Zsolt, the methods are defined as follows:
- receiveMessage() - Service Class - showTrafficMessages() - Activity Class - updateOverlay - ItemizedOverlay Class The receiveMessage() method is called in the run method of the receiving thread object. I see now that other methods are then executed in the receiving thread (due to callback) as well. I will check out the Handler and get back to you later. Thanks a lot for your advice! Lex On Aug 27, 6:40 pm, Zod <[email protected]> wrote: > Hi! > > It's not clear where your code is located and called. If it's in the > thread which receives the messages, than you're modifying UI elements > from another thread which is really bad. > > If your code is in the activity object, and you call it directly from > the network thread, than you also execute code in a thread which is > not the UI thread (very bad again), and therefore if the Overlay is > currently drawn and at that moment you receive a new message you will > try to modify a List while it is accessed by another thread (the UI). > > There is already a facility in the android api which can help you put > your data into the UI thread in a safe way. > > See:http://developer.android.com/reference/android/os/Handler.html > > Heres a simple example using Handler.post() > > In you activity where your UI components are. Create a Handler object, > (eg: mHandler = new Handler()) > > Pass this mHandler object to your network thread. When your network > thread receives a message use this handler to send a Runnable object > to be executed in the UI thread. Eg: > > receiveMessage(String msg) { > // send a runnable to execution in the thread which created the > handler > mHandler.post(new Runnable() { // implement the Runnable interface > public void run() { > activity.updateUI(); // <- what to call in the > handler thread. > } > }); > > } > > If your thread is implemented as an inner class of your activity, you > can call the necessary method directly in the Runnable.run method. > > I hope this helps. > > Zsolt. > > On Aug 27, 12:41 pm, Lex <[email protected]> wrote: > > > This post is in addition > > to:http://groups.google.com/group/android-developers/browse_thread/threa... > > > I have exactly the same problem and Doug pinpointed what's probably > > the issue in my case exactly: > > > So here's the deal: I have a Vector containing traffic messages > > (received from a server via UDP in an own thread). Each time a message > > is received, I create a new overlay object and populate it with the > > traffic messages: > > > public void receiveMessage(BinaryMessage binaryMsg) { > > > .... > > TrafficMessage message = createMessage(binaryMsg); > > // adds message to vector > > addTrafficMessage(message, > > CoCarMapView.trafficMessages); > > CoCarMapView.showTrafficMessages(); > > .... > > > } > > > public static void showTrafficMessages() { > > List<Overlay> overlays = mapView.getOverlays(); > > if (overlays.size() > 1) { > > overlays.remove(1); > > } > > Drawable warningIcon = context.getResources().getDrawable > > (R.drawable.sign_warning_small); > > CoCarItemizedOverlay trafficEventsOverlay = new > > CoCarItemizedOverlay > > (warningIcon); > > > // the overlay is populated here > > trafficEventsOverlay.updateOverlay(trafficMessages); > > > mapView.getOverlays().add(trafficEventsOverlay); > > mapView.postInvalidate(); > > > } > > > public void updateOverlay(Vector<TrafficMessage> messages) { > > for(int i=0; i < messages.size(); i++) { > > > TrafficMessage message = messages.elementAt(i); > > Drawable messageIcon = getMessageIcon(message); > > GeoPoint point = getGeoPoint(message); > > OverlayItem messageItem = createItem(messageIcon, > > point); > > this.addItem(messageItem); > > > } > > > } > > > I don't understand yet exactly where the error is caused, that is > > where to start improving stuff... > > > Thanks for your advice, > > > Lex --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
