Ringer Mode Silent를 쓰기 위해서 필요한 조치 Refer to KeepItSilent.apk androidManifest.xml에 permission 추가 onCreate()에 permission을 넣음 NotificationManager notificationManager = (NotificationManager) getApplicationContext().getSystemService(Context.NOTIFICATION_SERVICE); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && !notificationManager.isNotificationPolicyAccessGranted()) { Intent intent = new Intent..