Java generics and jackson mapper

Question

Hi I have the following classes:

public class MyRequest {
}

and

public class MyResponse {
}

and

public class Request<T> {
private String code;
private T request;

public setCode(String code) {
   this.code = codel
  }

public setRequest(T request) {
   this.request = request
   }
}

and following service request method:

public MyResponse getMyResponse(Request<MyRequest> myRequest) {
//process
try {
    ObjectMapper mapper = new ObjectMapper();
    String jsonInString = mapper.writeValueAsString(myRequest);
    System.out.println(jsonInString);
  } catch(Exception exp) {}
}

and following Json request is sending from JavaScript;

{
   "code":"TESTCODE",
   "request":null 
}

After I send the request I an getting an Invalid Json error. Can anyone tell me what is wrong with my request Json or something else is wrong..?

If you're positive that the generic isn't actually null, your problem is deserialization. This will help: http://stackoverflow.com/questions/11664894/jackson-deserialize-using-generic-class — Eric, Mar 06 '17 at 19:04
where is the code which is deserializing your JSON from javascript? — Coder, Mar 06 '17 at 19:11
Sending this using HTTP Request add-on of Firefox. This is not a full code... Previous code without Java generics was working perfectly.. Also Jackson is used on Spring side.. — Adds, Mar 06 '17 at 19:29
The error doesn't seems to be related to the code here as you don't have JSON at all. You are trying to write the object as a string which will have JSON structure but that's not the problem here — Coder, Mar 06 '17 at 20:58

score 0 · Answer 1 · answered Mar 06 '17 at 22:14

By any chance are you using the model 'Request' as an inner class. If yes,

just try using the modifier static with 'Request'.
or rather move out the model 'Request' to a separate class

Non-static Inner classes by design contain a reference to the outer-class, which does cause problems in deserialization.

http://www.cowtowncoder.com/blog/archives/2010/08/entry_411.html

Java generics and jackson mapper

1 Answers1