I have a javafx.scene.control.DatePicker. I want to extract the (Locale) week number from the selected date. Until now i haven't found a solution and i prefer not to write my own algorithm. I use Java8 and hope it is possible in the new java time library.
The Java-8-solution can take into account the local definition of a week using the value of a date-picker:
LocalDate date = datePicker.getValue(); // input from your date picker Locale locale = Locale.US; int weekOfYear = date.get(WeekFields.of(locale).weekOfWeekBasedYear());
Also keep in mind that the popular alternative Joda-Time does not support such a localized week-of-year fields. For example: In ISO-8601 (widely used) the week starts with Monday, in US with Sunday. Also the item when the first week of year starts in a given calendar year is dependent on the locale.
LocalDate localDate = LocalDate.of(2014, 9, 18); // assuming we picked 18 September 2014 int weekNumber = localDate.get(IsoFields.WEEK_OF_WEEK_BASED_YEAR);
This will give you the week number based on ISO convention.
For a locale based evaluation :
LocalDate localDate = LocalDate.of(2014, 9, 18); // assuming we picked 18 September 2014 WeekFields weekFields = WeekFields.of(Locale.US); int weekNumber = localDate.get(weekFields.weekOfWeekBasedYear());