读取 Firebase 值时出错：pricecode

Question

请告诉我我的错误是什么？我正在尝试计算 pricecode 并将其推入用户 -> 价格。但相反，它给出错误或 link，而不是值“1000”

enter image description here

public void onClickB1 (View view)
    {
        DatabaseReference bd = FirebaseDatabase.getInstance().getReference("User");
        DatabaseReference bd1 = bd.child("pricecode");
        String id = mDataBase.getKey();
        //String key = dataSnapshot.getKey();
        String name = String.valueOf(textB1.getText());
        **String price = bd1.child("pricecode").getValue(String.class);**
        User newUser = new User(id,name,price);
        //mDataBase.push().setValue(newUser);

        if (!TextUtils.isEmpty(name)) // проверка пустой строки
        {
            mDataBase.push().setValue(newUser);
        }
        else
        {
            Toast.makeText(this,"Заполните поля",Toast.LENGTH_LONG).show();
        }
    }

Answer 1

无法对 DatabaseReference. Why? Because there is no such method inside the class. On the other hand, DataSnapshot class contains a getValue() 方法类型的对象调用 getValue()。因此，为了能够读取该值，您必须附加一个侦听器，如以下代码行所示：

DatabaseReference db = FirebaseDatabase.getInstance().getReference();
DatabaseReference userRef = db.child("User");
userRef.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DataSnapshot> task) {
        if (task.isSuccessful()) {
            DataSnapshot snapshot = task.getResult();
            String priceCode = snapshot.child("pricecode").getValue(String.class);
            Log.d("TAG", "priceCode: " + priceCode);
        } else {
            Log.d("TAG", task.getException().getMessage()); //Never ignore potential errors!
        }
    }
});

正如我在之前的 问题中提到的那样，将价格存储为数字而不是 字符串。