Deserialization of arrays with Jackson

Question

i have something like JSON-RPC client, and i´m having trouble deserializing incoming json string into my java object. The incoming json format is:

{"value":"xxxx","type":"xxxx"}

The object i want to deserialize to:

@JsonAutoDetect
@JsonDeserialize()
public class ReturnValue {

private Object value;
private String type;

@JsonCreator
public ReturnValue(@JsonProperty("value") String val, @JsonProperty("type") String type) {
    value = val;
    this.type = type;
}

...getters, setters...

This seems to work ok, if the value is String, but if it´s of array type, it throws JsonMapping Exception - Can not deserialize instance of java.lang.String out of START_ARRAY token for the json like this:

{\"value\":[8, 10], \"type\":\"[int]\"}

The code is:

int[] arr = (int[])getReturnValue(jsonString).getValue();

Where getReturnValue is nothing special:

    ObjectMapper om = new ObjectMapper();
    ReturnValue rv = null;
    rv = om.readValue(json, ReturnValue.class);
    return rv;

The another problem is that i would want the type property to be of Class type, but this would throw another mapping exception. Is there any way in Jackson to do it, or do i have to convert from string to appropriate class myself. Thank you for any advice.

Answer 1

Change your constructor to be:

@JsonCreator
public ReturnValue(@JsonProperty("value") Object val, @JsonProperty("type") String type) {

since, like error points out, it does not know how to make a String out of array. But both String and JSON Array can be converted to Object; if so, it'll be Java String, or Java List (for JSON arrays), or Java Map (for JSON objects).