How to read first key value in a JSON string-CodePudding

In my Spring Boot app, I am trying to read the value of the first key under dates field in the following JSON:

{
    "Data": {
        "city": "Berlin",
        "population": 5545156
        "dates": {
            "2022-08-20": 12345, 
            "2022-08-19": 12340,
            "2022-08-18": 12300
          }
    }
}

I tried something using Jackson a shown below, but as the key is changed based on date, but it return null string. On the other hand, I should get the first value instead of giving key:

JsonNode jsonNode = new  ObjectMapper().readTree(jsonString);
String dataString = jsonNode.findValuesAsText("dates").get(0).toString();

So, how can I get the first key's ("2022-08-20") value (12345) under dates ?

CodePudding user response：

You could use jsonNode.findValue("dates").elements().next() or jsonNode.findValue("dates").fields().next().getValue() or jsonNode.findValue("dates").findValue(jsonNode.findValue("dates").fieldNames().next())