cardview not show shadow
<android.support.v7.widget.CardView android:id="@+id/item_card"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
app:cardCornerRadius="2dp"
app:cardUseCompatPadding="true"
app:cardElevation="2dp"
app:cardBackgroundColor="@color/md_white_1000"
android:foreground="?android:attr/selectableItemBackground"
android:clickable="true">
</android.support.v7.widget.CardView>