Printing DateTime in a Given Format

Printing Date/Time in a Given Format

Date todaysDate = new java.util.Date(); SimpleDateFormat formatter =   new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss"); String formattedDate = formatter.format(todaysDate); System.out.println("Today's Date and Time is: "   + formattedDate);

Java contains formatting classes that can be used to format a date into a desired format. The most commonly used class for formatting dates is the SimpleDateFormat class. This class takes a format string as input to its constructor and returns a format object that can then be used to format Date objects. Calling the format() method of the SimpleDateFormat object will return a string that contains the formatted representation of the Date that is passed into the method as a parameter.

The output of the phrase shown will be the following:

Today's Date and Time is: Mon, 27 Feb 2006 11:18:33

The formatting string passed to the SimpleDateFormat constructor can be a bit cryptic to read if you don't know the formatting codes to use. Table 5.1 shows the formatting codes that can be passed into the SimpleDateFormat constructor. In our phrase, we used the following formatting string:

"EEE, dd MMM yyyy HH:mm:ss"

Table 5.1. Time and Date Format Codes

Letter	Date or Time Component	Presentation	Examples
G	Era designator	Text	AD
y	Year	Year	1996; 96
M	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
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

Referring to Table 5.1, let's break down this format string to understand what we are asking for.

EEE  = 3 character representation of the day of the        week. (i.e. Tue) , = puts a comma in the output. dd = 2 character representation of the day of the      month. (i.e. 1  31) MMM = 3 character representation of the month of       the year. (i.e. Feb) yyyy = 4 digit year string. (i.e. 2006) HH:mm:ss = The hour minute and seconds separated by            semi-colons. (i.e. 11:18:33)

When we put this all together, we get the date string of

Mon, 27 Feb 2006 11:18:33

In addition to creating your own date formatting strings, you can use one of several predefined format strings by using the getTimeInstance(), getdateInstance(), or geTDateTimeInstance() methods of the DateFormat class. For example, the following code will return a formatter object that will use a date format for your default locale:

DateFormat df = DateFormat.getDateInstance();

The df formatter can then be used in the same way we used the SimpleDateFormat object in the phrase. See the JavaDoc available for the DateFormat class for a complete discussion of the available standard date/time formatting objects at http://java.sun.com/j2se/1.5.0/docs/api/java/text/DateFormat.html.