Get first day of a particular week in Joda-Time? java

In Joda-Time, is there a way to get the date of the first day of the week(monday).

开发者_如何学运维for instance i want to find out what date was this weeks monday based on todays current date 21/01/11

Cheers in advance.

edit: i also wish to find the date for the end of the week i.e sunday's date. cheers

Try LocalDate.withDayOfWeek:

LocalDate now = new LocalDate();
System.out.println(now.withDayOfWeek(DateTimeConstants.MONDAY)); //prints 2011-01-17
System.out.println(now.withDayOfWeek(DateTimeConstants.SUNDAY)); //prints 2011-01-23

LocalDate today = new LocalDate();
LocalDate weekStart = today.dayOfWeek().withMinimumValue();
LocalDate weekEnd = today.dayOfWeek().withMaximumValue();

Will give you the first and last days i.e Monday and sunday

Another option is to use roundFloorCopy. This looks like the following:

LocalDate startOfWeek = new LocalDate().weekOfWeekyear().roundFloorCopy();

For the last day of the standard week (Sunday) use roundCeilingCopy and minusDays…

LocalDate lastDateOfWeek = new LocalDate().weekOfWeekyear().roundCeilingCopy().minusDays( 1 );

Also works for DateTime. And works for end of week (exclusive).

DateTime dateTime = new DateTime();
DateTime startOfWeek = dateTime.weekOfWeekyear().roundFloorCopy();
DateTime endOfWeek = dateTime.weekOfWeekyear().roundCeilingCopy();

Dump to console…

System.out.println( "dateTime " + dateTime );
System.out.println( "startOfWeek " + startOfWeek );
System.out.println( "endOfWeek " + endOfWeek );

When run…

dateTime 2014-01-24T00:00:34.955-08:00
startOfWeek 2014-01-20T00:00:00.000-08:00
endOfWeek 2014-01-27T00:00:00.000-08:00

You can use the getDayOfWeek() method that gives you back 1 for Monday, 2 for Tue, .., 7 for Sunday in order to go back that many days and reach Monday:

import org.joda.time.DateTime;

    public class JodaTest {

        public static void main(String[] args) {
            DateTime date = new DateTime();
            System.out.println(date);
                    //2011-01-21T15:06:18.713Z
            System.out.println(date.minusDays(date.getDayOfWeek()-1));
                    //2011-01-17T15:06:18.713Z
        }
    }

See the section "Querying DateTimes" of the Joda-Time user guide.

Here is the general algorithm I would follow:

1. find the day-of-week of the target date (Jan 21 2011 as you mentioned)
2. determine how many days ahead of Monday this is
3. Subtract the value of #2 from the target date using dateTime.minusDays(n)