Recyclerview未更新屏幕onNotifydatasetchanged

Question

我与recyclerview聊天应用程序，它工作正常，直到我从通知回到聊天屏幕，当我从通知聊天屏幕我可以发送消息给其他用户和其他用户可以发送消息给我但聊天屏幕根本不更新我是发送消息还是收到消息。有一个名为chatDatabase()的功能我注意到，如果我评论该功能，那么即使我从通知进入聊天屏幕，屏幕也能正常工作而没有任何问题。但我无法弄清楚为什么它不能与chatDatabase()

一起使用

ChatScreenFragment

    public class Chat_Screen_Fragment extends Fragment implements View.OnClickListener, ChildEventListener{

    public static final String TAG = "###CHAT SCREEN###";

    List<Chat_Wrapper> message = new ArrayList<>();


    Chat_Adapter adapter;
    RecyclerView recyclerView;
    LinearLayoutManager layoutManager;


    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View v=inflater.inflate(R.layout.chat_screen_main_fragment,container,false);
        setRetainInstance(true);



        // GET INTENT VALUES FROM USER PROFILE CLASS

        UserName_Intent = getArguments().getString("Get_Name");
        UserImage_Intent = getArguments().getString("Get_Image");
        UserPhone_Intent = getArguments().getString("Get_Phone");
        UserID_Intent = getArguments().getString("Get_ID");
        FirebaseToken_Intent = getArguments().getString("Get_Token"); //Firebase Token of other person
        Room_Name_Intent = getArguments().getString("Get_Other"); // Room Name of chat
        UserLastSeen_Intent=getArguments().getString("LastSeen");
        //Sender_FCMToken = Session.getFirebaseID();







        // RECYCLER VIEW
        recyclerView = v.findViewById(R.id.Chat_Screen_Message_List);
        layoutManager = new LinearLayoutManager(getActivity());
        layoutManager.setStackFromEnd(true);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(layoutManager);
databaseReference = FirebaseDatabase.getInstance().getReference().child(Room_Name_Intent);
        databaseReference.addChildEventListener(this);

        adapter = new Chat_Adapter(getActivity(), message);
        recyclerView.setAdapter(adapter);
        // FETCH OLD MESSAGE FROM DATABASE
        chatDatabase();
        return v;
    }



    // FIREBASE REAL TIME DATABASE WHICH FETCH ALL MESSAGES (SYNC) FROM ONLINE DATABASE
    @Override
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        append_chat_conversation(dataSnapshot);
    }

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

    @Override
    public void onChildRemoved(DataSnapshot dataSnapshot) {

    }

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

    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }





    private synchronized void append_chat_conversation(DataSnapshot dataSnapshot) {
        iterator = dataSnapshot.getChildren().iterator();


        while (iterator.hasNext()) {
            // NOW GET ALL DATA FROM FIREBASE DATABASE AND SAVE IT INTO STRINGS THEN CHECK EACH BY ITS MESSAGE TYPE
            Chat_Msg = (String) ((DataSnapshot) iterator.next()).getValue();
            Chat_FROM = (String) ((DataSnapshot) iterator.next()).getValue();
            Chat_FCM_TO= (String) ((DataSnapshot) iterator.next()).getValue();

            Chat_Database tempChatDatabase = new Chat_Database(getActivity());
            boolean hasValue=tempChatDatabase.CheckValueExist(_ID);


            if (!hasValue) {
                Log.d(TAG,"Chat Message "+Chat_Msg);


                    long id=chat_database.Insert_Chat(Session.getUserID(),Room_Name_Intent, UserID_Intent, "Text", Chat_Msg, Chat_FROM, Chat_TO, Chat_TimeStamp, Chat_FCM_FROM, Chat_FCM_TO, Session.getPhoneNO(), UserPhone_Intent,Random_ID,UserImage_Intent,UserLastSeen_Intent,Chat_FROM_ID);

                    //Adding Chat Data Into Database
                    Log.d(TAG,"Database Entry ID "+id);
                    if (id==0){
                        Log.d(TAG,"Database Already Has Value Of This Random Id ");
                        return;
                    }
                    Chat_Wrapper chat_wrapper = new Chat_Wrapper(Chat_Msg, null, null, null, null, null, null, Chat_TimeStamp, User_Intent, UserImage_Intent, Chat_FROM, null,null,id);
                    message.add(chat_wrapper);
                  adapter.notifyDataSetChanged();
                Log.d(TAG, "FIREBASE STORAGE PHOTO-3-MESSAGE ARRAY SIZE " + message.size());
                recyclerView.post(new Runnable() {
                    @Override
                    public void run() {
                        Log.d(TAG, "Moving to Bottom");
                        recyclerView.smoothScrollToPosition(adapter.getItemCount());

                    }
                });

                }               

                }

            }

            Log.d(TAG, "MESSAGE ARRAY SIZE " + message.size());

            tempChatDatabase.isDatabaseClose();
        }

        adapter.notifyDataSetChanged();
        recyclerView.post(new Runnable() {
            @Override
            public void run() {
                Log.d(TAG, "Moving to Bottom");
                recyclerView.smoothScrollToPosition(message.size()-1);
                //recyclerView.smoothScrollToPosition(adapter.getItemCount());

            }
        });
    }



    private void chatDatabase(){
        //Database Init and Filling Adapter
        Log.d(TAG,"Chat Database Function");
        chat_database=new Chat_Database(getActivity());
        chatCursor=chat_database.getUserChat(UserID_Intent);
        boolean checkDB_Exist=functions.DatabaseExist(getActivity(),"CHAT_DATABASE.DB");
        boolean chatItemsCounts=chatCursor.getCount()>0;
        chatCursor.moveToFirst();
        Log.d(TAG,"Value At Chat Database "+ checkDB_Exist+" "+chatItemsCounts);
        if (checkDB_Exist && chatCursor.getCount()>0 && chatCursor.getString(chatCursor.getColumnIndex("RECEIVER_USER_ID")).equals(UserID_Intent)){

            Log.d(TAG,"Database Exist Chat Database");
            message.clear();
            chatCursor.moveToFirst();
            do {
                database_rowID=chatCursor.getInt(chatCursor.getColumnIndex("ID"));
                database_userID=chatCursor.getString(chatCursor.getColumnIndex("USER_ID"));
                database_RoomName =chatCursor.getString(chatCursor.getColumnIndex("ROOM_NAME"));
                database_ReceiverID=chatCursor.getString(chatCursor.getColumnIndex("RECEIVER_USER_ID"));
                database_MessageType=chatCursor.getString(chatCursor.getColumnIndex("MESSAGE_TYPE"));
                database_Message=chatCursor.getString(chatCursor.getColumnIndex("USER_MESSAGE"));
                database_MsgFrom=chatCursor.getString(chatCursor.getColumnIndex("SENDER_NAME"));
                database_MsgTo=chatCursor.getString(chatCursor.getColumnIndex("RECEIVER_NAME"));
                database_TimeStamp=chatCursor.getString(chatCursor.getColumnIndex("TIME_STAMP"));
                database_FCMfrom=chatCursor.getString(chatCursor.getColumnIndex("SENDER_TOKEN"));
                database_FCMto=chatCursor.getString(chatCursor.getColumnIndex("RECEIVER_TOKEN"));
                database_LocalPath=chatCursor.getString(chatCursor.getColumnIndex("DOWNLOADED_AT"));
                database_PhoneFrom=chatCursor.getString(chatCursor.getColumnIndex("MY_PHONE"));
                database_PhoneTo=chatCursor.getString(chatCursor.getColumnIndex("OTHER_PHONE"));

                Log.d(TAG,"Value Of Database Message String = "+database_Message);
                Log.d(TAG,"Row ID of Database "+database_rowID);
                // Check Message Type


                    Log.d(TAG,"Message Type Is Text");
                    Chat_Wrapper text = new Chat_Wrapper(database_Message, null, null, null, null, null, null, database_TimeStamp, database_PhoneTo, UserImage_Intent, database_MsgFrom,null,null,database_rowID);
                    message.add(text);



            }
            while(chatCursor.moveToNext());

            Room_Name_Intent = database_RoomName;
            layoutManager = new LinearLayoutManager(getActivity());
            recyclerView.setLayoutManager(layoutManager);
            adapter.notifyDataSetChanged();
            chatCursor.close();
            boolean value = chat_database.isDatabaseClose();
            recyclerView.post(new Runnable() {
                @Override
                public void run() {
                    Log.d(TAG, "Moving to Bottom");
                    recyclerView.smoothScrollToPosition(message.size()-1);

                }
            });
            Log.d(TAG,"Value Of Database Close or Not "+value);

        }
    }
}

更新：我只是退出并再次登录，然后从通知进入聊天屏幕，然后工作正常。此外，如果我从最近的应用程序中删除应用程序然后它也工作，但我仍然无法理解，为什么它发生。

Answer 1

我查看了您的chatDatabase函数，并在您在适配器上调用notifyDataSetChanged之前发现了一些可疑行为。我在我自己的项目中进行了测试，并注意到如果我在设置之后尝试在RecyclerView上设置LayoutManager，我的渲染也会停止。

您可以在开始时使用它设置您的RecyclerView，因此只要chatDatabase功能没有任何其他问题，删除新的调用就可以解决问题。如果从chatDatabase函数中删除LayoutManager行解决问题，请告诉我们。

layoutManager = new LinearLayoutManager(getActivity()); recyclerView.setLayoutManager(layoutManager); adapter.notifyDataSetChanged();