如何在完成之前从AsyncTask更新ListView

Question

I have a client application that uses sockets and input/output stream to communicate with a server and ask for some data. I've created an AsyncTask and on doInBackground() of it I make the connection and send/receive data.
doInBackground():

@Override
        protected Object doInBackground(Object... objIn) {

            // we create a TCPClient object and
            client = new T_Client(new T_Client.OnMessageReceived() {
                @Override
                // here the messageReceived method is implemented
                public void messageReceived(Object objIn) {
                    Log.v(tagTask, "Object Received: " + objIn);                        
                        Log.w(tagTask, "Object returned: " + objIn);
                        mapReturn = (Map<String, Integer>) objIn;
                        Log.i(tagTask, "Map Object Returned: " + mapReturn);
                        onProgressUpdate();                     
                }
            });
            client.run();

            return objIn;
        }

User is a simple class to help me process the data I get from the server. I get a Map from the server as a "Users List",which I want to display in a ListView on my Main Activity, with Username(String) and OnLine status(Integer) and I pass it to a local Map object. Then I call the onProgressUpdate() method of my AsyncTask.
onProgressUpdate():

@Override
        protected void onProgressUpdate(Void... voids) {
            super.onProgressUpdate();

            for (Entry<String, Integer> entry : mapReturn.entrySet()) {
                if (entry.getValue() == 1) {
                    User user = new User(entry.getKey(), "YES");
                    Log.v(tagTask, "UserName: " + user.getUser());
                    Log.v(tagTask, "Online Status : " + user.getOnLine());
                    listUsers.add(user);
                } else if (entry.getValue() == 0) {
                    User user = new User(entry.getKey(), "NO");
                    Log.v(tagTask, "UserName: " + user.getUser());
                    Log.v(tagTask, "Online Status : " + user.getOnLine());
                    listUsers.add(user);
                }
            }

             mAdapter.notifyDataSetChanged();
        }

    }

In here, I iterate through the Map object's entries and for each entry I create a User object and then add the user object to my ArrayList "listUsers", which is the array list I use for my ListView's adapter. Now when I run the mAdapter.notifyDataSetChanged() of course I get an error because I'm trying to update my main UI, not from the main UI thread. The reason that I can't use the onPostExecute() method is because I keep doInBackground() running(client.run()). And the reason I do that is because I have to keep the connection between the server and the client alive so that I can ask for data from the server and the server to send those data.

So I'm asking you guys if there is a way to update my ListView before the AsyncTask completes(which in this case, it'll never get to onPostExecute);

PS I've noticed something strange that I can't explain. When I tap on an EditText that I have in my activity, and the keyboard pops up, the ListView updates and I can see my data.

Answer 1

The reason that I can't use the onPostExecute() method is because I keep doInBackground() running(client.run()).

IMHO, that is an inappropriate use of AsyncTask . Do not tie up a resource from a resource pool indefinitely, when you are not the one who create and manage the pool.

Instead, create your own thread. Then use Handler to pass messages to code of yours that runs on the main application thread, to update your list.