CODE EXAMPLE FOR JAVA

Card view only top corner radius

<android.support.v7.widget.CardView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="-5dp"   // This is the imp thing 
    card_view:cardCornerRadius="4dp">
    
    <SomeView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="5dp"/>
        
</android.support.v7.widget.CardView>