hrs, int min, int sec) Calculates a UTC value from YMDHMS.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

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().

Method Detail

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.

Overrides:

equals in class Object

Parameters:

obj - the object to compare with

Returns:

true if the objects are the same; false otherwise.

See Also:

Hashtable

hashCode

public int hashCode()

Computes a hashCode.

Overrides:

hashCode in class Object

See Also:

Hashtable

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.