Incorrect boolean outcome using isWeekEnd method with Calendar instance

Question

None of the existing threads helped me understand why the date that I enter in the main method (2016, 25, 11) which is a Friday is popping up as true for my method isWeekend(). I've seen in the other threads people talking about setting the Calendar's first day of week to Monday but I don't see how that would change my results

public static boolean isWeekend(Calendar userDate){
    if (userDate.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY || 
    userDate.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY)
        return true;
    else return false;
    } 

public static void main(String[] args) {
    Calendar c1 = Calendar.getInstance();
    c1.set(2016, 25, 11);
   System.out.println(CalendarBankHoliday.isWeekend(c1));
}

Please can someone help me understand this

Edited: it correctly displays 2016,26,11 as a weekend(true) but 2016, 27, 11 as weekday(false)

It isn't a duplicate at all, the answer for my question is not the same as the one you've provided. Im asking for a boolean using Calendar static values not iterating through a week and skipping it if its saturday or sunday, the methods are completely different. — Aidan Moore, Nov 26 '16 at 22:26

Michael Liu · Accepted Answer · 2016-11-26T16:44:41.133

3

Two things:

The Calendar class works with 0-based months: January = 0, February = 1, etc.
The set method takes the year, month, and day in that order, not year, day, and month.

The statement c1.set(2016, 25, 11); actually sets the date to February 11, 2018 (a Sunday), because 25 = 2×12 + 1, so the year is incremented by 2 and the month is set to February. Similarly, the statement c1.set(2016, 26, 11); actually sets the date to March 11, 2018 (also a Sunday).

To set c1 to November 25, 2016, change 11 to 10, and swap the second and third arguments:

c1.set(2016, 10, 25); // Friday, November 25, 2016

If you're hard-coding the date, you can also use a static constant for clarity:

c1.set(2016, Calendar.NOVEMBER, 25);

edited Nov 26 '16 at 16:44

answered Nov 26 '16 at 16:04

Michael Liu

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is there anyway to edit this to make it so january is 1? – Aidan Moore Nov 26 '16 at 16:09
2

That's just the way the Calendar class works. If you're accepting the month from the user, then subtract 1 before passing it to the `set` method. – Michael Liu Nov 26 '16 at 16:11
ok thanks, its just that I have a premade list of Calendar instances with bank holiday dates inside of them, I guess I have to take 1 away from the month of those also? – Aidan Moore Nov 26 '16 at 16:14
3

Yes. Also note that you've mixed up the month and day arguments; the order should be "year, month, day", not "year, day, month". – Michael Liu Nov 26 '16 at 16:16
okay thanks for your help! – Aidan Moore Nov 26 '16 at 16:18
just seen the Calendar.NOVEMBER instead of hard coding 10, cheers for the tip! – Aidan Moore Nov 26 '16 at 17:44

score 2 · Answer 2 · answered Nov 26 '16 at 16:12

I would advise against using the legacy Calendar and Date classes. In Java 8, there is a new package called java.time which has much nicer classes to deal with dates.

In your case, because it's just a date (without a time), java.time.LocalDate is appropriate for your use case. Nice easy methods to check days of the week, and it also attempts months so that January = 1.

Incorrect boolean outcome using isWeekEnd method with Calendar instance

2 Answers2