JsonMappingException : START_ARRAY 토큰에서 벗어남

JsonMappingException : START_ARRAY 토큰에서 벗어남

---

다음 .json 파일이 제공됩니다.

[
    {
        "name" : "New York",
        "number" : "732921",
        "center" : [
                "latitude" : 38.895111, 
                "longitude" : -77.036667
            ]
    },
    {
        "name" : "San Francisco",
        "number" : "298732",
        "center" : [
                "latitude" : 37.783333, 
                "longitude" : -122.416667
            ]
    }
]

포함 된 데이터를 표현하기 위해 두 개의 클래스를 준비했습니다.

public class Location {
    public String name;
    public int number;
    public GeoPoint center;
}

...

public class GeoPoint {
    public double latitude;
    public double longitude;
}

.json 파일의 내용을 구문 분석하기 위해 Jackson 2.2.x를 사용 하고 다음 방법을 준비했습니다.

public static List<Location> getLocations(InputStream inputStream) {
    ObjectMapper objectMapper = new ObjectMapper();
    try {
        TypeFactory typeFactory = objectMapper.getTypeFactory();
        CollectionType collectionType = typeFactory.constructCollectionType(
                                            List.class, Location.class);
        return objectMapper.readValue(inputStream, collectionType);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}

center속성을 생략하는 한 모든 콘텐츠를 구문 분석 할 수 있습니다. 그러나 지리 좌표를 구문 분석하려고하면 다음 오류 메시지가 표시됩니다.

com.fasterxml.jackson.databind.JsonMappingException :
[Source : android.content.res.AssetManager$AssetInputStream@416a5850;에서 START_ARRAY 토큰에서 com.example.GeoPoint의 인스턴스를 deserialize 할 수 없습니다 . 줄 : 5, 열 : 25]
(참조 체인을 통해 : com.example.Location [ "center"])

---

Your JSON string is malformed: the type of center is an array of invalid objects. Replace [ and ] with { and } in the JSON string around longitude and latitude so they will be objects:

[
    {
        "name" : "New York",
        "number" : "732921",
        "center" : {
                "latitude" : 38.895111, 
                "longitude" : -77.036667
            }
    },
    {
        "name" : "San Francisco",
        "number" : "298732",
        "center" : {
                "latitude" : 37.783333, 
                "longitude" : -122.416667
            }
    }
]

---

JsonMappingException: out of START_ARRAY token exception is thrown by Jackson object mapper as it's expecting an Object {} whereas it found an Array [{}] in response.

This can be solved by replacing Object with Object[] in the argument for geForObject("url",Object[].class). References:

1. Ref.1
2. Ref.2
3. Ref.3

---

As said, JsonMappingException: out of START_ARRAY token exception is thrown by Jackson object mapper as it's expecting an Object {} whereas it found an Array [{}] in response.

A simpler solution could be replacing the method getLocations with:

public static List<Location> getLocations(InputStream inputStream) {
    ObjectMapper objectMapper = new ObjectMapper();
    try {
        TypeReference<List<Location>> typeReference = new TypeReference<>() {};
        return objectMapper.readValue(inputStream, typeReference);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}

On the other hand, if you don't have a pojo like Location, you could use:

TypeReference<List<Map<String, Object>>> typeReference = new TypeReference<>() {};
return objectMapper.readValue(inputStream, typeReference);

---

I sorted this problem as verifying the json from JSONLint.com and then, correcting it. And this is code for the same.

String jsonStr = "[{\r\n" + "\"name\":\"New York\",\r\n" + "\"number\": \"732921\",\r\n"+ "\"center\": {\r\n" + "\"latitude\": 38.895111,\r\n"  + " \"longitude\": -77.036667\r\n" + "}\r\n" + "},\r\n" + " {\r\n"+ "\"name\": \"San Francisco\",\r\n" +\"number\":\"298732\",\r\n"+ "\"center\": {\r\n" + "    \"latitude\": 37.783333,\r\n"+ "\"longitude\": -122.416667\r\n" + "}\r\n" + "}\r\n" + "]";

ObjectMapper mapper = new ObjectMapper();
MyPojo[] jsonObj = mapper.readValue(jsonStr, MyPojo[].class);

for (MyPojo itr : jsonObj) {
    System.out.println("Val of name is: " + itr.getName());
    System.out.println("Val of number is: " + itr.getNumber());
    System.out.println("Val of latitude is: " + 
        itr.getCenter().getLatitude());
    System.out.println("Val of longitude is: " + 
        itr.getCenter().getLongitude() + "\n");
}

Note: MyPojo[].class is the class having getter and setter of json properties.

Result:

Val of name is: New York
Val of number is: 732921
Val of latitude is: 38.895111
Val of longitude is: -77.036667
Val of name is: San Francisco
Val of number is: 298732
Val of latitude is: 37.783333
Val of longitude is: -122.416667

참고URL : https://stackoverflow.com/questions/19333106/jsonmappingexception-out-of-start-array-token