Updating listview isn't working

Question

So basically I'm collecting data from a json url in my listview. It's a chatroom type of app and in the lists I want to sync the chatroom contact lists with latest message and timestamps.

When the json gets updated I'm calling the fuction.

 public void addGroupAdapter() {
        Firebase jsonurl = new Firebase("firebase url");
        jsonurl.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                ContactListAdapter adapter = new ContactListAdapter(getContext(),dataSnapshot);
            try {
                Log.i("Response Array fire",new JSONArray(dataSnapshot.getValue(String.class)).toString());
                if (!adapted){
                    chatLists.setAdapter(adapter);
                    adapted = true;
                }else {
                    Log.i("update",dataSnapshot.getValue(String.class));
                    adapter.setContactList(dataSnapshot);
                }

            } catch (JSONException e) {
                e.printStackTrace();
            }
            }

            @Override
            public void onCancelled(FirebaseError firebaseError) {

            }
        });

That Json data is stored in the firebase database .

chatLists.setAdapter(adapter) works well.

But when I try to update. notifyDataSetChanged(); doesn't work.

 new ContactListAdapter(getContext(),dataSnapshot).notifyDataSetChanged();

I also tried invalidateviews method and same result. So where am I doing wrong?

After reading answers I tried this. SO now this my adapter class,

class ContactListAdapter extends BaseAdapter {
        Context c;
        List lists;
        Type type = new TypeToken<List<ChatroomLists>>(){}.getType();
        JsonParser parser = new JsonParser();
        ArrayList<ChatroomLists> ob1 = new ArrayList<ChatroomLists>();

        public void setContactList(DataSnapshot dataSnapshot) {
            Type listType = new TypeToken<ArrayList<ChatroomLists>>() {
            }.getType();
            ob1 = new Gson().fromJson((JsonArray)parser.parse(dataSnapshot.getValue(String.class)),listType);
        Log.i("setContactList",dataSnapshot.getValue(String.class));

            notifyDataSetChanged();
        }

        ContactListAdapter(Context c, DataSnapshot group_name) {
            this.c = c;
            this.groupids = group_name;
            Type listType = new TypeToken<ArrayList<ChatroomLists>>() {
            }.getType();
            ob1 = new Gson().fromJson((JsonArray)parser.parse(group_name.getValue(String.class)),listType);



        }


        @Override
        public int getCount() {

            return ob1.size();
        }

        @Override
        public Object getItem(int position) {
            return position;
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(final int position, View convertView, ViewGroup parent) {

            View row = convertView;
            GroupChat.viewHolder holder = null;

            if (row == null) {
                LayoutInflater inflater = (LayoutInflater) c.getSystemService (Context.LAYOUT_INFLATER_SERVICE);
                row = inflater.inflate (R.layout.chat_list_style, parent, false);
                holder = new GroupChat.viewHolder(row);
                row.setTag (holder);
            } else {
                holder = (GroupChat.viewHolder) row.getTag ();

            }

            ChatroomLists chatroomLists =  ob1.get(position);
            Iterator<ChatroomLists> iter = ob1.iterator();
            String id = chatroomLists.getId();
            String time = chatroomLists.getTimestamp();
            Log.i("updated data",id + time);

            viewHolder finalHolder = holder;
            Firebase chatlink = new Firebase ("firebase link");
            chatlink.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    for (DataSnapshot d: dataSnapshot.getChildren()){
                        finalHolder.user_message.setText (dataSnapshot.child(d.getKey()).child("message").getValue(String.class));

                    }
                }

                @Override
                public void onCancelled(FirebaseError firebaseError) {

                }
            });


            Firebase imageurl = new Firebase("firebase link");
            imageurl.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    Glide.with (getActivity ())
                            .load (dataSnapshot.getValue(String.class))
                            .error (R.drawable.man)
                            .into (finalHolder.user_img);
                }

                @Override
                public void onCancelled(FirebaseError firebaseError) {

                }
            });

            holder.user_name.setText (id);

            row.setOnClickListener (new View.OnClickListener () {
                @Override
                public void onClick(View v) {
                    Intent intent = new Intent (getActivity (), ChatRoom.class);
                    intent.putExtra ("group_name", id);
                    startActivity (intent);
                }
            });
            registerForContextMenu (row);
            return row;
        }
    }

But it's still not updating.. :(

UPDATE: Listview was so buggy in this case. And I changed to Recyclerview. Now everything is working smoothly.

Answer 1

This is because you are creating new adapter instance instead of updating data on existing adapter which is set on list/recyclerview.

    private ContactListAdapter mAdatper;

    public void addGroupAdapter() {
        Firebase jsonurl = new Firebase("firebase url");
        jsonurl.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                try {
                    Log.i("Response Array fire",new JSONArray(dataSnapshot.getValue(String.class)).toString());
                    if (!adapted){
                        mAdatper = new ContactListAdapter(getContext(),dataSnapshot);
                        chatLists.setAdapter(mAdapter);
                        adapted = true;
                    }else {
                        Log.i("update",dataSnapshot.getValue(String.class));
                        mAdatper.setContactList(dataSnapshot);                
                    }

                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onCancelled(FirebaseError firebaseError) {

            }
        });
    }

In your adapter, add setter method.

public void setContactList(DataSnapshot dataSnapshot) {
    // set contactList here
    notifyDataSetChanged();
}

Hope it might be helpful for you.

Answer 2

In your else case you are creating a new ContactListAdapter but you are not attaching that adapter to your chatLists. Anyway, you do not need to create a new CustomAdapter instance, just create a update method within your CustomAdapter and call it passing new dataSnapshot data.

You can Try something as the following inside your CustomAdapter.java:

public void updateData(Data data) {
    this.dataList = data;
    notifyDataSetChanged();
}

Then back into your addGroupAdapter method just call that method

Answer 3

You are calling notifyDataSetChanged() on a new instance of the adapter everytime. You should call it on the same adapter that you set on the list. And you should update the data in that particular instance of the adapter