how to hide BottomNavigationView on android-navigation lib

Question

I am trying to use android-navigation lib in my APP and I do the things as the tutorial said. I just wanna use one single activity in my APP. I am confused about one question. some fragments that just don't want the BottomNavigationView, how can I hide it. here is my main_layout

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical" 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"
        app:elevation="0dp"
        android:theme="@style/AppTheme.AppBarOverlay">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:minHeight="?attr/actionBarSize"
            android:fitsSystemWindows="true"
            app:popupTheme="@style/AppTheme.PopupOverlay" >

        </androidx.appcompat.widget.Toolbar>

    </com.google.android.material.appbar.AppBarLayout>

    <fragment
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        app:defaultNavHost="true"
        app:navGraph="@navigation/carkeeper_navigation"/>

<com.google.android.material.bottomnavigation.BottomNavigationView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/menu_bottom_nav"
    app:itemTextColor="@color/bottom_nav_title_color_selector"
    app:itemIconSize="@dimen/x40"
    app:menu="@menu/menu_main_bottom_nav"
    app:labelVisibilityMode="labeled">

</com.google.android.material.bottomnavigation.BottomNavigationView>

here is my mainActivity

class MainActivity : BaseActivity() {

private lateinit var navController: NavController
private lateinit var bottomNavigationView: BottomNavigationView
private lateinit var appBarConfiguration: AppBarConfiguration

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.home_activity)

    navController = Navigation.findNavController(this, R.id.nav_host_fragment)
    appBarConfiguration = AppBarConfiguration(navController.graph, null)
    setSupportActionBar(findViewById(R.id.toolbar))

    bottomNavigationView = findViewById(R.id.menu_bottom_nav)
    bottomNavigationView.setupWithNavController(navController)
    bottomNavigationView.itemIconTintList = null
}}

then the navigaton_graph

<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/carkeeper_navigation"
app:startDestination="@id/mainFragment">

<fragment
    android:id="@+id/mainFragment"
    android:name="com.saicfinance.carkeeper.func.main.MainFragment"
    android:label="MainFragment"
    tools:layout="@layout/home_fragment">
</fragment>

<fragment
    android:id="@+id/mineFragment"
    android:name="com.saicfinance.carkeeper.func.mine.MineFragment"
    android:label="@string/mine_title"
    tools:layout="@layout/mine_fragment" >

    <action android:id="@+id/action_mine_fragment_to_setting_fragment"
        app:destination="@id/settingFragment"
        app:enterAnim="@anim/slide_in_right"
        app:exitAnim="@anim/slide_out_left"
        app:popEnterAnim="@anim/slide_in_left"
        app:popExitAnim="@anim/slide_out_right"/>
</fragment>

<fragment
    android:id="@+id/settingFragment"
    android:name="com.freddy.func.setting.SettingFragment"
    android:label="setting_fragment"
    tools:layout="@layout/setting_fragment" />

I know I can set BottomNavigationView gone when navigating to settingFragment. then set BottomNavigationView visible when back to mine fragment. But that is strange. anyone who can help me, thanks in advance.

Answer 1

You could do something like this in your activity's onCreate. When ever an item in the nav bar is selected it will show or hide the nav based on the fragment id's.

private fun setupNav() {
    val navController = findNavController(R.id.nav_host_fragment)
    findViewById<BottomNavigationView>(R.id.bottomNav)
        .setupWithNavController(navController)

    navController.addOnDestinationChangedListener { _, destination, _ ->
        when (destination.id) {
            R.id.mainFragment -> showBottomNav()
            R.id.mineFragment -> showBottomNav()
            else -> hideBottomNav()
        }
    }
}

private fun showBottomNav() {
    bottomNav.visibility = View.VISIBLE
    
}

private fun hideBottomNav() {
    bottomNav.visibility = View.GONE
   
}