How to handle deserializing with polymorphism?

Question

I have a class like:

public class Barn {
    String type;
    Animal animal;
}

public class Horse extends Animal {
}

public class Cow extends Animal {
}
         


        

Answer 1

You could use Gson Fire for this. The code would look something like this:

GsonFireBuilder builder = new GsonFireBuilder()
    .registerTypeSelector(Barn.class, new TypeSelector() {
        @Override
        public Class getClassForElement(JsonElement readElement) {
            String type = readElement.getAsJsonObject().get("type").getAsString();
            if(type.equals("horse")){
                return Horse.class; 
            } else if(type.equals("cow")) {
                return Cow.class;
            } else {
                return null; //returning null will trigger Gson's default behavior
            }
        }
    });
Gson gson = builder.createGson();