CountDownTimer.kt

class Timer {

  fun printDifferenceDateForHours() {

            val currentTime = Calendar.getInstance().time
            val endDateDay = "03/02/2020 21:00:00"
            val format1 = SimpleDateFormat("dd/MM/yyyy hh:mm:ss",Locale.getDefault())
            val endDate = format1.parse(endDateDay)

            //milliseconds
            var different = endDate.time - currentTime.time
            countDownTimer = object : CountDownTimer(different, 1000) {

                override fun onTick(millisUntilFinished: Long) {
                    var diff = millisUntilFinished
                    val secondsInMilli: Long = 1000
                    val minutesInMilli = secondsInMilli * 60
                    val hoursInMilli = minutesInMilli * 60
                    val daysInMilli = hoursInMilli * 24

                    val elapsedDays = diff / daysInMilli
                    diff %= daysInMilli

                    val elapsedHours = diff / hoursInMilli
                    diff %= hoursInMilli

                    val elapsedMinutes = diff / minutesInMilli
                    diff %= minutesInMilli

                    val elapsedSeconds = diff / secondsInMilli

                    txt_timeleft.text = "$elapsedDays days $elapsedHours hs $elapsedMinutes min $elapsedSeconds sec"
                }

                override fun onFinish() {
                    txt_timeleft.text = "done!"
                }
            }.start()
        }

}