Show progress

TestFragment.java

public class TestFragment extends DialogFragment {

    private static final String INNER_TAG = "TEST_INNER_TAG";

    InnerFragment inner = null;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (savedInstanceState == null) {
            inner = new InnerFragment();
            inner.setParent(this);
            getChildFragmentManager().beginTransaction().add(inner, INNER_TAG).commit();
        } else {
            inner = (InnerFragment)getChildFragmentManager().findFragmentByTag(INNER_TAG);
            inner.setParent(this);
        }
    }

    @Override
    public void onPause() {
        super.onPause();
        inner.setParent(null);
    }

    public static class InnerFragment extends Fragment {
        boolean close = false;
        private TestFragment parent;

        @Override
        public void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setRetainInstance(true);
            new AsyncTask<Void, Void, Void>() {

                @Override
                protected Void doInBackground(Void... params) {
                    //do some stuff on background
                    return null;
                }

                @Override
                protected void onPostExecute(Void arg) {
                    //do some stuff on UI thread
                    if (parent == null)
                        close = true;
                    else
                        parent.dismiss();
                }
            }.execute();
        }

        public void setParent(TestFragment parent) {
            this.parent = parent;
            if (close)
                parent.dismiss();
        }
    }

    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final Dialog dialog = new AlertDialog.Builder(getActivity(), R.style.AppTheme_Dialog_Alert).setTitle(R.string.please_wait_fragment_title)
                .setView(R.layout.please_wait_fragment).setCancelable(false).create();
        dialog.setOnShowListener(new DialogInterface.OnShowListener() {
            @Override
            public void onShow(DialogInterface dialogInterface) {
                dialog.setCanceledOnTouchOutside(false);
                ((TextView) dialog.findViewById(R.id.please_wait_message)).setText(R.string.please_wait_message);
            }
        });
        return dialog;
    }
}