public class Date extends Objectimplements Serializable , Cloneable , Comparable <Date >
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:
- 1900. 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.
DateFormat,
Calendar,
TimeZone,
Serialized Form
| Constructor and Description |
|---|
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
Deprecated.
As of JDK version 1.1, replaced by
DateFormat.parse(String s).
|
| Modifier and Type | Method and Description |
|---|---|
boolean |
after(Date
Tests if this date is after the specified date.
|
boolean |
before(Date
Tests if this date is before the specified date.
|
Object |
clone()
Return a copy of this object.
|
int |
compareTo(Date
Compares two Dates for ordering.
|
boolean |
equals(Object
Compares two dates for equality.
|
static Date |
from(Instant
Obtains an instance of
Date from an
Instant object.
|
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)) / (60 * 1000).
|
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
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.
|
Instant |
toInstant()
Converts this
Date object to an
Instant.
|
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().
|
public Date()
Date object and initializes it so that it represents the time at which it was allocated, measured to the nearest millisecond.
System.currentTimeMillis()
public Date(long date)
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 - the milliseconds since January 1, 1970, 00:00:00 GMT.
System.currentTimeMillis()
@Deprecated public Date(int year, int month, int date)
Calendar.set(year + 1900, month, date) or GregorianCalendar(year + 1900, month, date).
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.
year - the year minus 1900.
month - the month between 0-11.
date - the day of the month between 1-31.
Calendar
@Deprecated public Date(int year, int month, int date, int hrs, int min)
Calendar.set(year + 1900, month, date, hrs, min) or GregorianCalendar(year + 1900, month, date, hrs, min).
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.
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.
Calendar
@Deprecated public Date(int year, int month, int date, int hrs, int min, int sec)
Calendar.set(year + 1900, month, date, hrs, min, sec) or GregorianCalendar(year + 1900, month, date, hrs, min, sec).
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.
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.
Calendar
@Deprecated public Date(Strings)
DateFormat.parse(String s).
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.
s - a string representation of the date.
DateFormat,
parse(java.lang.String)
public Objectclone()
@Deprecated public static long UTC(int year, int month, int date, int hrs, int min, int sec)
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().
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.
Calendar
@Deprecated public static long parse(Strings)
DateFormat.parse(String s).
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:
and whitespace characters.abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ 0123456789,+-:/
A consecutive sequence of decimal digits is treated as a decimal number:
SimpleDateFormat. 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.
s - a string to be parsed as a date.
DateFormat
@Deprecated public int getYear()
Calendar.get(Calendar.YEAR) - 1900.
Date object, as interpreted in the local time zone.
Calendar
@Deprecated public void setYear(int year)
Calendar.set(Calendar.YEAR, year + 1900).
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.)
year - the year value.
Calendar
@Deprecated public int getMonth()
Calendar.get(Calendar.MONTH).
0 and
11, with the value
0 representing January.
Calendar
@Deprecated public void setMonth(int month)
Calendar.set(Calendar.MONTH, int month).
month - the month value between 0-11.
Calendar
@Deprecated public int getDate()
Calendar.get(Calendar.DAY_OF_MONTH).
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.
Calendar
@Deprecated public void setDate(int date)
Calendar.set(Calendar.DAY_OF_MONTH, int date).
date - the day of the month value between 1-31.
Calendar
@Deprecated public int getDay()
Calendar.get(Calendar.DAY_OF_WEEK).
Calendar
@Deprecated public int getHours()
Calendar.get(Calendar.HOUR_OF_DAY).
Calendar
@Deprecated public void setHours(int hours)
Calendar.set(Calendar.HOUR_OF_DAY, int hours).
hours - the hour value.
Calendar
@Deprecated public int getMinutes()
Calendar.get(Calendar.MINUTE).
0 and
59.
Calendar
@Deprecated public void setMinutes(int minutes)
Calendar.set(Calendar.MINUTE, int minutes).
minutes - the value of the minutes.
Calendar
@Deprecated public int getSeconds()
Calendar.get(Calendar.SECOND).
0 and
61. The values
60 and
61 can only occur on those Java Virtual Machines that take leap seconds into account.
Calendar
@Deprecated public void setSeconds(int seconds)
Calendar.set(Calendar.SECOND, int seconds).
seconds - the seconds value.
Calendar
public long getTime()
public void setTime(long time)
Date object to represent a point in time that is
time milliseconds after January 1, 1970 00:00:00 GMT.
time - the number of milliseconds.
public boolean before(Datewhen)
when - a date.
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.
NullPointerException - if
when is null.
public boolean after(Datewhen)
when - a date.
true if and only if the instant represented by this
Date object is strictly later than the instant represented by
when;
false otherwise.
NullPointerException - if
when is null.
public boolean equals(Objectobj)
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.
public int compareTo(DateanotherDate)
compareTo in interface
Comparable<Date>
anotherDate - the
Date to be compared.
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.
NullPointerException - if
anotherDate is null.
public int hashCode()
getTime() method. That is, the hash code is the value of the expression:
(int)(this.getTime()^(this.getTime() >>> 32))
hashCode in class
Object
Object.equals(java.lang.Object) ,
System.identityHashCode(java.lang.Object)
public StringtoString()
Date object to a
String of the form:
where:dow mon dd hh:mm:ss zzz yyyy
toString in class
Object
toLocaleString(),
toGMTString()
@Deprecated public StringtoLocaleString()
DateFormat.format(Date date).
%c" format supported by the
strftime() function of ISO C.
DateFormat,
toString(),
toGMTString()
@Deprecated public StringtoGMTString()
DateFormat.format(Date date), using a GMT TimeZone.
where:d mon yyyy hh:mm:ss GMT
The result does not depend on the local time zone.
DateFormat,
toString(),
toLocaleString()
@Deprecated public int getTimezoneOffset()
-(Calendar.get(Calendar.ZONE_OFFSET) + Calendar.get(Calendar.DST_OFFSET)) / (60 * 1000).
Date object.
For example, in Massachusetts, five time zones west of Greenwich:
because on February 14, 1996, standard time (Eastern Standard Time) is in use, which is offset five hours from UTC; but:new Date(96, 1, 14).getTimezoneOffset() returns 300
because on June 1, 1996, daylight saving time (Eastern Daylight Time) is in use, which is offset only four hours from UTC.new Date(96, 5, 1).getTimezoneOffset() returns 240
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)
Calendar.ZONE_OFFSET ,
Calendar.DST_OFFSET ,
TimeZone.getDefault()
public static Datefrom(Instant instant)
Date from an
Instant object.
Instant uses a precision of nanoseconds, whereas Date uses a precision of milliseconds. The conversion will trancate any excess precision information as though the amount in nanoseconds was subject to integer division by one million.
Instant can store points on the time-line further in the future and further in the past than Date. In this scenario, this method will throw an exception.
instant - the instant to convert
Date representing the same point on the time-line as the provided instant
NullPointerException - if
instant is null.
IllegalArgumentException - if the instant is too large to represent as a
Date
public InstanttoInstant()
Date object to an
Instant.
The conversion creates an Instant that represents the same point on the time-line as this Date.
Date object