我正在使用YouTube数据API v3在我的应用中搜索YouTube视频。 昨晚工作正常，但现在当我单击搜索按钮时，它仍然崩溃。有人可以帮我吗？

我尝试重新生成API密钥，但存在相同的错误

当我更改为：返回mVideoList.size();

  

错误是：E / AndroidRuntime：致命异常：main
  流程：com.example.youtubeexampleproject，PID：7031

     

java.lang.NullPointerException：尝试在

的空对象引用上调用接口方法'int java.util.List.size（）'。      

YoutubeAdapter.getItemCount（YoutubeAdapter.java:108）指针指向：return mVideolist.size（）;

，对于以下错误，代码为：

{
      "code" : 400,"errors" : [ {    
        "domain" : "global","location" : "fields","locationType" : "parameter","message" : "Invalid field selection activity","reason" : "invalidParameter"   
      } ],"message" : "Invalid field selection activity"
    }

'

query = youtube.search（）。list（“ id，snippet”）;

        query.setKey(KEY);



        query.setType("video");


        query.setfields("items(id/kind,id/videoId,snippet/title,snippet/description,snippet/thumbnails/high/url/activity)");

    } catch (IOException e) {


        Log.d("YC","Could not initialize: " + e);
    }
}

public List<VideoItem> search(String keywords) {


    query.setQ(keywords);


    query.setMaxResults(MAXRESULTS);

    try {


        SearchListResponse response = query.execute();


        List<SearchResult> results = response.getItems();


        List<VideoItem> items = new ArrayList<VideoItem>();


        if (results != null) {


            items = setItemsList(results.iterator());
        }

        return items;

公共类YoutubeAdapter扩展了RecyclerView.Adapter {

private Context mContext;
private List<VideoItem> mVideoList;


public class MyViewHolder extends RecyclerView.ViewHolder{

    public ImageView thumbnail;
    public TextView video_title,video_id,video_description;
    public RelativeLayout video_view;

    public MyViewHolder(View view) {

        super(view);


        thumbnail =  view.findViewById(R.id.video_thumbnail);
        video_title =  view.findViewById(R.id.video_title);
        video_id = view.findViewById(R.id.video_id);
        video_description =  view.findViewById(R.id.video_description);
        video_view =  view.findViewById(R.id.video_view);
    }
}


public YoutubeAdapter(Context mContext,List<VideoItem> mVideoList) {
    this.mContext = mContext;
    this.mVideoList = mVideoList;
}


@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent,int viewType) {


    View itemView = LayoutInflater.from(parent.getcontext())
            .inflate(R.layout.video_item,parent,false);

    return new MyViewHolder(itemView);
}


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


    final VideoItem singleVideo = mVideoList.get(position);


    holder.video_id.setText("Video ID : "+singleVideo.getId()+" ");
    holder.video_title.setText(singleVideo.getTitle());
    holder.video_description.setText(singleVideo.getDescription());


    Picasso.get()
            .load(singleVideo.getThumbnailURL()).resize(480,270)
            .centerCrop()
            .into(holder.thumbnail);


    holder.video_view.setOnClicklistener(new View.OnClicklistener() {


        @Override
        public void onClick(View view) {


            Intent intent = new Intent();
            intent.setClass(mContext,Playeractivity.class);


            intent.putExtra("VIDEO_ID",singleVideo.getId());
            intent.putExtra("VIDEO_TITLE",singleVideo.getTitle());
            intent.putExtra("VIDEO_DESC",singleVideo.getDescription());

            intent.addflags(Intent.flaG_actIVITY_NEW_TASK);


            mContext.startactivity(intent);


        }
    });
}

@Override

  public int getItemCount() {    



       return mVideoList == null ? 0 : mVideoList.size();   


   }  
}'