Date formats milliseconds java

How to convert milliseconds to Date in Java — Tutorial example

Do you want to convert milliseconds to Date in Java? Actually java.util.Date is internally specified in milliseconds from epoch. So any date is the number of milliseconds passed since January 1, 1970, 00:00:00 GMT and Date provides constructor which can be used to create Date from milliseconds. Knowing the fact that Date is internally maintained in milliseconds allows you to store date in form of milliseconds in Server or in your Class because that can be effectively expressed with a long value.

In fact, many experienced Java programmers store Date as long values while writing Immutable class which requires Date, one of the reasons for that is Date being mutable and long value of Date can be very handy?

By the ways this is next in Date related article, we have already discussed How to convert String to Date and How to get a current month, year, and day of the week from Date in Java. If you haven’t read them already, you may find them useful. In this Java tutorial, we will see an example of converting milliseconds into Dates in Java.

Java program to convert millisecond to Date in Java

There are many different ways to convert milliseconds into Date in Java. One can use java.util.Date(long Millis) constructor or java.util.Calendar.setTimeInMillis() method. In this article, we will see examples of both methods to create Date from A millisecond in Java.

By the way here we are using SimpleDateFormat to format Date in Java which is not thread-safe and should not be shared between multiple threads.

import java.text.DateFormat ;
import java.text.SimpleDateFormat ;
import java.util.Calendar ;
import java.util.Date ;

/**
* Java program to convert Millisecond to Date in Java. Java API provides utility

* method to get millisecond from Date and convert Millisecond to Date in Java.
* @author http://javarevisited.blogspot.com
*/
public class MillisToDate

public static void main ( String args [])

//Converting milliseconds to Date using java.util.Date
//current time in milliseconds
long currentDateTime = System. currentTimeMillis () ;

//creating Date from millisecond
Date currentDate = new Date ( currentDateTime ) ;

//printing value of Date
System. out . println ( «current Date: » + currentDate ) ;

DateFormat df = new SimpleDateFormat ( «dd:MM:yy:HH:mm:ss» ) ;

//formatted value of current Date
System. out . println ( «Milliseconds to Date: » + df. format ( currentDate )) ;

//Converting milliseconds to Date using Calendar
Calendar cal = Calendar. getInstance () ;
cal. setTimeInMillis ( currentDateTime ) ;
System. out . println ( «Milliseconds to Date using Calendar:»

//copying one Date’s value into another Date in Java
Date now = new Date () ;
Date copiedDate = new Date ( now. getTime ()) ;

System. out . println ( «original Date: » + df. format ( now )) ;
System. out . println ( «copied Date: » + df. format ( copiedDate )) ;
>

Output:
current Date: Wed Feb 29 01: 58 : 46 VET 2012
Milliseconds to Date: 29 :02: 12 :01: 58 : 46
Milliseconds to Date using Calendar: 29 :02: 12 :01: 58 : 46
original Date: 29 :02: 12 :01: 58 : 46
copied Date: 29 :02: 12 :01: 58 : 46

Another useful usage of keeping Date in a millisecond is, It’s easy to convert between java.util.Date and java.sql.Date. SQL doesn’t provide Date in form of java.util.Date you often need to convert SQL Date to util Date but keep the value of Date as long millisecond value allows you to create both java.sql.Date and java.util.Date . One more benefit of keeping the date in long millisecond value is, it’s easy to copy the value of one Date into another in Java.

That’s all on how to convert milliseconds to Date in Java. We have seen two approaches one is using Date class while the other is using Calendar class. I personally prefer java.util.Date way. let me know if you come across any other way of converting milliseconds into Date in Java.

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Class SimpleDateFormat

SimpleDateFormat is a concrete class for formatting and parsing dates in a locale-sensitive manner. It allows for formatting (date → text), parsing (text → date), and normalization.

SimpleDateFormat allows you to start by choosing any user-defined patterns for date-time formatting. However, you are encouraged to create a date-time formatter with either getTimeInstance , getDateInstance , or getDateTimeInstance in DateFormat . Each of these class methods can return a date/time formatter initialized with a default format pattern. You may modify the format pattern using the applyPattern methods as desired. For more information on using these methods, see DateFormat .

Date and Time Patterns

Date and time formats are specified by date and time pattern strings. Within date and time pattern strings, unquoted letters from ‘A’ to ‘Z’ and from ‘a’ to ‘z’ are interpreted as pattern letters representing the components of a date or time string. Text can be quoted using single quotes ( ‘ ) to avoid interpretation. «»» represents a single quote. All other characters are not interpreted; they’re simply copied into the output string during formatting or matched against the input string during parsing.

The following pattern letters are defined (all other characters from ‘A’ to ‘Z’ and from ‘a’ to ‘z’ are reserved):

Chart shows pattern letters, date/time component, presentation, and examples.

Letter	Date or Time Component	Presentation	Examples
G	Era designator	Text	AD
y	Year	Year	1996 ; 96
Y	Week year	Year	2009 ; 09
M	Month in year (context sensitive)	Month	July ; Jul ; 07
L	Month in year (standalone form)	Month	July ; Jul ; 07
w	Week in year	Number	27
W	Week in month	Number	2
D	Day in year	Number	189
d	Day in month	Number	10
F	Day of week in month	Number	2
E	Day name in week	Text	Tuesday ; Tue
u	Day number of week (1 = Monday, . 7 = Sunday)	Number	1
a	Am/pm marker	Text	PM
H	Hour in day (0-23)	Number	0
k	Hour in day (1-24)	Number	24
K	Hour in am/pm (0-11)	Number	0
h	Hour in am/pm (1-12)	Number	12
m	Minute in hour	Number	30
s	Second in minute	Number	55
S	Millisecond	Number	978
z	Time zone	General time zone	Pacific Standard Time ; PST ; GMT-08:00
Z	Time zone	RFC 822 time zone	-0800
X	Time zone	ISO 8601 time zone	-08 ; -0800 ; -08:00

• Text: For formatting, if the number of pattern letters is 4 or more, the full form is used; otherwise a short or abbreviated form is used if available. For parsing, both forms are accepted, independent of the number of pattern letters.

• For formatting, if the number of pattern letters is 2, the year is truncated to 2 digits; otherwise it is interpreted as a number.
• For parsing, if the number of pattern letters is more than 2, the year is interpreted literally, regardless of the number of digits. So using the pattern «MM/dd/yyyy», «01/11/12» parses to Jan 11, 12 A.D.
• For parsing with the abbreviated year pattern («y» or «yy»), SimpleDateFormat must interpret the abbreviated year relative to some century. It does this by adjusting dates to be within 80 years before and 20 years after the time the SimpleDateFormat instance is created. For example, using a pattern of «MM/dd/yy» and a SimpleDateFormat instance created on Jan 1, 1997, the string «01/11/12» would be interpreted as Jan 11, 2012 while the string «05/04/64» would be interpreted as May 4, 1964. During parsing, only strings consisting of exactly two digits, as defined by Character.isDigit(char) , will be parsed into the default century. Any other numeric string, such as a one digit string, a three or more digit string, or a two digit string that isn’t all digits (for example, «-1»), is interpreted literally. So «01/02/3» or «01/02/003» are parsed, using the same pattern, as Jan 2, 3 AD. Likewise, «01/02/-3» is parsed as Jan 2, 4 BC.

If week year ‘Y’ is specified and the calendar doesn’t support any week years, the calendar year ( ‘y’ ) is used instead. The support of week years can be tested with a call to getCalendar() . isWeekDateSupported() .

• Letter M produces context-sensitive month names, such as the embedded form of names. Letter M is context-sensitive in the sense that when it is used in the standalone pattern, for example, «MMMM», it gives the standalone form of a month name and when it is used in the pattern containing other field(s), for example, «d MMMM», it gives the format form of a month name. For example, January in the Catalan language is «de gener» in the format form while it is «gener» in the standalone form. In this case, «MMMM» will produce «gener» and the month part of the «d MMMM» will produce «de gener». If a DateFormatSymbols has been set explicitly with constructor SimpleDateFormat(String,DateFormatSymbols) or method setDateFormatSymbols(DateFormatSymbols) , the month names given by the DateFormatSymbols are used.
• Letter L produces the standalone form of month names.

GMTOffsetTimeZone: GMT Sign Hours : Minutes Sign: one of + - Hours: Digit Digit Digit Minutes: Digit Digit Digit: one of 0 1 2 3 4 5 6 7 8 9

Hours must be between 0 and 23, and Minutes must be between 00 and 59. The format is locale independent and digits must be taken from the Basic Latin block of the Unicode standard. For parsing, RFC 822 time zones are also accepted.

RFC822TimeZone: Sign TwoDigitHours Minutes TwoDigitHours: Digit Digit

ISO8601TimeZone: OneLetterISO8601TimeZone TwoLetterISO8601TimeZone ThreeLetterISO8601TimeZone OneLetterISO8601TimeZone: Sign TwoDigitHours Z TwoLetterISO8601TimeZone: Sign TwoDigitHours Minutes Z ThreeLetterISO8601TimeZone: Sign TwoDigitHours : Minutes Z

Examples

The following examples show how date and time patterns are interpreted in the U.S. locale. The given date and time are 2001-07-04 12:08:56 local time in the U.S. Pacific Time time zone.

Examples of date and time patterns interpreted in the U.S. locale

Date and Time Pattern	Result
«yyyy.MM.dd G ‘at’ HH:mm:ss z»	2001.07.04 AD at 12:08:56 PDT
«EEE, MMM d, »yy»	Wed, Jul 4, ’01
«h:mm a»	12:08 PM
«hh ‘o»clock’ a, zzzz»	12 o’clock PM, Pacific Daylight Time
«K:mm a, z»	0:08 PM, PDT
«yyyyy.MMMMM.dd GGG hh:mm aaa»	02001.July.04 AD 12:08 PM
«EEE, d MMM yyyy HH:mm:ss Z»	Wed, 4 Jul 2001 12:08:56 -0700
«yyMMddHHmmssZ»	010704120856-0700
«yyyy-MM-dd’T’HH:mm:ss.SSSZ»	2001-07-04T12:08:56.235-0700
«yyyy-MM-dd’T’HH:mm:ss.SSSXXX»	2001-07-04T12:08:56.235-07:00
«YYYY-‘W’ww-u»	2001-W27-3

Synchronization

Date formats are not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally.

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Date formats milliseconds java

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