android - 卡片 View 阴影未显示

Question

这是我的card_view。我已经提到了 card_view:cardElevation。但是仍然没有显示阴影。 我搜索了很多链接。他们在任何地方都提到要使用 card_view:cardElevation。

<android.support.v7.widget.CardView
            android:id="@+id/card_view"
            xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            card_view:cardBackgroundColor="@color/white"
            card_view:cardCornerRadius="4dp"
            card_view:cardElevation="5dp"
            card_view:cardUseCompatPadding="true"
            app:cardPreventCornerOverlap="false">
</android.support.v7.widget.CardView>

你能告诉我这里缺少什么吗？

Answer 1

阅读https://developer.android.com/training/material/lists-cards.html

To create a card with a shadow, use the card_view:cardElevation attribute. CardView uses real elevation and dynamic shadows on Android 5.0 (API level 21) and above and falls back to a programmatic shadow implementation on earlier versions. For more information, see Maintaining Compatibility.

更新

如果您想看到阴影，请尝试为卡片添加边距

检查 https://developer.android.com/reference/android/support/v7/widget/CardView.html