Checking if LocalDateTIme is null in a conditional

sisternight438 :

Here I have a function that formats a string to a LocalDateTime and returns it.

val dateSentFormatted = timeFormatted(record.data.dateTime);

private fun timeFormatted(dateEmailSent: String?): LocalDateTime {
    val formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd:HH:mm:ss");
    return LocalDateTime.parse(dateEmailSent, formatter);
}

My question is I wanted an if statement to run on it elsewhere in my file to check whether it's null as in:

if (!dateSentFormatted != null ) {

}

But it doesn't like that, how else can I check whether a variable of type LocalDateTime is empty in an if statement?

ysakhno :

Method parse(CharSequence, DateTimeFormatter) of the java.time.LocalDateTime class does not accept null as the character sequence (first parameter), so you have to make an explicit null-check and rewrite the return from your function as

return if (dateEmailSent != null) LocalDateTime.parse(dateEmailSent, formatter) else null

(you don't have to have semicolons (;) by the way)

Moreover, the return type of your function as written is non-nullable, so you'll have to change it to LocalDateTime?.

And, since there is no point in creating a parser/formatter if it is not going to be used in case of dateEmailSent being null, I suggest to rewrite the entire function as follows:

fun timeFormatted(dateEmailSent: String?) = if (dateEmailSent != null) {
    LocalDateTime.parse(dateEmailSent, DateTimeFormatter.ofPattern("yyyy-MM-dd:HH:mm:ss"))
} else null

The last part is up to you, the rest is pretty much mandatory if you want to achieve the functionality you described in your question.