Android 保存铃声并再次获取

我正在开发一个应用程序，在该应用程序中，我获取当前铃声并将其保存在SharedReferences中，然后再次获取。我试着这样做，但不起作用。请告诉我错误在哪里？我是android新手。请用密码告诉我

Uri currentRintoneUri = RingtoneManager.getActualDefaultRingtoneUri(context
                                    .getApplicationContext(), RingtoneManager.TYPE_RINGTONE);
Ringtone currentRingtone = RingtoneManager.getRingtone(context, currentRintoneUri);
String stringUri;
stringUri = currentRingtone.toString();

sharedpreferences = getSharedPreferences(MyPRE, Context.MODE_PRIVATE);
String current = sharedpreferences.getString(CUR, "");
SharedPreferences.Editor editor = sharedpreferences.edit();
editor.putString(CUR, stringUri);
editor.commit();
t1.setText("Current Ringtone : " + currentRingtone.getTitle(context));

Ringtone currentRing = RingtoneManager.getRingtone(context, Uri.parse(current));
//  uri = Uri.parse(current);
currentRing.play();