How to use Jackson to deserialize a JSON document with dynamic keys?

Question

I have such a JSON formatted string and the key is a random number.

{
  "tasks": {
    "0": {
     "key1": "value1"
    },
    "100": {
      "key1": "value2"
    }
}

How can I convert it to Java object by using Jackson?

How to define the Java class so that I can use Jackson like this?

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.readValue(myStr, XXXX);

Possible duplicate of [jackson deserialization json to java-objects](https://stackoverflow.com/questions/14890129/jackson-deserialization-json-to-java-objects) — Andrii Abramov, Jun 05 '17 at 12:56
Thanks. Kind of different with the provided link. It's not a List in my JSON string. — Dragon, Jun 05 '17 at 13:01
have you looked at https://stackoverflow.com/questions/26586103/how-to-parse-json-with-dynamic-keyname? — Andrii Abramov, Jun 05 '17 at 13:16
Please let me know if my [answer](https://stackoverflow.com/a/44387683/1426227) works for you — cassiomolin, Jun 19 '17 at 12:15

cassiomolin · Answer 1 · 2017-06-06T11:47:01.340

There are a couple of approaches you could use depending on your needs:

Using `JsonNode`

You could parse your JSON into the Jackson tree model. That is, into JsonNode from the com.fasterxml.jackson.databind package:

ObjectMapper mapper = new ObjectMapper();
JsonNode tree = mapper.readTree(json);

You also can use Jackson to parse a JsonNode into a POJO:

MyBean bean = mapper.treeToValue(jsonNode, MyBean.class);

Using `Map<String, Object>`

Depending on your requirements, you could use a Map<String, Object> instead of JsonNode:

ObjectMapper mapper = new ObjectMapper();
Map<String, Object> parsed = mapper.readValue(json, 
                                 new TypeReference<Map<String, Object>>() {});

To convert a map into a POJO, use:

MyBean bean = mapper.convertValue(map, MyBean.class);

How to use Jackson to deserialize a JSON document with dynamic keys?

1 Answers1

Using JsonNode

Using Map<String, Object>

Using `JsonNode`

Using `Map<String, Object>`