👀 Views: 51 💬 Answers: 1 📅 Created: 2025-06-03

java jackson json deserialization Java

I just started working with I'm dealing with I'm trying to debug I'm working with issues while trying to deserialize a JSON response into a custom Java object using the Jackson library (version 2.13). The JSON structure I receive is nested and has fields that don't directly map to my Java object properties. Here’s the JSON structure: ```json { "user": { "id": 1, "name": "John Doe", "details": { "age": 30, "email": "john.doe@example.com" } } } ``` I have a Java class defined as follows: ```java public class User { private int id; private String name; private UserDetails details; // Getters and Setters } public class UserDetails { private int age; private String email; // Getters and Setters } ``` When I attempt to deserialize the JSON using the following code: ```java ObjectMapper objectMapper = new ObjectMapper(); User user = objectMapper.readValue(jsonString, User.class); ``` I encounter the following behavior: ``` com.fasterxml.jackson.databind.JsonMappingException: Unrecognized field "user" (class User), not marked as ignorable ``` It seems that Jackson is looking for fields in the `User` class that correspond directly to the top-level keys in the JSON, which is not the case since the user data is nested under the "user" key. I’ve tried using `@JsonRootName` annotation and also enabled `DeserializationFeature.UNWRAP_ROOT_VALUE`, but the scenario continues. Can someone guide me on how to properly map this JSON structure to my Java objects using Jackson? Are there any best practices or configuration settings that I might be missing? I'm working in a Ubuntu 22.04 environment. The stack includes Java and several other technologies. Is this even possible? I'm working with Java in a Docker container on Windows 11. Thanks in advance!