android - Loading images to custom listview - how to gradually load? -

i have custom listview - contains imageview, text , checkbox.

i loading images dropbox (taking thumnails or else getting shared url image) , loading them custom listview using imageadapter.

it slow load images in given folder. takes several seconds load few images, minute if there dozens, , app crashes assume out of memory exception if there lots of images.

it seems taking 2 seconds url dropbox (or bitmap if decode stream). taking 60 seconds retreive 30 image urls. excessive (not sure why taking long?)

i hoping can improve code lot faster. load images incrementally, i.e. keep ui responsive , load images in batches.

i using async task, can advise.

note have tried using universal image loader , still takes long time load images.

i should note think problem in retrieving image data dropbox. code below retrieves thumbnail file, , slow. have tried changing code instead retrieve url link image, again slow execute , loop.

so there way inside of loop images, to start displaying data in listview, before loop has completed? - don't wait until ontaskcompleted - rather start displaying images inside of doinbackground?

here doinbackground of async task:

 @override     protected boolean doinbackground(dbxfilesystem... params) {         //opens thumbnails each image contained in dropbox folder         try {             dbxfilesystem filesystem = params[0];               (dbxfileinfo fileinfo: filesystem.listfolder(currentpath)) {                 dbxfile file;  //this code below slow execute                 try{                     if(fileinfo.thumbexists) // if has thumbnail retrieve                     {                         file = filesystem.openthumbnail(fileinfo.path, thumbsize.xs, thumbformat.png);                         bitmap image = bitmapfactory.decodestream(file.getreadstream());                         pix.add(image);  // image display in custom listview                         paths.add(fileinfo.path); // path display in custom listview                          file.close();                                          }                     else                     {                         //must folder if has no thumb, add local drawable folder icon                         bitmap image = bitmapfactory.decoderesource(getresources(), r.drawable.dbfolder);                         pix.add(image);                         paths.add(fileinfo.path);                                         }                 }catch (dbxexception e1) {                     e1.printstacktrace();                 } catch (ioexception e) {                     e.printstacktrace();                 }                 system.gc();             }         }         catch (exception e) {             e.printstacktrace();              return false;         } {             loadingdialog.dismiss();         }         return true;     } 

then in ontaskcompleted set image adapter:

       public void ontaskcompleted(int requestid, arraylist<bitmap> urls, arraylist<dbxpath> path) {              lstview = (listview) findviewbyid(r.id.lstview);             this.paths = path;              imageadapter adapter = new imageadapter(this, urls, paths);             lstview.setadapter(adapter); } 

this getview of imageadapter.java:

    public view getview(int position, view arg1, viewgroup arg2) {         layoutinflater inflater = (layoutinflater) context                 .getsystemservice(context.layout_inflater_service);          view gridview;           gridview = new view(context);          // inflate image_helper layout         gridview = inflater.inflate(r.layout.list_row, null);          // set images         imageview imageview = (imageview) gridview                 .findviewbyid(r.id.list_image);          imageview.setimagebitmap(images.get(position));          textview textview = (textview) gridview                 .findviewbyid(r.id.filename);             textview.settext(foldername.get(position).tostring());          return gridview;     } 

for can use universal image loader jar universal-image-loader-1.9.2-snapshot-with-sources.jar

then adapter this

public class linkadapter extends arrayadapter<mediamodel>{      arraylist<mediamodel> medias;     activity context;     imageloader imageloader;     displayimageoptions options;      public linkadapter(activity context, int textviewresourceid,             arraylist<mediamodel> objects) {         super(context, textviewresourceid, objects);         this.medias = objects;         this.context = context;         imageloader = imageloader.getinstance();         imageloader.init(imageloaderconfiguration.createdefault(context));         options = new displayimageoptions.builder()         .showimageonloading(r.drawable.ic_launcher)         .showimageforemptyuri(r.drawable.ic_launcher)         .showimageonfail(r.drawable.ic_launcher).cacheinmemory(true)         .cacheondisc(true).considerexifparams(true)         .bitmapconfig(bitmap.config.rgb_565).build();     }      static class viewholder {         textview title;         textview description;         imageview iconimage;     }      @override     public view getview(int position, view convertview, viewgroup parent) {         view v = convertview;         viewholder holder;          if (convertview == null) {             layoutinflater vi = (layoutinflater) getcontext()                     .getsystemservice(context.layout_inflater_service);             v = vi.inflate(r.layout.link_row, null);              holder = new viewholder();             holder.title = (textview) v.findviewbyid(r.id.txt_row_title);             holder.description = (textview) v.findviewbyid(r.id.txt_row_description);             holder.iconimage = (imageview) v.findviewbyid(r.id.img_row_icon);             v.settag(holder);         } else {             holder = (viewholder) v.gettag();         }          holder.title.settext(medias.get(position).mediatitle);         holder.description.settext(medias.get(position).mediainfo);         imageloader.displayimage(medias.get(position).mediathumbimgurl, holder.iconimage,options);          return v;     }  }