Android RecyclerView平台之间的间距差异

Question

Disclosure up front, this is a school project.

I've run into a somewhat confusing-to-me layout issue regarding a list of CardViews inside of a RecyclerView, that being that the spacing between cards is non-existent on 5.0, whereas it's fine on 4.4. Here's two screenshots to demonstrate.

Android 4.4 (On Device, Galaxy S4)

Android 5.0.1 (On Device, Nexus 4)

I can see the card corners in the 5.x version, so the cards are there. I have a feeling this is something to do with some XML attribute that I need for running 5.x that the support library fakes automatically on 4.x, but googling has failed me. Here's the relevant XML:

Fragment Layout

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.hinodesoftworks.kanagt.HiraganaListFragment">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/hira_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />
</FrameLayout>

Card Layout

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    card_view:cardCornerRadius="4dp">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/kana_card_display"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="46sp"
            android:text="あ"/>

        <TextView
            android:id="@+id/kana_card_roma"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/kana_card_display"
            android:layout_toEndOf="@id/kana_card_display"
            android:text="a"
            />

        <TextView
            android:id="@+id/kana_card_info1_display"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/kana_card_display"
            android:layout_toEndOf="@id/kana_card_display"
            android:layout_below="@id/kana_card_roma"
            android:text="INFO 1"/>

        <TextView
            android:id="@+id/kana_card_info2_display"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/kana_card_display"
            android:layout_toEndOf="@id/kana_card_display"
            android:layout_below="@id/kana_card_info1_display"
            android:text="INFO 2"/>

    <HorizontalScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/kana_card_info2_display">
            <ImageView
                android:id="@+id/kana_card_diagram"
                android:layout_width="match_parent"
                android:layout_height="100dp"
                android:scaleType="fitStart"

                android:adjustViewBounds="true"/>
    </HorizontalScrollView>
    </RelativeLayout>

</android.support.v7.widget.CardView>

I'm really hoping this is a dumb mistake with a simple XML fix; that the support library version is working fine makes me hopeful of that.

Answer 1

If you want the padding on 5.0 follow the same rules as on previous platforms add this attribute to the CardView XML element

app:cardUseCompatPadding="true"

On Lollipop the shadows can be drawn outside of the view bounds. On Kitkat and lower extra space has to be reserved for the shadows. That's why on Lollipop the spacing would have to be set explicitly.