how to make button stop working once timer is over - android-studio

Question

i have created a 50 second timer. Once the timer reach zero a pop view will appear displaying the score and the button on the application should stop working but i am not sure how to make the button stop being clickable
equal.setOnClickListener{
++total
if(ans == ans4 || ans1 == ans4 || ans2 == ans4 || ans3 == ans4 || ans == ans5 || ans1 == ans5 || ans2 == ans5 || ans3 == ans5
|| ans == ans6 || ans1 == ans6 || ans2 == ans6 || ans3 == ans6){
answer.setText("Correct")
answer.setTextColor(Color.GREEN)
++correct
score.setText("Score: $correct/$total")
} else {
answer.setText("Wrong")
answer.setTextColor(Color.RED)
score.setText("Score: $correct/$total")
}
}
val timer = object: CountDownTimer(50000, 1000) {
override fun onTick(millisUntilFinished: Long) {
countTimer.setText("Remaining: " + millisUntilFinished / 1000);
if (correct >= 5){
countTimer.setText("Remaining: " + (millisUntilFinished + 10000 ) / 1000);
}
}
override fun onFinish() {
popup()
}
}
timer.start()
}
fun popup(){
var popupView: View = layoutInflater.inflate(R.layout.score, null)
var gameover_textView = popupView.findViewById<TextView>(R.id.endMessage)
gameover_textView.setText("Score: $correct/$total ")
var popupwindow = PopupWindow(this)
popupwindow.contentView = popupView
popupwindow.showAtLocation(popupView, Gravity.CENTER, 0, 100)
popupView.setOnClickListener{
popupwindow.dismiss()
}
}

Answer 1

equal.setClickable(false);
equal.setClickable(true);
//according to the requirement