JavaTM 2 Platform
Std. Ed. v1.3.1

java.util
Class Date

java.lang.Object
  |
  +--java.util.Date
All Implemented Interfaces:
Cloneable, Comparable, Serializable
Direct Known Subclasses:
Date, Time, Timestamp

public class Date
extends Object
implements Serializable, Cloneable, Comparable

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:

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.

Since:
JDK1.0
See Also:
DateFormat, Calendar, TimeZone, Serialized Form

Constructor Summary
Date()
          Allocates a Date object and initializes it so that it represents the time at which it was allocated, measured to the nearest millisecond.
Date(int year, int month, int date)
          Deprecated. As of JDK version 1.1, replaced by Calendar.set(year + 1900, month, date) or GregorianCalendar(year + 1900, month, date).
Date(int year, int month, int date, int hrs, int min)
          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).
Date(int year, int month, int date, int hrs, int min, int sec)
          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).
Date(long date)
          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.
Date(String s)
          Deprecated. As of JDK version 1.1, replaced by DateFormat.parse(String s).
 
Method Summary
 boolean after(Date when)
          Tests if this date is after the specified date.
 boolean before(Date when)
          Tests if this date is before the specified date.
 Object clone()
          Return a copy of this object.
 int compareTo(Date anotherDate)
          Compares two Dates for ordering.
 int compareTo(Object o)
          Compares this Date to another Object.
 boolean equals(Object obj)
          Compares two dates for equality.
 int getDate()
          Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.DAY_OF_MONTH).
 int getDay()
          Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.DAY_OF_WEEK).
 int getHours()
          Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.HOUR_OF_DAY).
 int getMinutes()
          Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.MINUTE).
 int getMonth()
          Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.MONTH).
 int getSeconds()
          Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.SECOND).
 long getTime()
          Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this Date object.
 int getTimezoneOffset()
          Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.ZONE_OFFSET) + Calendar.get(Calendar.DST_OFFSET).
 int getYear()
          Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.YEAR) - 1900.
 int hashCode()
          Returns a hash code value for this object.
static long parse(String s)
          Deprecated. As of JDK version 1.1, replaced by DateFormat.parse(String s).
 void setDate(int date)
          Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.DAY_OF_MONTH, int date).
 void setHours(int hours)
          Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.HOUR_OF_DAY, int hours).
 void setMinutes(int minutes)
          Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.MINUTE, int minutes).
 void setMonth(int month)
          Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.MONTH, int month).
 void setSeconds(int seconds)
          Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.SECOND, int seconds).
 void setTime(long time)
          Sets this Date object to represent a point in time that is time milliseconds after January 1, 1970 00:00:00 GMT.
 void setYear(int year)
          Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.YEAR, year + 1900).
 String toGMTString()
          Deprecated. As of JDK version 1.1, replaced by DateFormat.format(Date date), using a GMT TimeZone.
 String toLocaleString()
          Deprecated. As of JDK version 1.1, replaced by DateFormat.format(Date date).
 String toString()
          Converts this Date object to a String of the form:
static long UTC(int year, int month, int date, int hrs, int min, int sec)
          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().
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

Date

public Date()
Allocates a Date object and initializes it so that it represents the time at which it was allocated, measured to the nearest millisecond.
See Also:
System.currentTimeMillis()

Date

public Date(long date)
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.
Parameters:
date - the milliseconds since January 1, 1970, 00:00:00 GMT.
See Also:
System.currentTimeMillis()

Date

public Date(int year,
            int month,
            int date)
Deprecated. As of JDK version 1.1, replaced by Calendar.set(year + 1900, month, date) or GregorianCalendar(year + 1900, month, date).

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.
Parameters:
year - the year minus 1900.
month - the month between 0-11.
date - the day of the month between 1-31.
See Also:
Calendar

Date

public Date(int year,
            int month,
            int date,
            int hrs,
            int min)
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).

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.
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

Date

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

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.
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

Date

public Date(String s)
Deprecated. As of JDK version 1.1, replaced by DateFormat.parse(String s).

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.
Parameters:
s - a string representation of the date.
See Also:
DateFormat, parse(java.lang.String)
Method Detail

clone

public Object clone()
Return a copy of this object.
Overrides:
clone in class Object
Following copied from class: java.lang.Object
Returns:
a clone of this instance.
Throws:
CloneNotSupportedException - if the object's class does not support the Cloneable interface. Subclasses that override the clone method can also throw this exception to indicate that an instance cannot be cloned.
OutOfMemoryError - if there is not enough memory.
See Also:
Cloneable

UTC

public static long UTC(int year,
                       int month,
                       int date,
                       int hrs,
                       int min,
                       int sec)
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().

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 indecated is returned represented as the distance, measured in milliseconds, of that time from the epoch (00:00:00 GMT on January 1, 1970).
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

parse

public static long parse(String s)
Deprecated. As of JDK version 1.1, replaced by DateFormat.parse(String s).

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:

A consecutive sequence of letters is regarded as a word and treated as follows:

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.

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:
DateFormat

getYear

public int getYear()
Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.YEAR) - 1900.

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.
Returns:
the year represented by this date, minus 1900.
See Also:
Calendar

setYear

public void setYear(int year)
Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.YEAR, year + 1900).

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.)
Parameters:
year - the year value.
See Also:
Calendar

getMonth

public int getMonth()
Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.MONTH).

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.
Returns:
the month represented by this date.
See Also:
Calendar

setMonth

public void setMonth(int month)
Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.MONTH, int month).

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.
Parameters:
month - the month value between 0-11.
See Also:
Calendar

getDate

public int getDate()
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 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.
Returns:
the day of the month represented by this date.
See Also:
Calendar

setDate

public void setDate(int date)
Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.DAY_OF_MONTH, int date).

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.
Parameters:
date - the day of the month value between 1-31.
See Also:
Calendar

getDay

public int getDay()
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. 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.
Returns:
the day of the week represented by this date.
See Also:
Calendar

getHours

public int getHours()
Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.HOUR_OF_DAY).

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.
Returns:
the hour represented by this date.
See Also:
Calendar

setHours

public void setHours(int hours)
Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.HOUR_OF_DAY, int hours).

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.
Parameters:
hours - the hour value.
See Also:
Calendar

getMinutes

public int getMinutes()
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, as interpreted in the local time zone. The value returned is between 0 and 59.
Returns:
the number of minutes past the hour represented by this date.
See Also:
Calendar

setMinutes

public void setMinutes(int minutes)
Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.MINUTE, int minutes).

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.
Parameters:
minutes - the value of the minutes.
See Also:
Calendar

getSeconds

public int getSeconds()
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. 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.
Returns:
the number of seconds past the minute represented by this date.
See Also:
Calendar

setSeconds

public void setSeconds(int seconds)
Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.SECOND, int seconds).

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.
Parameters:
seconds - the seconds value.
See Also:
Calendar

getTime

public long getTime()
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.

setTime

public void setTime(long time)
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.

before

public boolean before(Date when)
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.

after

public boolean after(Date when)
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.

equals

public boolean equals(Object obj)
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.

Overrides:
equals in class Object
Parameters:
obj - the object to compare with.
Returns:
true if the objects are the same; false otherwise.
See Also:
getTime()

compareTo

public int compareTo(Date anotherDate)
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.
Since:
1.2

compareTo

public int compareTo(Object o)
Compares this Date to another Object. If the Object is a Date, this function behaves like compareTo(Date). Otherwise, it throws a ClassCastException (as Dates are comparable only to other Dates).
Specified by:
compareTo in interface Comparable
Parameters:
o - the Object to be compared.
Returns:
the value 0 if the argument is a Date equal to this Date; a value less than 0 if the argument is a Date after this Date; and a value greater than 0 if the argument is a Date before this Date.
Throws:
ClassCastException - if the argument is not a Date.
Since:
1.2
See Also:
Comparable

hashCode

public int hashCode()
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))
Overrides:
hashCode in class Object
Returns:
a hash code value for this object.

toString

public String toString()
Converts this Date object to a String of the form:
 dow mon dd hh:mm:ss zzz yyyy
where:
Overrides:
toString in class Object
Returns:
a string representation of this date.
See Also:
toLocaleString(), toGMTString()

toLocaleString

public String toLocaleString()
Deprecated. As of JDK version 1.1, replaced by DateFormat.format(Date date).

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.
Returns:
a string representation of this date, using the locale conventions.
See Also:
DateFormat, toString(), toGMTString()

toGMTString

public String toGMTString()
Deprecated. As of JDK version 1.1, replaced by DateFormat.format(Date date), using a GMT TimeZone.

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 i sthe 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.

Returns:
a string representation of this date, using the Internet GMT conventions.
See Also:
DateFormat, toString(), toLocaleString()

getTimezoneOffset

public int getTimezoneOffset()
Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.ZONE_OFFSET) + Calendar.get(Calendar.DST_OFFSET).

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 May 1, 1996, daylight savings time (Eastern Daylight Time) is in use, which is offset only four hours from UTC.

This method produces teh same result as if it computed:

 (this.getTime() - UTC(this.getYear(), 
                       this.getMonth(), 
                       this.getDate(),
                       this.getHours(), 
                       this.getMinutes(), 
                       this.getSeconds())) / (60 * 1000)
 
Returns:
the time-zone offset, in minutes, for the current locale.
See Also:
Calendar, TimeZone

JavaTM 2 Platform
Std. Ed. v1.3.1

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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