Deserializing Multiple inner classes using GSON

Question

I am trying Deserialize data from JSON object using gson. I am having trouble with 1)designing a class. 2) getting a null object from the inner list object.

Here is a sample of the JSON object

{
  "spatialReference" : {
    "wkid" : 102113
  },
  "candidates" : [
    {
      "address" : "202 S Van Ness Ave, San Francisco, CA, 94110",
      "location" : {
        "x" : -13627444.2697,
        "y" : 4546249.2471000031
      },
      "score" : 85.969999999999999,
      "attributes" : {
        "Loc_name" : "US_RoofTop",
        "Score" : 85.969999999999999,
        "Match_addr" : "505 S Van Ness Ave, San Francisco, CA, 94110",
        "House" : "505",
        "Side" : "R",
        "PreDir" : "S",
        "PreType" : "",
        "StreetName" : "Van Ness",
        "SufType" : "Ave",
        "SufDir" : "",
        "City" : "San Francisco",
        "State" : "CA",
        "ZIP" : "94110",
        "X" : -122.417416,
        "Y" : 37.764772999999998,
        "Disp_Lon" : -122.416991,
        "Disp_Lat" : 37.764809999999997,
        "Addr_type" : "StreetAddress",
        "Province" : "",
        "Postal" : "",
        "FromAddr" : "",
        "ToAddr" : "",
        "ZIP4" : "",
        "ZIP4_TYPE" : "",
        "User_fld" : "",
        "Ldu" : "",
        "xmin" : 0,
        "xmax" : 0,
        "ymin" : 0,
        "ymax" : 0
      }
    },
    {
      "address" : "505 Van Ness Ave, San Francisco, CA, 94102",
      "location" : {
        "x" : -13627778.172800001,
        "y" : 4548412.0926000029
      },
      "score" : 100,
      "attributes" : {
        "Loc_name" : "US_Streets",
        "Score" : 100,
        "Match_addr" : "505 Van Ness Ave, San Francisco, CA, 94102",
        "House" : "",
        "Side" : "L",
        "PreDir" : "",
        "PreType" : "",
        "StreetName" : "Van Ness",
        "SufType" : "Ave",
        "SufDir" : "",
        "City" : "San Francisco",
        "State" : "CA",
        "ZIP" : "94102",
        "X" : -122.42041500000001,
        "Y" : 37.780130999999997,
        "Disp_Lon" : 0,
        "Disp_Lat" : 0,
        "Addr_type" : "StreetAddress",
        "Province" : "",
        "Postal" : "",
        "FromAddr" : "501",
        "ToAddr" : "525",
        "ZIP4" : "",
        "ZIP4_TYPE" : "",
        "User_fld" : "",
        "Ldu" : "",
        "xmin" : 0,
        "xmax" : 0,
        "ymin" : 0,
        "ymax" : 0
      }
    }]

Here is a sample of the class i made for the json object to use with gson using java

    public class Response {

    public Response()
    {}

    SpatialReference spatial;

    public List<Candidates> candidate;

    public class Candidates
    {
        public Candidates()
        {}

        @SerializedName("address")
        public String address;

        Location location;

        @SerializedName("score")
        public double score;

        Attribute attributes;

        Double getScore()
        {
            return score;
        }

    }

    public class Attribute {

        public Attribute()
        {}

        @SerializedName("Disp_Lon")
        public double dispLong;

        @SerializedName("Disp_Lat")
        public double dispLat;

    }

    public class Location {

        public Location()
        {}

        @SerializedName("x")
        public double x;

        @SerializedName("y")
        public double y;

    }

    public class SpatialReference {

        SpatialReference()
        {}

        @SerializedName("wkid")
        public String wkid;

    }

}

Here is the sample code using gson

        Gson gson= new Gson()

        response1= gson.fromJson(reader, Response.class);

        return response1;

Any help would be appreciated and I am very new to GSON and retrieving JSON objects. Thank you very much

Answer 1

I'd get rid of the inner class definitions, unless there were some very compelling reason to have them. If namespace is the goal, then at least make them static nested class definitions. This will also make them easier to deserialize into.

I posted examples of deserializing into static nested classes and inner classes at http://programmerbruce.blogspot.com/2011/06/gson-v-jackson.html#TOC-Nested-Classes-including-Inner-Clas