push notification doesn't show number of messages

Question

I'm following this tutorial and its working fine, but problem is: it shows only the last message and all previous are removed. If I sent 3 messages from the server, it does not show number count as (3) in notification bar. It only displays the last message (all previous are deleted) as well.

public class MainActivity extends Activity {

    // label to display gcm messages
    TextView lblMessage;

    // Asyntask
    AsyncTask<Void, Void, Void> mRegisterTask;

    // Alert dialog manager
    AlertDialogManager alert = new AlertDialogManager();

    // Connection detector
    ConnectionDetector cd;

    public static String name;
    public static String email;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        cd = new ConnectionDetector(getApplicationContext());

        // Check if Internet present
        if (!cd.isConnectingToInternet()) {
            // Internet Connection is not present
            alert.showAlertDialog(MainActivity.this,
                    "Internet Connection Error",
                    "Please connect to working Internet connection", false);
            // stop executing code by return
            return;
        }

        // Getting name, email from intent
        Intent i = getIntent();

        name = i.getStringExtra("name");
        email = i.getStringExtra("email");      

        // Make sure the device has the proper dependencies.
        GCMRegistrar.checkDevice(this);

        // Make sure the manifest was properly set - comment out this line
        // while developing the app, then uncomment it when it's ready.
        GCMRegistrar.checkManifest(this);

        lblMessage = (TextView) findViewById(R.id.lblMessage);

        registerReceiver(mHandleMessageReceiver, new IntentFilter(
                DISPLAY_MESSAGE_ACTION));

        // Get GCM registration id
        final String regId = GCMRegistrar.getRegistrationId(this);

        // Check if regid already presents
        if (regId.equals("")) {
            // Registration is not present, register now with GCM           
            GCMRegistrar.register(this, SENDER_ID);
        } else {
            // Device is already registered on GCM
            if (GCMRegistrar.isRegisteredOnServer(this)) {
                // Skips registration.              
       Toast.makeText(getApplicationContext(),
                                     "Already registered with GCM",Toast.LENGTH_LONG).show();
            } else {
                // Try to register again, but not in the UI thread.
                // It's also necessary to cancel the thread onDestroy(),
                // hence the use of AsyncTask instead of a raw thread.
                final Context context = this;
                mRegisterTask = new AsyncTask<Void, Void, Void>() {

                    @Override
                    protected Void doInBackground(Void... params) {
                        // Register on our server
                        // On server creates a new user
            ServerUtilities.register(context, name, email, regId);
                        return null;
                    }

                    @Override
                    protected void onPostExecute(Void result) {
                        mRegisterTask = null;
                    }

                };
                mRegisterTask.execute(null, null, null);
            }
        }
    }       

    /**
     * Receiving push messages
     * */
    private final BroadcastReceiver mHandleMessageReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String newMessage = intent.getExtras().getString(EXTRA_MESSAGE);
            // Waking up mobile if it is sleeping
            WakeLocker.acquire(getApplicationContext());

            /**
             * Take appropriate action on this message
             * depending upon your app requirement
             * For now i am just displaying it on the screen
             * */

            // Showing received message
            lblMessage.append(newMessage + "\n");           
            Toast.makeText(getApplicationContext(), "New Message: " + newMessage,  
                    Toast.LENGTH_LONG).show();

            // Releasing wake lock
            WakeLocker.release();
        }
    };

    @Override
    protected void onDestroy() {
        if (mRegisterTask != null) {
            mRegisterTask.cancel(true);
        }
        try {
            unregisterReceiver(mHandleMessageReceiver);
            GCMRegistrar.onDestroy(this);
        } catch (Exception e) {
            Log.e("UnRegister Receiver Error", "> " + e.getMessage());
        }
        super.onDestroy();
    }
} 

Answer 1

While posting the notification using notificationManager.notify(0, notification) , the first parameter is notification id ie if you post multiple notification using same id those will be replace with latest one.

If you don't want to replace notifications, generate random number for every notification and use that while posting.

Answer 2

Hope this helps :

private static void generateNotification(Context context, String message, String query)              {

         int icon = R.drawable.icon;
    long when = Calendar.getInstance().getTimeInMillis();
    String appname = context.getResources().getString(R.string.app_name);
    NotificationManager notificationManager = (NotificationManager) context
            .getSystemService(Context.NOTIFICATION_SERVICE);

    Notification notification;

    Intent intent = new Intent(context, activity.class);


    PendingIntent contentIntent = PendingIntent.getActivity(context, 0,
            intent, 0);

            NotificationCompat.Builder builder = new NotificationCompat.Builder(
                    context);
            notification = builder.setContentIntent(contentIntent)
                    .setSmallIcon(icon).setTicker(appname).setWhen(when)
                    .setAutoCancel(true).setContentTitle(appname)
                    .setContentText(message).build();

            notificationManager.notify((int) when, notification);


    }