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Deserting multiple inner classes using GSON

I am trying to deserialize data from a JSON object using gson. I am having problems with 1) class design. 2) getting a null object from an internal list object.

Here is an example 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 an example of class i made for a 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 sample code using gson

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

Any help would be appreciated, and I'm very new to GSON and getting JSON objects. Thank you very much

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1 answer

I would get rid of the internal definitions of classes if there weren’t any very good reason to have them. If the namespace is the goal, then at least make them static nested class definitions. It will also facilitate their deserialization.

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

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