Fragment continue recreates again when back pressed several times before app closes-CodePudding

The

MainActivity

@AndroidEntryPoint class MainActivity : AppCompatActivity() { var APP_START_TIME: Long = 0 private lateinit var appBarConfiguration: AppBarConfiguration private var _binding: ActivityMainBinding? = null private val binding get() = _binding!! private lateinit var navController: NavController private lateinit var postViewModel: PostViewModel private var _navGraph: NavGraph? = null private val navGraph get() = _navGraph!! lateinit var adView: AdView private var adRequest: AdRequest? = null private val applicationScope = CoroutineScope(Dispatchers.Unconfined) override fun onDestroy() { super.onDestroy() adView.destroy() adRequest = null _binding = null } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) APP_START_TIME = System.currentTimeMillis() _binding = ActivityMainBinding.inflate(layoutInflater) setContentView(binding.root) adView = AdView(this) delayedInit() postViewModel = ViewModelProvider(this)[PostViewModel:: class.java] setSupportActionBar(binding.toolbar) val drawerLayout: DrawerLayout = binding.drawerLayout val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment? if (navHostFragment != null) { navController = navHostFragment.navController } appBarConfiguration = AppBarConfiguration( setOf( R.id.nav_home, R.id.nav_accessory, R.id.nav_arcade, R.id.nav_fashion, R.id.nav_food, R.id.nav_heath, R.id.nav_lifestyle, R.id.nav_sports, R.id.nav_favorites, R.id.settingsFragment ), drawerLayout ) setupActionBarWithNavController(this, navController, appBarConfiguration) setupWithNavController(binding.navView, navController) _navGraph = navController.navInflater.inflate(R.navigation.mobile_navigation) onBackPressedDispatcher.addCallback(this /* lifecycle owner */, object : OnBackPressedCallback(true) { override fun handleOnBackPressed() { // Back is pressed... Finishing the activity finish() } }) } // override fun onStart() { // super.onStart() // } override fun onPause() { super.onPause() adView.pause() } override fun onResume() { super.onResume() adView.resume() postViewModel.currentDestination.observe(this) { currentDestination -> Log.w(TAG, "currentDestination: at first run is $currentDestination") navGraph.setStartDestination(currentDestination) navController.graph = navGraph } navController.addOnDestinationChangedListener { _, destination, _ -> Log.d(TAG, "addOnDestinationChangedListener: " destination.id) if (destination.id != R.id.settingsFragment && destination.id != R.id.aboutFragment && destination.id != R.id.privacyPolicyFragment ) { postViewModel.saveCurrentDestination(destination.id) } } } private fun requestHomeBanner() { adRequest = Constants.callAndBuildAdRequest() adView.adListener = object : AdListener() { override fun onAdFailedToLoad(adError: LoadAdError) { Log.e(TAG, "onAdFailedToLoad: ${adError.cause.toString()}") Log.e(TAG, "onAdFailedToLoad: ${adError.responseInfo.toString()}") } } adRequest?.let { adView.loadAd(it) } } private fun delayedInit() = applicationScope.launch { binding.adViewContainer.addView(adView) adView.adUnitId = "ca-app-pub-3940256099942544/6300978111" adView.setAdSize(Constants.GET_AD_SIZE(this@MainActivity)) val testDeviceIds = listOf("048DC5C3C06FBD17D9AD205151167F48") val configuration = RequestConfiguration.Builder().setTestDeviceIds(testDeviceIds).build() MobileAds.setRequestConfiguration(configuration) if (Utils.hasInternetConnection(this@MainActivity)) { requestTheLatestConsentInformation(this@MainActivity) MobileAds.initialize(this@MainActivity) { Log.d(TAG, "onInitCompleted") } requestHomeBanner() } } override fun onSupportNavigateUp(): Boolean { return navController.navigateUp(appBarConfiguration) || super.onSupportNavigateUp() } }

My tries to solve

I tried to add the following code inside OnBackPressedCallback

navGraph.clear() binding.drawerLayout.removeAllViews() binding.navView.removeAllViews()

also I tried to add onBackPressedDispatcher callback inside addOnDestinationChangedListener

onBackPressedDispatcher.addCallback(this /* lifecycle owner */, object : OnBackPressedCallback(true) { override fun handleOnBackPressed() { // Back is pressed... Finishing the activity navController.clearBackStack(destination.id) finish() } })

I tried to handle back pressed from the fragment itself not from the activity like the following

requireActivity() .onBackPressedDispatcher .addCallback(viewLifecycleOwner, object : OnBackPressedCallback(true) { override fun handleOnBackPressed() { Log.d(TAG, "Fragment back pressed invoked") // hideShimmerEffect() // Do custom work here requireActivity().finish() // if you want onBackPressed() to be called as normal afterwards if (isEnabled) { isEnabled = false requireActivity().onBackPressed() } } })

I tried to pop the back stack or clear it by adding the following two lines to my above code

findNavController().popBackStack() findNavController().clearBackStack(R.id.nav_home)

and finally I tried to edit the onSupportNavigateUp like the following

override fun onSupportNavigateUp(): Boolean { return if(supportFragmentManager.backStackEntryCount > 0){ navController.navigateUp(appBarConfiguration) }else { finish() super.onSupportNavigateUp() } }

and this is my last edited code, all this tries not solved the problem

CodePudding user response：

if you want to go back to initial activity or quit the app in case of a single activity app add

android:noHistory="true"

in your Manifest file inside the activity tag

CodePudding user response：

Try to use this function to start your fragments:

private fun loadFragment(fragment: Fragment?) { if (fragment != null) { val fragmentManager = supportFragmentManager fragmentManager .beginTransaction() .replace(R.id.nav_host_fragment, fragment) .commit() } }

CodePudding user response：

In java i have used this type of method. Don't know weather it will works on you or not.

@Override public void onBackPressed() { if (getSupportFragmentManager().getBackStackEntryCount() == 1) { finish(); } else { super.onBackPressed(); } }

CodePudding user response：

I am not sure but i think it's because you are setting startDestination for second time in onResume(). First one was setted defaultly in onCreate(). That's why it stacks and you happen to press back button twice.
Moving below code to onCreate() might help:

postViewModel.currentDestination.observe(this) { currentDestination -> Log.w(TAG, "currentDestination: at first run is $currentDestination") navGraph.setStartDestination(currentDestination) navController.graph = navGraph } navController.addOnDestinationChangedListener { _, destination, _ -> Log.d(TAG, "addOnDestinationChangedListener: " destination.id) if (destination.id != R.id.settingsFragment && destination.id != R.id.aboutFragment && destination.id != R.id.privacyPolicyFragment ) { postViewModel.saveCurrentDestination(destination.id) } }