In the below code layout I have created floting action button layout. Here I have used CoordinatorLayout, LinearLayout, TextView and FloatingActionButton. FloatingActionButton move left or right when we changes layout_anchorGravity. In this layout FloatingActionButton is under LinearLayout id/viewA.
You can see the below example it will clearly describe you how to create Floting action button layout in android.

<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <LinearLayout
            android:id="@+id/viewA"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="0.6"
            android:background="@android:color/holo_purple"
            android:orientation="horizontal"
            android:textAlignment="center">
            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Evon"
                android:textSize="40dp"
                android:textStyle="bold"
                android:textAlignment="center"/>
            </LinearLayout>

        <LinearLayout
            android:id="@+id/viewB"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="0.5"
            android:background="@android:color/holo_orange_light"
            android:orientation="horizontal"/>

    </LinearLayout>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:clickable="true"
        android:src="@drawable/icon2"
        app:layout_anchor="@id/viewA"
        app:layout_anchorGravity="bottom|end|right"/>

</android.support.design.widget.CoordinatorLayout>