CODEWITHSUNDEEP
java
derek
derek

Reputation: 99

Util to get dates for a year

I have a table where I would like each row to be represented as a date along with some other columns to represent the characteristic of that particular date. So, basically I would be having 365 rows for a year. I need to write a batch job in Java, which I would trigger through a rest endpoint. I would pass a particular year to the controller (eg 2020). I would then want a method which would get me all 366 days (since 2020 is a leap year) for 2020 along with the days i.e. weekends (Sat/Sun) or weekdays (Mon-Fri).

I would later do a batch insert into DB of those 366 days.

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Can someone help me write this utility method.

Upvotes: 2

Views: 106

Answers (1)

deHaar
deHaar

Reputation: 18588

To receive a list of dates of a given year, you can create a method like the following one using java.time:

public static List<LocalDate> getDaysOfYear(int year) {
    // initialize a list of LocalDate
    List<LocalDate> yearDates = new ArrayList<>();
    /*
     * create a year object from the argument
     * to reliably get the amount of days that year has
     */
    Year thatYear = Year.of(year);
    // then just add a LocalDate per day of that year to the list
    for (int dayOfYear = 1; dayOfYear <= thatYear.length(); dayOfYear++) {
        yearDates.add(LocalDate.ofYearDay(year, dayOfYear));
    }
    // and return the list
    return yearDates;
}

You can use the result in order to extract information about each day (in a main for example):

public static void main(String[] args) {
    // receive the LocalDates of a given year
    List<LocalDate> yearDates = getDaysOfYear(2020);
    // define a locale for output (language, formats and so on)
    Locale localeToBeUsed = Locale.US;
    
    // then extract information about each date
    for (LocalDate date : yearDates) {
        // or extract the desired parts, like the day of week
        DayOfWeek dayOfWeek = date.getDayOfWeek();
        // the month
        Month month = date.getMonth();
        // the calendar week based on a locale (the one of your system here)
        WeekFields weekFields = WeekFields.of(localeToBeUsed);
        int calendarWeek = date.get(weekFields.weekOfWeekBasedYear());
        // and print the concatenated information (formatted, depending on the locale)
        System.out.println(date.format(DateTimeFormatter.ofPattern("uuuu-MM-dd",
                                                                    localeToBeUsed))
                + ", " + dayOfWeek.getDisplayName(TextStyle.FULL, localeToBeUsed)
                + ", CW " + calendarWeek
                + ", " + month.getDisplayName(TextStyle.FULL, localeToBeUsed));
    }
}

The output will look like this (just some of the lines for brevity):

2020-01-01, Wednesday, CW 1, January
...
2020-02-29, Saturday, CW 9, February
...
2020-05-08, Friday, CW 19, May
...
2020-12-31, Thursday, CW 1, December

Upvotes: 3

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