Question

I am using google gson-2.2.1 library for parsing large response of JSON.

I have to parse a JSON response where structure may vary.

First case, when the response contains more than one team:

 "Details":{

           "Role":"abc",
           "Team":[
              {
                 "active":"yes",
                 "primary":"yes",
                 "content":"abc"
              },
              {
                 "active":"yes",
                 "primary":"yes",
                 "content":"xyz"
              }
           ],

Second case, when only one team is passed:

"Details":{

           "Role":"abc",
           "Team":
              {
                 "active":"yes",
                 "primary":"yes",
                 "content":"abc"
              }
}

There are my base classes used for parsing:

class Details {
    public String Role;
    public ArrayList<PlayerTeams> Team = new ArrayList<PlayerTeams>();
        PlayerTeams Team; // when JsonObject
}

class PlayerTeams {
    public String active;
    public String primary;
    public String content;
}

The problem is that I can not use ArrayList<PlayerTeams> when I have only one of them and it’s returned as JsonObject.

Gson can identify static format of JSON response. I can trace full response dynamically by checking if “Team” key is instance of JsonArray or JsonObject but it would be great if a better solution is available for that.

Edit :
If my response is more dynamic..

"Details":{

       "Role":"abc",
       "Team":
          {
             "active":"yes",
             "primary":"yes",
             "content":"abc"
             "Test":
             {
                 "key1":"value1",
                 "key2":"value2",
                 "key3":"value3"
             }
          }
}

In my edited question, I am facing problem while my response is more dynamic..Team and Test can be JsonArray or JsonObject.. It really harassing me because sometime Test object may array when more data, may object when single data, string when no data. There is no consistency in response.

Answer 1

You need a type adapter. This adapter would be able to distinguish which format is coming and instance the right object with the right values.

You can do this by:

1. implement your own type adapter by creating a class that implements JsonSerializer<List<Team>>, JsonDeserializer<List<Team>>, of course JsonSerializer is just needed in case you need to serialize it in that matter too.
2. Register the type adapter to you GsonBuilder like: new GsonBuilder().registerTypeAdapter(new TypeToken<List<Team>>() {}.getType(), new CoupleAdapter()).create()

The deserialize method could look like:

public List<Team> deserialize(final JsonElement json, final Type typeOfT, final JsonDeserializationContext context)
        throws com.google.gson.JsonParseException {
    if (json.isJsonObject()) {
        return Collections.singleton(context.deserialize(json, Team.class));
    } else {
        return context.deserialize(json, typeOfT);
    }
}