JSON to Java and interfaces

[Jake Goldman]

Hello,

Very happy with JSON-lib, it's a fantastic library that made my life a lot easier, thank you to authors and contributors! A few questions:

My object model:

interface Shape() {
  String getName();
  void setName(String s);
}

class Rectangle implements Shape {
   private name = "rectangle"; // returned by getName, setName defaults to that
   draw() {..}
}

class Circle implements Shape {
  private name = "circle"; // returned by getName, setName defaults to that
  draw() {...}
}

class Palette {
  List<Shape> shapes;
}

1. When doing JSONSerializer.toJava with rootClass set to Palette, I get
"beanClass is an interface exception" for Shape. How do I tell json-lib that if it sees a Shape with "name" = "rectangle" to instantiate class Rectangle? I am open to modifying my object model, using DynaBeans, etc.

2. When serializing Palette to JSON, I'd like the following JSON:

{
  "shape1":   {
     "name" = "circle"
     "someProp" = "someVal"
  },
  "shape2" : {
     "name" = "circle"
     "someProp" = "someVal"
  }
}

I am not sure what method signatures need to be present on Palette but I don't think I can do it with a straight bean. Do I implement DynaBean then or use one of the provided DynaBean implementations to wrap Palette?

[aalmiray]

Hi Jake,

For issue #1 you can set a custom NewBeanInstanceStrategy via JsonConfig.setNewBeanInstanceStrategy(). You will receive a Class and the current JSONObject being processed, then you can make a choice based on the that objetc's properties (like name = "rectangle").

For issue #2 it seems that you'd like to turn an array into an object where each element follows a naming convention. Perhaps a JsonBeanProcessor will help you here, as outlined in tip #4 at http://jroller.com/aalmiray/entry/json_lib_hibernate_tips_and

Cheers,
Andres