Your reference to the Handler and the ArrayList in ConnectTask no
longer point to the fields of the Activity if it is destroyed and
recreated. This meens that the the thread cannot update the view
properly. I have no idea why it works for you when change the screen
rotation twice.
On Wed, Feb 10, 2010 at 11:26 AM, Noodles <brand...@gmail.com> wrote:
> Hi Chrigi! Thanks for your answer.
>
> My thread has a reference to the ListView.
> But I'm not sure that this is the reason, maybe it could be... but If
> you are right why, when i rotate display for the second times, do i
> see the list with data? If i lost the reference to the thread's
> listview, i would lose also then. or not?
>
> I show you a part of my code, maybe it can be usefull to understand
> better my problem.
>
> public class HelloMotoGp extends ListActivity {
>
> /*
> * VARIABILI
> */
> protected ArrayList<XMLitem> listaGP = new ArrayList<XMLitem>(); //
> creo la lista che conterrà i GP letti da XML
> private ProgressDialog dialog=null;
> protected Handler onDownloadFinished;
> ConnectTask downloadTk;
> Thread thread;
>
>
> /** Called when the activity is first created. */
> �...@override
> public void onCreate(Bundle savedInstanceState) {
> super.onCreate(savedInstanceState);
> Log.d("DEBUG", "on Create()");
> boolean restoreFlag = restore();
> if(!restoreFlag){
> manageDialog();
> downloadData();
> }
>
> }
>
>
> �...@override
> public void onStop(){
> super.onStop();
> Log.d("DEBUG", "onStop()");
> if(dialog!=null && dialog.isShowing()){
> dialog.dismiss();
> Log.d("DEBUG", "dialog dismiss onStop()");
> }
>
> }
>
>
> private void downloadData(){
>
> Log.d("DEBUG", "onDownload()");
> //creo il thread associato al task Connect
> downloadTk=new ConnectTask(url,listaGP, onDownloadFinished);
> thread=new Thread(downloadTk);
> thread.start();
> Log.d("DEBUG", "thread started");
>
> }
>
>
> private void populateList(){
> setListAdapter(new myAdapter(this, listaGP)); //my custom adapter
> Log.d("DEBUG", "populateList()");
> }
>
>
> �...@override
> protected void onListItemClick(ListView l, View v, int position,
> long id) {
> super.onListItemClick(l, v, position, id);
> Intent i = new Intent(this, GaraView.class);
> i.putExtra(GaraView.ITEM_LINK,
> listaGP.get(position).getDescription());
> startActivity(i);
> }
>
>
> �...@override
> public Object onRetainNonConfigurationInstance() {
> Log.d("DEBUG", "onRetainNonConfigurationInstance() saving
> listaGP");
> Vector<Object> vect = new Vector<Object>();
> vect.add(listaGP);
> return vect;
> }
>
>
>
> private boolean restore() {
> Vector<Object> obj =
> (Vector<Object>)getLastNonConfigurationInstance();
> if(obj!=null){
> listaGP = (ArrayList<XMLitem>) obj.elementAt(0);
> //mostro la lista a video se è vuota
> if(!listaGP.isEmpty()){
> Log.d("DEBUG", "ListaGP full");
> setContentView(R.layout.main);
> populateList();
> return true;
> }else{
> Log.d("DEBUG", "ListaGP, empty");
> //mostro la finestra di download in corso
> return true;
> }
> }else
> Log.d("DEBUG", "obj NULL");
> return false;
> }
>
>
> private void manageDialog(){
> //mostro la finestra di download in corso
> dialog = ProgressDialog.show(this,"Downloading...", "Updating
> Data", true, false);
>
> //handler utilizzato per determinare se il download è terminato
> onDownloadFinished = new Handler(){
> �...@override
> public void handleMessage(Message m){
> Log.d("DEBUG", "Handler Captured");
> if(dialog!=null && dialog.isShowing()){
> dialog.dismiss();
> Log.d("DEBUG", "DIALOG was showing now is
> DISMISSED");
> }
>
> if(listaGP.isEmpty())
> Log.d("DEBUG", "the list is empty!!!");
> else{
> //mostro la lista a video
> setContentView(R.layout.main);
> populateList();
> Log.d("DEBUG", "Show list after Handler");
> }
> }
> };
>
> }
>
>
>
> }
>
>
> ***MY RUNNABLE****
>
> public class ConnectTask implements Runnable{
>
> private String url; //url sorgente xml
> private Handler downloadFinished;
> private boolean isListDownload; //flag che indica quale download sto
> effettuando
> ArrayList<XMLitem> lista; //SD per ListActivity
> String [] array; //SD per la GaraVIew Activity
>
> public ConnectTask(String url, ArrayList<XMLitem> list, Handler h){
> this.url=url;
> this.lista=list;
> this.downloadFinished = h;
> this.isListDownload = true;
>
> }
>
>
> public void run(){
>
>
> /*** my thread work... ***/
>
>
> //send to the main activity a message to signal the thread has
> terminated. This message will be caputerd with an handler in the
> activity
> Message msg = new Message();
> msg.what = HelloMotoGp.DOWNLOAD_COMPLETED;
> this.downloadFinished.sendMessage(msg);
> Log.d("DEBUG", "thread termina.");
>
>
> }
>
>
> }
>
>
>
> On 9 Feb, 11:20, Christoph Renner <chrigi.ren...@gmail.com> wrote:
>> Hi Noodles,
>>
>> I guess the problem is the following: your thread has a reference to
>> the Activity or ListView. When the download is finished the thread
>> uses this reference to add the items to the ListView. However when the
>> screen orientation has changed, the activity has been destroyed and
>> recreated and the reference points not anymore to the activity (and
>> listview) which is displayed. Therefore your adding items (e.g. by
>> calling setAdapter) on a listview which is not displayed.
>>
>> Possible solution:
>> - Thread has reference to activity (thread.activity)
>> - when onRetainNonConfigurationInstance is called set thread.activity
>> = null and return a reference to the thread
>> - onCreate: if getLastNonConfigurationInstance returns state (not
>> null) call state.thread.setActivity(this)
>> - whenever your thread wants to access the activity (or the list
>> view) it needs to make sure that thread.activity != null, if
>> thread.activity == null the action needs to be cached for later
>> execution (for example by using a list of runnables)
>>
>> I hope that helps, if something is unclear or you have additional
>> questions don't hesitate to ask!
>>
>> Chrigi
>>
>>
>>
>> On Mon, Feb 8, 2010 at 5:39 PM, Noodles <brand...@gmail.com> wrote:
>> > I have a problem with rotation, during my ListActivity is loading data
>> > from the network.
>> > To do it I use a background thread which recovers data and put them
>> > inside an ArrayList. While this thread works, there is Progress dialog
>> > activated in foreground.
>>
>> > For the rotation I use the method with
>> > onRetainNonConfigurationInstance() to save my ArrayList's state. After
>> > android calls this method, I call dismiss() on the progress dialog on
>> > onStop(). Then the activity is created as new with onCreate(), but it
>> > use the getLastNonConfigurationInstance() to recover the ArrayList's
>> > state.
>>
>> > Now, my problem...
>>
>> > If I rotate from portrait to lanscape when the download is terminated
>> > and I see the data in portrait yet, everything is ok.
>> > If I rotate during progress dialog is showing I have two cases:
>>
>> > 1- onRetainNonConfigurationInstance() saves the arraylist fully
>> > recovered, the thread terminates and everything is ok.
>> > 2- onRetainNonConfigurationInstance() saves the arraylist empty, i
>> > think the download isn't finished yet.
>> > The onCreate is called and my list is empty, the thread terminates,
>> > but i don't see anything in my list.
>>
>> > ... if I am in this case and I still rotate from landscape to portrait
>> > now I can see my list full with all the data.
>>
>> > Why?? Where am I wrong?
>>
>> > p.s. sorry for my english, I hope everything is clear.
>>
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>
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