android - Cannot deserialize instance of object out of START_ARRAY token in Spring Webservice

Question

I'm currently having trouble connecting to my webservice on android. I use jackson-core/databind/annotation-2.2.4 and Spring RESTWebService. If I access the URL from the browser I can see the JSON response: (server return ListShop looks like:)

[{"name":"shopqwe","mobiles":[],"address":{"town":"city",
"street":"streetqwe","streetNumber":"59","cordX":2.229997,"cordY":1.002539},
"shoe" [{"shoeName":"addidas","number":"631744030","producent":"nike","price":999.0,
"sizes":[30.0,35.0,38.0]}]

From a Client endpoint (Android application) I receive this error message:

08-26 17:43:07.406: E/AllShopsAsyc(28203): Could not read JSON: Can not deserialize
instance of com.auginzynier.data.ShopContainer out of START_ARRAY token
08-26 17:43:07.406: E/AllShopsAsyc(28203):  at [Source:
com.android.okhttp.internal.http.HttpTransport$ChunkedInputStream@41efbd48; line: 1,
column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException:
Can not deserialize instance of com.auginzynier.data.ShopContainer out of START_ARRAY
token
08-26 17:43:07.406: E/AllShopsAsyc(28203):  at [Source:
com.android.okhttp.internal.http.HttpTransport$ChunkedInputStream@41efbd48; line: 1,
column: 1] 
08-26 17:43:07.406: E/AllShopsAsyc(28203):
org.springframework.http.converter.HttpMessageNotReadableException: Could not read
JSON: Can not deserialize instance of com.auginzynier.data.ShopContainer out of
START_ARRAY token

My server request

RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
ShopContainer response  = restTemplate.getForObject(url, ShopContainer.class);

where ShopContainer is:

public class ShopContainer {
   private List<Shop> shops;

structure of Shop, Address and Shoe is : (I've omitted getters and setters):

public class Shop {
@JsonProperty("name")    private String name;
@JsonProperty("mobiles")   private List<String> mobiles = new ArrayList<String>();
@JsonProperty("address")   private Address address;
@JsonProperty("shoe") private List<Shoe> shoe = new ArrayList<Shoe>();

public class Address {
@JsonProperty("town") private String town;
@JsonProperty("street") private String street;
@JsonProperty("streetNumber") private String streetNumber;
@JsonProperty("cordX") private Double cordX;
@JsonProperty("cordY") private Double cordY;

public class Shoe {
@JsonProperty("shoeName") private String shoeName;
@JsonProperty("number") private String number;
@JsonProperty("producent") private String producent;
@JsonProperty("price") private Double price;
@JsonProperty("sizes") private List<Double> sizes = new ArrayList<Double>();

I've look here and on google but still can't figure out what I am missing at this point.

Any response would be greatly helpful.

Regards.

@UPDATE

I've fixed the JSON by using jackson's ObjectMapper with RequestMethod.GET. It now returns a String.

list is List<Shop>

ObjectMapper mapper = new ObjectMapper();
mapper.writeValue(new File("D:\Android\shop.json"), list);
System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(list));
return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(list);

JSON in console looks like:

[ {
  "name" : "shopqwe",
  "mobiles" : [ ],
  "address" : {
    "town" : "city",
    "street" : "streetqwe",
    "streetNumber" : "59",
    "cordX" : 2.229997,
    "cordY" : 2.002539
  },
  "shoe" : [ {
    "shoeName" : "addidas",
    "number" : "631744033",
    "producent" : "nike",
    "price" : 10.0,
    "sizes" : [ 30.0, 35.0, 38.0 ]
  } ]
} ]

Request still doesn't work - error is the same.

Answer 1

Your json contains an array, but you're trying to parse it as an object. This error occurs because objects must start with {.

You have 2 options:

1. You can get rid of the ShopContainer class and use Shop[] instead

   ShopContainer response  = restTemplate.getForObject(
       url, ShopContainer.class);
   

   replace with

   Shop[] response  = restTemplate.getForObject(url, Shop[].class);
   

   and then make your desired object from it.

2. You can change your server to return an object instead of a list

   return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(list);
   

   replace with

   return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(
       new ShopContainer(list));