java - fragment -E/RecyclerView : No adapter attached; skipping layout

Question

我几乎尝试了所有方法，但 Recycleview 没有显示在屏幕上。我不断收到此错误“E/RecyclerView:未连接适配器；跳过布局'。这几天一直在断断续续地尝试解决这个问题。

顺便说一句，我正在使用 Fragment，这可能就是为什么这让我很痛苦。

uploadsFragment.java

private RecyclerView mRecylcerView;
    private ImageAdapter mAdapter;
    private ProgressBar mProgressCircle;
    private DatabaseReference mDatabaseRef;
    private List<Upload> mUploads;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable 
ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_uploads, container, 
false);

        mRecylcerView = 
        (RecyclerView)view.findViewById(R.id.RecyclerView);
        mRecylcerView.setHasFixedSize(true);
        mRecylcerView.setLayoutManager(new 
LinearLayoutManager(getActivity()));
        mProgressCircle =                                     
        (ProgressBar)view.findViewById(R.id.progress_circle2);
    mUploads = new ArrayList<>();
    mDatabaseRef = FirebaseDatabase.getInstance().getReference("uploads");

    mDatabaseRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for(DataSnapshot postSnapshot : dataSnapshot.getChildren()){
                Upload upload = postSnapshot.getValue(Upload.class);
                mUploads.add(upload);
            }

            mAdapter = new ImageAdapter(getActivity(), mUploads);
            mRecylcerView.setHasFixedSize(true);
            mRecylcerView.setLayoutManager(new 
            LinearLayoutManager(getActivity()));
            mRecylcerView.setAdapter(mAdapter);
            mProgressCircle.setVisibility(View.INVISIBLE);
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
            Toast.makeText(getActivity(),databaseError.getMessage(), 
Toast.LENGTH_SHORT).show();
            mProgressCircle.setVisibility(View.INVISIBLE);
        }
    });

    return view;
}

ImageAdapter.java

private Context mContext;
private List<Upload> mUploads;

public ImageAdapter(Context context, List<Upload> upload){
    mContext = context;
    mUploads = upload;
}

@NonNull
@Override
public ImageViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    View view = LayoutInflater.from(mContext).inflate(R.layout.image_item, viewGroup, false);
    return new ImageViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull ImageViewHolder imageViewHolder, int i) {
    Upload uploadCurrent = mUploads.get(i);
    imageViewHolder.textViewName.setText(uploadCurrent.getName());
    Picasso.get()
            .load(uploadCurrent.getmImageUrl())
            .placeholder(R.mipmap.ic_launcher)
            .fit()
            .centerCrop()
            .into(imageViewHolder.imageView);
}

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

public class ImageViewHolder extends RecyclerView.ViewHolder{

    public TextView textViewName;
    public ImageView imageView;

    public ImageViewHolder(@NonNull View itemView) {
        super(itemView);

        textViewName = itemView.findViewById(R.id.text_view_name);
        imageView = itemView.findViewById(R.id.image_view_upload);
    }
}

Answer 1

在收到 Firebase 查询的响应后，您正在使用 RecyclerView 设置适配器。

1. 因此，首先请确保您的 Firebase 查询返回成功的响应。
2. 收到响应后检查“mUploads”列表是否不为空。