Java JSON serialization - best practice

Question

I need to implement JSON serialization for some objects, and I've encountered a problem when it came to integration with generic collections.

All serializable classes implement this interface (JSONObject comes from this library):

interface JSONSerializable{     public JSONObject dump() throws JSONException //serializes object     public void load(JSONObject obj) throws JSONException //deserializes object } 

Code for my collection based on java.util.list looks more or less like this:

class AwesomeList<T extends JSONSerializable> implements JSONSerializable{     private LinkedList<T> items = new LinkedList<T>();     ...     ...      public JSONObject dump() throws JSONException {         JSONObject result = new JSONObject();         JSONArray a = new JSONArray();         for(T i : items){             a.put(i.dump());         }         result.put("items", a);         return result;     }      public void load(JSONObject obj) throws JSONException{         //here is my problem     } } 

My problem is: When I load AwesomeList from JSONObject, I need to create its elements but it's impossible since java forbids me to write

T newItem = new T(); newItem.load(obj); 

How should I modify my approach to this task?

Answer 1

Are you tied to this library? Google Gson is very popular. I have myself not used it with Generics but their front page says Gson considers support for Generics very important.

Answer 2

As others have hinted, you should consider dumping org.json's library. It's pretty much obsolete these days, and trying to work around its problems is waste of time.

But to specific question; type variable T just does not have any information to help you, as it is little more than compile-time information. Instead you need to pass actual class (as 'Class cls' argument), and you can then create an instance with 'cls.newInstance()'.