攝即是空

在建立資料夾或檔案後 加入

MediaScannerConnection.scanFile(this, new String[] { file.toString() }, null,
    new MediaScannerConnection.OnScanCompletedListener() {
        public void onScanCompleted(String path, Uri uri) {
            Log.i("ExternalStorage", "Scanned " + path + ":");
            Log.i("ExternalStorage", "-> uri=" + uri);
       }
    });

http://stackoverflow.com/questions/22366217/cant-create-folder-on-external-storage-on-android