Children Count in Firebase Real-time Database Android Studio

 

private void countAndSum() {
    FirebaseDatabase.getInstance().getReference().child("Hospital").child("Users").child(uid).child("Cart")
            .addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull DataSnapshot snapshot) {


                    if(snapshot.exists()){

                        int numberOfItems = (int) snapshot.getChildrenCount();
                        Toast.makeText(CartActivity.this, String.valueOf(numberOfItems), Toast.LENGTH_SHORT).show();
                        
                    }
                }

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

                }
            });
}