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Java string to date conversion

980

What is the best way to convert a String in the format ‘January 2, 2010’ to a Date in Java?

Ultimately, I want to break out the month, the day, and the year as integers so that I can use

Date date = new Date();
date.setMonth()..
date.setYear()..
date.setDay()..
date.setlong currentTime = date.getTime();

to convert the date into time.

7

1803

That’s the hard way, and those java.util.Date setter methods have been deprecated since Java 1.1 (1997). Moreover, the whole java.util.Date class was de-facto deprecated (discommended) since introduction of java.time API in Java 8 (2014).

Simply format the date using DateTimeFormatter with a pattern matching the input string (the tutorial is available here).

In your specific case of “January 2, 2010” as the input string:

  1. “January” is the full text month, so use the MMMM pattern for it
  2. “2” is the short day-of-month, so use the d pattern for it.
  3. “2010” is the 4-digit year, so use the yyyy pattern for it.
String string = "January 2, 2010";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMMM d, yyyy", Locale.ENGLISH);
LocalDate date = LocalDate.parse(string, formatter);
System.out.println(date); // 2010-01-02

Note: if your format pattern happens to contain the time part as well, then use LocalDateTime#parse(text, formatter) instead of LocalDate#parse(text, formatter). And, if your format pattern happens to contain the time zone as well, then use ZonedDateTime#parse(text, formatter) instead.

Here’s an extract of relevance from the javadoc, listing all available format patterns:

SymbolMeaningPresentationExamples
GeratextAD; Anno Domini; A
uyearyear2004; 04
yyear-of-erayear2004; 04
Dday-of-yearnumber189
M/Lmonth-of-yearnumber/text7; 07; Jul; July; J
dday-of-monthnumber10
Q/qquarter-of-yearnumber/text3; 03; Q3; 3rd quarter
Yweek-based-yearyear1996; 96
wweek-of-week-based-yearnumber27
Wweek-of-monthnumber4
Eday-of-weektextTue; Tuesday; T
e/clocalized day-of-weeknumber/text2; 02; Tue; Tuesday; T
Fweek-of-monthnumber3
aam-pm-of-daytextPM
hclock-hour-of-am-pm (1-12)number12
Khour-of-am-pm (0-11)number0
kclock-hour-of-am-pm (1-24)number0
Hhour-of-day (0-23)number0
mminute-of-hournumber30
ssecond-of-minutenumber55
Sfraction-of-secondfraction978
Amilli-of-daynumber1234
nnano-of-secondnumber987654321
Nnano-of-daynumber1234000000
Vtime-zone IDzone-idAmerica/Los_Angeles; Z; -08:30
ztime-zone namezone-namePacific Standard Time; PST
Olocalized zone-offsetoffset-OGMT+8; GMT+08:00; UTC-08:00;
Xzone-offset ‘Z’ for zerooffset-XZ; -08; -0830; -08:30; -083015; -08:30:15;
xzone-offsetoffset-x+0000; -08; -0830; -08:30; -083015; -08:30:15;
Zzone-offsetoffset-Z+0000; -0800; -08:00;

Do note that it has several predefined formatters for the more popular patterns. So instead of e.g. DateTimeFormatter.ofPattern("EEE, d MMM yyyy HH:mm:ss Z", Locale.ENGLISH);, you could use DateTimeFormatter.RFC_1123_DATE_TIME. This is possible because they are, on the contrary to SimpleDateFormat, thread safe. You could thus also define your own, if necessary.

For a particular input string format, you don’t need to use an explicit DateTimeFormatter: a standard ISO 8601 date, like 2016-09-26T17:44:57Z, can be parsed directly with LocalDateTime#parse(text) as it already uses the ISO_LOCAL_DATE_TIME formatter. Similarly, LocalDate#parse(text) parses an ISO date without the time component (see ISO_LOCAL_DATE), and ZonedDateTime#parse(text) parses an ISO date with an offset and time zone added (see ISO_ZONED_DATE_TIME).


Pre-Java 8

In case you’re not on Java 8 yet, or are forced to use java.util.Date, then format the date using SimpleDateFormat using a format pattern matching the input string.

String string = "January 2, 2010";
DateFormat format = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH);
Date date = format.parse(string);
System.out.println(date); // Sat Jan 02 00:00:00 GMT 2010

Note the importance of the explicit Locale argument. If you omit it, then it will use the default locale which is not necessarily English as used in the month name of the input string. If the locale doesn’t match with the input string, then you would confusingly get a java.text.ParseException even though when the format pattern seems valid.

Here’s an extract of relevance from the javadoc, listing all available format patterns:

LetterDate or Time ComponentPresentationExamples
GEra designatorTextAD
yYearYear1996; 96
YWeek yearYear2009; 09
M/LMonth in yearMonthJuly; Jul; 07
wWeek in yearNumber27
WWeek in monthNumber2
DDay in yearNumber189
dDay in monthNumber10
FDay of week in monthNumber2
EDay in weekTextTuesday; Tue
uDay number of weekNumber1
aAm/pm markerTextPM
HHour in day (0-23)Number0
kHour in day (1-24)Number24
KHour in am/pm (0-11)Number0
hHour in am/pm (1-12)Number12
mMinute in hourNumber30
sSecond in minuteNumber55
SMillisecondNumber978
zTime zoneGeneral time zonePacific Standard Time; PST; GMT-08:00
ZTime zoneRFC 822 time zone-0800
XTime zoneISO 8601 time zone-08; -0800; -08:00

Note that the patterns are case sensitive and that text based patterns of four characters or more represent the full form; otherwise a short or abbreviated form is used if available. So e.g. MMMMM or more is unnecessary.

Here are some examples of valid SimpleDateFormat patterns to parse a given string to date:

Input stringPattern
2001.07.04 AD at 12:08:56 PDTyyyy.MM.dd G 'at' HH:mm:ss z
Wed, Jul 4, ’01EEE, MMM d, ''yy
12:08 PMh:mm a
12 o’clock PM, Pacific Daylight Timehh 'o''clock' a, zzzz
0:08 PM, PDTK:mm a, z
02001.July.04 AD 12:08 PMyyyyy.MMMM.dd GGG hh:mm aaa
Wed, 4 Jul 2001 12:08:56 -0700EEE, d MMM yyyy HH:mm:ss Z
010704120856-0700yyMMddHHmmssZ
2001-07-04T12:08:56.235-0700yyyy-MM-dd'T'HH:mm:ss.SSSZ
2001-07-04T12:08:56.235-07:00yyyy-MM-dd'T'HH:mm:ss.SSSXXX
2001-W27-3YYYY-'W'ww-u

An important note is that SimpleDateFormat is not thread safe. In other words, you should never declare and assign it as a static or instance variable and then reuse it from different methods/threads. You should always create it brand new within the method local scope.

5

  • Hi, in option O, how to let it print UTC+08:00 instead of GMT+08:00. I couldn’t get any example.

    Apr 18, 2018 at 14:26

  • There are many ways to parse dates, here are various use cases of DateFormat.parse

    – drorw

    Jun 4, 2018 at 16:05


  • Hi BalusC, I have a string 20-JUN-16 12.00.00.000000000 AM, need help to convert this to Date. Your help is much appreciated!!

    – mannedear

    Jul 24, 2018 at 6:57

  • @mannedear oh sorry.. that was my mistake. Anyway I got the answer you can see it here : stackoverflow.com/questions/50982310/…

    Jul 30, 2018 at 13:59

  • What if we need to use API 23< and below? All this “parse” methods are for Java8+

    Apr 8, 2021 at 11:57

79

Ah yes the Java Date discussion, again. To deal with date manipulation we use Date, Calendar, GregorianCalendar, and SimpleDateFormat. For example using your January date as input:

Calendar mydate = new GregorianCalendar();
String mystring = "January 2, 2010";
Date thedate = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH).parse(mystring);
mydate.setTime(thedate);
//breakdown
System.out.println("mydate -> "+mydate);
System.out.println("year   -> "+mydate.get(Calendar.YEAR));
System.out.println("month  -> "+mydate.get(Calendar.MONTH));
System.out.println("dom    -> "+mydate.get(Calendar.DAY_OF_MONTH));
System.out.println("dow    -> "+mydate.get(Calendar.DAY_OF_WEEK));
System.out.println("hour   -> "+mydate.get(Calendar.HOUR));
System.out.println("minute -> "+mydate.get(Calendar.MINUTE));
System.out.println("second -> "+mydate.get(Calendar.SECOND));
System.out.println("milli  -> "+mydate.get(Calendar.MILLISECOND));
System.out.println("ampm   -> "+mydate.get(Calendar.AM_PM));
System.out.println("hod    -> "+mydate.get(Calendar.HOUR_OF_DAY));

Then you can manipulate that with something like:

Calendar now = Calendar.getInstance();
mydate.set(Calendar.YEAR,2009);
mydate.set(Calendar.MONTH,Calendar.FEBRUARY);
mydate.set(Calendar.DAY_OF_MONTH,25);
mydate.set(Calendar.HOUR_OF_DAY,now.get(Calendar.HOUR_OF_DAY));
mydate.set(Calendar.MINUTE,now.get(Calendar.MINUTE));
mydate.set(Calendar.SECOND,now.get(Calendar.SECOND));
// or with one statement
//mydate.set(2009, Calendar.FEBRUARY, 25, now.get(Calendar.HOUR_OF_DAY), now.get(Calendar.MINUTE), now.get(Calendar.SECOND));
System.out.println("mydate -> "+mydate);
System.out.println("year   -> "+mydate.get(Calendar.YEAR));
System.out.println("month  -> "+mydate.get(Calendar.MONTH));
System.out.println("dom    -> "+mydate.get(Calendar.DAY_OF_MONTH));
System.out.println("dow    -> "+mydate.get(Calendar.DAY_OF_WEEK));
System.out.println("hour   -> "+mydate.get(Calendar.HOUR));
System.out.println("minute -> "+mydate.get(Calendar.MINUTE));
System.out.println("second -> "+mydate.get(Calendar.SECOND));
System.out.println("milli  -> "+mydate.get(Calendar.MILLISECOND));
System.out.println("ampm   -> "+mydate.get(Calendar.AM_PM));
System.out.println("hod    -> "+mydate.get(Calendar.HOUR_OF_DAY));

1

  • 18

    Don’t forget that January is month number… 0

    Jul 16, 2013 at 12:54

61

String str_date = "11-June-07";
DateFormat formatter = new SimpleDateFormat("dd-MMM-yy");
Date date = formatter.parse(str_date);

1

  • 17

    What is the purpose of separating declarations and definitions (though not done for the first variable)?

    Mar 22, 2018 at 23:37