FragmentContainerView as NavHostFragment

Question

Seems like using the FragmentContainerView doesn't work right out of the box?

<androidx.fragment.app.FragmentContainerView
        class="androidx.navigation.fragment.NavHostFragment"
        android:id="@+id/fragment_nav_host"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_app" />

Here's my code using fragment-ktx:1.2.0-rc01 and I'm just always getting this error:

Caused by: java.lang.IllegalStateException: Activity ...MainActivity@797467d does not have a NavController set on 2131296504

Just using <fragment> works and AFAIK, it's just supposed to be replaced by FragmentContainerView.

Am I missing something or was anyone able to use FragmentContainerView as a NavHostFragment?

Many thanks!

Alireza Noorali · Accepted Answer · 2021-04-26 12:16:07Z

152

Due to this bug-report: https://issuetracker.google.com/issues/142847973

This is the only way (currently):

val navHostFragment = supportFragmentManager
    .findFragmentById(R.id.my_nav_host_fragment) as NavHostFragment
val navController = navHostFragment.navController

(Java):

NavHostFragment navHostFragment =
    (NavHostFragment) getSupportFragmentManager()
        .findFragmentById(R.id.my_nav_host_fragment);
NavController navController = navHostFragment.getNavController();

edited Apr 26, 2021 at 12:16

Alireza Noorali

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answered Nov 14, 2019 at 14:28

Ove Stoerholt

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4 Comments

hmac Over a year ago

surely better just to use fragmentrather than worrying about having to remember to use this workaround? We were seeing crashes but only for some users, weird...

Banana Over a year ago

@hmac In the issue linked they discuss why you shouldn't use fragment: issuetracker.google.com/issues/142847973#comment15: The Lint check is there exactly because you absolutely should switch over to FragmentContainerView in all cases.

Junia Montana Over a year ago

does not show anything. It's weird I am stuck with using <fragment>!

Tippu Fisal Sheriff Over a year ago

what we have to do with navController, because the variable is unused

Vince · Accepted Answer · 2020-08-27 22:38:37Z

51

August 2020 update

Here is the solution recommended by the official Android documentation.

Kotlin version:

val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
val navController = navHostFragment.navController

Java version:

NavHostFragment navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment);
NavController navController = navHostFragment.getNavController();

I quote the doc:

When creating the NavHostFragment using FragmentContainerView or if manually adding the NavHostFragment to your activity via a FragmentTransaction, attempting to retrieve the NavController in onCreate() of an Activity via Navigation.findNavController(Activity, @IdRes int) will fail. You should retrieve the NavController directly from the NavHostFragment instead.

The bug-report reported by Ove Stoerholt will not be fixed. You can see here the "Won't Fix (Infeasible)" status.

answered Aug 27, 2020 at 22:38

Vince

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1 Comment

Sharp Over a year ago

While the original task was tagged as "Won't Fix (Infeasible)", they did link to another task so they might plan to fix the issue after all: issuetracker.google.com/issues/143145612

hata · Accepted Answer · 2020-05-25 06:32:16Z

10

What I did was to wait for the NavHostFragment to inflate its view:

Kotlin:

super.onCreate(savedInstanceState)

// Set up the form and list.
setContentView(R.layout.activity_xxx)

// Set up navigation - action bar and sidebar.
/// Let the navigation view check/uncheck the menu items.
nav_view.post { // wait for NavHostFragment to inflate
    val navController = findNavController()
    nav_view.setupWithNavController(navController)
    nav_view.setNavigationItemSelectedListener(this)
}

Java8 (with lambda):

navigationView.post(() -> { // wait for NavHostFragment to inflate
    navController = Navigation.findNavController(activity, R.id.nav_host_fragment);
    NavigationUI.setupWithNavController(navView, navController);
    navView.setNavigationItemSelectedListener(navItemSelectedListener);
});

edited May 25, 2020 at 6:32

hata

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answered Apr 21, 2020 at 12:53

Pnemonic

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1 Comment

hata Over a year ago

I had used <fragment> to avoid the bug. But I was troubled another unknown error. So I found this @Pnemonic's late answer and tried it in order to use <FragmentContainerView>. The problem has been cleared, thank you!

Phani Rithvij · Accepted Answer · 2021-11-04 14:38:12Z

3

I have the same problem when using kotlin:

val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment

val navController = navHostFragment.navController

Just add it to

setupActionBarWithNavController(navController)

edited Nov 4, 2021 at 14:38

Phani Rithvij

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answered Nov 3, 2021 at 8:20

Galih Al

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Comments

chihara · Accepted Answer · 2019-12-18 09:19:13Z

-7

using android:name instead of class. works.

<androidx.fragment.app.FragmentContainerView
    android:name="androidx.navigation.fragment.NavHostFragment"
    ...

answered Dec 18, 2019 at 9:19

chihara

211 bronze badge

1 Comment

MikeMcC Over a year ago

This answer worked for me. As the docs states: FragmentContainerView can also be used to add a Fragment by using the android:name attribute. developer.android.com/reference/androidx/fragment/app/…

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