Kotlin: How to detect 'date change'? - kotlin

Question

I will use Timer() to execute function by 5 minutes in Kotlin.
And when I execute function by 5m, if a day passed,I want count var to be 0.
So my idea was
declare two vars
var todayDate = LocalDate.now() // 2019-09-23
var todayCount:Int = 0
After that I will check this vars in 5 minutes by using Timer()
Then todayDate value differs from previous todayDate, then I can detect date change.
However, I don't know how to compare current todayDate and previous todayDate.
Any idea? or is there any other way to know day change?

Answer 1

For your specific question about comparing dates you can use the isEqual() method on your LocalDate instance (docs). Something like the following would likely do what you want:
// initial state
var todayDate = LocalDate.now()
var todayCount = 0
// in each timer iteration:
val now = LocalDate.now()
if (!todayDate.isEqual(now)) {
// it's a new day
todayCount = 0
todayDate = now
} else {
// it's the same day
++todayCount
}
However if you're talking about Android and using its Timer class, you need to be aware that that runs on a background thread and you will need to persist your todayDate and todayCount values somewhere (which could be app preferences, your app DB, etc.).