Kotlin check for null twice in if else

Question

I have an item with variable datePurchased, which can be null. Based on purchase date, I generate a label. When I check if datePurchased is null, in else branch I still have to check for null. It says that smart cast is impossible, because it's a mutable property.

Here's what I've tried so far:

if (datePurchased == null) {
    ""
} else {
    if (datePurchased.isToday()) {//error here
    }
}

    when {
        datePurchased == null    -> {

        }
        datePurchased.isToday() -> {//smart cast bla bla mutable bla bla
        datePurchased?.isToday() -> {//expected Boolean, got Boolean?
        datePurchased?.isToday()?:false -> {//all good, but does not look nice, since datePurchased can't be null here
        }
        else                     -> {

        }
    }

Answer 1

Thanks to marstran, I ended up with such solution:

        return datePurchased?.let {
            when {
                it.isToday()     -> {
                    "Today"
                }
                it.isYesterday() -> {
                    "Yesterday"
                }
                else             -> {
                    dateFormat.format(it)
                }

            }
        } ?: ""