如何找到带有视图绑定的导航控制器？

Question

I am using view binding in my app. But now I am facing issue with finding navcontroller with view binding.

If I use traditional way to set content view with layout, I can easily find navcontroller with this piece of code.

Navigation.findNavController(this, R.id.nav_host_fragment)

But if I use view binding to set content view how can I find navcontroller since the above code requires ID of navHostFragment but view bending returns fragment if I give binding.navHostFragment

Answer 1

ViewBinding , As its name implies, is used to bind views not to bind resource identifiers .

What ViewBinding offers you in its simple form, that you don't have to findViewById(view_id) anymore; instead it offers binding.myView .. Both cases returns a view.

But in the NavController context, you don't have to get a view (but a resource id), so that view binding won't benefit you (again because it binds views not ids).

So, you will have to use the same code to get the NavController :

Navigation.findNavController(this, R.id.nav_host_fragment)

Answer 2

Fist thing you have to use FragmentContainerView instead of fragment don't forget to use the same name attribute and that's it! now you can find it in the binding elements

so as example you have to change this :

        <fragment
        android:id="@+id/mainFragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/mobile_navigation" />

into this :

        <androidx.fragment.app.FragmentContainerView
        android:id="@+id/fragmentContainerView"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/mobile_navigation"
        />