Develop Reference

How to set startDestination in Navigation Component based on the fragment/nav_graph I come from?

I'm using Navigation Component with Kotlin, and have three main tabs in nav_dashboard - Explore, My Groups and Profile. When I start application the startDestination is nav_explore, but then I want to go from there to different screens eg. CreateGroupFragment/nav_create_group and from there I have button that I want to redirect me to nav_dashboard but with My Groups selected - I guess that then the startDestination needs to be nav_profile. But how I can I implement that?
Dashboard Fragment (it contains Fragment Container View in XML):
internal class DashboardFragment : Fragment() {
lateinit var navigator: DashboardNavigator
private var _binding: FragmentDashboardBinding? = null
private val binding
get() = _binding!!
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
_binding = FragmentDashboardBinding.inflate(layoutInflater, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
initBottomNavigation()
}
private fun initBottomNavigation() {
with(binding.bottomNavigationView) {
setupWithNavController(getDashboardNestedNavController())
}
}
private fun getDashboardNestedNavController(): NavController {
val navHostFragment = childFragmentManager.findFragmentById(R.id.nav_host_container) as NavHostFragment
val navGraph = navHostFragment.navController.navInflater.inflate(R.navigation.nav_dashboard_menu)
navHostFragment.navController.addOnDestinationChangedListener { _, destination, bundle ->
when (destination.id) {
R.id.exploreFragment, R.id.myGroupsFragment, R.id.profileFragment -> setBottomNavVisibility(View.VISIBLE)
else -> setBottomNavVisibility(View.GONE)
}
}
return navHostFragment.navController
}
private fun setBottomNavVisibility(visibility: Int) {
binding.bottomNavigationView.visibility = visibility
}
}
nav_dashboard:
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/nav_dashboard_menu"
app:startDestination="#id/nav_explore">
<include app:graph="#navigation/nav_explore" />
<include app:graph="#navigation/nav_my_groups" />
<include app:graph="#navigation/nav_profile" />
</navigation>
nav_create_group:
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/nav_create_group"
app:startDestination="#id/createGroupFragment">
<include app:graph="#navigation/nav_create_group_map" />
<include app:graph="#navigation/nav_my_groups" />
<fragment
android:id="#+id/createGroupFragment"
android:name="com.wojciechkula.locals.presentation.creategroup.CreateGroupFragment"
android:label="#string/create_group_create_group"
tools:layout="#layout/fragment_create_group">
<action
android:id="#+id/openMap"
app:destination="#id/nav_create_group_map" />
<!-- Here I want another action to navigate to nav_dashboard with startDestination: nav_my_groups-->
</fragment>
</navigation>

First of all, you don't need to change the startDestination.
Secondly, why are you using multiple graphs? That usually makes things more complicated!
Anyway, you can just set the selected tab manually.
binding.bottomNavigationView.menu.findItem(R.id.tabId).isChecked = true
"tabId" is the id of the item in your bottom nav xml file.

Navigate to certain fragment from another dynamic module

Is there any way to navigate to a certain fragment from another dynamic module and not navigate to the start destination? If not, what are the alternatives?
<fragment
android:id="#+id/loginFragment"
android:name="com.example.feature.login.presentation.LoginFragment"
android:label="LoginFragment">
<action
android:id="#+id/actionLoginToHome"
app:destination="#id/featureHomeNavGraph" />
</fragment>
<include-dynamic
android:id="#+id/featureHomeNavGraph"
app:graphResName="feature_home_nav_graph"
app:moduleName="feature_home" />
While this code works fine, it navigates me to the start destination but I need to navigate to another one.

Solution 1: Navigate to specific fragment and do not use <include-dynamic>
<fragment
android:id="#+id/profileDetailsFragment"
android:name="com.example.feature.profiles.presentation.details.ProfileDetailsFragment"
android:label="Profile Details"
app:moduleName="feature_profiles" />
Solution 2: Create a new graph XML with different start destination.

A good way to do this for embedded nav graphs is to have a blank Navigation Fragment. You get your action to go to this fragment and then send it arguments on where to navigate next. Some sample code:
class NavigatorFragment : Fragment() {
companion object {
const val REQUEST_PAGE_NAME = "REQUEST_PAGE_NAME"
const val PAGE_TYPE_ACTIVATE_CARD = "PAGE_TYPE_ACTIVATE_CARD"
const val PAGE_TYPE_CREDIT_LIMIT = "PAGE_TYPE_CREDIT_LIMIT"
const val PAGE_TYPE_SCC_HUB = "PAGE_TYPE_SCC_HUB"
const val PAGE_TYPE_ABOUT_CARD = "about_card"
const val PAGE_TYPE_MAKE_PAYMENT = "PAGE_TYPE_MAKE_PAYMENT"
fun createBundle(pageName: String) =
Bundle().apply {
putString(REQUEST_PAGE_NAME, pageName)
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
when (arguments?.getString(REQUEST_PAGE_NAME)) {
PAGE_TYPE_ACTIVATE_CARD ->
findNavController().navigate(R.id.to_activateSecuredCard)
PAGE_TYPE_CREDIT_LIMIT ->
findNavController().navigate(R.id.to_creditLimit)
PAGE_TYPE_ABOUT_CARD ->
findNavController().navigate(R.id.to_aboutSecuredCard, arguments)
PAGE_TYPE_SCC_HUB ->
findNavController().navigate(R.id.to_sccHub)
PAGE_TYPE_MAKE_PAYMENT ->
findNavController().navigate(R.id.to_sccMakePayment)
}
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val binding: FragmentSecuredCardNavigatorBinding = DataBindingUtil.inflate(inflater, R.layout.fragment_secured_card_navigator, container, false)
binding.lifecycleOwner = viewLifecycleOwner
if (findNavController()
.currentDestination.toString()
.contains(this.javaClass.name)
){
findNavController().popBackStack()
}
return binding.root
}
}
main navigation:
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
app:startDestination="#+id/home_dashboard_fragment">
<include app:graph="#navigation/nav_graph_secured_card" />
<!-- rest of navigation graph-->
.....
</navigation>
secured card navigation:
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/nav_root_secured_card"
app:startDestination="#id/securedCardNavigator">
<fragment
android:id="#+id/securedCardNavigator"
android:name="com.greendotcorp.securedcard.fragment.NavigatorFragment">
<action
android:id="#+id/to_activateSecuredCard"
app:destination="#+id/activateSecuredCard"
app:popUpTo="#+id/securedCardNavigator"
app:popUpToInclusive="true" />
</fragment>
</navigation>
Navigating to secured card navigation:
findNavController().navigate(R.id.nav_root_secured_card, NavigatorFragment.createBundle(NavigatorFragment.PAGE_TYPE_SCC_HUB))

How to pass arguments to a fragment using bottom navigation view and Android Navigation component?

Is it possible to pass and access arguments in a fragment using a bottom navigation view and the Navigation component?
I'm using a one activity with many fragments approach where my top level fragment requires an argument(Usually done via the newInstance generated method). I've had a look at the Navigation component developer guide and the codelab but it only mentions using safeargs and adding argument tags in the destinations and actions.
Here's my navigation graph:
<navigation xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
app:startDestination="#id/homeFragment">
<fragment android:id="#+id/homeFragment"
android:name="uk.co.homeready.homeready.HomeFragment"
android:label="fragment_home"
tools:layout="#layout/fragment_home">
<!--Do I create an argument block here?-->
</fragment>
<fragment android:id="#+id/calculatorFragment"
android:name="uk.co.homeready.homeready.CalculatorFragment"
android:label="fragment_calculator"
tools:layout="#layout/fragment_calculator"/>
<fragment android:id="#+id/resourcesFragment"
android:name="uk.co.homeready.homeready.ResourcesFragment"
android:label="fragment_resources"
tools:layout="#layout/fragment_resources"/>
</navigation>
Bottom Navigation View menu:
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:id="#+id/homeFragment"
android:icon="#drawable/ic_home_black_24dp"
android:title="#string/title_home"/>
<item
android:id="#+id/calculatorFragment"
android:icon="#drawable/ic_baseline_attach_money_24px"
android:title="#string/title_calculator"/>
<item
android:id="#+id/resourcesFragment"
android:icon="#drawable/ic_baseline_library_books_24px"
android:title="#string/title_resources"/>
</menu>
MainActivity:
override fun onCreate(savedInstanceState: Bundle?) {
...
val navController = Navigation.findNavController(this,
R.id.nav_host_fragment)
bottom_navigation.setupWithNavController(navController)
....
}
activity_main.xml
<android.support.constraint.ConstraintLayout>
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
app:layout_constraintBottom_toTopOf="#id/bottom_navigation"
app:defaultNavHost="true"
app:navGraph="#navigation/nav_graph"/>
<android.support.design.widget.BottomNavigationView
android:id="#+id/bottom_navigation"
app:menu="#menu/bottom_navigation"/>
</android.support.constraint.ConstraintLayout>
HomeFragment
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val argument = //TODO access argument here
...
}

If I understood you correctly, you want to pass arguments to destinations that is tied to menu items. Try to use 'OnDestinationChangedListener' inside your activity onCreate method, something like this:
navController.addOnDestinationChangedListener { controller, destination, arguments ->
when(destination.id) {
R.id.homeFragment -> {
val argument = NavArgument.Builder().setDefaultValue(6).build()
destination.addArgument("Argument", argument)
}
}
}
Update:
If you want that your start destination will receive default arguments the implementation should be different.
First, remove 'app:navGraph="#navigation/nav_graph"' from your 'NavHostFragment' xml tag.
Then, inside your activity onCreate you need to inflate the graph:
val navInflater = navController.navInflater
val graph = navInflater.inflate(R.navigation.nav_graph)
Then add your arguments to graph(this arguments will be attached to start destination)
val navArgument1=NavArgument.Builder().setDefaultValue(1).build()
val navArgument2=NavArgument.Builder().setDefaultValue("Hello").build()
graph.addArgument("Key1",navArgument1)
graph.addArgument("Key2",navArgument2)
Then attach the graph to NavController:
navController.graph=graph
Now your first destination should receive the attached arguments.

The correct way to do this is indeed with an <argument> block on your destination.
<fragment android:id="#+id/homeFragment"
android:name="uk.co.homeready.homeready.HomeFragment"
android:label="fragment_home"
tools:layout="#layout/fragment_home">
<argument
android:name="Argument"
android:defaultValue="value"
/>
</fragment>
This will automatically populate the arguments of the Fragment with the default value without any additional code needed. As of Navigation 1.0.0-alpha09, this is true whether you use the Safe Args Gradle Plugin or not.

Default values was not usable for me, because I have dynamic menu items that could have multiple of the same destination with different arguments. (changed from server)
Implement BottomNavigationView.OnNavigationItemSelectedListener:
override fun onNavigationItemSelected(item: MenuItem): Boolean {
val fragmentId = item.itemId
val arguments = argumentsByFragmentId[fragmentId] // custom mutableMapOf<Int, Bundle?>() with arguments
navController().navigate(fragmentId, arguments)
return true
}
To use that you will takeover the navigation, by replacing the listener. The order of calls here are important:
bottomNavigationView.setupWithNavController(navController)
bottomNavigationView.setOnNavigationItemSelectedListener(this)

Jetpack navigation: Title and back/up arrow in the action bar?

I have installed the latest canary version of Android Studio, and followed this (https://developer.android.com/topic/libraries/architecture/navigation/navigation-implementing) instruction to implement a simple two page navigation. Basically page1 has a button, and when it is clicked, the app shows page2.
It works, but there is one problem... It does not seem to do anything with the action bar automatically. Is it supposed to show up/back arrow and the "Label" attribute on the action bar automatically by the navigation library? Or am I supposed to do all the work manually as before? I want to show the back arrow and "Details" on action(tool) bar when page2 is showing.
On button click at page 1.
override fun onViewCreated(view: View, savedInstanceState: Bundle?)
{
button1.setOnClickListener {
val nav = NavHostFragment.findNavController(this);
nav.navigate(R.id.show_page2)
}
}
Main activity XML. By default it was the default Action Bar, I have replaced it with a ToolBar. There was no difference.
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_height="?attr/actionBarSize"
android:elevation="4dp"
android:background="?attr/colorPrimary"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:theme="#style/ThemeOverlay.AppCompat.ActionBar"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"
android:layout_width="match_parent">
</androidx.appcompat.widget.Toolbar>
<fragment
android:id="#+id/my_nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/toolbar"
app:navGraph="#navigation/nav_graph"/>
</androidx.constraintlayout.widget.ConstraintLayout>
Nav graph XML.
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/nav_graph"
app:startDestination="#id/page1">
<activity
android:id="#+id/mainActivity2"
android:name="com.android.navtest.MainActivity"
android:label="activity_main"
tools:layout="#layout/activity_main"/>
<fragment
android:id="#+id/page1"
android:name="com.android.navtest.BlankFragment2"
android:label="Home page"
tools:layout="#layout/page1">
<action
android:id="#+id/show_page2"
app:destination="#id/page2"
app:enterAnim="#anim/anim1"
app:popExitAnim="#anim/anim2"/>
</fragment>
<fragment
android:id="#+id/page2"
android:name="com.android.navtest.BlankFragment"
android:label="Details"
tools:layout="#layout/page2"/>
</navigation>

You can connect your ActionBar to a NavController using NavigationUI.setupActionBarWithNavController(). This is generally done in your Activity, right after you call setSupportActionBar():
supportActionBar = findViewById<Toolbar>(R.id.toolbar)
// Get the NavController for your NavHostFragment
val navController = findNavController(R.id.nav_host_fragment)
// Set up the ActionBar to stay in sync with the NavController
setupActionBarWithNavController(navController)
This approach is covered in the Navigation talk at Google I/O 2018.

If you want to have navigation back button hidden in more than one place (default is only for home fragment) you can add ids of fragments to AppBarConfiguration and pass this as second parameter of setupActionBarWithNavController, for example:
val appBarConfiguration = AppBarConfiguration(setOf(R.id.splashFragment, R.id.onboardingFragment, R.id.homeFragment))
setupActionBarWithNavController(findNavController(R.id.nav_host), appBarConfiguration)

This is what I have done.
onSupportNavigateUp is called when the user navigates up and it set again. by calling this setupActionBarWithNavController tell android to update the title of toolbar.
navigateUp Handles the Up button by delegating its behavior to the given NavController. This should generally be called from AppCompatActivity.onSupportNavigateUp().
private lateinit var appBarConfiguration: AppBarConfiguration
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val binding: ActivityGameConfigBinding =
DataBindingUtil.setContentView(this, R.layout.activity_game_config)
supportActionBar?.show()
val navController = Navigation.findNavController(this, R.id.myNavHostFragment)
NavigationUI.setupActionBarWithNavController(this, navController, null)
appBarConfiguration = AppBarConfiguration.Builder(navController.graph)
.build()
NavigationUI.setupWithNavController(binding.navView, navController)
}
override fun onSupportNavigateUp(): Boolean {
val navController = Navigation.findNavController(this, R.id.myNavHostFragment)
return NavigationUI.navigateUp(navController, appBarConfiguration)
}

my solution with binding - the code is in MainActivity
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this, R.layout.main_activity)
navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
navController = navHostFragment.navController
setSupportActionBar(toolbar)//needs to be after binding
toolbar.setupWithNavController(navController,AppBarConfiguration(navController.graph))
}
as for the titles - first I removed labels (android:label) from the fragments in navigation graph (label overwrites title from what I've tested)
<fragment
android:id="#+id/productListFragment"
android:name="com.example.ProductListFragment"
android:label="TO_BE_REMOVED"
tools:layout="#layout/product_list_fragment">
<action
android:id="#+id/action_productListFragment_to_mainMenuFragment"
app:destination="#id/mainMenuFragment" />
</fragment>
each fragment sets the title and subtitle in onResume, here example from ProductListFragment
override fun onResume() {
super.onResume()
val actionBar = (activity as AppCompatActivity).supportActionBar
actionBar?.title = getString(R.string.product_list_title)
actionBar?.subtitle = getString(R.string.product_list_subtitle)
}

New navigation component from arch with nested navigation graph

I have one case and wish to implement it by arch navigation component. For example I have 2 Nav Graphs (main and nested). Can I call main graph from nested and how?

The point is to get the right NavController to navigate in the right graph.
Let's take this scenario as an example:
MainActivity
|- MainNavHost
|- NavBarFragment
| |- NestedNavHost
| | |-NestedContentFragment1
| | |-NestedContentFragment2
| |
| |- BottomNavigationView
|
|- LoginFragment
The main graph and the nested graph are in separate xml files: this is required, as far as I understood, because the navigations target different layout areas, so they require two different NavHosts. Each Navhost will need to reference its graph by id, which requires them to be in different resource files.
The point is that to navigate in a specific graph, we must get a reference to the right graph's owner: to do this, when calling Navigation.findNavController(view), the view argument is crucial.
Docs say that
NavHostFragments register their navigation controller at the root of their view subtree such that any descendant can obtain the controller instance through the Navigation helper class's methods
So for example, if inside NavBarFragment we write
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
navController = Navigation.findNavController(view)
}
here view is a parent of the NestedNavHost (that is the nested NavHostFragment), not a descendant, meaning that findNavController will search upstream in the tree and will return the MainNavHost's NavController.
If instead we write
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
val nestedNavHostFragment = childFragmentManager.findFragmentById(R.id.nestedNavHostFragment) as? NavHostFragment
navController = nestedNavHostFragment?.navController
}
where nestedNavHostFragment is the id of the FragmentContainerView in the layout, we get a reference to the correct NestedNavHost. Note the use of childFragmentManager, not parentFragmentManager.
In case you're still using the deprecated xml <fragment> tag, you can write
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
val fragmentContainer = view.findViewById<View>(R.id.nestedNavHostFragment)
navController = Navigation.findNavController(fragmentContainer)
}
where nestedNavHostFragment is the id of the <fragment> tag. We get a reference to the correct NestedNavHost now, because the view we pass to findNavController belongs to the NestedNavHost's subtree.
Similarly, if you need to get a reference to the main NavController from inside a NestedContentFragment, here's what we can do:
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
// we can get the innermost NavController using this view,
// because we are inside its subtree:
nestedNavController = Navigation.findNavController(view)
// we can find the outer NavController passing the owning Activity
// and the id of a view associated to that NavController,
// for example the NavHostFragment id:
mainNavController = Navigation.findNavController(activity!!, R.id.mainNavHostFragment)
}

Actually you could use Global actions to navigate from a nested nav graph destination to a main nav graph destination.
Create a global action from nested nav graph to desired destination in main nav graph (highlighted in the image below)
example:
<navigation android:id="#+id/main_nav_graph"
... >
<fragment android:id="#+id/fragStart" .../>
<fragment .../>
<fragment .../>
<navigation android:id="#+id/nested_nav_graph">
...
<!-- Global Action -->
<action
android:id="#+id/action_global_start"
app:destination="#id/fragStart" />
</navigation>
</navigation>
To navigate to main graph destination use
findNavController().navigate(R.id.action_global_start)

I created an answer with the info devrocca provided. It's a full answer from scratch, i didn't skip anything if anyone ever needs.
This is the main fragment for navigation. Camera is direct destination without any nested graph, Dashboard has it's own nested graph but it's added to same backstack camera fragment is added. Home has 3 fragments with it's own nav host
MainActivity
|- MainNavHost
|- HomeNavHostFragment
| |- NestedNavHost
| |-HomeFragment1
| |-HomeFragment2
| |-HomeFragment3
|
|- nav_graph_dashboard
|
|- CameraFragment
Here is the navigation files
Main Navigation nav_graph.xml
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/nav_graph"
app:startDestination="#id/main_dest">
<!-- MainFragment-->
<fragment
android:id="#+id/main_dest"
android:name="com.smarttoolfactory.tutorial1_3navigation_nestednavhost.blankfragment.MainFragment"
android:label="MainFragment"
tools:layout="#layout/fragment_main">
<!-- Camera -->
<action
android:id="#+id/action_main_dest_to_cameraFragment"
app:destination="#id/cameraFragment" />
<!-- Home NavGraph -->
<action
android:id="#+id/action_main_dest_to_nav_graph_home"
app:destination="#id/nav_graph_home" />
<!-- Dashboard NavGraph-->
<action
android:id="#+id/action_main_dest_to_nav_graph_dashboard"
app:destination="#id/nav_graph_dashboard" />
</fragment>
<!-- Camera -->
<fragment
android:id="#+id/cameraFragment"
android:name="com.smarttoolfactory.tutorial1_3navigation_nestednavhost.blankfragment.CameraFragment"
android:label="CameraFragment" />
<!-- Home-->
<include app:graph="#navigation/nav_graph_home" />
<!-- Dashboard-->
<include app:graph="#navigation/nav_graph_dashboard" />
<!-- Global Action Start -->
<action
android:id="#+id/action_global_start"
app:destination="#id/main_dest"
app:popUpTo="#id/main_dest"
app:popUpToInclusive="true" />
</navigation>
Dashboard nested navigation graph
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/nav_graph_dashboard"
app:startDestination="#id/dashboard_dest">
<fragment
android:id="#+id/dashboard_dest"
android:name="com.smarttoolfactory.tutorial1_3navigation_nestednavhost.blankfragment.DashboardFragment1"
android:label="DashboardFragment1"
tools:layout="#layout/fragment_dashboard1">
<action
android:id="#+id/action_dashboardFragment1_to_dashboardFragment2"
app:destination="#id/dashboardFragment2" />
</fragment>
<fragment
android:id="#+id/dashboardFragment2"
android:name="com.smarttoolfactory.tutorial1_3navigation_nestednavhost.blankfragment.DashboardFragment2"
android:label="DashboardFragment2"
tools:layout="#layout/fragment_dashboard2">
</fragment>
</navigation>
And nested navigation graph with it's own NavHost nav_graph_home
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/nav_graph_home"
app:startDestination="#id/home_dest">
<fragment
android:id="#+id/home_dest"
android:name="com.smarttoolfactory.tutorial1_3navigation_nestednavhost.blankfragment.HomeNavHostFragment"
android:label="HomeHost"
tools:layout="#layout/fragment_home_navhost" />
<fragment
android:id="#+id/homeFragment1"
android:name="com.smarttoolfactory.tutorial1_3navigation_nestednavhost.blankfragment.HomeFragment1"
android:label="HomeFragment1"
tools:layout="#layout/fragment_home1">
<action
android:id="#+id/action_homeFragment1_to_homeFragment2"
app:destination="#id/homeFragment2" />
</fragment>
<fragment
android:id="#+id/homeFragment2"
android:name="com.smarttoolfactory.tutorial1_3navigation_nestednavhost.blankfragment.HomeFragment2"
android:label="HomeFragment2"
tools:layout="#layout/fragment_home2">
<action
android:id="#+id/action_homeFragment2_to_homeFragment3"
app:destination="#id/homeFragment3" />
</fragment>
<fragment
android:id="#+id/homeFragment3"
android:name="com.smarttoolfactory.tutorial1_3navigation_nestednavhost.blankfragment.HomeFragment3"
android:label="HomeFragment3"
tools:layout="#layout/fragment_home3" />
</navigation>
Layouts, i only add necessary ones, others are simple layouts with buttons, i add link for sample project with other navigation components samples included.
MainActivity
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:popupTheme="#style/ThemeOverlay.AppCompat.ActionBar" />
</com.google.android.material.appbar.AppBarLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<androidx.fragment.app.FragmentContainerView
android:id="#+id/main_nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:defaultNavHost="true"
app:navGraph="#navigation/nav_graph"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
</layout>
Main Fragment, this is first fragment that shown in the image used as start of main navigation
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/parentLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="#+id/btnDestCam"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Destination Camera"
app:layout_constraintBottom_toTopOf="#+id/btnNavGraphHome"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintLeft_toRightOf="parent"
app:layout_constraintRight_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/btnNavGraphHome"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Nested NavHost Graph Home"
app:layout_constraintBottom_toTopOf="#+id/btnNavGraphDashboard"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintLeft_toRightOf="parent"
app:layout_constraintRight_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#+id/btnDestCam" />
<Button
android:id="#+id/btnNavGraphDashboard"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Nested Graph Dashboard"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintLeft_toRightOf="parent"
app:layout_constraintRight_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#+id/btnNavGraphHome" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
Layout that contains inner NavHostFragment for home navigation
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.fragment.app.FragmentContainerView
android:id="#+id/nested_nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:defaultNavHost="false"
app:navGraph="#navigation/nav_graph_home" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
MainActivity is for checking main navigation back stack, important thing here is
supportFragmentManager back stack is not updated as you navigate it's childFragmentManager even for main navigation, even if you only have one
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Get NavHostFragment
val navHostFragment =
supportFragmentManager.findFragmentById(R.id.main_nav_host_fragment)
// ChildFragmentManager of NavHostFragment
val navHostChildFragmentManager = navHostFragment?.childFragmentManager
navHostChildFragmentManager?.addOnBackStackChangedListener {
val backStackEntryCount = navHostChildFragmentManager.backStackEntryCount
val fragments = navHostChildFragmentManager.fragments
}
}
}
Fragment that contains Home navigation's host
class HomeNavHostFragment : BaseDataBindingFragment<FragmentHomeNavhostBinding>() {
override fun getLayoutRes(): Int = R.layout.fragment_home_navhost
private var navController: NavController? = null
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val nestedNavHostFragment =
childFragmentManager.findFragmentById(R.id.nested_nav_host_fragment) as? NavHostFragment
navController = nestedNavHostFragment?.navController
navController?.navigate(R.id.homeFragment1)
listenBackStack()
}
private fun listenBackStack() {
// Get NavHostFragment
val navHostFragment =
childFragmentManager.findFragmentById(R.id.nested_nav_host_fragment)
// ChildFragmentManager of the current NavHostFragment
val navHostChildFragmentManager = navHostFragment?.childFragmentManager
navHostChildFragmentManager?.addOnBackStackChangedListener {
val backStackEntryCount = navHostChildFragmentManager!!.backStackEntryCount
val fragments = navHostChildFragmentManager!!.fragments
Toast.makeText(
requireContext(),
"HomeNavHost backStackEntryCount: $backStackEntryCount, fragments: $fragments",
Toast.LENGTH_SHORT
).show()
}
val callback = object : OnBackPressedCallback(true) {
override fun handleOnBackPressed() {
val backStackEntryCount = navHostChildFragmentManager!!.backStackEntryCount
Toast.makeText(
requireContext(),
"HomeNavHost backStackEntryCount: $backStackEntryCount",
Toast.LENGTH_SHORT
).show()
if (backStackEntryCount == 1) {
OnBackPressedCallback# this.isEnabled = false
requireActivity().onBackPressed()
} else {
navController?.navigateUp()
}
}
}
requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner, callback)
}
}
There is one thing i don't know if it's improved in graph or code with nested NavHostFragment
If you set start destination of nav_graph_home HomeFragment1 instead of HomeNavHostFragment it works as dashboard which ignores nested NavHost and added to main back stack of fragments.
Since you are in inner NavHostFragment findNavController() in any home fragment returns the inner one
class HomeFragment3 : BaseDataBindingFragment<FragmentHome3Binding>() {
override fun getLayoutRes(): Int = R.layout.fragment_home3
private var count = 0
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
dataBinding.btnIncrease.setOnClickListener {
dataBinding.tvTitle.text = "Count: ${count++}"
}
val mainNavController =
Navigation.findNavController(requireActivity(), R.id.main_nav_host_fragment)
dataBinding.btnGoToStart.setOnClickListener {
// 🔥Using destination belong to main_nav_host with nested navHost causes app to crash
// findNavController().navigate(R.id.action_global_start)
mainNavController.navigate(R.id.action_global_start)/**/
}
}
}
You can also use global action but it's not required since back navigation in inner navHost directly moves you back to main navigation if you don't use OnBackPressed.
Link for full example and the other nav component samples if you are interested.

Actually is working,
using
val host: NavHostFragment? = (childFragmentManager.findFragmentById(R.id.main_app_fragment_container) as NavHostFragment?)
I can navigate from main fragment

I found a temporary solution to the problem of inner NavController being covered.
You can use custom NavHostFragment which provides you with desired navController.
My code:
<androidx.fragment.app.FragmentContainerView
...
android:name="MyNavHostFragment"
app:defaultNavHost="false"
app:navGraph="#navigation/inner_nav">
...
</androidx.fragment.app.FragmentContainerView>
...
class MyNavHostFragment: NavHostFragment() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
MainFragment.innerNavController = navController
}
}
...
class MainFragment : Fragment() {
companion object{
lateinit var innerNavController: NavController
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val bottomNavigationView =
view!!.findViewById<BottomNavigationView>(R.id.bottom_navigation_view)
bottomNavigationView.setupWithNavController(innerNavController)
}
}

we can achieve it by finding the root navhost controller and then navigating through root nav host controller
val Fragment.findRootNavHost: NavController?
get() = this.activity?.let {
Navigation.findNavController(it, your_root_fragment_id)
}
findRootNavHost?.navigate(`your_destination_fragment_id`)
Kindly check the medium article link
Github repo for the same