Navigate without creating a new instance of Fragment - Navigation Component

Question

Is it possible to use navigate function from Android Navigation Component without creating a new instance of fragment but as restoring the previous one?

I tried to restore the previous fragment but only with the use of the navigate function data can be transferred between the fragments.

Answer 1

Not yet but i guess they are working on it. New instance is always being created for now. But if you write your own navigator, it's possible.

@Navigator.Name("keep_state_fragment") // `keep_state_fragment` is used in navigation xml
class KeepStateNavigator(
    private val context: Context,
    private val manager: FragmentManager, // Should pass childFragmentManager.
    private val containerId: Int
) : FragmentNavigator(context, manager, containerId) {

    override fun navigate(
        destination: Destination,
        args: Bundle?,
        navOptions: NavOptions?,
        navigatorExtras: Navigator.Extras?
    ): NavDestination? {
        val tag = destination.id.toString()
        val transaction = manager.beginTransaction()

        var initialNavigate = false
        val currentFragment = manager.primaryNavigationFragment
        if (currentFragment != null) {
            transaction.detach(currentFragment)
        } else {
            initialNavigate = true
        }

        var fragment = manager.findFragmentByTag(tag)
        if (fragment == null) {
            val className = destination.className
            fragment = manager.fragmentFactory.instantiate(context.classLoader, className)
            transaction.add(containerId, fragment, tag)
        } else {
            transaction.attach(fragment)
        }

        transaction.setPrimaryNavigationFragment(fragment)
        transaction.setReorderingAllowed(true)
        transaction.commitNow()

        return if (initialNavigate) {
            destination
        } else {
            null
        }
    }
}

Then you must call like below

val navigator = KeepStateNavigator(this, navHostFragment.childFragmentManager, R.id.nav_host_fragment)
        navController.navigatorProvider.addProvider(navigator)

This is the sample: Github