AlertDialog Display Lag

Question

I have a process which takes some time to execute, deleteImages. I want the UI thread blocked while this task executes. I tried to create an AlertDialog and show it before deleteImages starts so there is not simply unexplained hang time. However, even though I call dialog.show() before the call to deleteImages, the dialog only shows after deleteImages has completed. What am I doing wrong?

AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
LayoutInflater inflater = getLayoutInflater();
View content = inflater.inflate(R.layout.deletion_dialog, null);
builder.setView(content);

AlertDialog dialog = builder.create();
dialog.show();

deleteImages(dataStringsToDelete);

Answer 1

Try running your your deleteImages(dataStringsToDelete); in async task and hide your dialog in OnPostExecute()

Like this:

new AsyncTask<Void, Void, Void> {
 protected Long doInBackground(Void... void) {

     deleteImages(dataStringsToDelete);

 }

 protected void onPostExecute(Long result) {
     dialog.dismiss();
 }
}.execute()