Calculate years in millis long negative answer

user_10490583 0
Viewed 116

I'm trying convert 14 years in millis, using function

    fun getMinimumAgeInMillis(): Long {
        val long: Long = 1000 * 60 * 60 * 24 * 365 * 14
        return (long)
    }

But instead of my value I got negative value -877631488. So, where a problem? I dont hit long limitations

kotlin
1 Answers

If you use an IDE like IntelliJ, it'll hint you to the issue:

enter image description here

It will overflow because the types don't match. Kotlin is strict when it comes to types, and this is kinda similar to integer division, except with multiplication.

1000 implies integer. It will autobox it to a long, but you start with an int. Related, remember how 1 / 3 != 1f / 3f. All you need to do is explicitly declare the type once. You could also do it for all, but I managed to fix it with a single one.

So instead of your current multiplication, use 1000L * 60 * 60 * 24 * 365 * 14. Notice the added L, which converts a single type to a Long. Otherwise they default as integers, which results in an overflow that's cast to a Long.

If you use IntelliJ or Android Studio, try removing the explicit type. If you have those labels enabled (not entirely sure what they're called, but that's beside the point), you'll see that it shows Int, not Long:

enter image description here

Add L to one of them, and it changes to Long as expected. Note that the L needs to be added early in the multiplication. If you add it at i.e. 14, it'll overflow before it's converted to an integer. Taking 1 / 3 as an example again, 1f / 3f is one approach, but 1 / 3f and 1f / 3 is also valid. Basically, the types need to be correct before the "wrong" operation happens.

user_62965610
Related