| Java™ Platform Standard Ed. 6 | ||||||||||
java.lang.Objectjava.util.Date
public classDate
The classDate represents a specific instant in time, with millisecond precision.
Prior to JDK 1.1, the classDate 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, theCalendar class should be used to convert between dates and time fields and theDateFormat class should be used to format and parse date strings. The corresponding methods inDate are deprecated.
Although theDate 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 isnot 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 classDate 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 FormDate()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) orGregorianCalendar(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) orGregorianCalendar(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) orGregorianCalendar(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). | |
after(Date when)Tests if this date is after the specified date. | |
before(Date when)Tests if this date is before the specified date. | |
clone()Return a copy of this object. | |
compareTo(Date anotherDate)Compares two Dates for ordering. | |
equals(Object obj)Compares two dates for equality. | |
getDate()Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.DAY_OF_MONTH). | |
getDay()Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.DAY_OF_WEEK). | |
getHours()Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.HOUR_OF_DAY). | |
getMinutes()Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.MINUTE). | |
getMonth()Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.MONTH). | |
getSeconds()Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.SECOND). | |
getTime()Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by thisDate object. | |
getTimezoneOffset()Deprecated. As of JDK version 1.1, replaced by -(Calendar.get(Calendar.ZONE_OFFSET) + Calendar.get(Calendar.DST_OFFSET)) / (60 * 1000). | |
getYear()Deprecated. As of JDK version 1.1, replaced by Calendar.get(Calendar.YEAR) - 1900. | |
hashCode()Returns a hash code value for this object. | |
parse(String s)Deprecated. As of JDK version 1.1, replaced by DateFormat.parse(String s). | |
setDate(int date)Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.DAY_OF_MONTH, int date). | |
setHours(int hours)Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.HOUR_OF_DAY, int hours). | |
setMinutes(int minutes)Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.MINUTE, int minutes). | |
setMonth(int month)Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.MONTH, int month). | |
setSeconds(int seconds)Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.SECOND, int seconds). | |
setTime(long time)Sets this Date object to represent a point in time that istime milliseconds after January 1, 1970 00:00:00 GMT. | |
setYear(int year)Deprecated. As of JDK version 1.1, replaced by Calendar.set(Calendar.YEAR, year + 1900). | |
toGMTString()Deprecated. As of JDK version 1.1, replaced by DateFormat.format(Date date), using a GMTTimeZone. | |
toLocaleString()Deprecated. As of JDK version 1.1, replaced by DateFormat.format(Date date). | |
toString()Converts this Date object to aString of the form: | |
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) orGregorianCalendar(year + 1900, month, date, hrs, min, sec), using a UTCTimeZone, followed byCalendar.getTime().getTime(). | |
| Methods inherited from class java.lang.Object |
|---|
finalize,getClass,notify,notifyAll,wait,wait,wait |
publicDate()
Date object and initializes it so that it represents the time at which it was allocated, measured to the nearest millisecond.System.currentTimeMillis()publicDate(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()publicDate(int year, int month, int date)
Calendar.set(year + 1900, month, date) orGregorianCalendar(year + 1900, month, date).Date object and initializes it so that it represents midnight, local time, at the beginning of the day specified by theyear,month, anddate arguments.year - the year minus 1900.month - the month between 0-11.date - the day of the month between 1-31.CalendarpublicDate(int year, int month, int date, int hrs, int min)
Calendar.set(year + 1900, month, date, hrs, min) orGregorianCalendar(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 theyear,month,date,hrs, andmin 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.CalendarpublicDate(int year, int month, int date, int hrs, int min, int sec)
Calendar.set(year + 1900, month, date, hrs, min, sec) orGregorianCalendar(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 theyear,month,date,hrs,min, andsec 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.CalendarpublicDate(String s)
DateFormat.parse(String s).Date object and initializes it so that it represents the date and time indicated by the strings, which is interpreted as if by theparse(java.lang.String) method.s - a string representation of the date.DateFormat,parse(java.lang.String)publicObjectclone()
clone in classObjectCloneablepublic static longUTC(int year, int month, int date, int hrs, int min, int sec)
Calendar.set(year + 1900, month, date, hrs, min, sec) orGregorianCalendar(year + 1900, month, date, hrs, min, sec), using a UTCTimeZone, followed byCalendar.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.Calendarpublic static longparse(String s)
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 strings is processed from left to right, looking for data of interest. Any material ins that is within the ASCII parenthesis characters( and) is ignored. Parentheses may be nested. Otherwise, the only characters permitted withins 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.DateFormatpublic intgetYear()
Calendar.get(Calendar.YEAR) - 1900.Date object, as interpreted in the local time zone.Calendarpublic voidsetYear(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.Calendarpublic intgetMonth()
Calendar.get(Calendar.MONTH).0 and11, with the value0 representing January.Calendarpublic voidsetMonth(int month)
Calendar.set(Calendar.MONTH, int month).month - the month value between 0-11.Calendarpublic intgetDate()
Calendar.get(Calendar.DAY_OF_MONTH).1 and31 representing the day of the month that contains or begins with the instant in time represented by thisDate object, as interpreted in the local time zone.Calendarpublic voidsetDate(int date)
Calendar.set(Calendar.DAY_OF_MONTH, int date).date - the day of the month value between 1-31.Calendarpublic intgetDay()
Calendar.get(Calendar.DAY_OF_WEEK).Calendarpublic intgetHours()
Calendar.get(Calendar.HOUR_OF_DAY).Calendarpublic voidsetHours(int hours)
Calendar.set(Calendar.HOUR_OF_DAY, int hours).hours - the hour value.Calendarpublic intgetMinutes()
Calendar.get(Calendar.MINUTE).0 and59.Calendarpublic voidsetMinutes(int minutes)
Calendar.set(Calendar.MINUTE, int minutes).minutes - the value of the minutes.Calendarpublic intgetSeconds()
Calendar.get(Calendar.SECOND).0 and61. The values60 and61 can only occur on those Java Virtual Machines that take leap seconds into account.Calendarpublic voidsetSeconds(int seconds)
Calendar.set(Calendar.SECOND, int seconds).seconds - the seconds value.Calendarpublic longgetTime()
public voidsetTime(long time)
Date object to represent a point in time that istime milliseconds after January 1, 1970 00:00:00 GMT.time - the number of milliseconds.public booleanbefore(Date when)
when - a date.true if and only if the instant of time represented by thisDate object is strictly earlier than the instant represented bywhen;false otherwise.NullPointerException - ifwhen is null.public booleanafter(Date when)
when - a date.true if and only if the instant represented by thisDate object is strictly later than the instant represented bywhen;false otherwise.NullPointerException - ifwhen is null.public booleanequals(Object obj)
true if and only if the argument is notnull and is aDate object that represents the same point in time, to the millisecond, as this object. Thus, twoDate objects are equal if and only if thegetTime method returns the samelong value for both.
equals in classObjectobj - the object to compare with.true if the objects are the same;false otherwise.getTime()public intcompareTo(Date anotherDate)
compareTo in interfaceComparable<Date>anotherDate - theDate to be compared.0 if the argument Date is equal to this Date; a value less than0 if this Date is before the Date argument; and a value greater than0 if this Date is after the Date argument.NullPointerException - ifanotherDate is null.public inthashCode()
getTime() method. That is, the hash code is the value of the expression:(int)(this.getTime()^(this.getTime() >>> 32))
hashCode in classObjectObject.equals(java.lang.Object),HashtablepublicStringtoString()
Date object to aString of the form:where:dow mon dd hh:mm:ss zzz yyyy
toString in classObjecttoLocaleString(),toGMTString()publicStringtoLocaleString()
DateFormat.format(Date date).%c" format supported by thestrftime() function of ISO C.DateFormat,toString(),toGMTString()publicStringtoGMTString()
DateFormat.format(Date date), using a GMTTimeZone.d mon yyyy hh:mm:ss GMTwhere:
The result does not depend on the local time zone.
DateFormat,toString(),toLocaleString()public intgetTimezoneOffset()
-(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()| Java™ Platform Standard Ed. 6 | ||||||||||