Calculate age from BirthDate

Question

I have DatePicker Dialog, When I select date at that time I want to calculate age it\'s working but when I select date of current year at that time it showing the -1 age instead

Answer 1

Here is a Kotlin extension of the Date class returning the age corresponding to a Date object

val Date.age: Int
get() {
    val calendar = Calendar.getInstance()
    calendar.time = Date(time - Date().time)
    return 1970 - (calendar.get(Calendar.YEAR) + 1)
}

It is compatible for all Android versions. If you wonder what '1970' is, that's the Unix Epoch. The timestamp is 0 on January 1, 1970.