Save data on Android to external Directory

Ionic Framework ionic-v3
1

Hi all ! Could anyone suggest please … how to save data on Android to external directory ? I am trying like this, but file also saved on dataDirectory.

        if (this.platform.is('android')) {
          if (this.file.externalDataDirectory != null || this.file.externalDataDirectory != '') {
            this.storage = this.file.externalDataDirectory;
          }
          else {
            this.storage = this.file.dataDirectory;
          }
        }