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?
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.