Kotlin Android Countdown

countdown.kt

private fun stopCountDown(){
        val t = Toast.makeText(this,"Stopping countdown",Toast.LENGTH_SHORT).show()
        timer1.cancel()
        timer1IsRunning=false
    }

private fun startCountDown(){
    timer1 = object : CountDownTimer(duration, interval) {
        override fun onFinish() {
            txtTimer1.text = "0"
            timer1IsRunning=false
        }

        override fun onTick(millisUntilFinished: Long) {
            txtTimer1.text = (millisUntilFinished / 1000).toString()
        }
    }
    timer1.start()
    timer1IsRunning=true
}