Parse json to java object: Expected BEGIN_OBJECT but was BEGIN_ARRAY

Question

Can someone help me with parsing json string to object, I´m trying but always get error like this:

Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 3 path $[0]

Here is my code:

Item class:

@JsonInclude(JsonInclude.Include.NON_NULL)
public class Item{

    @JsonProperty("id")
    String id;
    
    @JsonProperty("dTime")
    long dTime;
    
    @JsonProperty("aTime")
    long aTime;
}

converting json to object:

String jsonString = "[
    [
        {
            "id":"string",
            "dTime": 1111111111,
            "aTime": 1111111111
        },
        {
            "id":"string",
            "dTime": 1111111111,
            "aTime": 1111111111
        }
    ]
]";
Gson gson = new Gson();
Type listType = new TypeToken<List<Item>>() {}.getType();
List<Item> list = gson.fromJson(jsonString, listType);

System.out.println(gson.toJson(list));

Update: Because i get this json as response from external API:

ResponseEntity<String> response = restTemplate.exchange(url, HttpMethod.POST, request, String.class);

Is it possible to make this converting to Array of Item objects inside this restTemplate.exchange(..) or this with gson is better way?

The input JSON string contains duplicate list/array. You could either fix the type of the parsed object to be List<List<Item>> or strip the extra pair of [ and ]: jsonString.substring(1, jsonString.length() - 1) — Nowhere Man
– Nowhere Man, Commented Oct 26, 2020 at 8:30
Yes, you have two objects within an array within an array. According to the JSON you have, it should be List<List<Item>>. — MC Emperor
– MC Emperor, Commented Oct 26, 2020 at 8:37
The answer by Eklavya provides better handling of the response - it transforms the string returned by the external API into List<List<Item>> immediately, without extra manual parsing with Gson — Nowhere Man
– Nowhere Man, Commented Oct 26, 2020 at 9:01

Eklavya · Accepted Answer · 2020-10-26 09:00:32Z

1

You can use ParameterizedTypeReference to directly map in java list object and use List<List<Item>> since your data wrap in []

ParameterizedTypeReference<List<List<Item>>> responseType =
                    new ParameterizedTypeReference<List<List<Item>>>() {};
ResponseEntity<List<List<Item>>> response = 
                    restTemplate.exchange(url, HttpMethod.POST, request, responseType);

edited Oct 26, 2020 at 9:00

answered Oct 26, 2020 at 8:54

Eklavya

18.6k4 gold badges33 silver badges62 bronze badges

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

Comments

allkenang · Accepted Answer · 2020-10-26 08:37:13Z

0

Your jsonString has an extra '['. It should be

String jsonString = "
[
    {
        "id":"string",
        "dTime": 1111111111,
        "aTime": 1111111111
    },
    {
        "id":"string",
        "dTime": 1111111111,
        "aTime": 1111111111
    }
]
";

answered Oct 26, 2020 at 8:37

allkenang

1,65516 silver badges15 bronze badges

Collectives™ on Stack Overflow

Parse json to java object: Expected BEGIN_OBJECT but was BEGIN_ARRAY

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related