Question

The idea is simple. Create a new TextView, attach it to ListView and then start downloading contents from a server. When there is no content downloading, the ListView is instantly updated. But after adding the TextView to the ListView I started downloading, refreshing listView on screen is done after the downloading is finished.

Main function

TextView startingDownloadingText = createTextView("Downloading started");
linearLayout.addView(startingDownloadingText);
boolean success = downloadFromUrl(stringUri, fileName, context);
if (success) {......

Function for downloading

public boolean downloadFromUrl(String stringURL, String fileName, Context myContext) { 

    try {
        URL url = new URL(stringURL);             
        Resources res = myContext.getResources();
        String envDirectory = Environment.getExternalStorageDirectory().toString();
        String zipDirectory = envDirectory.concat(res.getString(R.string.zipDirectory));

        File fileDirectory = new File(zipDirectory);
        fileDirectory.mkdirs();

        ZipDownloader zipDownloader = new ZipDownloader(zipDirectory, fileName);
        AsyncTask<URL, Void, Boolean> asynZipDownloader = zipDownloader.execute(url);
        Boolean success = null;
        try {
            success = asynZipDownloader.get();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
        if (success){
            Log.d("DownloadFromUrl", "file ready");
            return true;
        }
        return false;
    } catch (IOException e) {
        Log.e("DownloadFromUrl", "Error: " + e);
        return false;
    }

}

Why is this happening ?

UPDATE

AsyncTask<…>.get() is UI blocking and using onPostExecute() in AsyncTask will do the work in non blocking way. Example : android asynctask sending callbacks to ui

Answer 1

You appear to be downloading from the UI Thread, take a look at AsyncTask and try and implement that instead. See here

When you request a download it blocks on the UI Thread until completed. If you put it into a separate AsyncTask then this frees up your UI Thread and you can call back into the UI Thread to provide the result and update your UI