Custom Action bar manipulation (e.g. making the title centered, displaying the up button)

activity_main.xml

<com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay"
            android:id="@+id/appBar">

    <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="#28344E"
            app:popupTheme="@style/AppTheme.PopupOverlay">

        <TextView
                android:id="@+id/toolbar_title"
                style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="[YOUR TITLE HERE]" />

    </androidx.appcompat.widget.Toolbar>
</com.google.android.material.appbar.AppBarLayout>

activity_main_sample_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        tools:showIn="@layout/activity_quote"
        android:orientation="vertical">

    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay"
            android:id="@+id/appBar">

    <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="#28344E"
            app:popupTheme="@style/AppTheme.PopupOverlay">

        <TextView
                android:id="@+id/toolbar_title"
                style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="Send a Quote" />

    </androidx.appcompat.widget.Toolbar>

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


    <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

        <FrameLayout
                android:id="@+id/frame_layout"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_above="@id/bottom_nav"></FrameLayout>

        <com.google.android.material.bottomnavigation.BottomNavigationView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:id="@+id/bottom_nav"
                android:layout_alignParentBottom="true"
                app:menu="@menu/bottom_nav_quote"/>

    </RelativeLayout>


</LinearLayout>

CustomActionBar.kt

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        // Tell Android to use the Toolbar as the ActionBar
        setSupportActionBar(toolbar)
        
        // Remove default title, so we can use our custom title
        supportActionBar!!.setDisplayShowTitleEnabled(false)
        
        // Show the up/back button
        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
        supportActionBar!!.setDisplayShowHomeEnabled(true)
        
        // Show the up/back button - if inside fragment
        (activity as ParentActivity).supportActionBar!!.setDisplayHomeAsUpEnabled(true)
        (activity as ParentActivity).supportActionBar!!.setDisplayShowHomeEnabled(true)
}