DroidFS/app/src/main/res/layout/activity_explorer.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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="sushi.hardcore.droidfs.explorers.ExplorerActivity">

    <include layout="@layout/toolbar"/>

    <include layout="@layout/explorer_info_bar"/>

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

        <include layout="@layout/explorer_content"/>

        <com.google.android.material.floatingactionbutton.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_alignParentEnd="true"
            android:layout_margin="15dp"
            android:src="@drawable/icon_add"/>

    </RelativeLayout>

</LinearLayout>