I know of date formats such as

"yyyy-mm-dd" -which displays date in format 2011-02-26

"yyyy-MMM-dd"-which displays date in format 2011-FEB-26

to be used in eg:

SimpleDateFormat formatter = new SimpleDateFormat(
                "yyyy/MMM/dd ");

I want a format which would help me display the day of the week like 2011-02-MON or anything. I j开发者_开发问答ust want the day of the week to be displayed in characters with the month and the year. Can you tell me of a format like this?

This should display 'Tue':

new SimpleDateFormat("EEE").format(new Date());

This should display 'Tuesday':

new SimpleDateFormat("EEEE").format(new Date());

This should display 'T':

new SimpleDateFormat("EEEEE").format(new Date());

So your specific example would be:

new SimpleDateFormat("yyyy-MM-EEE").format(new Date());

Yep - 'E' does the trick

http://download.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html

Date date = new Date();
DateFormat df = new SimpleDateFormat("yyyy-MM-E");
System.out.println(df.format(date));

tl;dr

LocalDate.of( 2018 , Month.JANUARY , 23 )
         .format( DateTimeFormatter.ofPattern( “uuuu-MM-EEE” , Locale.US )  )

java.time

The modern approach uses the java.time classes.

LocalDate ld = LocalDate.of( 2018 , Month.JANUARY , 23 ) ;

Note how we specify a Locale such as Locale.CANADA_FRENCH to determine the human language used to translate the name of the day.

DateTimeFormatter f = DateTimeFormatter.ofPattern( “uuuu-MM-EEE” , Locale.US ) ;
String output = ld.format( f ) ;

ISO 8601

By the way, you may be interested in the standard ISO 8601 week numbering scheme: yyyy-Www-d.

2018-W01-2

Week # 1 has the first Thursday of the calendar-year. Week starts on a Monday. A year has either 52 or 53 weeks. The last/first few days of a calendar-year may land in the next/previous week-based-year.

The single digit on the end is day-of-week, 1-7 for Monday-Sunday.

Add the ThreeTen-Extra library class to your project for the YearWeek class.

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • Later versions of Android bundle implementations of the java.time classes.
  • For earlier Android, the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

SimpleDateFormat sdf=new SimpleDateFormat("EEE");

EEE stands for day of week for example Thursday is displayed as Thu.

Use "E"

See the section on Date and Time Patterns:

JavaDocs for SimpleDateFormat

I know the question is about getting the day of week as string (e.g. the short name), but for anybody who is looking for the numeric day of week (as I was), you can use the new "u" format string, supported since Java 7. For example:

new SimpleDateFormat("u").format(new Date());

returns today's day-of-week index, namely: 1 = Monday, 2 = Tuesday, ..., 7 = Sunday.