Question

I’m getting an exception while parsing a JSON with Gson.

The following is the exception :

com.google.gson.JsonParseException: The JsonDeserializer StringTypeAdapter failed to deserialize json object {"CGLIB$BOUND":true,"CGLIB$CONSTRUCTED":true,"CGLIB$CALLBACK_0":{"interfaces":[{}],"constructed":true,"persistentClass":{},"getIdentifierMethod":{"clazz":{},"slot":0,"name":"getmId","returnType":{},"parameterTypes":[],"exceptionTypes":[],"modifiers":1,"annotations":[0,3,0,67,0,0,0,68,0,0,0,69,0,1,0,70,115,0,71],"root":{"clazz":{},"slot":0,"name":"getmId","returnType":{},"parameterTypes":[],"exceptionTypes":[],"modifiers":1,"annotations":[0,3,0,67,0,0,0,68,0,0,0,69,0,1,0,70,115,0,71],"override":false},"override":false},"setIdentifierMethod":{"clazz":{},"slot":1,"name":"setmId","returnType":{},"parameterTypes":[{}],"exceptionTypes":[],"modifiers":1,"root":{"clazz":{},"slot":1,"name":"setmId","returnType":{},"parameterTypes":[{}],"exceptionTypes":[],"modifiers":1,"override":false},"override":false},"overridesEquals":false,"initialized":false,"entityName":"com.domain.Hotel","id":1,"unwrap":false},"mId":0,"mHotelLatitude":0.0,"mHotelLongitude":0.0,"mHotelRating":0.0,"mHotelAvgPrice":0.0} given the type class java.lang.String

JSON:

{
    "CGLIB$BOUND": true,
    "CGLIB$CONSTRUCTED": true,
    "CGLIB$CALLBACK_0": {
        "interfaces": [
            {}
        ],
        "constructed": true,
        "persistentClass": {},
        "getIdentifierMethod": {
            "clazz": {},
            "slot": 0,
            "name": "getmId",
            "returnType": {},
            "parameterTypes": [],
            "exceptionTypes": [],
            "modifiers": 1,
            "annotations": [
                0,
                3,
                0,
                67,
                0,
                0,
                0,
                68,
                0,
                0,
                0,
                69,
                0,
                1,
                0,
                70,
                115,
                0,
                71
            ],
            "root": {
                "clazz": {},
                "slot": 0,
                "name": "getmId",
                "returnType": {},
                "parameterTypes": [],
                "exceptionTypes": [],
                "modifiers": 1,
                "annotations": [
                    0,
                    3,
                    0,
                    67,
                    0,
                    0,
                    0,
                    68,
                    0,
                    0,
                    0,
                    69,
                    0,
                    1,
                    0,
                    70,
                    115,
                    0,
                    71
                ],
                "override": false
            },
            "override": false
        },
        "setIdentifierMethod": {
            "clazz": {},
            "slot": 1,
            "name": "setmId",
            "returnType": {},
            "parameterTypes": [
                {}
            ],
            "exceptionTypes": [],
            "modifiers": 1,
            "root": {
                "clazz": {},
                "slot": 1,
                "name": "setmId",
                "returnType": {},
                "parameterTypes": [
                    {}
                ],
                "exceptionTypes": [],
                "modifiers": 1,
                "override": false
            },
            "override": false
        },
        "overridesEquals": false,
        "initialized": false,
        "entityName": "com.domain.Hotel",
        "id": 1,
        "unwrap": false
    },
    "mId": 0,
    "mHotelLatitude": 0,
    "mHotelLongitude": 0,
    "mHotelRating": 0,
    "mHotelAvgPrice": 0
}

Does anybody have an idea about why this exception would come?

Regards

Answer 1

I can get this JSON to parse in Gson. The error above is generated when you have incorrectly mapped a JSON property type to Java member type in your POJO (an array type in JSON is declared as a String type in your POJO for example).

The error is a little curious to me as Gson will usually print out the JSON from the property that couldn’t be mapped. In your case that would be CGLIB$BOUND which is a boolean, but Gson behaves nicely in this case, giving you a String value "true". We can more accurately identify your problem if you provide the POJO you are trying to deserialise to.