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java.lang.Object | +----java.util.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.
Date() Date object and initializes it so that it represents the time at which it was allocated measured to the nearest millisecond. Date(int, int, int) 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. Deprecated. Date(int, int, int, int, int) Date object and initializes it so that it represents the specified hour and minute, local time, of the date specified by the year, month, date, hrs, and min arguments. Deprecated. Date(int, int, int, int, int, int) Date object and initializes it so that it represents the specified hour, minute, and second, local time of the date specified by the year, month, date, hrs, min, and sec arguments. Deprecated. Date(long) Date object and initializes it to represent the specified number of milliseconds since January 1, 1970, 00:00:00 GMT. Date(String) 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 method. Deprecated. 
after(Date) before(Date) equals(Object) getDate() getDay() getHours() getMinutes() getMonth() getSeconds() getTime() getTimezoneOffset() getYear() hashCode() 
parse(String) setDate(int) setHours(int) setMinutes(int) setMonth(int) setSeconds(int) setTime(long) setYear(int) toGMTString() toLocaleString() toString() UTC(int, int, int, int, int, int) 
Date
public Date()
Date object and initializes it so that it represents the time at which it was allocated measured to the nearest millisecond. Date
public Date(long date)
Date object and initializes it to represent the specified number of milliseconds since January 1, 1970, 00:00:00 GMT. Date
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. Date
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 specified hour and minute, local time, of the date specified by the year, month, date, hrs, and min arguments. Date
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 specified hour, minute, and second, local time of the date specified by the year, month, date, hrs, min, and sec arguments. Date
public Date(String s)
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 method. 
UTC
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(). parse
public static long parse(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.
getYear
public int getYear()
Calendar.get(Calendar.YEAR) - 1900. setYear
public void setYear(int year)
Calendar.set(Calendar.YEAR, year + 1900). getMonth
public int getMonth()
Calendar.get(Calendar.MONTH). 0 and 11, with the value 0 representing January. setMonth
public void setMonth(int month)
Calendar.set(Calendar.MONTH, int month). getDate
public int getDate()
Calendar.get(Calendar.DAY_OF_MONTH). 1 and 31. setDate
public void setDate(int date)
Calendar.set(Calendar.DAY_OF_MONTH, int date). getDay
public int getDay()
Calendar.get(Calendar.DAY_OF_WEEK). 0 and 6, where 0 represents Sunday. getHours
public int getHours()
Calendar.get(Calendar.HOUR_OF_DAY). 0 and 23, where 0 represents midnight. setHours
public void setHours(int hours)
Calendar.set(Calendar.HOUR_OF_DAY, int hours). getMinutes
public int getMinutes()
Calendar.get(Calendar.MINUTE). 0 and 59. setMinutes
public void setMinutes(int minutes)
Calendar.set(Calendar.MINUTE, int minutes). getSeconds
public int getSeconds()
Calendar.get(Calendar.SECOND). 0 and 60. The value 60 can only occur on those Java Virtual Machines that take leap seconds into account. setSeconds
public void setSeconds(int seconds)
Calendar.set(Calendar.SECOND, int seconds). getTime
public long getTime()
setTime
public void setTime(long time)
before
public boolean before(Date when)
true if this date is before the argument date; false otherwise. after
public boolean after(Date when)
true if this date is after the argument date; false otherwise. equals
public boolean equals(Object obj)
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.
true if the objects are the same; false otherwise. hashCode
public int hashCode()
toString
public String toString()
"Sat Aug 12 02:30:00 PDT 1995". toLocaleString
public String toLocaleString()
DateFormat.format(Date date). %c" format supported by the strftime() function of ISO C. toGMTString
public String toGMTString()
DateFormat.format(Date date), using a GMT TimeZone. "12 Aug 1995 02:30:00 GMT" in which the day of the month is always one or two digits. The other fields have exactly the width shown. The time zone is always given as "GMT".
getTimezoneOffset
public int getTimezoneOffset()
Calendar.get(Calendar.ZONE_OFFSET) + Calendar.get(Calendar.DST_OFFSET). All Packages Class Hierarchy This Package Previous Next Index