java - to get the start date and end date of each week for the given month

Question

Following is the code that I am using to calculate the week start date and end date for the given month. Assume week start day is MONDAY and week end day is SUNDAY. For exa

Answer 1

You are using terrible date-time classes that were supplanted years ago by the modern java.time classes defined in JSR 310. This work is much easier now.

YearMonth

The YearMonth class represents a specific month as a whole. Specify the month using the Month enum.

YearMonth ym = YearMonth.of( 2013 , Month.JANUARY ) ;

LocalDate

Get the first of the month.

LocalDate firstOfMonth = ym.atDay( 1 ) ;

TemporalAdjuster

Get the previous Monday, or stay with this date if it is a Monday.

TemporalAdjuster ta = TemporalAdjusters.previousOrSame( DayOfWeek.MONDAY ) ;
LocalDate previousOrSameMonday = firstOfMonth.with( ta ) ;

Then loop a week at a time.

LocalDate endOfMonth = ym.atEndOfMonth() ;
LocalDate weekStart = previousOrSameMonday ; 
do {
    LocalDate weekStop = weekStart.plusDays( 6 ) ;
    System.out.println( "Week: " + weekStart + " to " + weekStop ) ;
    // Set up the next loop.
    weekStart = weekStart.plusWeeks( 1 ) ;
} while ( ! weekStart.isAfter( endOfMonth ) ) ;

See this code run live at IdeOne.com.

Week: Monday, December 31, 2012 to Sunday, January 6, 2013

Week: Monday, January 7, 2013 to Sunday, January 13, 2013

Week: Monday, January 14, 2013 to Sunday, January 20, 2013

Week: Monday, January 21, 2013 to Sunday, January 27, 2013

Week: Monday, January 28, 2013 to Sunday, February 3, 2013

By the way, you might want to learn about, and consider using, the ISO 860 standard definition of a week. And then use the YearWeek class of the ThreeTen-Extra library.