java - fragment 不会显示多个项目

Question

我创建了一个 Android 聊天应用程序，其中包含 Firebase 并创建了一个包含当前用户消息的 fragment 。当用户向多个人发送消息时，会发生此错误，并且以下图像链接显示了第一条消息的显示方式，而最新的消息则不可见。有谁知道为什么会这样？我将在下面列出我的一些类(class)。

我的 firebase 显示如下，消息首先包含用户 ID、收件人 ID，然后是唯一消息 ID，后面是实际消息和发送者。

fragment 类

public class ChatFragment extends Fragment {


private RecyclerView convList;
private FirebaseAuth auth;
private DatabaseReference userDatabase, messageDatabase;
private View view;

public ChatFragment() {
    // Required empty public constructor
}

// Chat Fragment initialised
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    view = inflater.inflate(R.layout.fragment_chat, container, false);

    convList = (RecyclerView) view.findViewById(R.id.conv_list);
    convList.setHasFixedSize(true);
    convList.setLayoutManager(new LinearLayoutManager(getContext()));

    auth = FirebaseAuth.getInstance();

    String currentUser;
    currentUser = auth.getCurrentUser().getUid();

    messageDatabase = FirebaseDatabase.getInstance().getReference().child("Messages").child(currentUser);
    messageDatabase.keepSynced(true);
    userDatabase = FirebaseDatabase.getInstance().getReference().child("Users");
    userDatabase.keepSynced(true);

    return view;
}

// Use FirebaseRecyclerAdapter to populate each user of which messages have been sent between, the latest message sent between each user displayed, ordering the list by most recent message and the user's online status
@Override
public void onStart() {
    super.onStart();

    Query conversationQuery = messageDatabase.orderByChild("time");

    FirebaseRecyclerAdapter<UserConversation, ConvViewHolder> friendsRecyclerViewAdapter = new FirebaseRecyclerAdapter<UserConversation, ConvViewHolder>(

            UserConversation.class,
            R.layout.activity_user_list,
            ConvViewHolder.class,
            conversationQuery

    ) {
        @Override
        protected void populateViewHolder(final ConvViewHolder friendsViewHolder, final UserConversation friends, int i) {

            final String user_id = getRef(i).getKey();

            Query lastMessageQuery = messageDatabase.child(user_id).limitToLast(1);

            // Retrieving data stored in Firebase for each message and its information
            lastMessageQuery.addChildEventListener(new ChildEventListener() {
                @Override
                public void onChildAdded(DataSnapshot dataSnapshot, String s) {

                    String data = dataSnapshot.child("message").getValue().toString();
                    ConvViewHolder.setMessage(data);

                    String time = dataSnapshot.child("time").getValue().toString();
                    ConvViewHolder.setTime(time);

                }

                @Override
                public void onChildChanged(DataSnapshot dataSnapshot, String s) {

                }

                @Override
                public void onChildRemoved(DataSnapshot dataSnapshot) {

                }

                @Override
                public void onChildMoved(DataSnapshot dataSnapshot, String s) {

                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

            userDatabase.child(user_id).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {

                    final String userName = dataSnapshot.child("name").getValue().toString();
                    String userThumb = dataSnapshot.child("thumb_image").getValue().toString();
                    String online = dataSnapshot.child("online").getValue().toString();

                    friendsViewHolder.setName(userName);
                    friendsViewHolder.setUserImage(userThumb, getContext());
                    friendsViewHolder.setUserOnline(online);

                    friendsViewHolder.mView.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {

                            Intent intent = new Intent(getContext(), Messenger.class);
                            intent.putExtra("user_id", user_id);
                            intent.putExtra("user_name", userName);
                            try {
                                startActivity(intent);
                            }
                            catch (ActivityNotFoundException e) {
                                Log.i("Activity Not Found", "Error");
                            }
                        }
                    });
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

        }
    };

    convList.setAdapter(friendsRecyclerViewAdapter);

}


public static class ConvViewHolder extends RecyclerView.ViewHolder {

    static View mView;

    public ConvViewHolder(View itemView) {
        super(itemView);

        mView = itemView;

    }

    public static void setMessage(String message){

        TextView userStatusView = (TextView) mView.findViewById(R.id.user_single_status);
        userStatusView.setText(message);
    }

    public void setName(String name) {

        TextView userNameView = (TextView) mView.findViewById(R.id.user_single_name);
        userNameView.setText(name);

    }

    public void setUserImage(String thumb_image, Context ctx) {

        CircleImageView userImageView = (CircleImageView) mView.findViewById(R.id.user_single_image);
        Picasso.with(ctx).load(thumb_image).placeholder(R.drawable.default_avatar).into(userImageView);

    }

    public static void setTime (String time){
        TextView test = (TextView) mView.findViewById(R.id.time_sent);
        test.setText(DateFormat.format("dd-MM-yyyy (HH:mm:ss)", Long.parseLong(time)));
    }

    public void setUserOnline(String online) {

        ImageView userOnlineView = (ImageView) mView.findViewById(R.id.user_single_online_icon);

        if(online.equals("true")){

            userOnlineView.setVisibility(View.VISIBLE);

        } else {

            userOnlineView.setVisibility(View.INVISIBLE);

        }

    }
}

Answer 1

正如我在您的代码中看到的，您使用的是旧版本的 Firebase-UI 库，其中由于错误，您明确不需要使用固定大小。为了在 RecyclerView 中显示数据，请删除/注释以下代码行:

convList.setHasFixedSize(true);

请参阅here更多信息。