how to save rating bar value using shared preferences?

my "rate the app" is in navigation drawer.i have shared preferences for saving the value of rating bar but when I open again it is showing blank in rating bar.where am I getting wrong? Following is my code:

 case R.id.nav_rate:

                    try {

                        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                        View layout= null;
                        LayoutInflater inflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                        layout = inflater.inflate(R.layout.rating, null);
                       final RatingBar ratingBar = (RatingBar)layout.findViewById(R.id.ratingBar);
                        builder.setTitle("Rate Us");
                        builder.setMessage("Thank you for rating us , it will help us to provide you the best service .");
                        builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                Float value = ratingBar.getRating();
                                Toast.makeText(MainActivity.this,"Rating is : "+value,Toast.LENGTH_LONG).show();
                                SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); // 0 - for private mode
                                SharedPreferences.Editor editor = pref.edit();
                                editor.putFloat("numStars", value);//put value
                                editor.commit();

                                float rating = pref.getFloat("numStars", 0f);
                                ratingBar.setRating(rating);//save
                            }
                        });
                        builder.setNegativeButton("No,Thanks", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                dialog.dismiss();
                            }
                        });
                        builder.setCancelable(false);
                        builder.setView(layout);
                        builder.show();

                    } catch (Exception e) {
                        e.printStackTrace();
                    }}

Please write below code before builder.setTitle because You are only initializing after user presses OK button.

haredPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); // 0 - for private mode

                                float rating = pref.getFloat("numStars", 0f);
                                ratingBar.setRating(rating);