如何更新Firebase数据库中的子节点数据？

DatabaseReference ref = FirebaseDatabase.getInstance().getReference("path/to/child");

ref.setValue("new data");

Map<String, Object> updates = new HashMap<>();
updates.put("field1", "new value");
updates.put("field2", "new value");
ref.updateChildren(updates);

FirebaseFirestore db = FirebaseFirestore.getInstance();
DocumentReference docRef = db.collection("collection").document("document");

Map<String, Object> data = new HashMap<>();
data.put("field", "new value");
docRef.set(data, SetOptions.merge());

Map<String, Object> updates = new HashMap<>();
updates.put("field1", "new value");
updates.put("field2", "new value");
docRef.update(updates);