Question

I have an inner class that downloads some images from the server. The problem is that the ProgressDialog does not dismiss() onPostExecute() method and don’t understand why.
I understand that the progress dialog should be shown onPreExecute() method, and the after the code from the doInBackground() finished , in the onPostExecute() method the dialog should be dismiss. Do you have any idea what i am doing wrong here? Thank you.

 /**
 * Download images from server
 */
public class DownloadAsyncTask extends AsyncTask<Void, Integer, Void> {
    private ProgressDialog mDialog;

    // execution of result of Long time consuming operation
    protected void onPostExecute(Void result) {

        // progressDialog.show();
        if (mDialog.isShowing()) {
            mDialog.dismiss();
        }


    }

    // Things to be done before execution of long running operation.
    protected void onPreExecute() {
        mDialog = ProgressDialog
                .show(ImagesActivity.this, getString(R.string.pleasewait),
                        getString(R.string.loading));
    }

    // perform long running operation operation
    protected Void doInBackground(Void... params) {
        System.out.println("doInBackground loading.." + id);
        String tempPath = FileUtils.createTempFile(id);
        for (int i = 0; i < imagePaths.size(); i++) {
            imagePaths.get(i).trim();
            try {
                Bitmap imgTemp;
                imgTemp = FileUtils.downloadBitmapFromURL(id,
                        imagePaths.get(i), tempPath);
                System.out.println("imgTemp: " + imgTemp);
                if (imgTemp != null) {
                    // save image on sdcard.
                    // compress it for performance
                    Bitmap img = Bitmap.createScaledBitmap(imgTemp, 90, 80,
                            true);
                    imgTemp.recycle();
                    FileUtils.saveDataToFile(img, tempPath,
                            imagePaths.get(i));
                } else {
                    continue;
                }
            } catch (IOException e) {
                e.printStackTrace();
                mDialog.dismiss();
            }
        }

        Looper.prepare();
        mDialog.dismiss();
        return null;
    }

    /*
     * Things to be done while execution of long running operation is in
     * progress. 
     */
    protected void onProgressUpdate(Integer... values) {
        if (mDialog.isShowing()) {
            mDialog.dismiss();
        }
    }
}

Answer 1

actually what you are trying to do is to access the UI Thread from another thread and that is not possible , in your case you are using AsyncTask class enables proper and easy use of the UI thread without having to manipulate threads and/or handlers. use onPostExecute(Result) to access the UI Thread.

so this should work

protected void onPostExecute(Void result) {

     progressDialog.show();
    if (mDialog.isShowing()) {
        mDialog.dismiss();
    }
}