错误：不兼容的类型：视图无法转换为RecyclerView

Question

我是Android编程的新手。我正在尝试制作一个包含视频列表的单页应用程序，我可以滚动并执行此操作，我正在使用RecyclerView。在我的活动中，它说视图无法转换为RecyclerView，据我所知，RecyclerView没有任何小部件。我该怎么办？我会附上我的代码。

我的活动：

package com.arvindsudheer.youtubeplayertesting;

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

/**
 * Created by ArvindSudheer on 6/10/2017.
 */

class RecyclerView {


public LinearLayoutManager layoutManager;
public MyAdapter adapter;
public boolean hasFixedSize;

private void setLayoutManager(LinearLayoutManager layoutManager) {
    this.layoutManager = layoutManager;
}

private void setAdapter(MyAdapter adapter) {
    this.adapter = adapter;
}

private void setHasFixedSize(boolean hasFixedSize) {
    this.hasFixedSize = hasFixedSize;
}

/**
 * Created by ArvindSudheer on 6/9/2017.
 */

public class MyActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.childview1);
        RecyclerView recyclerView=(RecyclerView)findViewById(R.id.list);
        recyclerView.setHasFixedSize(true);
        //to use RecycleView, you need a layout manager. default is 
LinearLayoutManager
        LinearLayoutManager linearLayoutManager=new 
LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        recyclerView.setLayoutManager(linearLayoutManager);
        MyAdapter adapter=new MyAdapter(MyActivity.this);
        recyclerView.setAdapter(adapter);
    }
}
}

我的适配器：

    package com.arvindsudheer.youtubeplayertesting;

    import android.app.Activity;
    import android.content.Context;
    import android.content.Intent;
    import android.support.v7.widget.RecyclerView;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ImageView;
    import android.widget.RelativeLayout;

    import com.google.android.youtube.player.YouTubeInitializationResult;
    import com.google.android.youtube.player.YouTubeStandalonePlayer;
    import com.google.android.youtube.player.YouTubeThumbnailLoader;
    import com.google.android.youtube.player.YouTubeThumbnailView;

    public class MyAdapter extends RecyclerView.Adapter<MyAdapter.VideoInfoHolder> {

    //these ids are the unique id for each video
    String[] VideoID = {"kN6lRqzmcOY", "MzmSFocMdJk", "L3LixkCN5tM","EuNaQCUjtCw","d-I2JSlEKtA","rwSf_12aMfE","13HIRNVFRlk","BH5_7IYvcVE","Lxc8-INx5G0","iwE8foegHkM","kCKUZdqo600","dr36AF4MqjY","IrMLXTw0528","gyxgVsXMYq0","71MTp2Ley3U","oeNRrGaGV20","loxMW2honqw","Sv63K3ESstA","7U8NzRAvy-I","2kdcR1QBqAI","n3w5c2VYcoU","2zA8W7h7ays","qfkbvujyPpc","JVF8pE1KxaA","f0bi0yl7uZU","5DbdWFAs8EI","5DbdWFAs8EI","2BFUvmCrn1o","yuYbVcoq9nk","lkFlQ5ECM8Q","JuYrl_49WA4","r3L87CUTxeU","RJMvq0pgvkg","9TuDEhfOLUc","HFTTDvuPMOs","fHRh1ksUOJg","OW7Gwuz8vTU","NitQnVpvzd4","-QOEEyuKPMY"};
    Context ctx;

    public MyAdapter(Context context) {
        this.ctx = context;
    }

    @Override
    public VideoInfoHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.my_list_view, parent, false);
        return new VideoInfoHolder(itemView);
    }

    @Override
    public void onBindViewHolder(final VideoInfoHolder holder, final int position) {


        final YouTubeThumbnailLoader.OnThumbnailLoadedListener  onThumbnailLoadedListener = new YouTubeThumbnailLoader.OnThumbnailLoadedListener(){
            @Override
            public void onThumbnailError(YouTubeThumbnailView youTubeThumbnailView, YouTubeThumbnailLoader.ErrorReason errorReason) {

            }

            @Override
            public void onThumbnailLoaded(YouTubeThumbnailView youTubeThumbnailView, String s) {
                youTubeThumbnailView.setVisibility(View.VISIBLE);
                holder.relativeLayoutOverYouTubeThumbnailView.setVisibility(View.VISIBLE);
            }
        };

        holder.youTubeThumbnailView.initialize(Resource.KEY, new YouTubeThumbnailView.OnInitializedListener() {
            @Override
            public void onInitializationSuccess(YouTubeThumbnailView youTubeThumbnailView, YouTubeThumbnailLoader youTubeThumbnailLoader) {

                youTubeThumbnailLoader.setVideo(VideoID[position]);
                youTubeThumbnailLoader.setOnThumbnailLoadedListener(onThumbnailLoadedListener);
            }

            @Override
            public void onInitializationFailure(YouTubeThumbnailView youTubeThumbnailView, YouTubeInitializationResult youTubeInitializationResult) {
                //write something for failure
            }
        });
    }

    @Override
    public int getItemCount() {
        return VideoID.length;
    }

    public class VideoInfoHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        protected RelativeLayout relativeLayoutOverYouTubeThumbnailView;
        YouTubeThumbnailView youTubeThumbnailView;
        protected ImageView playButton;

        public VideoInfoHolder(View itemView) {
            super(itemView);
            playButton=(ImageView)itemView.findViewById(R.id.btnYoutube_player);
            playButton.setOnClickListener(this);
            relativeLayoutOverYouTubeThumbnailView = (RelativeLayout) itemView.findViewById(R.id.relativeLayout_over_youtube_thumbnail);
            youTubeThumbnailView = (YouTubeThumbnailView) itemView.findViewById(R.id.youtube_thumbnail);
        }

        @Override
        public void onClick(View v) {

            Intent intent = YouTubeStandalonePlayer.createVideoIntent((Activity) ctx, Resource.KEY, VideoID[getLayoutPosition()]);
            ctx.startActivity(intent);
        }



    }

    private class Resource {
        public static final String KEY = "AIzaSyDOv0yWBimW8L8zIiYfTDYH9_9jFpZWgEw";
    }
    }

每个项目的布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/parent_relativeLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    <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_width="match_parent"
        android:layout_height="wrap_content"
        android:clickable="true"
        android:foreground="@drawable/image_ripple"
        card_view:cardCornerRadius="5dp"
        card_view:cardElevation="0dp"
        android:layout_marginTop="10dp"
        card_view:cardBackgroundColor="@android:color/black"

        card_view:cardPreventCornerOverlap="false"
        card_view:cardUseCompatPadding="true">


        <com.google.android.youtube.player.YouTubeThumbnailView
            android:id="@+id/youtube_thumbnail"
            android:layout_width="match_parent"
            android:layout_height="250dp"
            android:scaleType="centerCrop"
            android:visibility="visible"/>

        <RelativeLayout android:id="@+id/relativeLayout_over_youtube_thumbnail"
            android:layout_width="match_parent"
            android:layout_height="250dp"
            android:background="@color/color_background_transparent"
            android:visibility="visible">

            <ImageView android:id="@+id/btnYoutube_player"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="center"
                android:src="@mipmap/ic_youtube_play_button"/>

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

</RelativeLayout>

主要布局：

 <?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">
 <android.support.v7.widget.RecyclerView
 android:id="@+id/list"
 android:layout_width="match_parent"
 android:layout_height="wrap_content" />

 </LinearLayout>