Kotlin - press a button 1 time, show messages several times in TextView - loops

Question

How to implement showing several messages in a TextView field one by one with a required delay by clicking button only one time?
I tried this (look at the code below) and got such a result:
three seconds go by and only "3" is shown in the end. Digits 1 and 2 aren't shown.
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
binding.button.setOnClickListener {test()}
}
fun test() {
for (i in (1..3)){
binding.text1.text = "${i}"
Thread.sleep(1000L)
}
}
}

Answer 1

You really shouldn't sleep Main Thread. Main thread is used to display UI by sleeping it you are blocking the whole UI and that is why it is not updating. You can use Timer to run code every second
new Timer().scheduleAtFixedRate(new TimerTask() {
#Override
public void run() {
//your method
}
}, 0, 1000);//1 second
So for example you can start timer on button click and stop it after 3 seconds

Answer 2

Thanks for the tip about Timer.
This thread helped me further.
How to create a simple countdown timer in Kotlin?
Now my code looks like this and it works and does what I wanted:
fun test() {
var cnt = 3
val timer = object: CountDownTimer(3000, 1000) {
override fun onTick(millisUntilFinished: Long) {
binding.text1.text = cnt.toString()
cnt--
}
override fun onFinish() {
binding.text1.text = "That's it"
}
}
timer.start()
}

Answer 3

Sleeping the main thread isn't solution for such simple task you should use concurrency like the code below using corouties
suspend fun test(){
for(i in (1..3) {
delay(1000L)
binding.text1.text = i.toStrong()
}
}
And invokeOnCompletion {} is pretty good callback to handle completion