使用 jackson 反序列化 json 响应时出现 IndexOutOfBoundException

Question

I am trying to deserialize a json response from another API but i keep on getting indexoutofboundException. Below is my json response that i am trying to deserialize -

{
  "data" : [ ],
  "metadata" : {
    "transactionId" : "cfba12f56eaf6f24"
  }
}

For deserializing i am using below implementation -

ResponseEntity<String>response=restTemplate.exchange(meta_uri,HttpMethod.POST,httpEntity,String.class);
            String source=response.getBody();

            mapper.enable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY);
            DataResponse metaResponse=mapper.readValue(source,DataResponse.class);

DataResponse.class looks like this -

import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.*;

import java.util.ArrayList;

@AllArgsConstructor
@NoArgsConstructor
@Setter
@Getter
@ToString
public class DataResponse {

    @JsonProperty
    private ArrayList<APIData>data;


    @JsonProperty
    private MetaData metadata;

}

APIData.class looks like this -

import com.fasterxml.jackson.annotation.JsonProperty;

import lombok.*;
import java.util.*;


@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
@ToString
public class APIData {


    @JsonProperty
    private Map<String,Object> key;


    @JsonProperty
    private List<String> contacts;


}

Basically my implementation works when the json response is like this -

    {
  "data": [
    {
      "key": "123",
      "contacts": [
        "jon_doe@email.com",
        "jon1_do3@email.com"
      ]
    }
  ],
  "metadata": {
    "transactionId": "11112233333"
  }
}

but gives me indexOutofBoundException when data array inside the response is empty -

{
  "data" : [ ],
  "metadata" : {
    "transactionId" : "cfba12f56eaf6f24"
  }
}

Answer 1

I guess maybe data that post request return is wrong. I do a test with string as your said. it is work.

    @Test
    public void mapper() throws Exception{
        String json = "{\n" +
                "  \"data\" : [ ],\n" +
                "  \"metadata\" : {\n" +
                "    \"transactionId\" : \"cfba12f56eaf6f24\"\n" +
                "  }\n" +
                "}";

        ObjectMapper mapper = new ObjectMapper();

        mapper.enable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY);
        DataResponse metaResponse=mapper.readValue( json ,DataResponse.class);
        System.out.println("=========" + metaResponse);


        // output
        // =========DataResponse(data=[], metadata=MetaData(transactionId=cfba12f56eaf6f24))
    }