CountDownTimer

countdowntimer.kt

       // Simple Date Format
        val dateformat = SimpleDateFormat("hh:mm:ss",Locale.getDefault())
        
        // Get Current time like dateformat above
        val currentTime = dateformat.format(Date())
        
        // Counter Endtime with Second
        val endTime = "10:30:00"
        
        // Format time as Parse to Milisecond for run counter
        val ctime = dateformat.parse(currentTime)
        val eDate = dateformat.parse(endTime)
        
        //How much milliseconds need to run counter (result from current time vs end time)
        val result = eDate.time - ctime.time

        // Counter Interval time in Second (e.g 1000milisecond = 1 second)
        val interval = 1000

        // Run Timer
        val timer = object: CountDownTimer(result, interval) {
            override fun onTick(millisUntilFinished: Long) {

                val textview = findViewById<TextView>(R.id.text)

                var diff = millisUntilFinished
                val secondsInMilli: Long = 1000
                val minutesInMilli = secondsInMilli * 60
                val hoursInMilli = minutesInMilli * 60

                val elapsedHours = diff / hoursInMilli
                diff %= hoursInMilli

                val elapsedMinutes = diff / minutesInMilli
                diff %= minutesInMilli

                val elapsedSeconds = diff / secondsInMilli

                // Set Runtime Result to Text View
                textview.text = "$elapsedHours hour $elapsedMinutes minute $elapsedSeconds second"

            }

            override fun onFinish() {
                // Toast When Counter Finished
                Toast.makeText(this@MainActivity, "Counter finish", Toast.LENGTH_SHORT).show()
            }
        }
        timer.start()