How to randomly navigate to other fragments? - android-studio

Question

I have 20 fragments. I want to navigate fragments randomly with a button.It works correctly but I don't want to revisit the same fragments. If I navigate from fragment 5 to 9, I don't want to re-navigate to 5 anymore. I want to see every fragment just once. In every fragment I did this:
btnNavigateNewFragment.setOnClickListener {
val list: MutableList<Int> = mutableListOf(
R.id.nav_new_game_eighteen,
R.id.nav_dealgame,
R.id.nav_new_game_one,
R.id.nav_new_game_two,
R.id.nav_new_game_three,
R.id.nav_new_game_four,
R.id.nav_new_game_five,
R.id.nav_new_game_six,
R.id.nav_new_game_seven,
R.id.nav_new_game_eight,
R.id.nav_new_game_nine,
R.id.nav_new_game_ten,
R.id.nav_new_game_eleven,
R.id.nav_new_game_twelve,
R.id.nav_new_game_thirteen,
R.id.nav_new_game_fourteen,
R.id.nav_new_game_fifteen,
R.id.nav_new_game_sixteen,
R.id.nav_new_game_seventeen
)
val randomFragment= list.random()
findNavController().navigate(randomFragment)
What logic should I use to not visit the fragment that navigated once ?

Answer 1

I would keep track of the visited fragments in an Activity-scoped ViewModel. If you keep it in a Fragment or Activity property, it will be lost if there's a configuration change.
class MyViewModel: ViewModel() {
private val destinations = listOf(
R.id.nav_new_game_eighteen,
R.id.nav_dealgame,
R.id.nav_new_game_one,
//...
R.id.nav_new_game_seventeen
)
private val remainingDestinations = mutableListOf<Int>().apply { addAll(destinations) }
fun getNextNavDestination(): Int {
if (remainingDestinations.isEmpty()) {
remainingDestinations.addAll(destinations)
// or whatever logic you want to do when all destinations have been used
}
val destination = remainingDestinations.random()
remainingDestinations.remove(destination)
return destination
}
}
In your fragment that goes to one of the random destinations:
class MyFragment: Fragment() {
private val myViewModel by activityViewModels()
override fun onViewCreated(view: View, savedInstanceState: Bundle) {
super.onViewCreated(view, savedInstanceState)
//...
btnNavigateNewFragment.setOnClickListener {
indNavController().navigate(myViewModel.getNextNavDestination())
}
}
}