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 {
// đŸ”¥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
Related
Take a Bottom Navigation activity from android studio template. there are 3 fragment with 3 item in BottomNavBar (HomeFragment, DashboardFragment, NotificationsFragment) navigate to DashboardFragment from HomeFragment by a button click. after that home item click from BottomNavBar should open Homefragment. But not working as expected.
Go to DashboardFrament from HomeFrament by
textView.setOnClickListener {
findNavController().navigate(R.id.navigation_dashboard)
}
MainActivity.kt
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
val navView: BottomNavigationView = binding.navView
val navController = findNavController(R.id.nav_host_fragment_activity_main)
navView.setupWithNavController(navController)
}
}
main_activity.xml
<?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"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="?attr/actionBarSize">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_view"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="0dp"
android:layout_marginEnd="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/bottom_nav_menu" />
<fragment
android:id="#+id/nav_host_fragment_activity_main"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintBottom_toTopOf="#id/nav_view"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="#navigation/mobile_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>
HomeFramgent.kt
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val textView: TextView = view.findViewById(R.id.text_home)
textView.setOnClickListener {
findNavController().navigate(R.id.navigation_dashboard)
}
}
navigation.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/mobile_navigation"
app:startDestination="#+id/navigation_home">
<fragment
android:id="#+id/navigation_home"
android:name="com.app.bottomnav.ui.home.HomeFragment"
android:label="#string/title_home"
tools:layout="#layout/fragment_home" />
<fragment
android:id="#+id/navigation_dashboard"
android:name="com.app.bottomnav.ui.dashboard.DashboardFragment"
android:label="#string/title_dashboard"
tools:layout="#layout/fragment_dashboard" />
<fragment
android:id="#+id/navigation_notifications"
android:name="com.app.bottomnav.ui.notifications.NotificationsFragment"
android:label="#string/title_notifications"
tools:layout="#layout/fragment_notifications" />
</navigation>
Whenever you are navigating to any root destination from another fragment, you should have to clear the previous stack using popUpTo option builder.
Update your code navigation code in your home fragment.
findNavController()
.navigate(R.id.navigation_dashboard,
null,
NavOptions.Builder()
.setPopUpTo(R.id.navigation_home, true)
.build()
)
I don't know what is the best solution for that problem but here is a workaround:
In your activity you add public method:
fun navigateToNavBarDestination(destinationId: Int) {
binding.navView.setSelectedItemId(destinationId)
}
And in your fragments referenced in BottomNavigationView instead calling NavController::navigate you navigate in that way, lets say to dashboard:
fun navigateToDashboard() {
(activity as? MainActivity)?.navigateToNavBarDestination(R.id.dashboard)
}
Its not the perfect solution but works.
Add these lines in your MainActivity onCreate.
val appBarConfiguration = AppBarConfiguration(
setOf(
R.id.navigation_home,
R.id.navigation_dashboard,
R.id.navigation_notifications
))
setupActionBarWithNavController(navController, appBarConfiguration)
I'm trying to update my app to use BottomNavigationView. The first tab contains a HostFragment with a loading spinner that performs a network request to determine which fragment, either HomeFragment or LockedFragment, should be shown in that tab.
MainActivity handles the initial setup of the BottomNavigationView:
class MainActivity : AppCompatActivity() {
private lateinit var navController: NavController
private lateinit var appBarConfiguration: AppBarConfiguration
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val navHostFragment = supportFragmentManager.findFragmentById(
R.id.nav_host_container
) as NavHostFragment
navController = navHostFragment.navController
val bottomNavigationView = findViewById<BottomNavigationView>(R.id.bottom_nav)
bottomNavigationView.setupWithNavController(navController)
appBarConfiguration = AppBarConfiguration(
setOf(R.id.mainFragment)
)
setupActionBarWithNavController(navController, appBarConfiguration)
}
My main nav graph looks like this:
<?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_graph"
app:startDestination="#+id/home">
<include app:graph="#navigation/home"/>
<include app:graph="#navigation/list"/>
<include app:graph="#navigation/form"/>
</navigation>
with the home graph looking like:
<?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/home"
app:startDestination="#+id/hostFragment">
<fragment
android:id="#+id/hostFragment"
android:name="com.example.android.bottomnav.homescreen.HostFragment"
android:label="Host">
<action
android:id="#+id/action_hostFragment_to_homeFragment"
app:destination="#id/homeFragment" />
<action
android:id="#+id/action_hostFragment_to_lockedFragment"
app:destination="#id/lockedFragment" />
</fragment>
<fragment
android:id="#+id/homeFragment"
android:name="com.example.android.bottomnav.homescreen.HomeFragment"
android:label="Home" />
<fragment
android:id="#+id/lockedFragment"
android:name="com.example.android.bottomnav.homescreen.LockedFragment"
android:label="Locked"/>
</navigation>
HostFragment get's shown fine and loads it's data:
class HostFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_host, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
determineFragmentToShow()
}
private fun determineFragmentToShow() {
lifecycleScope.launchWhenStarted {
// mock network call to determine tab
delay(1500)
// show HomeFragment for the sake of the example, but note that
// this would be dependent on the network call's result above
findNavController().navigate(R.id.action_hostFragment_to_homeFragment)
}
}
}
which successfully navigates us to HomeFragment.
Now the problem is that whenever I press the back button from HomeFragment it goes back to HostFragment instead of closing the app.You can see the behavior in this video here.
I tried to set the popUpTo and popUpInclusive tags inside of home.xml like this:
<fragment
android:id="#+id/hostFragment"
android:name="com.example.android.bottomnav.homescreen.HostFragment"
android:label="Host">
<action
android:id="#+id/action_hostFragment_to_homeFragment"
app:destination="#id/homeFragment"
app:popUpTo="#id/home"
app:popUpToInclusive="true"/>
<action
android:id="#+id/action_hostFragment_to_lockedFragment"
app:destination="#id/lockedFragment"
app:popUpTo="#id/home"
app:popUpToInclusive="true"/>
</fragment>
That got the app to close when pressing back from HomeFragment, but now each time I switch to a new tab, it creates a new instance of the fragment and adds it to the backstack. Pressing the back button then will traverse them all backwards. You can see that behavior in this video here.
So how can I update the start destination of a nested navigation graph?
I'm using the latest 2.4.0-alpha10 of navigation component so that I can get native support for multiple backstacks. Any help is greatly appreciated!
I was able to utilize the answer here to get a solution working for me.
Inside of determineFragmentToShow() in HostFragment, I just replaced findNavController().navigate(R.id.action_hostFragment_to_homeFragment) with
val navController = findNavController()
val graph = navController.graph
val walletGraph = graph.findNode(R.id.home) as NavGraph
walletGraph.setStartDestination(R.id.homeFragment)
navController.navigate(R.id.action_hostFragment_to_homeFragment)
I still needed to include the popUpTo and popUpInclusive tags here
<fragment
android:id="#+id/hostFragment"
android:name="com.example.android.bottomnav.homescreen.HostFragment"
android:label="Host">
<action
android:id="#+id/action_hostFragment_to_homeFragment"
app:destination="#id/homeFragment"
app:popUpTo="#id/home"
app:popUpToInclusive="true"/>
<action
android:id="#+id/action_hostFragment_to_lockedFragment"
app:destination="#id/lockedFragment"
app:popUpTo="#id/home"
app:popUpToInclusive="true"/>
</fragment>
but this got me the back behavior I was looking for!
I am using jetpack navigation in two different activities each with its navigation host. I have Main activity which everything just works fine and Setup activity which have 2 fragments, one has a button which should navigate to other fragment when clicked .
The activity's code is as follows:
class SetupActivity : AppCompatActivity() {
private val navController by lazy { findNavController(R.id.nav_host_fragment) }
private lateinit var appBarConfig: AppBarConfiguration
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
DataBindingUtil.setContentView<ActivitySetupBinding>(this, R.layout.activity_setup)
setSupportActionBar(toolbar)
appBarConfig = AppBarConfiguration(navController.graph)
setupActionBarWithNavController(navController, appBarConfig)
}
override fun onSupportNavigateUp(): Boolean {
return navController.navigateUp(appBarConfig) || super.onSupportNavigateUp()
}
}
Below is activity's xml:
<?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"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context=".ui.SetupActivity"
tools:showIn="#layout/activity_setup">
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="#navigation/setup" />
</androidx.constraintlayout.widget.ConstraintLayout>
Below is code of first fragment which is also a start Destination
class ConfirmClassFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val binding = FragmentConfirmClassBinding.inflate(inflater, container, false)
binding.fragment = this
return binding.root
}
fun navigate() {
toast("clicked") //this get called
val direction = ConfirmClassFragmentDirections.actionConfirmToSetup()
findNavController().navigate(direction) //THE PROBLEM IS HERE
//findNavController().navigate(R.id.setup)
}
}
I am using data binding to call fun navigate() as below:
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable
name="fragment"
type="com.nux.ui.fragments.ConfirmClassFragment" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="#dimen/spacing_middle">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="#{() -> fragment.navigate()}"
android:text="#string/continue_" />
</LinearLayout>
</layout>
and this how navigation xml looks like:
<?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/setup"
app:startDestination="#id/confirm">
<fragment
android:id="#+id/setup"
android:name="com.nux.ui.fragments.SetInfoFragment"
android:label="#string/setup"
tools:layout="#layout/fragment_set_info" />
<fragment
android:id="#+id/confirm"
android:name="com.nux.ui.fragments.ConfirmClassFragment"
android:label="#string/data_confirmation"
tools:layout="#layout/fragment_confirm_class">
<action
android:id="#+id/action_confirm_to_setup"
app:destination="#id/setup" />
</fragment>
</navigation>
When I click button fun gets called but nothing happens! What could be wrong?
From the code i can see you have the same id for 3 elements in the navigation graph.
#id/setup should only be used once and please change the name of the navigation graph from setup to something else.
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)
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)
}