片段不使用 FragmentContainerView 切换

Question

I simply want to use bottomNavigation with Navigation Component . I tried multiple ways but fragment not switching . Only BottomNavigation display's

I have a running sample that uses fragment instead of FragmentContainerView. But I don't know why it's too complex to use the latest techtiques DashboardActivity

@AndroidEntryPoint
class DashboardActivity : PBActivity(R.layout.activity_dashboard) {
    val binding: ActivityDashboardBinding by viewbind()
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val appBarConfiguration: AppBarConfiguration = AppBarConfiguration.Builder(
            R.id.rankingFragment, R.id.homeFragment, R.id.profileFragment
        ).build()

        setSupportActionBar(binding.toolbar)
        val navHostFragment =
            supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
        val navController = navHostFragment.navController
        /*val navView = findViewById<BottomNavigationView>(R.id.bottom_nav)
        NavigationUI.setupWithNavController(navView,navController)*/

        ///binding.navigationBb.setupWithNavController(navController)
        ///binding.toolbar.setupWithNavController(navController,null)
        //binding.navHostFragment.s
        binding.toolbar.setupWithNavController(navController,appBarConfiguration)
        ///binding.bottomNav.setupWithNavController(navController)

        NavigationUI.setupWithNavController(binding.bottomNav, navController)
        ///NavigationUI.setupWithNavController(binding.bottomNav,navController)
    }
 }

activity_dashboard.xml

<?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">

    <data>

    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="0dp"
        android:layout_height="0dp">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent">

        </androidx.appcompat.widget.Toolbar>

        <androidx.fragment.app.FragmentContainerView
            android:id="@+id/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" />

        <com.google.android.material.bottomnavigation.BottomNavigationView
            android:id="@+id/bottom_nav"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:layout_width="match_parent"
            app:menu="@menu/dashboard_nav_menu"
            android:background="?android:attr/windowBackground"
            android:layout_height="wrap_content" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

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/homeFragment">

    <fragment
        android:id="@+id/homeFragment"
        tools:layout="@layout/fragment_home"
        android:name="uk.co.planetbeyond.game_show_app.presentation.ui.main.fragments.HomeFragment"
        android:label="HomeFragment" />
    <fragment
        android:id="@+id/rankingFragment"
        tools:layout="@layout/fragment_ranking"
        android:name="uk.co.planetbeyond.game_show_app.presentation.ui.main.fragments.RankingFragment"
        android:label="RankingFragment" />
    <fragment
        android:id="@+id/profileFragment"
        tools:layout="@layout/fragment_profile"
        android:name="uk.co.planetbeyond.game_show_app.presentation.ui.main.fragments.ProfileFragment"
        android:label="ProfileFragment" />
</navigation>

dashboard_nav_menu.xml

 <?xml version="1.0" encoding="utf-8"?>
    <menu xmlns:android="http://schemas.android.com/apk/res/android">
    
        <item
            android:id="@+id/rankingFragment"
            android:icon="@drawable/rankings_button_selected"
            android:title="Ranking" />
        <item
            android:id="@+id/homeFragment"
            android:icon="@drawable/home_button_selected"
            android:title="@string/title_home" />
        <item
            android:id="@+id/profileFragment"
            android:icon="@drawable/profile_icon_selected"
            android:title="Profile" />
    </menu>

Answer 1

The problem is not in the navigation components, your code looks fine regarding it; but that your main layout has a 0 size:

You need to set the root layout to match parent:

<androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
...

Side note: the fragments will draw behind the toolbar as it constraints to the parent top edge; The same for the bottom part.

To fix this constraint it to the toolbar:

In the FragmentContainerView Replace:

app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"

With:

app:layout_constraintTop_toBottomOf="@+id/toolbar"
app:layout_constraintBottom_toTopOf="@+id/bottom_nav"