Java Jackson - Unexpected token (START_ARRAY), expected VALUE_STRING

Question

Hi I am trying to deserialize the json data using jackson in java. I am facing an error as follows:Unexpected token (START_ARRAY), expected VALUE_STRING: need JSON String that contains type id (for subtype of Attachment) Here is the code I have used. Please let me know how to resolve this issue. Thanks in advance.

 ObjectMapper mapper = new ObjectMapper();
     mapper.enableDefaultTyping();
     Audio audio = new Audio(2,2,"www.google.com","HelloWorld");

     List<Link1> link = new ArrayList<Link1>();
     link.add(audio);

     try {

         String jsonDataString=  mapper.writerWithDefaultPrettyPrinter().writeValueAsString(link);
           System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(link));

               Attachment f1 = new Attachment();
                 f1 = mapper.readValue(jsonDataString,Attachment.class);
        } catch (JsonProcessingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

JSON:

[[
    "Audio",
    {
        "url" : "www.google.com",
        "title" : "HelloWorld",
        "aid" : 2,
        "owner_id" : 2
    }
]]