4-4-5 accounting calendar in java

Question

I have to use the 4-4-5 accounting calendar in java.

I'm finding a way to have, given a specific date the current month, the corresponding accounting month.

For example, for the year 2020 I will have this accounting months:

29-Dec  25-Jan
26-Jan  22-Feb
23-Feb  28-Mar
29-Mar  25-Apr
26-Apr  23-May
24-May  27-Jun
28-Jun  25-Jul
26-Jul  22-Aug
23-Aug  26-Sep
27-Sep  24-Oct
25-Oct  21-Nov
22-Nov  26-Dec

So, for example, given a date 28 Apr I need to receive something like this:

26-Apr  23-May

I tried to use also ThreeTen-Extra project with AccountingChronology an AccountingChronologyBuilder. But, sincerely, I struggle to understand how to use it.

Answer 1

Easy enough to get those dates using the ThreeTen-Extra library.

Define your chronology. Instantiate a AccountingChronology by using AccountingChronologyBuilder. Specify the attributes that fit your particular business practices. Notice how we specify 4-4-5 via the AccountingYearDivision.

AccountingChronology acctChrono = new AccountingChronologyBuilder()
        .endsOn(DayOfWeek.SATURDAY)
        .inLastWeekOf(Month.DECEMBER)
        .withDivision(AccountingYearDivision.QUARTERS_OF_PATTERN_4_4_5_WEEKS)
        .leapWeekInMonth(12)
        .toChronology();

Use that chronology to instantiate AccountingDate. Use a TemporalAdjuster to move from one date to another.

for (int month = 1; month <= 12; month++) {
    AccountingDate start = acctChrono.date(2020, month, 1);
    AccountingDate end = start.with(TemporalAdjusters.lastDayOfMonth());
    System.out.println(start.format(DateTimeFormatter.ISO_LOCAL_DATE) + "  "
                     + end.format(DateTimeFormatter.ISO_LOCAL_DATE));
}

Output

2019-12-29  2020-01-25
2020-01-26  2020-02-22
2020-02-23  2020-03-28
2020-03-29  2020-04-25
2020-04-26  2020-05-23
2020-05-24  2020-06-27
2020-06-28  2020-07-25
2020-07-26  2020-08-22
2020-08-23  2020-09-26
2020-09-27  2020-10-24
2020-10-25  2020-11-21
2020-11-22  2020-12-26