从Firebase数据库显示值

Question

嘿，我想在我的应用程序中显示节点点的值 enter image description here

我尝试了这段代码，但是没有用

        final TextView points_textview= findViewById(R.id.customerPoints_TextView);

 String userId = FirebaseAuth.getInstance().getCurrentUser().getUid();
    FirebaseDatabase firebaseDatabaseSeller = FirebaseDatabase.getInstance();
    final DatabaseReference reference =firebaseDatabaseSeller.getReference().child("users").child("customers").child(userId);
    reference.child("points").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            points_textview.setText(dataSnapshot.getValue(String.class));
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });