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!

score 145 · Accepted Answer · edited Apr 26 '21 at 12:16

145

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 '21 at 12:16

Alireza Noorali

3,129
2
33
80

answered Nov 14 '19 at 14:28

Ove Stoerholt

3,843
4
25
33

13

surely better just to use `fragment`rather than worrying about having to remember to use this workaround? We were seeing crashes but only for some users, weird... – hmac Mar 19 '20 at 09:40
6

@hmac In the issue linked they discuss why you shouldn't use fragment: https://issuetracker.google.com/issues/142847973#comment15: *The Lint check is there exactly because you absolutely should switch over to FragmentContainerView in all cases.* – Banana Aug 10 '20 at 14:18
does not show anything. It's weird I am stuck with using ! – Junia Montana Nov 09 '20 at 04:44
1

what we have to do with navController, because the variable is unused – Tippu Fisal Sheriff Apr 04 '21 at 07:40

score 47 · Answer 2 · answered Aug 27 '20 at 22:38

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.

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: https://issuetracker.google.com/issues/143145612 — Sharp, Oct 25 '20 at 10:04

score 10 · Answer 3 · edited May 25 '20 at 06:32

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);
});

I had used `` 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 ``. The problem has been cleared, thank you! — hata, May 25 '20 at 06:36

score 3 · Answer 4 · edited Nov 04 '21 at 14:38

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 04 '21 at 14:38

Phani Rithvij

4,030
3
25
60

answered Nov 03 '21 at 08:20

Galih Al

41
2

score -8 · Answer 5 · answered Dec 18 '19 at 09:19

-8

using android:name instead of class. works.

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

answered Dec 18 '19 at 09:19

chihara

1
1

FragmentContainerView as NavHostFragment

5 Answers5

Linked