Importance of @JsonRootName Annotation Using Jackson in Java

The @JsonRootName annotation can be used to wrap an object to serialize with a top-level element. We can pass the name as a parameter to @JsonRootName annotation. We can use the "WRAP_ROOT_VALUE" feature of SerializationFeature enum that can be enabled to make root value wrapped within a single property JSON object where the key is a root name.

Example

import com.fasterxml.jackson.annotation.JsonRootName;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.SerializationFeature;

public class JsonRootNameAnnotationTest {
   public static void main(String args[]) throws JsonProcessingException {
      ObjectMapper mapper = new ObjectMapper();
      String jsonString = mapper.enable(SerializationFeature.WRAP_ROOT_VALUE).writeValueAsString(new Employee());
      System.out.println(jsonString);
   }
}

@JsonRootName(value = "user")
class Employee {
   public int empId = 125;
   public String empName = "Raja Ramesh";
}

Output

{"user":{"empId":125,"empName":"Raja Ramesh"}}