Importance of @JsonUnwrapped annotation using Jackson in Java?

The @JsonUnwrapped annotation can be used to unwrap values during the serialization and deserialization process. It helps to render the values of a composed class as if it belongs to the parent class.

Syntax

@Target(value={ANNOTATION_TYPE,FIELD,METHOD,PARAMETER})
@Retention(value=RUNTIME)
public @interface JsonUnwrapped

Example

import com.fasterxml.jackson.annotation.JsonUnwrapped;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.JsonProcessingException;
public class JsonUnwrappedAnnotationTest {
   public static void main(String args[]) throws JsonProcessingException {
      ObjectMapper mapper = new ObjectMapper();
      String jsonString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(new Employee());
      System.out.println(jsonString);
   }
}
class Employee {
   public int empId = 110;
   public String empName = "Raja Ramesh";
   @JsonUnwrapped
   public Address address = new Address();
   // Address class 
   public static class Address {
      public String doorNumber = "1118";
      public String street = "madhapur";
      public String pinCode = "500081";
      public String city = "Hyderabad";
   }
}

Output

{
   "empId" : 110,
   "empName" : "Raja Ramesh",
   "doorNumber" : "1118",
   "street" : "madhapur",
   "pinCode" : "500081",
   "city" : "Hyderabad"
}

raja

Updated on: 09-Jul-2020

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