CODE EXAMPLE FOR JAVA

transparent card background android

<android.support.v7.widget.CardView
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/myCardView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    card_view:cardBackgroundColor="@android:color/transparent"
    card_view:cardElevation="0dp">