groovy dependencies { implementation 'com.google.android.gms:play-services-tasks:17.2.1' implementation 'com.google.android.gms:play-services-auth:19.2.0' } import com.google.android.gms.tasks.OnCompleteListener; import com.google.android.gms.tasks.Task; db.collection("users") .get() .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() { @Override public void onComplete(@NonNull Task<QuerySnapshot> task) { if (task.isSuccessful()) { QuerySnapshot querySnapshot = task.getResult(); List<DocumentSnapshot> documents = querySnapshot.getDocuments(); for (DocumentSnapshot document : documents) { Log.d(TAG, document.getId() + " => " + document.getData()); } } else { Log.w(TAG, "Error getting documents.", task.getException()); } } });