基于Java streams的ID将数据合并在一起

Question

目前，我在java应用程序中从API中提取了一组数据。返回的数据如下所示：

{
  "id": 1,
  "receiptId": "123456",
  "selections": [
    {
      "name": "Apple",
      "price": "£1"
    }
  ]
},
{
  "id": 2,
  "receiptId": "678910",
  "selections": [
    {
      "name": "Pear",
      "price": "£0.5"
    }
  ]
},
{
  "id": 3,
  "receiptId": "123456",
  "selections": [
    {
      "name": "Banana",
      "price:": "£2.00"
    }
  ]
}

如您所见，其中两个receiptId是相同的，我想将任何重复的receiptId's数据合并成一个块。即：

{
  "id": 1,
  "receiptId": "123456",
  "selections": [
    {
      "name": "Apple",
      "price": "£1"
    },
    {
      "name": "Banana",
      "price": "£2.00"
    }
  ]
},
{
  "id": 2,
  "receiptId": "678910",
  "selections": [
    {
      "name": "Pear",
      "price": "£0.5"
    }
  ]
},

目前，我正在通过以下操作将数据流式传输到地图中：

List<String> data = data.getData()
                         .stream()
                         .map(this::dataToReadable)
                         .collect(Collectors.toList());

dataToReadable执行以下操作：

  private String dataToReadable(List data) {
    return new DataBuilder().fromData(data)
                           .buildData();
  }

fromData执行以下操作：

public DataBuilder fromData(List data) {
    this.withId(data.getId())
    this.withSelections(data.getSelections())
    this.withReceiptId(data.getReceiptId())
    return this;
  }

Answer 1

看看这是否有效

 data.getData()
        .stream()
        .collect(Collectors.groupingBy(Data::getRecieptId))
        .entrySet()
        .stream()
        .map(item -> dataToReadable(item.getValue()))
        .collect(Collectors.toList());