Check if date between date range that also handle null values Java

Question

My standard method for checking if a date is between two dates in Java looks like this:

public static boolean isWithinRange(Date date, Date startDate, Date endDate) {
    return !(date.before(startDate) || date.after(endDate));
}

I want to add support for null values on startDate or endDate (meaning user hasn't entered a date. If startDate is null I only want to check endDate and if endDate is null I only want to check startDate and if both null then it is true. My current solution looks like this:

public static boolean isWithinRange(Date date, Date startDate, Date endDate) {
    if (startDate == null && endDate == null) {
        return true;
    }

    if (!(startDate != null || !date.after(endDate))) {
        return true;
    }

    if (!(endDate != null || !date.before(startDate))) {
        return true;
    }

    return !(date.before(startDate) || date.after(endDate));
}

alternative more readable example:

public static boolean isWithinRange(Date date, Date startDate, Date endDate) {
    if (startDate == null && endDate == null) {
        return true;
    }

    if (startDate == null && date.before(endDate))) {
        return true;
    }

    if (endDate == null && date.after(startDate))) {
        return true;
    }

    return date.after(startDate) && date.before(endDate));
}

But it feels like really bad code. Is there any other way to deal with this?

All the !'s are making it rather difficult for me to read. But you might consider whether this would be a better fit for codereview.stackexchange.com. — , Oct 26 '16 at 11:49
It's to make it inclusive instead of strictly before and after. — uraza, Oct 26 '16 at 11:50
assylias’ answer is best, but the second version of your code is pretty reasonable. — VGR, Oct 26 '16 at 12:19

assylias · Accepted Answer · 2016-10-26T11:58:18.900

11

How about:

return (startDate == null || !date.before(startDate))
    && (endDate == null || !date.after(endDate));

This uses the fact that these two statements are equivalent:

!(date.before(startDate) || date.after(endDate))
!date.before(startDate) && !date.after(endDate)

And the fact that || is a short-circuit, which prevents NullPointerExceptions.

edited Oct 26 '16 at 11:58

answered Oct 26 '16 at 11:51

assylias

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This is the cleanliest answer here. Might even use it myself since I have a similar case. – Murat Karagöz Oct 26 '16 at 11:53
This seems to work. I added a null check for date too to avoid NPE. – uraza Oct 26 '16 at 12:16
@uraza I suspect a null date would be a bug so you could add `Objects.requireNonNull(date);` on the first line of your method. – assylias Oct 26 '16 at 12:18
This will fail for null start & end dates and gives opposite results, – saran3h Apr 08 '21 at 18:32

Mureinik · Answer 2 · 2016-10-26T18:21:25.660

3

Java 8's enhances to the Comaparator interface provide a pretty elegant way of doing this:

private static final Comparator<Date> NULL_SAFE_BEFORE =
        Comparator.nullsFirst(Comparator.naturalOrder());

private static final Comparator<Date> NULL_SAFE_AFTER =
        Comparator.nullsLast(Comparator.naturalOrder());

public static boolean isWithinRange(Date date, Date startDate, Date endDate) {
    return NULL_SAFE_BEFORE.compare(startDate, date) < 0 &&
            NULL_SAFE_AFTER.compare(date, endDate) < 0;
}

edited Oct 26 '16 at 18:21

answered Oct 26 '16 at 12:00

Mureinik

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Can you add some example code showing how to use this in the context of the Question? – Basil Bourque Oct 26 '16 at 16:16
@BasilBourque not sure what you mean - I did not change the signature of the `isWithinRange` method. Could you clarify what exactly you're asking? – Mureinik Oct 26 '16 at 18:22
Yes, I see that now. I misread you code, thinking you were quoting from the `Comparator` class rather than using it. – Basil Bourque Oct 26 '16 at 19:31

score 1 · Answer 3 · answered Oct 26 '16 at 11:52

1

This should be equivalent:

public static boolean isWithinRange(Date date, Date startDate, Date endDate) {
    return !(startDate != null && date.before(startDate) || endDate != null && date.after(endDate));
}

answered Oct 26 '16 at 11:52

ArcticLord

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Check if date between date range that also handle null values Java

3 Answers3