JsonMappingException: Can not deserialize instance of java.util.List out of START_OBJECT token

Question

I have a JSON below that I'm trying to parse to a POJO using Jackson

{
    "Response": {
        "userIds": [
            "http://example.com:10249/User/526241869918679991"
        ],
        "userGroupIds": [
            "http://example.com:10249/UserGroup/1056659494710887089"
        ],
        "accountIds": [
            "http://example.com:10249/ServiceAccount/3354613317986071030"
        ],
        "success": true
    }
}

My Response POJO snippet is as below

private boolean success;
private List<String> accountIds;
private List<String> userIds;
private List<String> userGroupIds;

and their getter and setters

Is my declaration wrong as I'm getting "org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.util.List out of START_OBJECT token" error on parse"

The parse logic is as below:

jsonMapper.readValue(responseJSONString, new TypeReference<List<Response>>() {});

Any idea where I'm making the mistake?

aioobe · Accepted Answer · 2014-10-09 19:41:25Z

3

First of all, your input starts with "Response": ... which must correspond to a field in some object. So what you have there is a json representation of a Response container:

class ResponseContainer {
    Response Response;
}

Secondly, your try to parse a list but your input doesn't start with [ (which lists should start with) but { which indicates that it's an object. So if you want it to be a list, wrap the input in [ ... ]:

So either change your input to be a list:

|
V

[
    {
        "Response": {
            "userIds": [
                "http://example.com:10249/User/526241869918679991"
            ],
            "userGroupIds": [
                "http://example.com:10249/UserGroup/1056659494710887089"
            ],
            "accountIds": [
                "http://example.com:10249/ServiceAccount/3354613317986071030"
            ],
            "success": true
        }
    }
]

^
|

edited Oct 9, 2014 at 19:41

answered Oct 9, 2014 at 19:19

aioobe

423k115 gold badges831 silver badges844 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

JB Nizet Over a year ago

Your JSON array is an array of response containers, not an array of responses.

aioobe Over a year ago

Wops. Thanks. I'll revise.

Collectives™ on Stack Overflow

JsonMappingException: Can not deserialize instance of java.util.List out of START_OBJECT token

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related