uraza uraza - 1 month ago 8
Java Question

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

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?

Answer

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.