How to deserialize JSON null to a NullNode instead of Java null?

Question

Note: Jackson 2.1.x.

The problem is quite simple but I could not find a solution so far. I have browsed through existing documentation etc and could not find an answ

Answer 1

OK, well, I haven't read the documentation enough, and it is in fact very simple.

There is a JsonNodeDeserializer implementation of JsonDeserializer, which you can extend. And JsonDeserializer has a.getNullValue() method.

So, a custom deserializer was in order:

public final class JsonNullAwareDeserializer
    extends JsonNodeDeserializer
{
    @Override
    public JsonNode getNullValue()
    {
        return NullNode.getInstance();
    }
}

And, in the problematic class:

@JsonDeserialize(using = JsonNullAwareDeserializer.class)
protected final JsonNode value;