Get All Dates In Calendar In Current Month

How to get all dates in the calendar in current/some month? for example for this month, like the picture So the result is ['07-31-2016', '08-01-2016', '08-02-2016' ... '08-31-2016

Solution 1:

Well, with Calendar and its constants you can achieve this quite easy:

Given month and year get first day of the month and place calendar on monday:

Calendar start = Calendar.getInstance();
start.set(MONTH, month - 1);  // month is 0 based on calendar
start.set(YEAR, year);
start.set(DAY_OF_MONTH, 1);
start.getTime();   // to avoid problems getTime make set changes apply
start.set(DAY_OF_WEEK, SUNDAY);
if (start.get(MONTH) <= (month - 1))  // check if sunday is in same month!
    start.add(DATE, -7);

Given month and year get last day of month and move calendar to sunday

Calendar end = Calendar.getInstance();
end.set(MONTH, month);  // next month 
end.set(YEAR, year);
end.set(DAY_OF_MONTH, 1);
end.getTime();   // to avoid problems getTime make set changes apply
end.set(DATE, -1);
end.set(DAY_OF_WEEK, SATURDAY);
if (end.get(MONTH) != month)  
    end.add(DATE, + 7);

Test it:

publicstaticvoidmain(String[] args) {
    int month = 8, year = 2016; 

    Calendar start = Calendar.getInstance();
    start.set(MONTH, month - 1);  // month is 0 based on calendar
    start.set(YEAR, year);
    start.set(DAY_OF_MONTH, 1);
    start.getTime();
    start.set(DAY_OF_WEEK, SUNDAY);
    if (start.get(MONTH) <= (month - 1))  
        start.add(DATE, -7);

    System.out.println(printCalendar(start));

    Calendar end = Calendar.getInstance();
    end.set(MONTH, month);  // next month 
    end.set(YEAR, year);
    end.set(DAY_OF_MONTH, 1);
    end.getTime();
    end.set(DATE, -1);
    end.set(DAY_OF_WEEK, SATURDAY);
    start.getTime();
    if (end.get(MONTH) != month)  
        end.add(DATE, + 7);

    System.out.println(printCalendar(end));
}

Combined with:

importstatic java.util.Calendar.*;

and

privatefinalstaticSimpleDateFormatdf=newSimpleDateFormat("yyyy/MM/dd");
privatestatic String printCalendar(Calendar c) {
    return df.format(c.getTime()); 
}

OUTPUT:

2016/07/312016/09/03

WITH

intmonth=5, year=2015; 

OUTPUT:

2015/04/262015/06/06

Now, just iterate over starting Calendar adding +1 to Calendar.DATE in a while loop (in the example I split by weeks to be more clear):

int i = 1;
while (start.before(end)) {
    System.out.print(printCalendar(start));
    if (i % 7 == 0) {   // last day of the week
        System.out.println();
        i  = 1;
    } else {
        System.out.print(" - ");
        i++;
    }
    start.add(DATE, 1);
}

OUTPUT:

2015/04/26-2015/04/27-2015/04/28-2015/04/29-2015/04/30-2015/05/01-2015/05/022015/05/03-2015/05/04-2015/05/05-2015/05/06-2015/05/07-2015/05/08-2015/05/092015/05/10-2015/05/11-2015/05/12-2015/05/13-2015/05/14-2015/05/15-2015/05/162015/05/17-2015/05/18-2015/05/19-2015/05/20-2015/05/21-2015/05/22-2015/05/232015/05/24-2015/05/25-2015/05/26-2015/05/27-2015/05/28-2015/05/29-2015/05/302015/05/31-2015/06/01-2015/06/02-2015/06/03-2015/06/04-2015/06/05-2015/06/06

Solution 2:

java.time

You can use the nice java.time classes built into Java 8 and later. Both the above solutions work, this is a way to do in Java 8. Can be done with a little more brevity , split it just for understanding.

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.temporal.TemporalAdjusters;
import java.util.ArrayList;
import java.util.List;

publicclassClazz {
    publicstaticvoidmain(String[] args)throws Exception {
        LocalDatetoday= LocalDate.now();
        LocalDatefirstDayOfTheMonth= today.with(TemporalAdjusters.firstDayOfMonth());
        LocalDatelastDayOfTheMonth= today.with(TemporalAdjusters.lastDayOfMonth());
        LocalDatesquareCalendarMonthDayStart= firstDayOfTheMonth
                .with(TemporalAdjusters.previousOrSame(DayOfWeek.SUNDAY));
        LocalDatesquareCalendarMonthDayEnd= lastDayOfTheMonth
                .with(TemporalAdjusters.nextOrSame(DayOfWeek.SATURDAY));
        List<LocalDate> totalDates = newArrayList<>();
        while (!squareCalendarMonthDayStart.isAfter(squareCalendarMonthDayEnd)) {
            totalDates.add(squareCalendarMonthDayStart);
            squareCalendarMonthDayStart = squareCalendarMonthDayStart.plusDays(1);
        }

        totalDates.forEach(System.out::println);
    }
}

Solution 3:

Get the monday before the 1st of that month:

Calendarc= Calendar.getInstance();
c.setFirstDayOfWeek(Calendar.MONDAY);
c.set(2016, 08, 01);

Calendarstart= Calendar.getInstance();
start.setFirstDayOfWeek(Calendar.MONDAY);
start.setWeekDate(2016,c.getWeekYear(), Calendar.MONDAY);

Get the sunday after the last day of that month:

c.set(2016,08,31);
Calendar end = Calendar.getInstance();
end.setFirstDayOfWeek(Calendar.MONDAY);
end.setWeekDate(2016, c.getWeekYear(), Calendar.SUNDAY);

Then print all dates between start and end

Solution 4:

Write a common method like this and use it -

fungetAllDateOfCurrentMonth(): List<LocalDate> {
            val yearMonth= YearMonth.now()
            val firstDayOfTheMonth = yearMonth.atDay(1)
            val datesOfThisMonth = mutableListOf<LocalDate>()
            for (daysNo in0 until yearMonth.lengthOfMonth()){
                datesOfThisMonth.add(firstDayOfTheMonth.plusDays(daysNo.toLong()))
            }
            return datesOfThisMonth
        }