Failed to deserialize an object with List using Gson

问题

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?

回答1:

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.

来源：https://stackoverflow.com/questions/18756130/failed-to-deserialize-an-object-with-list-using-gson

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java

json

gson