How to compare objects of LocalDate and Calendar class?

Question

I am trying to compare dates from two object having different types. Is there any way to convert Calendar object to LocalDater or vice-versa?

Thank you :)

public class ABC{

    public static void main(String args[]){
        Calendar c1= Calendar.getInstance();
        LocalDate c2= LocalDate.now();      
        System.out.println(c1.compareTo(c2));
    }
}

What about doing a cast? I'm not sure it will works, since Calendar doesn't extends from LocalDate and viceversa. — HessianMad, Apr 14 '17 at 13:52

score 6 · Accepted Answer · edited May 23 '17 at 12:25

6

You need to compare dates, so let's do just that.

Using this answer as reference:

Calendar calendar = Calendar.getInstance();
LocalDate localDate = LocalDate.now();

LocalDate calendarAsLocalDate = calendar.toInstant()
    .atZone(calendar.getTimeZone().toZoneId())
    .toLocalDate();

return calendarAsLocalDate.compareTo(localDate)

edited May 23 '17 at 12:25

Community

1
1

answered Apr 14 '17 at 14:06

Olivier Grégoire

33,839
23
96
137

You should replace ZoneId.systemDefault() with `calendar.getTimeZone().toZoneId()`, to guarantee the conversion handles every Calendar object correctly. – VGR Apr 14 '17 at 14:08
@VGR Thank you, I fixed it. – Olivier Grégoire Apr 14 '17 at 14:09

score 1 · Answer 2 · answered Apr 14 '17 at 13:50

1

    private int compare(Calendar c1, LocalDate c2) {
        int yearCompare = ((Integer) c1.get(Calendar.YEAR)).compareTo(c2.getYear());
        if (yearCompare == 0)
            return ((Integer) c1.get(Calendar.DAY_OF_YEAR)).compareTo(c2.getDayOfYear());
        else
            return yearCompare;
    }

answered Apr 14 '17 at 13:50

Jeff

1,871
1
17
28

You can do comparisons of int values by simply subtracting them. For instance, `int yearCompare = c1.get(Calendar.YEAR) - c2.getYear();`. This works even when there is integer overflow, due to the nature of twos-complement representation. – VGR Apr 14 '17 at 14:06

How to compare objects of LocalDate and Calendar class?

2 Answers2