android - 无法查看 RecyclerView 中的条目

Question

我目前正在使用 RecyclerView 在水平方向的列表中显示一组带有文本的图像。问题是在设置适配器并通知它数据更改后，我没有看到正在填充的网格。我以前使用 gridView 和 arrayAdapter 没有任何问题。我错过了一些基本的东西吗？

** 另外，我查看了 logcat，但没有发现任何异常。但是，如果您需要查看它，请告诉我，我会在此处添加 **

我已经按照以下方式设置了我的数据和适配器:

模型:CastViewObject

public class CastViewObject {


    String castImageUrl;
    String castName;
    String castCharName;

    public CastViewObject(String castName, String castCharName, String castImageUrl) {
        this.castImageUrl = castImageUrl;
        this.castName = castName;
        this.castCharName = castCharName;
    }

    public String getCastImageUrl() {
        return castImageUrl;
    }

    public void setCastImageUrl(String castImageUrl) {
        this.castImageUrl = castImageUrl;
    }

    public String getCastCharName() {
        return castCharName;
    }

    public void setCastCharName(String castCharName) {
        this.castCharName = castCharName;
    }

    public String getCastName() {
        return castName;
    }

    public void setCastName(String castName) {
        this.castName = castName;
    }

}

适配器:CastViewAdapter(扩展 RecyclerView.Adapter)- 目前仅显示覆盖的方法。

public static class ViewHolder extends RecyclerView.ViewHolder {

    public ImageView imageView;
    public TextView textView;


    public ViewHolder(View itemView) {
        super(itemView);
        imageView = (ImageView) itemView.findViewById(R.id.cast_image);
        textView = (TextView) itemView.findViewById(R.id.cast_name);
    }
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    mContext = parent.getContext();
    LayoutInflater layoutInflater = LayoutInflater.from(mContext);
    View castView = layoutInflater.inflate(R.layout.cast_item_layout,parent,false);
    ViewHolder viewHolder = new ViewHolder(castView);
    return  viewHolder;
}

@Override
public void onBindViewHolder(CastViewAdapter.ViewHolder holder, int position) {
        final String LOG_TAG = getClass().getSimpleName();
        CastViewObject castObject = castViewList.get(position);
        TextView textView = holder.textView;
        textView.setText(castObject.getCastName());

    Picasso
            .with(mContext)
            .load(castViewList.get(position).getCastImageUrl())
            .resize(500, 750)
            .error(R.drawable.user_placeholder_image)
            .into(holder.imageView, new Callback() {
                @Override
                public void onSuccess() {
                    count++;
                }

                @Override
                public void onError() {
                    Log.e(LOG_TAG, "Error in loading images");
                }
            });
}

@Override
public int getItemCount() {
    return castViewList.size();
}

自定义行:cast_item_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
    <ImageView
        android:id="@+id/cast_image"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"/>
    <TextView
        android:id="@+id/cast_name"
        android:layout_alignParentBottom="true"
        android:background="@color/title_background_color"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal|bottom"
        android:textColor="@color/title_text_color"/>
</LinearLayout>

fragment 布局中的 RecyclerView:

      <android.support.v7.widget.RecyclerView
        android:id="@+id/cast_list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignLeft="@+id/movie_image_detail"
        android:layout_alignStart="@+id/movie_image_detail"
        android:layout_below="@+id/cast_divider"
        android:layout_marginTop="10dp"
        android:clickable="false" />

这是我在 onCreateView 方法中设置适配器的方式:

    RecyclerView recyclerView = (RecyclerView)view.findViewById(R.id.cast_list_view);
    castAdapter = new CastViewAdapter(new ArrayList<CastViewObject>());
    recyclerView.setAdapter(castAdapter);
    LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
    linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
    recyclerView.setLayoutManager(linearLayoutManager);
    requestMovieDetails();

.. 并通知适配器数据的变化:

    public void setCastView(List<CastViewObject> castViewList){
        castAdapter.setCastViewList(castViewList);
        castAdapter.notifyDataSetChanged();
    }

Answer 1

你必须 setAdapter在这一行之后:

recyclerView.setLayoutManager(linearLayoutManager);

更新:

您刚刚将新对象分配给 this.castViewList , 但您的适配器绑定(bind)到空的旧对象，因此 RecyclerView 中没有任何内容可显示.你必须做这样的事情:

this.castViewList.clear();
this.castViewList.addAll(castViewList);