I want to map the following json to a pojo in Java. In the snippet shown below, result is a Json object, whose value is another json object which is a map. I tried converting this to a Pojo, but it failed. The keys in the result map are dynamic, and I cannot guess them prior.
final_result :
{
"result":
{
"1597696140": 70.32,
"1597696141": 89.12,
"1597696150": 95.32,
}
}
The pojo that I created is :
@JsonIgnoreProperties(ignoreUnknown = true)
public class ResultData {
Map<Long, Double> resultMap;
public ResultData(Map<Long, Double> resultMap) {
this.resultMap = resultMap;
}
public ResultData() {
}
@Override
public String toString() {
return super.toString();
}
}
Upon trying to create the pojo using ObjectMapper :
ObjectMapper objectMapper = new ObjectMapper();
ResultData resultData = objectMapper.readValue(resultData.getJSONObject("result").toString(), ResultData.class);
What am I possible doing wrong here ?
Answer
Assume, your JSON payload looks like below:
{
"final_result": {
"result": {
"1597696140": 70.32,
"1597696141": 89.12,
"1597696150": 95.32
}
}
}
You can deserialise it to class:
@JsonRootName("final_result")
class ResultData {
private Map<Long, Double> result;
public Map<Long, Double> getResult() {
return result;
}
@Override
public String toString() {
return result.toString();
}
}
Like below:
import com.fasterxml.jackson.annotation.JsonRootName;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.io.IOException;
import java.util.Map;
public class Main {
public static void main(String[] args) throws IOException {
File jsonFile = new File("./src/main/resources/test.json");
ObjectMapper mapper = new ObjectMapper();
mapper.enable(DeserializationFeature.UNWRAP_ROOT_VALUE);
ResultData resultData = mapper.readValue(jsonFile, ResultData.class);
System.out.println(resultData);
}
}
Above code prints:
{1597696140=70.32, 1597696141=89.12, 1597696150=95.32}