Updating Progress bar in listview while downloading a file

Question

How can we update a progress bar in ListView. When each progress bar is associated download of a file and which is done via AsyncTask.

• So where to update ProgressBar
  1. In update progress (I have tried this is not working)
  2. In the View Inflation process of ListView. (This is also not working)

Basically i whenever i get an file like .mp3 in browser, i call this asynctask, so there can be n instance of asynctask. but then how to update a particular progress bar with particular Aysnctask task.

            public class CopyOfDownloadsListActivity extends ListActivity {
            /** Called when the activity is first created. */

            //  static ArrayList<String> pthreads = new ArrayList<String>();
            static ImageView bt;
            static ProgressBar pb;
            static ListView allList;
            static TextView tv;
            String fileName;
            String mp3URL;
            URL url2;
            int myProgress;
            static int filecount  = 0;
            MyCustomAdapter adapter;

            private class DownloadFile extends AsyncTask<String, Integer, Void>{
                int count = 0;
                ProgressDialog dialog;
                int myProgess = 0;
                ProgressBar progressBar;

                @Override
                protected Void doInBackground(String... u) {

                    try {                   
                        URL ul = new URL(u[0]);
                        Log.i("UI",ul.toString());
                   //   int len = CopyOfMusicDownloader.mp3urls.size();
                   //   URL url2 = new URL(CopyOfMusicDownloader.mp3urls.get(len-1));
                        HttpURLConnection c = (HttpURLConnection) ul.openConnection();
                        c.setRequestMethod("GET");
                        c.setDoOutput(true);
                        c.connect();

                        int lengthOfFile = c.getContentLength();

                        String PATH = Environment.getExternalStorageDirectory()
                                + "/download/";
                        Log.v("", "PATH: " + PATH);
                        File file = new File(PATH);
                        file.mkdirs();

                        fileName = "Track";
                        filecount++;

                        fileName =  fileName + Integer.toString(filecount) + ".mp3";


                        File outputFile = new File(file, fileName);
                        FileOutputStream fos = new FileOutputStream(outputFile);
                        InputStream is = c.getInputStream();

                        byte[] buffer = new byte[1024];
                        int len1 = 0;      
                        while ((len1 = is.read(buffer)) != -1) {
                            myProgress = (int)(len1*100/lengthOfFile);
                            //myProgress = (int)(len1);

                            Log.i("My Progress", Integer.toString(myProgress));
                            publishProgress(myProgress);
                            //  publishProgress((int)(len1*100/lengthOfFile));
                            fos.write(buffer, 0, len1);
                        }
                        fos.close();
                        is.close();

                        }catch (IOException e) {
                               e.printStackTrace();
                        }
                    return null;
                }

                protected void onPostExecute() {

                }

                @Override
                protected void onPreExecute() {
                      setListAdapter(new MyCustomAdapter(CopyOfDownloadsListActivity.this, R.layout.row, CopyOfMusicDownloader.mp3urls));

                }



                @Override
                protected void onProgressUpdate(Integer... values) {
                     pb.setProgress(count);// HERE IS THE PROBLEM

                     count++;
                     Log.i("Values", Integer.toString(values[0]));
                }
             }  

            @Override
            public void onCreate(Bundle savedInstanceState) {
                requestWindowFeature(Window.FEATURE_NO_TITLE);
                super.onCreate(savedInstanceState);

                int len = CopyOfMusicDownloader.mp3urls.size();
                try {
                    url2 = new URL(CopyOfMusicDownloader.mp3urls.get(len-1));
                    new DownloadFile().execute(url2.toString());
                    Log.i("url",url2.toString());
                } catch (MalformedURLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

             }

            @Override
            public boolean onCreateOptionsMenu(Menu menu) {
                 MenuInflater myMenuInflater = getMenuInflater();
                 myMenuInflater.inflate(R.menu.menu, menu);
                return true;
            }

            @Override
            public boolean onOptionsItemSelected(MenuItem item) {
                 switch(item.getItemId()){
                 case(R.id.browsermenu):
                 Intent i = new Intent(CopyOfDownloadsListActivity.this, MusicDownloader.class);  
                 startActivity(i);
                 break;
                 case(R.id.downloaderrmenu):      
                 break; 
                 case(R.id.playermenu):
                 Intent j = new Intent(CopyOfDownloadsListActivity.this, Players.class);  
                 startActivity(j);
                break;
          }
             return true;
            }


            public class MyCustomAdapter extends ArrayAdapter<String> {     
                public MyCustomAdapter(Context context, int textViewResourceId, ArrayList<String> pthreads) {
                super(context, textViewResourceId, pthreads);
                }

                @Override
                public View getView(int position, View convertView, ViewGroup parent) {
                        LayoutInflater inflater = getLayoutInflater();
                        View row = inflater.inflate(R.layout.row, parent, false);
                        bt =(ImageView)row.findViewById(R.id.cancel_btn);
                        tv =(TextView)row.findViewById(R.id.filetext);
                        pb = (ProgressBar)row.findViewById(R.id.progressbar_Horizontal);
                        return row;
                    }
                }


        }

Answer 1

Children of a list view are built by an adapter. This adapter has some underneath data that is 'transformed' to views in getView() method. This means you have to change that data in update progress method of async task and call adapter.notifyDataSetChanged(). And your getView method should just 'transform' data to the list view child.

AsyncTask:

protected void onProgressUpdate(final int... values) {
  data[i].progress = values[0];
  adapter.notifyDataSetChanged();
}

Adapter:

public View getView(final int position, final View convertView, final ViewGroup parent) {
  ...
  progress.setProgress(getItem(position).progress);
  ...
}