Android Firebase获取子值

Question

我有ởFirebase数据库结构如下所示。 enter image description here 我想从红色区域获取数据。我试过这段代码：

ref.child("shop").child("orders").addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                if (dataSnapshot.getValue() != null) {
                    for (DataSnapshot temp : dataSnapshot.getChildren()) {
                        Receipt temp2 = temp.getValue(Receipt.class);
                    }
                }
            }

收据temp2返回null。请有人告诉我如何获取这些数据。提前致谢 编辑1： 这是我的收据类：

public class Receipt {
    private String name;
    private String province;
    private String district;
    private String address;
    private String phoneNumber;
    private String style_payment;
    private int state;
    private int tmp;
    private int cost;
    private int total;
    private ArrayList<ProductInReceipt> productList;

    public Receipt(){}
    public Receipt(String name, String province, String district, String address, String phoneNumber, int state, ArrayList<ProductInReceipt> productList,String style_payment,
                   int tmp,int cost, int total) {
        this.name = name;
        this.province = province;
        this.district = district;
        this.address = address;
        this.phoneNumber = phoneNumber;
        this.state = state;
        this.productList = productList;
        this.style_payment = style_payment;
        this.tmp = tmp;
        this.cost = cost;
        this.total = total;
    }
}

Answer 1

您的数据结构似乎是：

orders
  $uid
    $orderid
      ...

您的代码会读取所有/orders，然后遍历结果。这意味着你正在循环用户。所以至少你错过了代码中的循环。

ref.child("shop").child("orders").addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
      for (DataSnapshot userSnapshot: dataSnapshot.getChildren()) {
        for (DataSnapshot receiptSnapshot: dataSnapshot.getChildren()) {
            Receipt receipt = receiptSnapshot.getValue(Receipt.class);
        }
      }
    }
    ...