Deserialize this Json Object using Jackson? - json

Question

I have been trying to deserialize the data received from this API:
{
"result": "success",
"timestamp": 1521038012878,
"data": {
"GB": 14,
"DE": 2,
"US": 2
},
"totalIsPublic": true,
"advanced": false,
"totalDownloads": {
"GB": 14,
"DE": 2,
"US": 2
}
}
Here is the POJO class:
public class BintrayDownloadCounts {
private List<Integer> totalDownloads = new ArrayList<>();
#JsonProperty("totalDownloads")
public List<Integer> getTotalDownloads() {
return totalDownloads;
}
public void setTotalDownloads(List<Integer> totalDownloads) {
this.totalDownloads = totalDownloads;
}
}
When I tried deserializing using :
downloadCounts = mapper.readValue(json, BintrayDownloadCounts.class);
I get this error:
com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.lang.Integer out of START_OBJECT token
I have seen many questions containing this error but I am unable to figure out a solution for this particular use case. It may be noted that the totalDownloads object is dynamic i.e. its contents are not constant.

Answer 1

The totalDownloads property is not an array, so it cannot be mapped to a List<Integer>. Use Map<String, Integer> instead and ensure that you tell Jackson to ignore the properties that are not mapped to avoid mapping errors:
#JsonIgnoreProperties(ignoreUnknown = true)
public class BintrayDownloadCounts {
#JsonProperty("totalDownloads")
private Map<String, Integer> totalDownloads;
public Map<String, Integer> getTotalDownloads() {
return totalDownloads;
}
public void setTotalDownloads(Map<String, Integer> totalDownloads) {
this.totalDownloads = totalDownloads;
}
}
Then you are good to go:
ObjectMapper mapper = new ObjectMapper();
BintrayDownloadCounts downloadCounts = mapper.readValue(json, BintrayDownloadCounts.class);