import java.time.LocalDateTime
import java.time.temporal.ChronoUnit

fun main(args : Array<String>) {

    // 2019-05-24 14:17:00 | 2019-09-13 14:15:51
    val start = "2019-05-24 14:17:00"
    val end = "2019-09-13 14:15:51"

    daysBetweenDates(start, end)
}


fun daysBetweenDates(start: String, end: String) {
    val mStart = LocalDateTime.parse(start)
    val mEnd = LocalDateTime.parse(end)

    val difference = ChronoUnit.DAYS.between(mStart, mEnd)
    println("START => $mStart")
    println("END => $mEnd")
    println("DIFFERENCE => $difference days")
}

Exception in thread "main" java.time.format.DateTimeParseException: Text '2019-05-24 14:17:00' could not be parsed at index 10
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1949)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1851)
    at java.time.LocalDateTime.parse(LocalDateTime.java:492)
    at java.time.LocalDateTime.parse(LocalDateTime.java:477)
    at MainKt.daysBetweenDates(main.kt:16)
    at MainKt.main(main.kt:11)