Android: Parse Json Response When A Key Can Be A Json Object Or A Json Array

I am fetching data from API provided by our Backend team. One of the keys data sometimes contains JSONObject and sometimes it contains JSONArray. I am using GSON to parse the respo

Solution 1:

You need to use a custom JsonDeserializer. Here's the solution :

publicclassCollectionListItem {

    @SerializedName ("type")
    String type;

    @SerializedName ("order")
    Integer order;

    @SerializedName ("id")
    Integer id;

    @SerializedName ("type_id")
    Integer typeId;

    DataType1 dataType1;
    List<DataType2> dataType2;
    List<DataType3> dataType3;

    finalstaticStringDATA_TYPE_1="SHOP";
    finalstaticStringDATA_TYPE_2="TOP_AUDIOS";
    finalstaticStringDATA_TYPE_3="MEDIA_COLLECTION";

    //Public getters and setterspublicstaticclassCollectionItemDeserializerimplementsJsonDeserializer<CollectionListItem> {

        @Overridepublic CollectionListItem deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)throws JsonParseException {
            CollectionListItemcollectionItem=newGson().fromJson(json, CollectionListItem.class);
            JsonObjectjsonObject= json.getAsJsonObject();

            if (collectionItem.getType() != null) {

                JsonElementelement= jsonObject.get("data");
                switch(collectionItem.getType()){
                    case CollectionListItem.DATA_TYPE_1 :
                        collectionItem.dataType1 = newGson().fromJson(element, DataType1.class);
                        break;

                    case CollectionListItem.DATA_TYPE_2:
                        List<DataType2> values = newGson().fromJson(element, newTypeToken<ArrayList<DataType2>>() {}.getType());
                        collectionItem.dataType2 = values;
                        break;

                    case CollectionListItem.DATA_TYPE_3:
                        List<DataType3> values_ = newGson().fromJson(element, newTypeToken<ArrayList<DataType3>>() {}.getType());
                        collectionItem.dataType3 = values_;
                        break;
                }
            }
            return collectionItem;
        }
    }

}

DataType1, DataType2, etc are the individual classes for different responses.

Also, add this line to register your custom deserializer with gson

Gson gson = newGsonBuilder()
            .registerTypeAdapter(CollectionListItem.class,
                    new CollectionListItem.CollectionItemDeserializer())
            .create();