List-view is not showing server data

Question

I have following code to get data from server to list-view.

public class ServerFileList extends Activity {

    URL urlAudio;
    ListView mListView;
    ProgressDialog pDialog;
    private List<String> myList = new ArrayList<String>();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.serverfilelist);

        mListView = (ListView) findViewById(R.id.listAudio);
        new getAudiofromServer().execute();

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, myList);
        adapter.notifyDataSetChanged();
        mListView.setAdapter(adapter);
        mListView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
        mListView.setCacheColorHint(Color.TRANSPARENT);
    }

    class getAudiofromServer extends AsyncTask<String, String, String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(ServerFileList.this);
            pDialog.setMessage("Uploading audio file to server. Please wait ...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        @SuppressWarnings("unchecked")
        @Override
        protected String doInBackground(String... arg0) {
            try {
                System.out.println("Inside first try");
                urlAudio = new URL("server-name/folder/folder");
            } catch (MalformedURLException e) {
                System.out.println("Inside first catch");
                e.printStackTrace();
            }
            ApacheURLLister lister1 = new ApacheURLLister();
            try {
                System.out.println("Inside second try");
                myList = lister1.listAll(urlAudio);
            } catch (IOException e) {
                System.out.println("Inside second catch");
                e.printStackTrace();
            }
            System.out.println("ABCD===" + myList);
            return null;
        }

        protected void onPostExecute(String file_url) {
            if (pDialog.isShowing()) {
                pDialog.dismiss();
            }
        }
    }
}

So basically what i am trying is listing all audio files from server to list-view, so i got code from this link and i have bit modified as per my requirement. But still list-view is empty, it is not showing any data.

I have also imported ivy-2.0.0-rc1.jar inside my project..

So what i am doing wrong. How can i list all file of server's particular folder inside list-view. Is this correct or do i need to use some other approach.

Thank you.

Answer 1

Move the following code

 ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, myList);
    adapter.notifyDataSetChanged();
    mListView.setAdapter(adapter);
    mListView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    mListView.setCacheColorHint(Color.TRANSPARENT);

to onPostExecute of getAudiofromServer. If you do this on onCreate its possible that getAudiofromServer may not have completed execution and hence myList may be populated. So the ListView will not show any items in it.

If you do it in onPostExecute you will have got the list of audio files stored on your server in myList and so they will be seen in the ListView

Answer 2

Your myList is not populated until doInbackground does its computation.

Move this

    ArrayAdapter<String> adapter = new ArrayAdapter<String>( ServerFileList.this,
            android.R.layout.simple_list_item_1, myList);
    adapter.notifyDataSetChanged();
    mListView.setAdapter(adapter);
    mListView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    mListView.setCacheColorHint(Color.TRANSPARENT);

to onPostExecute. Make sure myList is populated.