👀 Views: 37 💬 Answers: 1 📅 Created: 2025-06-08

java jackson deserialization json object-mapping Java

Hey everyone, I'm running into an issue that's driving me crazy... I'm relatively new to this, so bear with me. I'm working with a question when using Jackson's `ObjectMapper` to deserialize JSON into a nested object structure. Specifically, I have a parent class `Person` that contains a field of type `Address`, which is also a class. For some reason, when the JSON input doesn't include the `Address` field, Jackson doesn't set it to `null` as I expected, but instead, it initializes it as an empty object. Here's the relevant class structure: ```java public class Person { private String name; private Address address; // Getters and Setters } public class Address { private String street; private String city; // Getters and Setters } ``` When I run the following code: ```java ObjectMapper objectMapper = new ObjectMapper(); String jsonString = "{ \"name\": \"John Doe\" }"; Person person = objectMapper.readValue(jsonString, Person.class); ``` I expect `person.getAddress()` to return `null`, but it actually returns an `Address` object with both `street` and `city` fields set to `null`. I've tried using `@JsonInclude(JsonInclude.Include.NON_NULL)` and `@JsonProperty` annotations on the `address` field, but this doesn't seem to affect the deserialization behavior. Is there a configuration or annotation I might be missing to ensure that Jackson doesn't instantiate an empty `Address` object when the field is absent in the JSON input? Any insights would be greatly appreciated! My development environment is macOS. Any ideas what could be causing this? My team is using Java for this application.