FAB is hiding under Bottom Sheet

Question

I have following XML:

<android.support.design.widget.CoordinatorLayout
    android:id="@+id/sliding_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@id/app_bar">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <fragment
            android:id="@+id/fragment1"
            android:name="com.xyz.Fragment1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            tools:layout="@layout/fragment_layout1" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/layoutBottomSheet"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:elevation="@dimen/global_margin"
        android:orientation="vertical"
        app:layout_behavior="@string/bottom_sheet_behavior">

        <fragment
            android:id="@+id/fragment2"
            android:name="com.xyz.Fragment2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center|top"
            tools:layout="@layout/fragment_layout2" />
    </LinearLayout>

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="@dimen/global_margin"
        android:layout_marginRight="@dimen/global_margin"
        android:src="@drawable/ic_add_white_24dp"
        app:borderWidth="0dp"
        app:elevation="4dp"
        app:layout_anchor="@id/layoutBottomSheet"
        app:layout_anchorGravity="top|right|end" />
</android.support.design.widget.CoordinatorLayout>

The layout should appear as, Fragment1 then below that Fragment2 and FAB is anchored to Fragment2 but, above Fragment2 and not under it.

Actually it is showing as,

What is going wrong? Any idea?

Answer 1

<LinearLayout
        android:id="@+id/layoutBottomSheet"
        android:elevation="@dimen/global_margin"
        ...>

layoutBottomSheet probably has too much elevation, FloatingActionButton's default elevation is 4dp, that's the reason your button is hidden behind the higher layout.

Try a elevation value lower or equal to 4dp