Android: Progress Dialog shows a black screen

Question

This is my code that am I using to implement a ProgressDialog when a camera fired and photo taken.

public void onPhotoTaken() {

        _taken = true;

        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inSampleSize = 4;

        Bitmap bitmap = BitmapFactory.decodeFile(_path, options);

        try {
            ProgressDialog dialog = ProgressDialog.show(this, "Loading", "Please wait...", true);
            ExifInterface exif = new ExifInterface(_path);
            int exifOrientation = exif.getAttributeInt(
                    ExifInterface.TAG_ORIENTATION,
                    ExifInterface.ORIENTATION_NORMAL);

On clicking on the save button of my android device, instead of displaying the Progress Dialog, it displays a black screen. Please what could be wrong.

Answer 1

You should remember when it comes to Progress dialog is that you should run it in a separate thread. If you run it in your UI thread you'll see no dialog.

If you are new to Android Threading then you should learn about AsyncTask . Which helps you to implement painless Threads .

Sample code:

private class CheckTypesTask extends AsyncTask<Void, Void, Void>{
        ProgressDialog asyncDialog = new ProgressDialog(IncidentFormActivity.this);
        String typeStatus;


        @Override
        protected void onPreExecute() {
            //set message of the dialog
            asyncDialog.setMessage(getString(R.string.loadingtype));
            //show dialog
            asyncDialog.show();
            super.onPreExecute();
        }

        @Override
        protected Void doInBackground(Void... arg0) {

            //don't touch dialog here it'll break the application
            //do some lengthy stuff like calling login webservice

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            //hide the dialog
            asyncDialog.dismiss();

            super.onPostExecute(result);
        }

}

Good luck.

EDIT

The method show() must be called from the User-Interface (UI) thread, while doInBackground() runs on different thread which is the main reason why AsyncTask was designed.

You have to call show() either in onProgressUpdate() or in onPostExecute

Answer 2

It is working for me just using your ProgressDialog line of code so the problem must be elsewhere but you can try:

ProgressDialog dialog = new ProgressDialog(this);
dialog.setMessage("Please wait...");
dialog.setTitle("Loading");
dialog.show();