ViewHolder 不显示数据

Question

我想根据帖子的时间戳对帖子进行排序。帖子包含标题和描述。我正在使用 firebase 检索数据。但是视图中没有显示任何内容。视图为空白。有什么我做错了吗？

public class AlertsActivity extends AppCompatActivity {
    public static class BlogViewHolder extends RecyclerView.ViewHolder {
        View mview;
        public BlogViewHolder(View itemView) {
            super(itemView);
            mview = itemView;
        }

        public void setTitle(String title) {
            TextView post_title = (TextView)mview.findViewById(R.id.blog_title);
            post_title.setText(title);

        }

        public void setDesp(String desp) {
            TextView post_desp = (TextView) mview.findViewById(R.id.blog_desp);
            post_desp.setText(desp);
        }


        public void setTimestampCreated(HashMap<String, Object> timestamp) {
            TextView show_ts = (TextView) mview.findViewById(blog_timestamp);
            show_ts.setText(String.valueOf(timestamp));
        }
    }

适配器：

      mDatabase = FirebaseDatabase.getInstance().getReference().child("Blog");
      mDatabase.keepSynced(true);
      mDatabase.orderByChild("timestamp");        

      FirebaseRecyclerAdapter<Blog, BlogViewHolder> firebaseRecyclerAdapter = new
            FirebaseRecyclerAdapter<Blog, BlogViewHolder>(
                    Blog.class,
                    R.layout.blog_row,
                    BlogViewHolder.class, mDatabase) {
                @Override
                protected void populateViewHolder(final BlogViewHolder viewHolder, final Blog model, int position) {
                    mDatabase.child("Blog").orderByChild("timestamp").addValueEventListener(new ValueEventListener() {

                        @Override
                        public void onDataChange(DataSnapshot dataSnapshot) {
                            String alerts = dataSnapshot.getValue(String.class);
                            HashMap<String, Object> time = (HashMap<String, Object>) dataSnapshot.getValue();
                            viewHolder.setTitle(alerts);
                            viewHolder.setDesp(alerts);
                            viewHolder.setTimestampCreated(time);
                        }


                        @Override
                        public void onCancelled(DatabaseError databaseError) {

                        }
                    });
                }
            };
    mbloglist.setAdapter(firebaseRecyclerAdapter);
    }

数据库图片： https://i.stack.imgur.com/GNouK.png

Answer 1

对于这样一个简单的结构，您的代码看起来太复杂了。使用 FirebaseUI 中的适配器的主要目的是让您不必自己处理侦听器。据我所知，您只需要：

mDatabase = FirebaseDatabase.getInstance().getReference().child("Blog");
Query orderedBlogs = mDatabase.orderByChild("timestamp");        

FirebaseRecyclerAdapter<Blog, BlogViewHolder> firebaseRecyclerAdapter = new
        FirebaseRecyclerAdapter<Blog, BlogViewHolder>(
                Blog.class,
                R.layout.blog_row,
                BlogViewHolder.class, orderedBlogs) {
    @Override
    protected void populateViewHolder(BlogViewHolder viewHolder, Blog model, int position) {
        viewHolder.setTitle(blog.title);
        viewHolder.setDesp(blog.desp);
        viewHolder.setTimestampCreated(blog.timestamp);
    }
};
mbloglist.setAdapter(firebaseRecyclerAdapter);

这是对应的最小Blog类：

public class Blog {
  public String desp;
  public long timestamp;
  public string title;
}