Not able to Parse JSON data to POJO - json

Question

I have JSON data with following structure. I have tried creating POJOs with same structure and with same names. I have taken a DTO which contains a list (of DTOs with structure of the numeral objects in the following JSON) and a String "Notice". I am not able to get the data in the DTO.
{
"notice": "This API is in a pre-launch state, and will go through significant changes.",
"1": {
"next_renewal_date": "2014-08-01",
"next_renewal_fee": {
"price": "800.0",
"currency": "USD"
},
"next_renewal_description": "1st Annuity - Official Fee",
"next_per_claim_fee": {
"price": "0.0",
"currency": "USD",
"free_claims": 0,
"claim_type": "claims_count"
},
"next_agent_fee": {
"price": "0.0",
"currency": "USD"
},
"grace_period_end_date": "2015-02-01"
},
"2": {
"next_renewal_date": "2018-08-01",
"next_renewal_fee": {
"price": "1800.0",
"currency": "USD"
},
"next_renewal_description": "2nd Annuity - Official Fee",
"next_per_claim_fee": {
"price": "0.0",
"currency": "USD",
"free_claims": 0,
"claim_type": "claims_count"
},
"next_agent_fee": {
"price": "0.0",
"currency": "USD"
},
"grace_period_end_date": "2019-02-01"
}
}
POJO:
public class RenewalAPICallListDTO {
private Map<Integer,JSONCallDto> apiCallList;
public Map<Integer, JSONCallDto> getApiCallList() {
return apiCallList;
}
public void setApiCallList(Map<Integer, JSONCallDto> apiCallList) {
this.apiCallList = apiCallList;
}
private String notice;
public String getNotice() {
return notice;
}
public void setNotice(String notice) {
this.notice = notice;
}
}
Method call:
Gson gson = new Gson();
RenewalAPICallListDTO respDto = gson.fromJson(response1.toString(), RenewalAPICallListDTO.class);

Answer 1

What you are looking for can be achieve with Jackson with a custom deserializer, as the following:
public class CustomDeserializer extends JsonDeserializer<RenewalAPICallListDTO> {
private static final ObjectMapper mapper = new ObjectMapper();
static {
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
}
#Override
public RenewalAPICallListDTO deserialize(JsonParser jp, DeserializationContext ctxt)
throws IOException {
JsonNode node = jp.getCodec().readTree(jp);
Iterator<Entry<String, JsonNode>> nodeIterator = node.fields();
RenewalAPICallListDTO dto = new RenewalAPICallListDTO();
Map<Integer, JsonCallDto> map = new HashMap<>();
while (nodeIterator.hasNext()) {
Map.Entry<String, JsonNode> entry = nodeIterator.next();
if (entry.getKey().equalsIgnoreCase("notice")) {
dto.setNotice(entry.getValue().toString());
} else {
map.put(Integer.parseInt(entry.getKey()), mapper.readValue(entry.getValue().toString(), JsonCallDto.class));
}
}
dto.setApiCallList(map);
return dto;
}
}
Usage:
public static void main(String[] args) throws Exception {
ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.addDeserializer(RenewalAPICallListDTO.class, new CustomDeserializer());
mapper.registerModule(module);
RenewalAPICallListDTO dto = mapper.readValue(JSON, RenewalAPICallListDTO.class);
}
The final dto will be correctly serialized like you want, even with the correct types already set.

Answer 2

The json and POJO do not match. The attribute apiCallList is missing in your JSON string.
The structure should be like:
{
"notice": "random string",
"apiCallList": {
"1": {
"next_renewal_date": "2014-08-01",
...
},
"2": {
"next_renewal_date": "2014-08-01",
....
}
}
}

Answer 3

I have found a way. Thanks for the help.
I have converted the JSON into Hashmap using :
Map data = mapper.readValue(json,Map.class);
and then iterated the map, using the objects to populate POJOs.