android - Implementing a GalleryAdapter getCount that fetches its content from a remote server -

this looong explanation, please bear me... here dragons...

ok have android gallery , implemented galleryadapter creates views , stuff:

public class galleryadapter extends baseadapter {.... .... etc ... 

now, before start, of examples out there show how assume know how many images there going in gallery. in case, not. arbitrary number of images @ least there's consistent naming convention 001, 002, 003 etc

i have folder somewhere on server has images in should displayed in gallery:

http://www.somedomain.com/content/pictures

in pictures folder might have
0001.jpg
0002.jpg
0003.jpg
000n.jpg
etc ad infinitum

now baseadapter extending, expects override public int getcount()
if know have 20 images go:

public int getcount() {return 20;}   

and on merry way. case?
way have gotten around till requiring count.txt file placed in root of directory images contains integer tells there x amount of images in it. remember, http location.

so getcount looks more this

public int getcount() {   int count = getremoteimagecount();   if(count == -1)   {       return 0;//oh crap, went wrong, now?!   } else {     return count;   }  public int getremoteimagecount()   try {     url url = new url(strurl);     urlconnection conn = url.openconnection();     conn.setusecaches(true);     conn.connect();      inputstream instream = conn.getinputstream();     inputstreamreader reader = new inputstreamreader(instream);      string strcount = new string();     int data = reader.read();     while(data != -1){       char thechar = (char) data;       strcount += thechar;       data = reader.read();     }      reader.close();      count = integer.parseint(strcount);     } catch (exception e) {       count = -1   }      return count; } 

ok, have bit of context, here actual question. if chance fail fetch count.txt file , cannot tell how many images there in remote folder need tell user have failed using dialog , ask them if want retry or ignore it. how go doing that? next bit of code attempt fails horribly couple of reasons, because dialogs shown synchronously. how implement (retry/cancel) galleryadapter state network , can server images in gallery?

here's my, non working attempt. alternatives suggestions welcome.

public int getcount() {     // todo fetch image amount remotely          int imagecount;      {         remotebitmaphelper rbmh = new remotebitmaphelper();              imagecount = rbmh.getbitmapcount(baseurl + "count.txt");          if(imagecount == -1) {             imagecount = 0;             new alertdialog.builder(this.context)             .settitle("connection error")             .setmessage("there error connecting server")             .setpositivebutton("retry",                 new dialoginterface.onclicklistener() {                     @override                     public void onclick(dialoginterface dialog, int whichbutton) {                         setretrygetcount(true);                     }                 })             .setnegativebutton("continue",                 new dialoginterface.onclicklistener() {                                  @override                     public void onclick(dialoginterface dialog, int which) {                         setretrygetcount(false);                     }                 })             .setcancelable(false)             .show();         }      } while(retrygetcount && imagecount <= 0);       return imagecount; } 

this not perfect idea. first try image count , try retrieve images. actually, should try this example. although fetches images external storage, later can convert fetch images server. hope you.