如何合并在Java 2个物体

我想在dynamodb DB表JSON数据保存为列名和相应的值，I，E：如何合并在Java 2个物体

Date = 2017-06-12 
Cash Buyer = 5751.0

推数据到dynamodb表我需要的JSON格式为List<Map<String,Object>>格式。

JSON数据是这样的：

{"dataset":{"id":19701916,"column_names":["Date","Cash Buyer","Cash Seller \u0026 Settlement","3-months Buyer","3-months Seller","15-months Buyer","15-months Seller","Dec 1 Buyer","Dec 1 Seller","Dec 2 Buyer","Dec 2 Seller","Dec 3 Buyer","Dec 3 Seller"],"frequency":"daily","type":"Time Series","premium":false,"limit":null,"transform":null,"column_index":null,"start_date":"2012-01-03","end_date":"2017-06-14","data":[["2017-06-14",5684.0,5684.5,5715.0,5717.0,null,null,5780.0,5790.0,5790.0,5800.0,5790.0,5800.0],["2017-06-13",5658.0,5659.0,5692.0,5693.0,null,null,5750.0,5760.0,5765.0,5775.0,5760.0,5770.0],["2017-06-12",5751.0,5752.0,5782.0,5783.0,null,null,5835.0,5845.0,5850.0,5860.0,5845.0,5855.0]"database_id":13206}}

这JSON数据在一个列表中有列名，而在另一个阵列List.I thier相应的价值正在从API得到这个JSON数据。有人可以帮助我吗？

来源

2017-06-16 user7990897

我理解正确吗，你想要一个像这样的json：'{“columnName1”：“value1”，“columnName2”：“value2”，...}'？ –

是的...... – user7990897

首先，json无效（您可以验证它here）。一旦经过验证，您可以使用任何Json序列化工具来读取和转换它。下面是Jackson的一个例子（文档here）：

//Deserialisation 
ObjectMapper mapper = new ObjectMapper(); 
Map<String, Object> dataMap = (Map<String, Object>) mapper.readValue("{\"dataset\":{\"id\":19701916,\"column_names\":[\"Date\",\"Cash Buyer\",\"Cash Seller Settlement\",\"3-months Buyer\",\"3-months Seller\",\"15-months Buyer\",\"15-months Seller\",\"Dec 1 Buyer\",\"Dec 1 Seller\",\"Dec 2 Buyer\",\"Dec 2 Seller\",\"Dec 3 Buyer\",\"Dec 3 Seller\"],\"frequency\":\"daily\",\"type\":\"Time Series\",\"premium\":false,\"limit\":null,\"transform\":null,\"column_index\":null,\"start_date\":\"2012-01-03\",\"end_date\":\"2017-06-14\",\"data\":[[\"2017-06-14\",5684.0,5684.5,5715.0,5717.0,null,null,5780.0,5790.0,5790.0,5800.0,5790.0,5800.0],[\"2017-06-13\",5658.0,5659.0,5692.0,5693.0,null,null,5750.0,5760.0,5765.0,5775.0,5760.0,5770.0],[\"2017-06-12\",5751.0,5752.0,5782.0,5783.0,null,null,5835.0,5845.0,5850.0,5860.0,5845.0,5855.0]]}}", Map.class); 
System.out.println(transform((Map<String, Object>)dataMap.get("dataset"))); 


//Transformation 

private static List<Map<String,Object>> transform (Map<String, Object> dataMap){ 
    List<Map<String,Object>> result = new ArrayList<>(); 
    List<String> columns = (List<String>) dataMap.get("column_names"); 
    List<List<Object>> data = (List<List<Object>>) dataMap.get("data"); 

    for(List<Object> dataElement : data){ 
     Map<String, Object> element = new HashMap<>(); 
     for(int i = 0 ; i < dataElement.size() ; i++){ 
      element.put(columns.get(i), dataElement.get(i)); 
     } 
     result.add(element); 
    } 

    return result; 
}

P.S.这只是使用Map和List的一个示例。您可以创建Pojos并使用它们来摆脱投射。

来源

2017-06-16 09:05:23

非常感谢。 – user7990897

如何合并在Java 2个物体

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