Yes, you can. You have to build your own serializer first. For instance:
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public static String toJson(List<Item> items){
try{
JSONObject jsonObj = new JSONObject();
JSONArray jsonArr = new JSONArray();
for(Item i : items){
JSONObject itemObj = new JSONObject();
itemObj.put("names", i.getName());
itemObj.put("companies", i.getCompanies());
itemObj.put("colors", i.getColors());
itemObj.put("numbers", i.getNumbers());
itemObj.put("candy", i.getCandy());
jsonArr.put(itemObj);
}
jsonObj.put("items", jsonArr);
return jsonObj.toString();
} catch(JSONException ex){
ex.printStackTrace();
}
return null;
}