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 <[email protected]> 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 <[email protected]> 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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