How to get an array from Firestore?

I have the data structure illustrated below stored in Cloud Firestore. I want to save the dungeon_group which is an array of strings stored in Firestore.

I have difficulty in getting the data and stored as an array. I am just able to get a weird string but any method to store as a string array? Below is the code I used.

I am able to achieve this in Swift as follow, but not sure how to do the same in Android.

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Swift:

Firestore.firestore().collection("dungeon").document("room_en").getDocument { 
    (document, error) in
    if let document = document {
        let group_array = document["dungeon_group"] as? Array ?? [""]
        print(group_array)
    }    
}

Java Android:

FirebaseFirestore.getInstance().collection("dungeon")
                 .document("room_en").get()
                 .addOnCompleteListener(new 
                     OnCompleteListener<DocumentSnapshot>() {
                     @Override
                     public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                         DocumentSnapshot document = task.getResult();
                         String group_string= document.getData().toString();
                         String[] group_array = ????
                         Log.d("myTag", group_string);
                     }
                 });

Console output as the follow:

{dungeon_group=[3P, Urgent, Mission Challenge, Descended, Collaboration, Daily, Technical, Normal]}

Answer

When you call DocumentSnapshot.getData(), it returns a Map. You’re just calling toString() on that map, which is going to give you a dump of all the data in the document, and that’s not particularly helpful. You need to access the dungeon_group field by name:

DocumentSnapshot document = task.getResult();
List<String> group = (List<String>) document.get("dungeon_group");
  • edit: syntax error in typecasting

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