How can I add business days to the current date in Java?

Question

How can I add business days to the current date in Java?

public Calendar addBusinessDate(Calendar cal, int days) {
//
// code goes over here
//
}

Note:

It should consider weekends too.

Answer 1

Use:

public Calendar addBusinessDate(Calendar cal, int numBusinessDays) {
  int numNonBusinessDays = 0;

  for(int i = 0; i < numBusinessDays; i++) {
    cal.add(Calendar.DATE, 1);

    /*
       It's a Canadian/American custom to get the Monday (sometimes Friday) off
       when a holiday falls on a weekend.
    */
    for(int j = 0; j < holidays; j++) { //holidays is list of dates
      if(cal.getTime() == (Date)holidays.get(j)) {
        numNonBusinessDays++;
      }
    }

    if(cal.get(Calendar.DAY_OF_WEEK) == 1 ||
       cal.get(Calendar.DAY_OF_WEEK) == 7) {
      numNonBusinessDays++;
    }
  }

  if(numNonBusinessDays > 0) {
    cal.add(Calendar.DATE, numNonBusinessDays);
  }

  return cal;
}

You'd have to populate a list of dates in order to handle holidays. There's common ones like New Years, but Thanksgiving is different between Canada & the US for instance. Also mind that holidays can fall on a weekend, so the weekend becomes a 3 day weekend.

Reference:

• Calendar
• Calendar Constant Values

PS: There isn't really a need to return the Calendar instance if you are updating the value as in the example. But it is valid if you want to create a separate Calendar instance, use:

public Calendar addBusinessDate(Calendar cal, int numBusinessDays) {
  Calendar cal2 = Calendar.getInstance();
  cal2.setTime(cal.getTime());

  int numNonBusinessDays = 0;

  for(int i = 0; i < numBusinessDays; i++) {
    cal2.add(Calendar.DATE, 1);

    /*
       It's a Canadian/American custom to get the Monday (sometimes Friday) off
       when a holiday falls on a weekend.
    */
    for(int j = 0; j < holidays; j++) { //holidays is list of dates
      if(cal2.getTime() == (Date)holidays.get(j)) {
        numNonBusinessDays++;
      }
    }

    if(cal2.get(Calendar.DAY_OF_WEEK) == 1 ||
       cal2.get(Calendar.DAY_OF_WEEK) == 7) {
      numNonBusinessDays++;
    }
  }

  if(numNonBusinessDays > 0) {
    cal2.add(Calendar.DATE, numNonBusinessDays);
  }

  return cal2;
}

Answer 2

You may want to consider using ObjectLab Kit to do the heavy lifting for you.

Assuming the requirement is simply to return the next business day when the computed date falls on a non-business day:

package bizdays.example;

import java.util.HashSet;
import net.objectlab.kit.datecalc.common.DateCalculator;
import net.objectlab.kit.datecalc.common.DefaultHolidayCalendar;
import net.objectlab.kit.datecalc.common.HolidayHandlerType;
import net.objectlab.kit.datecalc.joda.LocalDateKitCalculatorsFactory;
import static org.junit.Assert.assertThat;
import org.junit.Before;
import org.junit.Test;
import static org.hamcrest.Matchers.equalTo;
import org.joda.time.LocalDate;

public class BizDayTest {
    private DateCalculator<LocalDate> dateCalculator;
    private final LocalDate startDate = new LocalDate(2009, 12, 23);

    @Before
    public void setUp() {
        HashSet<LocalDate> holidays = new HashSet<LocalDate>();
        holidays.add(new LocalDate(2009, 12, 25));  // Friday

        DefaultHolidayCalendar<LocalDate> holidayCalendar =
            new DefaultHolidayCalendar<LocalDate>(holidays);

        LocalDateKitCalculatorsFactory.getDefaultInstance()
                .registerHolidays("example", holidayCalendar);
        dateCalculator = LocalDateKitCalculatorsFactory.getDefaultInstance()
                .getDateCalculator("example", HolidayHandlerType.FORWARD);
        dateCalculator.setStartDate(startDate);
    }

    @Test
    public void should_not_change_calendar_start_date_even_after_moving() {
        assertThat(
            dateCalculator.moveByBusinessDays(6).getStartDate(),
            equalTo(startDate));
    }

    @Test
    public void moveByBusinessDays_will_return_24_dec_2009_as_next_business_day() {
        assertThat(
            dateCalculator.moveByBusinessDays(1).getCurrentBusinessDate(),
            equalTo(new LocalDate(2009, 12, 24)));
    }

    @Test
    public void moveByBusinessDays_will_return_28_dec_2009_as_two_business_days_later() {
        assertThat(
            dateCalculator.moveByBusinessDays(2).getCurrentBusinessDate(),
            equalTo(new LocalDate(2009, 12, 28)));

    }

    @Test
    public void moveByDays_will_also_return_28_dec_2009_as_two_business_days_later() {
        assertThat(
            dateCalculator.moveByDays(2).getCurrentBusinessDate(),
            equalTo(new LocalDate(2009, 12, 28)));
    }

    @Test
    public void moveByBusinessDays_will_exclude_25_26_and_27_dec_when_computing_business_days() {
        assertThat(
            dateCalculator.moveByBusinessDays(5).getCurrentBusinessDate(),
            equalTo(new LocalDate(2009, 12, 31)));
    }


    @Test
    public void moveByDays_will_include_25_26_and_27_dec_when_computing_business_days() {
        assertThat(
            dateCalculator.moveByDays(5).getCurrentBusinessDate(),
            equalTo(new LocalDate(2009, 12, 28)));
    }
}

The library defaults the working week to be from Monday to Friday, but you can change the defaults by supplying a custom WorkingWeek to DateCalculator's setWorkingWeek().

As shown in the last two examples, moveByDays() includes the weekends when moving the days, whereas moveByBusinessDays() excludes weekends.

The library also allows you to use java.util.Calendar instead of Joda Time's LocalDate. The example uses Joda Time library because it is the preferred library to use when handling dates in Java.

Answer 3

Here is the modified version to find date calculation.

public  Calendar algorithm2(int businessDays){
 Calendar cal2 = Calendar.getInstance();
 Calendar cal = Calendar.getInstance(); 
 int totalDays= businessDays/5*7;
 int remainder = businessDays % 5;
 cal2.add(cal2.DATE, totalDays); 

 switch(cal.get(Calendar.DAY_OF_WEEK)){
  case 1:
    break;
  case 2: 
    break;
  case 3: 
    if(remainder >3)
    cal2.add(cal2.DATE,2);
    break;
  case 4: 
    if(remainder >2)
    cal2.add(cal2.DATE,2);
    break;
  case 5: 
    if(remainder >1)
    cal2.add(cal2.DATE,2);
    break;
  case 6: 
    if(remainder >1)
    cal2.add(cal2.DATE,2);
    break;
  case 7: 
    if(remainder >1)
    cal2.add(cal2.DATE,1);
    break;
 }

 cal2.add(cal2.DATE, remainder); 
 return cal2;

}

Blockquote

Answer 4

Will this work? Of course, this is not handling holidays.

public static Date addBusinessDays(Date baseDate, int numberOfDays){

    if(baseDate == null){
        baseDate = new Date();
    }

    Calendar baseDateCal = Calendar.getInstance();
    baseDateCal.setTime(baseDate);

    for(int i = 0; i < numberOfDays; i++){

        baseDateCal.add(Calendar.DATE,1);
        if(baseDateCal.get(Calendar.DAY_OF_WEEK)
                         == Calendar.SATURDAY){
           baseDateCal.add(Calendar.DATE,2);
        }
    }
    return baseDateCal.getTime();
}

Answer 5

This algorithm calculates the next business date for a given date (business days are from monday to friday in my country), you can adapt it to iterate the number of days you need to add.

public Calendar nextBusinessDate(Calendar cal) {

    List<Calendar> holidays = ********
    // Here get list of holidays from DB or some other service...

    GregorianCalendar calCp = new GregorianCalendar();
    calCp.setTime(cal.getTime());
    calCp.add(Calendar.DAY_OF_MONTH, 1);

    boolean isSaturday = (calCp.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY);
    boolean isSunday = (calCp.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY);
    boolean isHoliday = holidays.contains(calCp);

    while (isSaturday || isSunday || isHoliday) {
      if (isSaturday) {
       calCp.add(Calendar.DAY_OF_MONTH, +2); // is saturday, make it monday
        } else {
     if (isSunday) {
         calCp.add(Calendar.DAY_OF_MONTH, +1); // is sunday, make it monday
     } else {
         if (isHoliday) {
           calCp.add(Calendar.DAY_OF_MONTH, +1); // is holiday, make it next day
            }
         }
        }
      calCp = new GregorianCalendar();
      calCp.setTime(cal.getTime());
      isSaturday = (calCp.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY);
      isSunday = (calCp.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY);
    isHoliday = holidays.contains(calCp);
    } // end while

    return calCp;
}