BottomNavigationView jumping when hidding ActionBar

Question

I'm trying to show the ActionBar only in some fragments like this:

    override fun onResume() {
    super.onResume()
    (requireActivity() as AppCompatActivity).supportActionBar?.show()
}


override fun onPause() {
    super.onPause()
    (requireActivity() as AppCompatActivity).supportActionBar?.hide()
}

But for some reason each time I hide it the bottom navbar "jumps"

Code for MainActivity.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

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

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/nav_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?android:attr/windowBackground"
        app:itemBackground="@color/colorPrimary"
        app:itemIconTint="@drawable/selector"
        app:itemTextColor="@drawable/selector"
        app:menu="@menu/bottom_nav_menu" />
</LinearLayout>

Answer 1

Use the NoActionBar theme, for exemple Theme.MaterialComponents.Light.NoActionBar for your activity.

And add manualy in your layout the 'ActionBar'

Your MainActivity.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize" />
    </com.google.android.material.appbar.AppBarLayout>

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

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/nav_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?android:attr/windowBackground"
        app:itemBackground="@color/colorPrimary"
        app:itemIconTint="@drawable/selector"
        app:itemTextColor="@drawable/selector"
        app:menu="@menu/bottom_nav_menu" />
</LinearLayout>

Don't forget to call in your activity setupWithNavController

NavigationUI.setupWithNavController(toolbar, navController)

And change the visibility any way you want.

OR

Add the Toolbar only in the layout of your fragment. But I think the NavigationUI needs a toolbar.