Query explained:

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.

How to convert string to date in Java? Answer #1:

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:

Symbol	Meaning	Presentation	Examples
G	era	text	AD; Anno Domini; A
u	year	year	2004; 04
y	year-of-era	year	2004; 04
D	day-of-year	number	189
M/L	month-of-year	number/text	7; 07; Jul; July; J
d	day-of-month	number	10
Q/q	quarter-of-year	number/text	3; 03; Q3; 3rd quarter
Y	week-based-year	year	1996; 96
w	week-of-week-based-year	number	27
W	week-of-month	number	4
E	day-of-week	text	Tue; Tuesday; T
e/c	localized day-of-week	number/text	2; 02; Tue; Tuesday; T
F	week-of-month	number	3
a	am-pm-of-day	text	PM
h	clock-hour-of-am-pm (1-12)	number	12
K	hour-of-am-pm (0-11)	number	0
k	clock-hour-of-am-pm (1-24)	number	0
H	hour-of-day (0-23)	number	0
m	minute-of-hour	number	30
s	second-of-minute	number	55
S	fraction-of-second	fraction	978
A	milli-of-day	number	1234
n	nano-of-second	number	987654321
N	nano-of-day	number	1234000000
V	time-zone ID	zone-id	America/Los_Angeles; Z; -08:30
z	time-zone name	zone-name	Pacific Standard Time; PST
O	localized zone-offset	offset-O	GMT+8; GMT+08:00; UTC-08:00;
X	zone-offset ‘Z’ for zero	offset-X	Z; -08; -0830; -08:30; -083015; -08:30:15;
x	zone-offset	offset-x	+0000; -08; -0830; -08:30; -083015; -08:30:15;
Z	zone-offset	offset-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:

Letter	Date or Time Component	Presentation	Examples
G	Era designator	Text	AD
y	Year	Year	1996; 96
Y	Week year	Year	2009; 09
M/L	Month in year	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 in week	Text	Tuesday; Tue
u	Day number of week	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

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

Answer #2:

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));

Answer #3:

While some of the answers are technically correct, they are not advisable.

• The java.util.Date & Calendar classes are notoriously troublesome. Because of flaws in design and implementation, avoid them. Fortunately we have our choice of two other excellent date-time libraries:
  • Joda-Time
    This popular open-source free-of-cost library can be used across several versions of Java.
  • java.time.* package
    This new set of classes are inspired by Joda-Time and defined by JSR 310. These classes are built into Java 8. A project is underway to backport these classes to Java 7, but that backporting is not backed by Oracle.
• As Kristopher Johnson correctly noted in his comment on the question, the other answers ignore vital issues of:
  • Time of Day
    Date has both a date portion and a time-of-day portion)
  • Time Zone
    The beginning of a day depends on the time zone. If you fail to specify a time zone, the JVM’s default time zone is applied. That means the behavior of your code may change when run on other computers or with a modified time zone setting. Probably not what you want.
  • Locale
    The Locale’s language specifies how to interpret the words (name of month and of day) encountered during parsing. (The first answer handles this properly.) Also, the Locale affects the output of some formatters when generating a string representation of your date-time.

Joda-Time

A few notes about Joda-Time follow.

Time Zone

In Joda-Time, a DateTime object truly knows its own assigned time zone. This contrasts the java.util.Date class which seems to have a time zone but does not.

Note in the example code below how we pass a time zone object to the formatter which parses the string. That time zone is used to interpret that date-time as having occurred in that time zone. So you need to think about and determine the time zone represented by that string input.

Since you have no time portion in your input string, Joda-Time assigns the first moment of the day of the specified time zone as the time-of-day. Usually this means 00:00:00 but not always, because of Daylight Saving Time (DST) or other anomalies. By the way, you can do the same to any DateTime instance by calling withTimeAtStartOfDay.

Formatter Pattern

The characters used in a formatter’s pattern are similar in Joda-Time to those in java.util.Date/Calendar but not exactly the same. Carefully read the doc.

Immutability

We usually use the immutable classes in Joda-Time. Rather than modify an existing Date-Time object, we call methods that create a new fresh instance based on the other object with most aspects copied except where alterations were desired. An example is the call to withZone in last line below. Immutability helps to make Joda-Time very thread-safe, and can also make some work more clear.

Conversion

You will need java.util.Date objects for use with other classes/framework that do not know about Joda-Time objects. Fortunately, it is very easy to move back and forth.

Going from a java.util.Date object (here named date) to Joda-Time DateTime…

org.joda.time.DateTime dateTime = new DateTime( date, timeZone );

Going the other direction from Joda-Time to a java.util.Date object…

java.util.Date date = dateTime.toDate();

Sample Code

String input = "January 2, 2010";

java.util.Locale locale = java.util.Locale.US;
DateTimeZone timeZone = DateTimeZone.forID( "Pacific/Honolulu" ); // Arbitrarily chosen for example.
DateTimeFormatter formatter = DateTimeFormat.forPattern( "MMMM d, yyyy" ).withZone( timeZone ).withLocale( locale );
DateTime dateTime = formatter.parseDateTime( input );

System.out.println( "dateTime: " + dateTime );
System.out.println( "dateTime in UTC/GMT: " + dateTime.withZone( DateTimeZone.UTC ) );

When run…

dateTime: 2010-01-02T00:00:00.000-10:00
dateTime in UTC/GMT: 2010-01-02T10:00:00.000Z

Answer #4:

With Java 8 we get a new Date / Time API (JSR 310).

The following way can be used to parse the date in Java 8 without relying on Joda-Time:

 String str = "January 2nd, 2010";

---

// if we 2nd even we have changed in pattern also it is not working please workout with 2nd 
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMMM Q, yyyy", Locale.ENGLISH);
LocalDate date = LocalDate.parse(str, formatter);

---

// access date fields
int year = date.getYear(); // 2010
int day = date.getDayOfMonth(); // 2
Month month = date.getMonth(); // JANUARY
int monthAsInt = month.getValue(); // 1

---

LocalDate is the standard Java 8 class for representing a date (without time). If you want to parse values that contain date and time information you should use LocalDateTime. For values with timezones use ZonedDateTime. Both provide a parse() method similar to LocalDate:

LocalDateTime dateWithTime = LocalDateTime.parse(strWithDateAndTime, dateTimeFormatter);
ZonedDateTime zoned = ZonedDateTime.parse(strWithTimeZone, zoneFormatter);

The list formatting characters from DateTimeFormatter Javadoc:

All letters 'A' to 'Z' and 'a' to 'z' are reserved as pattern letters. 
The following pattern letters are defined:

Symbol  Meaning                     Presentation      Examples
------  -------                     ------------      -------
 G       era                         text              AD; Anno Domini; A
 u       year                        year              2004; 04
 y       year-of-era                 year              2004; 04
 D       day-of-year                 number            189
 M/L     month-of-year               number/text       7; 07; Jul; July; J
 d       day-of-month                number            10

 Q/q     quarter-of-year             number/text       3; 03; Q3; 3rd quarter
 Y       week-based-year             year              1996; 96
 w       week-of-week-based-year     number            27
 W       week-of-month               number            4
 E       day-of-week                 text              Tue; Tuesday; T
 e/c     localized day-of-week       number/text       2; 02; Tue; Tuesday; T
 F       week-of-month               number            3

 a       am-pm-of-day                text              PM
 h       clock-hour-of-am-pm (1-12)  number            12
 K       hour-of-am-pm (0-11)        number            0
 k       clock-hour-of-am-pm (1-24)  number            0

 H       hour-of-day (0-23)          number            0
 m       minute-of-hour              number            30
 s       second-of-minute            number            55
 S       fraction-of-second          fraction          978
 A       milli-of-day                number            1234
 n       nano-of-second              number            987654321
 N       nano-of-day                 number            1234000000

 V       time-zone ID                zone-id           America/Los_Angeles; Z; -08:30
 z       time-zone name              zone-name         Pacific Standard Time; PST
 O       localized zone-offset       offset-O          GMT+8; GMT+08:00; UTC-08:00;
 X       zone-offset 'Z' for zero    offset-X          Z; -08; -0830; -08:30; -083015; -08:30:15;
 x       zone-offset                 offset-x          +0000; -08; -0830; -08:30; -083015; -08:30:15;
 Z       zone-offset                 offset-Z          +0000; -0800; -08:00;

Convert string to date in Java- Examples:

1.

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

2.

DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
Date date;
try {
    date = dateFormat.parse("2013-12-4");
    System.out.println(date.toString()); // Wed Dec 04 00:00:00 CST 2013

    String output = dateFormat.format(date);
    System.out.println(output); // 2013-12-04
} 
catch (ParseException e) {
    e.printStackTrace();
}

Hope you learned something from this post. The primary source of this article is StackOverflow.

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