I make a chat room with AsyncTask for receive messages, so it always checking the coming messages and show it to client, but the code seems not works what i hope.   

in client only show all old datas, for the new datas not show up.
because when I try to send messages from server, the new data didn't show in client.   

I got confused with this problem, and really need help. anyone please help me, thank you.

AsyncTask for receive

```
public class ReceivedTask extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {

        }

        @Override
        protected String doInBackground(String... arg0) {
            // TODO Auto-generated method stub
            try{
                HttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(SERVER_URL);
                ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
                //add parameter
                    httpPost.setEntity(new UrlEncodedFormEntity(param));

                    HttpResponse httpRespose = httpClient.execute(httpPost);
                    HttpEntity httpEntity = httpRespose.getEntity();

                    //read content
                    InputStream in = httpEntity.getContent();
                    BufferedReader read = new BufferedReader(new InputStreamReader(in));

                    String content = "";
                    String line = "";

                    while((line = read.readLine())!=null){
                       content += line;
                    }
                   Log.d("ADBUG", "content: "+content);

                   //json
                    if(!content.equals("null")){
                        try{
                            JSONArray jArr = new JSONArray(content);

                              //String messages="";
                              for(int i=0; i < jArr.length() ; i++){ 
                                  JSONObject jObj = jArr.getJSONObject(i);

                                     String message = jObj.getString("message");

                                     showMessage(message, false);
                              }

                        }catch(JSONException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                    else{
                        Toast.makeText(ChatRoom.this, "Error", Toast.LENGTH_LONG).show();
                     }
            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();}
            catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            return null;

                }
        }

```

the whole code

```
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.chatpage);

        messagesContainer = (ViewGroup) findViewById(R.id.messagesContainer);
        scrollContainer = (ScrollView) findViewById(R.id.scrollContainer);

        Button sendMessageButton = (Button) findViewById(R.id.sendButton);

        Bundle bundle = this.getIntent().getExtras();
        /*final String paramnama = bundle.getString("nama");*/
        messageText = (EditText) findViewById(R.id.messageEdit);
        meLabel = (TextView) findViewById(R.id.meLabel);
        friendLabel = (TextView) findViewById(R.id.friendLabel);
        meLabel.setText("me");

        final String param1 = bundle.getString("keyCourseId");
        final String param2 = bundle.getString("keyUserId");
        final String param3 = bundle.getString("keyChatsId");
         String param4 = bundle.getString("keyMessagesId");

        sendMessageButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                //for send part already works fine

        });

        HttpURLConnection connection;
        URL url = null;
        try{
            linkurl = new Koneksi(this);
            SERVER_URL = linkurl.getUrl();
            SERVER_URL += "/mobile/ChatRoom.php?idu="+param2+"&idch="+param3;
            url = new URL(SERVER_URL);
            connection = (HttpURLConnection) url.openConnection();
            connection.setDoOutput(true);
            connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            connection.setRequestMethod("POST");
            new ReceivedTask().execute();

            }
        catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

            }

    public class ReceivedTask extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {

        }

        @Override
        protected String doInBackground(String... arg0) {
            // TODO Auto-generated method stub
            try{
                HttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(SERVER_URL);
                ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
                //add parameter
                    httpPost.setEntity(new UrlEncodedFormEntity(param));

                    HttpResponse httpRespose = httpClient.execute(httpPost);
                    HttpEntity httpEntity = httpRespose.getEntity();

                    //read content
                    InputStream in = httpEntity.getContent();
                    BufferedReader read = new BufferedReader(new InputStreamReader(in));

                    String content = "";
                    String line = "";

                    while((line = read.readLine())!=null){
                       content += line;
                    }
                   Log.d("ADBUG", "content: "+content);

                   //json
                    if(!content.equals("null")){
                        try{
                            JSONArray jArr = new JSONArray(content);

                             // String messages="";
                              for(int i=0; i < jArr.length() ; i++){ 
                                  JSONObject jObj = jArr.getJSONObject(i);

                                     String message = jObj.getString("message");

                                     showMessage(message, false);
                              }
                        }catch(JSONException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                    else{
                        Toast.makeText(ChatRoom.this, "Error", Toast.LENGTH_LONG).show();
                     }
            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();}
            catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            return null;

                }
        }

    public void showMessage(String message, boolean leftSide) {
        final TextView textView = new TextView(ChatRoom.this);
        textView.setTextColor(Color.BLACK);
        textView.setText(message);

        int bgRes = R.drawable.left_message_bg;

        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);

        if (!leftSide) {
            bgRes = R.drawable.right_message_bg;
            params.gravity = Gravity.RIGHT;
        }

        textView.setLayoutParams(params);

        textView.setBackgroundResource(bgRes);

        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                messagesContainer.addView(textView);

                // Scroll to bottom
                if (scrollContainer.getChildAt(0) != null) {
                    scrollContainer.scrollTo(scrollContainer.getScrollX(), scrollContainer.getChildAt(0).getHeight());
                }
                scrollContainer.fullScroll(View.FOCUS_DOWN);
            }
        });
    }

```