Failed to deserialize an object with List using Gson

Question

I have the following exception while deserializing an JSON to object using Gson:

com.google.gson.JsonParseException: The JsonDeserializer com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter@588722d6 failed to deserialized json object [{"time":1378911600000,"total":0},{"time":1378912500000,"total":0},{"time":1378913400000,"total":2,"sum":130000,"avgLen":65000.0}] given the type com.google.gson.ParameterizedTypeImpl@490ca2fa

The class which should represent the JSON is:

public class Api{

   private List<ApiData> avgEngLength;

   public Api() {
   }
}

public class ApiData{

private Long time;
private Long total;
private Long sum;
private Double avgLen;

public ApiData(Long time, Long total, Long sum, Double avgLen) {
    this.time = time;
    this.total= total;
    this.sum= sum;
    this.avgLen= avgLen;
 }
}

the deserialized code is:

 String json = "{\"avgEngLength\":[{\"time\":1378905300000,\"total\":0},{\"time\":1378906200000,\"total\":2,\"sum\":130000,\"avgLen\":65000.0}]}";
 Gson gson = new GsonBuilder().create();
 return gson.fromJson(json, Api.class);

The odd thing is that it works on some machines and not on others. Any idea?

What version of Gson are you using? are you providing some customized behaviour to you builder that is not reported in example? — giampaolo

giampaolo giampaolo · Accepted Answer · 2013-09-12T05:51:10

I tried your example with this:

public static void main(String[] args) {

    String s = "{\"avgEngLength\":[{\"time\":1378905300000,\"total\":0},{\"time\":1378906200000,\"total\":2,\"sum\":130000,\"avgLen\":65000.0}]}";

    Gson gson = new GsonBuilder().create();
    Api a = gson.fromJson(s, Api.class);
    System.out.println(a);
    }

and it worked (pay attention that your string in example has no escaped quotes).

Api [avgEngLength=[ApiData [time=1378905300000, total=0, sum=null, avgLen=null], ApiData [time=1378906200000, total=2, sum=130000, avgLen=65000.0]]]

So my best guess it that your team is working with different versions of the library. I'm using Gson 2.2.4 and I checked the source code: that error string is not present in the library.

Failed to deserialize an object with List using Gson

1 Answers