how to get next and previous week date in android

Question

public  String getCurrentWeekDate() {
    Calendar c = GregorianCalendar.getInstance();
    System.out.println("Current week = " + Calendar.DAY_OF_WEEK);
    c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
    System.out.println("Current week = " + Calendar.DAY_OF_WEEK);
    DateFormat df = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());
    String startDate = "", endDate = "";
    startDate = df.format(c.getTime());
    c.add(Calendar.DATE, 6);
    endDate = df.format(c.getTime());
    System.out.println("Start Date = " + startDate);
    System.out.println("End Date = " + endDate);

    return  "";
}

this is my code from which I am getting current week date in given time format like 2017-07-17 to 2017-07-23 .

if (v.getId() == R.id.previousButtonView) {
     getCurrentWeekDate();
} else if (v.getId() == R.id.nextButtonView) {
     getCurrentWeekDate();
}

this is my code from which I have to display next week and previous week date please suggest me how to increase and decrease week date i am new in android.

Answer 1

For next week calendar.add(Calendar.DAY_OF_WEEK, 1);

For previous week calendar.add(Calendar.DAY_OF_WEEK, -1);

public void getCurrentWeekDate(int week) {
    Calendar c = GregorianCalendar.getInstance();
    c.setFirstDayOfWeek(Calendar.MONDAY);
    c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek());
    c.add(Calendar.DAY_OF_WEEK, week);
    DateFormat df = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());
    String startDate;
    String endDate;
    startDate = df.format(c.getTime());
    c.add(Calendar.DAY_OF_MONTH, 6);
    endDate = df.format(c.getTime());
    System.out.println("Start Date = " + startDate);
    System.out.println("End Date = " + endDate);
}

Answer 2

If you want the previous week start and end date, decrement currentWeekNumber by 1

else if you want next week start and end date increment currentWeekNumber by 1

    //initialize Calendar
    Calendar c = Calendar.getInstance();
    
    //get current week number
    int currentWeekNumber = c.get(Calendar.WEEK_OF_YEAR);
    
    //decrement week number by 1 for the previous week
    c.set(Calendar.WEEK_OF_YEAR, currentWeekNumber - 1);

    //increment week number by 1 for the next week
    //c.set(Calendar.WEEK_OF_YEAR, currentWeekNumber + 1);        

    //set first day of week
    c.set(Calendar.DAY_OF_WEEK, 1);
    
    //get start date of previous week
    DateFormat df = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());
    String startDate = df.format(c.getTime());
    
    //set last day of week
    c.set(Calendar.DAY_OF_WEEK, 7);
    
    //get end date of previous week
    String endDate = df.format(c.getTime());

    Log.d("LOG_TAG", "Start Date = " + startDate);
    Log.d("LOG_TAG", "End Date = " + endDate);

Answer 3

Since you have already found current week's date, all you have to do is subtract 7 days for previous week dates and add 7 days for next week date.

You can do that by following code

int x = -7;
Calendar cal = GregorianCalendar.getInstance();
cal.add( Calendar.DAY_OF_YEAR, x);
Date sevenDaysAgo = cal.getTime();

So your code will look like below -

 public void getCurrentWeekDate(int week) {
    Calendar c = GregorianCalendar.getInstance();
    System.out.println("Current week = " + Calendar.DAY_OF_WEEK);
    c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
    System.out.println("Current week = " + Calendar.DAY_OF_WEEK);
    DateFormat df = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());
    String startDate;
    String endDate;
    startDate = df.format(c.getTime());

    // previous week calculation
    Calendar previousWeekCalendar = c;
    previousWeekCalendar.add( Calendar.DAY_OF_YEAR, -7);
    startPreviousWeekDate = df.format(previousWeekCalendar.getTime());
    previousWeekCalendar.add(Calendar.DATE, 6);
    endPreviousWeekDate = df.format(previousWeekCalendar.getTime());

    c.add(Calendar.DATE, 6);
    //for previous week
    //c.add(Calendar.DAY_OF_WEEK, -1);
    //for next week
    c.add(Calendar.DAY_OF_WEEK, week);
    endDate = df.format(c.getTime());


    // Do next week calculation same as previous week. Just check what is the value of c before starting the calculation
    System.out.println("Start Date = " + startDate);
    System.out.println("End Date = " + endDate);
    System.out.println("End Date = " + endDate);

}

Answer 4

So many tries I got this result:

fun getWeekDates(currentWeek: Int): Array<String?> {
   val daysOfWeek = arrayOfNulls<String>(7)
   val calendar = Calendar.getInstance()
   calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY)
   calendar.set(Calendar.WEEK_OF_MONTH, currentWeek)
   for (i in 0..6) {
      daysOfWeek[i] = changeDateFormat(LocalDate(calendar.time))
      calendar.add(Calendar.DAY_OF_MONTH, 1)
  }
  return daysOfWeek
}

Answer 5

private val calendar = Calendar.getInstance()
fun getLastWeekRange(): String {
    val calendarFrom = Calendar.getInstance()
    val calendarTo = Calendar.getInstance()
    val dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK)
    val fotmat = SimpleDateFormat("dd.MM.yyyy")
    if (dayOfWeek == 1) {
        calendarFrom.add(Calendar.DATE, -(dayOfWeek + 12))
        calendarTo.add(Calendar.DATE, -(dayOfWeek + 6))
    } else {
        calendarFrom.add(Calendar.DATE, -(dayOfWeek + 5))
        calendarTo.add(Calendar.DATE, -(dayOfWeek - 1))
    }

    return "[${fotmat.format(calendarFrom.time)} - ${fotmat.format(calendarTo.time)}]"
}