Android: Get Data from Firebase Firestore : I just need to get the data "user_id" from Firebase and put it instead of xxx in condition (xxx == user_id). How can I do it? (Look at the Pictures)

[Firebase Firestore][1]


[Android Studio][2]


  [1]: https://i.stack.imgur.com/jMfr0.png
  [2]: https://i.stack.imgur.com/O0dAC.png