ProgressDialog in AsyncTask

Fixed by moving the view modifiers to onPostExecute so the fixed code is :

public class Soirees extends ListActivity {
    private List<Message> messages;
    private TextView tvSorties;

    //private MyProgressDialog dialog;
    @Override
    public void onCreate(Bundle icicle) {

        super.onCreate(icicle);

        setContentView(R.layout.sorties);

        tvSorties=(TextView)findViewById(R.id.TVTitle);
        tvSorties.setText("Programme des soirées");

        new ProgressTask(Soirees.this).execute();


   }


    private class ProgressTask extends AsyncTask<String, Void, Boolean> {
        private ProgressDialog dialog;
        List<Message> titles;
        private ListActivity activity;
        //private List<Message> messages;
        public ProgressTask(ListActivity activity) {
            this.activity = activity;
            context = activity;
            dialog = new ProgressDialog(context);
        }



        /** progress dialog to show user that the backup is processing. */

        /** application context. */
        private Context context;

        protected void onPreExecute() {
            this.dialog.setMessage("Progress start");
            this.dialog.show();
        }

            @Override
        protected void onPostExecute(final Boolean success) {
                List<Message> titles = new ArrayList<Message>(messages.size());
                for (Message msg : messages){
                    titles.add(msg);
                }
                MessageListAdapter adapter = new MessageListAdapter(activity, titles);
                activity.setListAdapter(adapter);
                adapter.notifyDataSetChanged();

                if (dialog.isShowing()) {
                dialog.dismiss();
            }

            if (success) {
                Toast.makeText(context, "OK", Toast.LENGTH_LONG).show();
            } else {
                Toast.makeText(context, "Error", Toast.LENGTH_LONG).show();
            }
        }

        protected Boolean doInBackground(final String... args) {
            try{    
                BaseFeedParser parser = new BaseFeedParser();
                messages = parser.parse();


                return true;
             } catch (Exception e){
                Log.e("tag", "error", e);
                return false;
             }
          }


    }

}

@Vladimir, thx your code was very helpful.

AsyncTask is very helpful!

class QueryBibleDetail extends AsyncTask<Integer, Integer, String>{
        private Activity activity;
        private ProgressDialog dialog;
        private Context context;

        public QueryBibleDetail(Activity activity){
            this.activity = activity;
            this.context = activity;
            this.dialog = new ProgressDialog(activity);
            this.dialog.setTitle("查询经文");
            this.dialog.setMessage("正在查询："+tome+chapterID+":"+sectionFromID+"-"+sectionToID);
            if(!this.dialog.isShowing()){
                this.dialog.show();
            }
        }

        @Override
        protected String doInBackground(Integer... params) {
            Log.d(TAG,"经文doInBackground");
            publishProgress(params[0]);

            if(sectionFromID > sectionToID){
                return "";
            }

            String queryBible = "action=query_bible&article="+chapterID+"&id="+tomeID+"&verse_start="+sectionFromID+"&verse_stop="+sectionToID+"";
            try{
                String bible = (Json.getRequest(HOST+queryBible)).trim();
                bible = android.text.Html.fromHtml(bible).toString();
                return bible;
            }catch(Exception e){
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String bible){
            Log.d(TAG,"经文onPostExecute");
            TextView bibleBox = (TextView) findViewById(R.id.bibleBox);
            bibleBox.setText(bible);
            this.dialog.dismiss();
        }
    }

A couple of days ago I found a very nice solution of this problem. Read about it here. In two words Mike created a AsyncTaskManager that mediates ProgressDialog and AsyncTask. It's very easy to use this solution. You just need to include in your project several interfaces and several classes and in your activity write some simple code and nest your new AsyncTask from BaseTask. I also advice you to read comments because there are some useful tips.

/**
 * this class performs all the work, shows dialog before the work and dismiss it after
 */
public class ProgressTask extends AsyncTask<String, Void, Boolean> {

    public ProgressTask(ListActivity activity) {
        this.activity = activity;
        dialog = new ProgressDialog(activity);
    }

    /** progress dialog to show user that the backup is processing. */
    private ProgressDialog dialog;
    /** application context. */
    private ListActivity activity;

    protected void onPreExecute() {
        this.dialog.setMessage("Progress start");
        this.dialog.show();
    }

        @Override
    protected void onPostExecute(final Boolean success) {
        if (dialog.isShowing()) {
            dialog.dismiss();
        }


        MessageListAdapter adapter = new MessageListAdapter(activity, titles);
        setListAdapter(adapter);
        adapter.notifyDataSetChanged();


        if (success) {
            Toast.makeText(context, "OK", Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(context, "Error", Toast.LENGTH_LONG).show();
        }
    }

    protected Boolean doInBackground(final String... args) {
       try{    
          BaseFeedParser parser = new BaseFeedParser();
          messages = parser.parse();
          List<Message> titles = new ArrayList<Message>(messages.size());
          for (Message msg : messages){
              titles.add(msg);
          }
          activity.setMessages(titles);
          return true;
       } catch (Exception e)
          Log.e("tag", "error", e);
          return false;
       }
    }
}

public class Soirees extends ListActivity {
    private List<Message> messages;
    private TextView tvSorties;
    private MyProgressDialog dialog;
    @Override
    public void onCreate(Bundle icicle) {

        super.onCreate(icicle);

        setContentView(R.layout.sorties);

        tvSorties=(TextView)findViewById(R.id.TVTitle);
        tvSorties.setText("Programme des soirées");

        // just call here the task
        AsyncTask task = new ProgressTask(this).execute();
   }

   public void setMessages(List<Message> msgs) {
      messages = msgs;
   }

}