Dates and Strings
Dates and times
DateFormat

The DateFormat class

java.text.DateFormat;

Common static methods

Method	Description
getDateInstance()	Returns a DateFormat object with date, but not time.
getTimeInstance()	Returns a DateFormat object with time, but not date.
getDateTimeInstance()	Returns a DateFormat object with date and time.
getDateInstance(intField) getTimeInstance(intField) getDateTimeInstance( intField, intField)	Same as above, but you can use the fields shown next to override the default date or time format.

Common fields of the DateFormat class

Style	Date example	Time example
SHORT	12/31/05	12:00 AM
MEDIUM	Dec 31, 2005	7:30:00 PM
LONG	December 31, 2005	7:30:00 AM PST
FULL	Saturday, December 31, 2005	7:30:00 AM PST

Common method

Method	Description
format(Date)	Returns a String object of the Date object with the format that's specified by the DateFormat object.

Code that formats a Date object

Date now = new Date();
DateFormat defaultDate = DateFormat.getDateTimeInstance();
String nowString = defaultDate.format(now);

Code that formats a GregorianCalendar object

GregorianCalendar gregEndDate = new GregorianCalendar(2005,11,31,7,30);
Date endDate = gregEndDate.getTime();
DateFormat defaultDate = DateFormat.getDateInstance();
String endDateString = defaultDate.format(endDate);

Code that overrides the default date and time formats

DateFormat shortDate = DateFormat.getDateInstance(DateFormat.SHORT);
DateFormat shortTime = DateFormat.getTimeInstance(DateFormat.SHORT);
DateFormat shortDateTime = DateFormat.getDateTimeInstance
                           		(DateFormat.SHORT, DateFormat.SHORT);

The SimpleDateFormat class

java.text.SimpleDateFormat;

If we want to display the moth, day, and year in the MM/dd/yy shorthand format, such as 07/20/11, we write

Date today;
SimpledateFormat sdf;
today = new Date();
sdf = new SimpleDateFormat("MM/dd/yy");
system.out.println(sdf.format());

Symbol	Meaning	Value	Sample
y	Year	Number	yyyy -> 2011
M	Month in year	text or number	MM -> 07 MMM -> Jul MMMM -> July
d	Day in month	Number	dd -> 20
D	Day in year	Number	DDD -> 201
h	Hour in AM/PM	Number	hh -> 12
H	Hour in day (0-23)	Number	HH -> 00
a	AM/PM marker	Text	a -> AM
m	Minutes in hour	Number	mm -> 01
s	Seconds in minute	Number	ss -> 06
S	Millisecond	Number	mmm -> 026
E	Day in week	Text	E -> Wed EEEE -> Wednesday

import java.util.*;	// for Date
import java.text.*;	// for SimpleDateFormat

public class DateDisplay
{

	public static void main(String[] args)
	{
		Date today;
		SimpleDateFormat simpleDF1, simpleDF2;
		today = new Date();
		simpleDF1 = new SimpleDateFormat();
		simpleDF2 = new SimpleDateFormat("EEEE MMMM dd, yyyy");
		// Default short format display
		System.out.println("Today is " + simpleDF1.format(today));

		// programmer-designated long format display
		System.out.println("Today is " + simpleDF2.format(today));

	}
}