The previous section, Using Predefined Formats, described the formatting styles provided by the DateFormat class. In most cases these predefined formats are adequate. However, if you want to create your own customized formats, you can use the SimpleDateFormat class.

The code examples that follow demonstrate the methods of the SimpleDateFormat class. You can find the full source code for the examples in the file named SimpleDateFormatDemo.

About Patterns

When you create a SimpleDateFormat object, you specify a pattern String. The contents of the pattern String determine the format of the date and time. For a full description of the pattern's syntax, see the tables in Date Format Pattern Syntax.

The following code formats a date and time according to the pattern String passed to the SimpleDateFormat constructor. The String returned by the format method contains the formatted date and time that are to be displayed.

Date today;
String output;
SimpleDateFormat formatter;

formatter = new SimpleDateFormat(pattern, currentLocale);
today = new Date();
output = formatter.format(today);
System.out.println(pattern + " " + output);

The following table shows the output generated by the previous code example when the U.S. Locale is specified:

Customized Date and Time Formats

Pattern	Output
dd.MM.yy	09.04.98
yyyy.MM.dd G 'at' hh:mm:ss z	1998.04.09 AD at 06:15:55 PDT
EEE, MMM d, ''yy	Thu, Apr 9, '98
h:mm a	6:15 PM
H:mm	18:15
H:mm:ss:SSS	18:15:55:624
K:mm a,z	6:15 PM,PDT
yyyy.MMMMM.dd GGG hh:mm aaa	1998.April.09 AD 06:15 PM

Patterns and Locale

The SimpleDateFormat class is locale-sensitive. If you instantiate SimpleDateFormat without a Locale parameter, it will format the date and time according to the default Locale. Both the pattern and the Locale determine the format. For the same pattern, SimpleDateFormat may format a date and time differently if the Locale varies.

In the example code that follows, the pattern is hardcoded in the statement that creates the SimpleDateFormat object:

Date today;
String result;
SimpleDateFormat formatter;

formatter = new SimpleDateFormat("EEE d MMM yy",
				 currentLocale);
today = new Date();
result = formatter.format(today);
System.out.println("Locale: " + currentLocale.toString());
System.out.println("Result: " + result);

When the currentLocale is set to different values, the preceding code example generates this output:

Locale: fr_FR
Result: ven 10 avr 98
Locale: de_DE
Result: Fr 10 Apr 98
Locale: en_US
Result: Thu 9 Apr 98

Date Format Pattern Syntax

You can design your own format patterns for dates and times from the list of symbols in the following table:

Symbol	Meaning	Presentation	Example
G	era designator	Text	AD
y	year	Number	1996
M	month in year	Text & Number	July & 07
d	day in month	Number	10
h	hour in am/pm (1-12)	Number	12
H	hour in day (0-23)	Number	0
m	minute in hour	Number	30
s	second in minute	Number	55
S	millisecond	Number	978
E	day in week	Text	Tuesday
D	day in year	Number	189
F	day of week in month	Number	2 (2nd Wed in July)
w	week in year	Number	27
W	week in month	Number	2
a	am/pm marker	Text	PM
k	hour in day (1-24)	Number	24
K	hour in am/pm (0-11)	Number	0
z	time zone	Text	Pacific Standard Time
'	escape for text	Delimiter	(none)
'	single quote	Literal	'

Characters that are not letters are treated as quoted text. That is, they will appear in the formatted text even if they are not enclosed within single quotes.

The number of symbol letters you specify also determines the format. For example, if the "zz" pattern results in "PDT," then the "zzzz" pattern generates "Pacific Daylight Time." The following table summarizes these rules:

Presentation	Number of Symbols	Result
Text	1 - 3	abbreviated form, if one exists
Text	>= 4	full form
Number	minimum number of digits is required	shorter numbers are padded with zeros (for a year, if the count of 'y' is 2, then the year is truncated to 2 digits)
Text & Number	1 - 2	number form
Text & Number	3	text form