在 RecyclerView 中设置 CardView 的背景图片会导致程序在滚动时崩溃

Question

我有一个包含 CardView 列表的 RecyclerView，其中包含从服务器中提取的信息，有些卡片只有背景颜色，但有些包含背景图像。如果所有卡片都只有背景颜色，则 RecyclerView 会相应地运行（我也可以设置边距和圆角半径）。但是，如果任何一张卡片包含背景图片，当我尝试滚动 up/down 列表时会发生崩溃（尽管背景图片将在没有先前设置的角半径的情况下加载）。

这是崩溃日志：

java.lang.ClassCastException: android.graphics.drawable.BitmapDrawable cannot be cast to android.support.v7.widget.RoundRectDrawable
        at android.support.v7.widget.CardViewApi21.setBackgroundColor(CardViewApi21.java:107)
        at android.support.v7.widget.CardView.setCardBackgroundColor(CardView.java:234)
        at co.roverlabs.sdk.ui.CardListAdapter.onBindViewHolder(CardListAdapter.java:88)
        at co.roverlabs.sdk.ui.CardListAdapter.onBindViewHolder(CardListAdapter.java:28)
        at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:4402)
        at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:3717)
        at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:3609)
        at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1859)
        at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1311)
        at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1274)
        at android.support.v7.widget.LinearLayoutManager.scrollBy(LinearLayoutManager.java:1102)
        at android.support.v7.widget.LinearLayoutManager.scrollVerticallyBy(LinearLayoutManager.java:959)
        at android.support.v7.widget.RecyclerView$ViewFlinger.run(RecyclerView.java:3062)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
        at android.view.Choreographer.doCallbacks(Choreographer.java:580)
        at android.view.Choreographer.doFrame(Choreographer.java:549)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5254)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

这是我的 onBindViewHolder() 方法（使用硬编码值进行了简化以便于阅读）：

public void onBindViewHolder(final CardViewHolder holder, int position) {

    //Set margins
    CardView.LayoutParams cardLayoutParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 2000);
    cardLayoutParams.setMargins(20, 20, 20, 20);
    holder.cardView.setLayoutParams(cardLayoutParams);

    //Set background color or image
    if(view.hasBackgroundImage()) {
        holder.cardView.setBackground(R.drawable.background);
    }
    else {
        holder.cardView.setCardBackgroundColor(Color.CYAN);
    }

    //Set border radius
    holder.cardView.setRadius(20);

    //Set elevation
    holder.cardView.setCardElevation(0);

这是我的 onCreateViewHolder() 方法和自定义 Recycler.ViewHolder 方法：

public CardViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

    View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_view, parent, false);
    return new CardViewHolder(itemView);
}

public class CardViewHolder extends RecyclerView.ViewHolder {

    protected CardView cardView;

    public CardViewHolder(View view) {

        super(view);
        cardView = (CardView)view.findViewById(R.id.single_card_view);
    }
}

最后，这是我的 XML CardView 文件：

<android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/single_card_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <RelativeLayout
        android:id="@+id/single_card_view_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </RelativeLayout>

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

我只是想知道如何将 CardView 的背景设置为自定义图像而不仅仅是颜色，以及是否有任何解决方法。能够设置卡片的角半径对我来说很重要。谢谢！

Answer 1

假设您正在使用 CardView，您不能更改背景可绘制对象，因为 CardView 使用背景可绘制对象来绘制卡片。您可以通过 setCardBackgroundColor.

更改卡片背景颜色

在 RecyclerView 中设置 CardView 的背景图片会导致程序在滚动时崩溃

Setting the background image of a CardView inside RecyclerView causes the program to crash when scrolling

java

android

android-cardview

android-recyclerview