java Firebase回收器视图适配器（从Firebase检索）

Question

我无法使用Firebase回收器适配器显示。我希望你能帮我解决我的问题

main活动

    FirebaseRecyclerOptions<Blog> options =
            new FirebaseRecyclerOptions.Builder<Blog>()
                    .setQuery(mDatabase, Blog.class)
                    .build();
FirebaseRecyclerAdapter<Blog, BlogViewHolder> firebaseRecyclerAdapter = new 
FirebaseRecyclerAdapter<Blog, BlogViewHolder>(options) {
@Override
protected void onBindViewHolder(@NonNull BlogViewHolder holder, int 
position, @NonNull Blog model) {
    holder.post_title.setText(model.getTitle());
    holder.post_desc.setText(model.getDesc());
}
@NonNull
@Override
public BlogViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int 
viewType) {
   BlogViewHolder viewHolder = null;
        return viewHolder;
}
};
    mBlogList.setAdapter(firebaseRecyclerAdapter);
}
public static class BlogViewHolder extends RecyclerView.ViewHolder{
   View mView;
   private TextView post_title,post_desc;
    public BlogViewHolder(View itemView) {
        super(itemView);
        mView = itemView;
    }
    public void setTitle(String title){
       post_title = mView.findViewById(R.id.post_title);
       post_title.setText(title);
    }
    public void setDesc (String desc){
        post_desc = mView.findViewById(R.id.post_desc);
        post_desc.setText(desc);
    }
}

Blog是我的模型类，所有内容都在那里初始化。所有的getter和setter，包括构造函数

Answer 1

问题在于这些方面：

@NonNull
@Override
public BlogViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    BlogViewHolder viewHolder = null;
    return viewHolder;
}

您正在返回null。应该是这样的：

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    ViewHolder viewHolder = super.onCreateViewHolder(parent, viewType);
    return viewHolder;
}