Question

Is there a JSON library for Java that can handle something like the following scenario:

public class BaseShapeSender<T extends Shape> {
{
  Collection<T> shapes;

  public void send
  {
    // Sending the shapes collection with JSON
  }
}

public class CircleSender extends BaseShapeSender<Circle>
{

}

Currently I’m using Jersey, but calling circleSender.send() with the above above scenario gives an exception

A message body writer for Java type, class java.util.ArrayList, and MIME media type, application/json, was not found

even when using GenericEntity to send the collection (apparently Jersey can handle Collection<Circle> but the second level of generics is too much). So, I found myself duplicating the sending code in every subclass:

public class CircleSender extends BaseShapeSender<Circle>
{
  Collection<Circle> circles;

  public void send
  {
    // Sending the circles collection with JSON
  }
}

I would love to avoid that if possible since the sending logic is basically the same in all subclasses.

Answer 1

According to this answer Jackson supports both generics as well as polymorphism. GSON (which I’ve stuck with so far) does not until issue 231 is resolved.