FloatingActionButton with BottomNavigationView

  1. If you stick it in a linear layout and move the bottom nav outside of the coordinator view, it will be below it on the screen.

  2. You could do it this way, but I prefer using an empty fragment container which I put in the hosting activity, and then place the fragment inside of it in code.

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/appbar_padding_top"
        android:theme="@style/AppTheme.AppBarOverlay">
    
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways"
           app:popupTheme="@style/AppTheme.PopupOverlay">
    
        </android.support.v7.widget.Toolbar>
    
    </android.support.design.widget.AppBarLayout>
    
    <FrameLayout
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">
    
    
    </FrameLayout>
    
    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab_electricity"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|right"
        app:srcCompat="@drawable/ic_add_electro"/>
    
    
    
    </android.support.design.widget.CoordinatorLayout>
    <android.support.design.widget.BottomNavigationView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_gravity="bottom">
    
    </android.support.design.widget.BottomNavigationView>
    </LinearLayout>
    

A quick search to FloatingActionButton.Behavior tells us the following thing.

@Override
public void onAttachedToLayoutParams(@NonNull CoordinatorLayout.LayoutParams lp) {
    if (lp.dodgeInsetEdges == Gravity.NO_GRAVITY) {
        // If the developer hasn't set dodgeInsetEdges, lets set it to BOTTOM so that
        // we dodge any Snackbars
        lp.dodgeInsetEdges = Gravity.BOTTOM;
    }
}

Since BottomNavigationView also resides at the bottom of the layout. Add following element to your BottomNavigationView and CoordinatorLayout will handle the inset and dodging for you automatically.

app:layout_insetEdge="bottom"