CODEWITHSUNDEEP
javajsonjacksonjson-deserialization
user1382278
user1382278

Reputation: 421

Deserialize error with jackson json in case of list in java

I have create a JSON with Jackson based on this class:

    public class One {
    public long param;

    public List<Two> two;

    public static class Two{
        public long param;
        public List<Short> param2;
    }
}

I have defined two constructor for each class and I use it for the creation of the objects that later are written on the json file. The outcome is (valid JSON):

[{"param":1,"Two":[{"param":4,"param2":[1,2,3]},{"param":5,"parma2":[4,5,6]}]},{"param":2,"Two":[{"param":6,"param2":[1,2,3]}]}]

Now I would like to read and load the parameters and I define:

    mapper.configure(Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true); //tried with and without
    JsonFactory f = new JsonFactory();
    JsonParser jp;
jp = f.createJsonParser(FILE);
    jp.nextToken();
    while (jp.nextToken() == JsonToken.START_OBJECT) {
         mapper.readValue(jp, One.class);
     }
     jp.close();

I have this error:

Can not deserialize instance of json.One$Two out of START_ARRAY

Upvotes: 0

Views: 1834

Answers (1)

user1382278
user1382278

Reputation: 421

I have found the solution.

Load of the json file:

List<One> myObjects = new ArrayList<One>();
myObjects = mapper.readValue(FILE, mapper.getTypeFactory().constructCollectionType(List.class, One.class));

The code in the class is edited by adding only @JsonProperty("Two"):

   public class One {
    public long param;
    @JsonProperty("Two")
    public List<Two> two;

    public static class Two{
        public long param;
        public List<Short> param2;
    }
}

Upvotes: 1

Related Questions