rectangle_background_with_bottom_coners_radius.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item>
        <shape android:shape="rectangle">
            <!-- draw a 4 dp width border around the rectangle shape -->
            <stroke  android:width="0dp"/>
        </shape>
    </item>

    <item android:bottom="2dp">
        <shape android:shape="rectangle">
            <corners
               android:bottomLeftRadius="20dp"
                android:bottomRightRadius="20dp"/>
            <solid android:color="@color/colorPrimary"/>
        </shape>
    </item>
</layer-list>