Jackson Annotations - @JsonInclude

Overview

@JsonInclude annotation is used to exclude properties having null/empty or default values.

Example - Serialization without using @JsonInclude

JacksonTester.java

package com.tutorialspoint;

import java.io.IOException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonTester {
   public static void main(String args[]){
      ObjectMapper mapper = new ObjectMapper();
      try {
         Student student = new Student(1,null);       
         String jsonString = mapper
            .writerWithDefaultPrettyPrinter()
            .writeValueAsString(student);
         System.out.println(jsonString);
      }
      catch (IOException e) { 
         e.printStackTrace();
      }     
   }
}

class Student { 
   public int id; 
   public String name;

   Student(int id,String name){
      this.id = id;
      this.name = name;
   }   
}

Output

Run the JacksonTester and verify the output −

{
  "id" : 1,
  "name" : null
}

Example - Serialization with @JsonInclude

JacksonTester.java

package com.tutorialspoint;

import java.io.IOException;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonTester {
   public static void main(String args[]){
      ObjectMapper mapper = new ObjectMapper();
      try {
         Student student = new Student(1,null);       
         String jsonString = mapper
            .writerWithDefaultPrettyPrinter()
            .writeValueAsString(student);
         System.out.println(jsonString);
      }
      catch (IOException e) { 
         e.printStackTrace();
      }     
   }
}
@JsonInclude(JsonInclude.Include.NON_NULL)
class Student { 
   public int id; 
   public String name;

   Student(int id,String name){
      this.id = id;
      this.name = name;
   }   
}

Output

Run the JacksonTester and verify the output −

{
  "id" : 1
}

Here we can see, without using @JsonInclude, Jackson is serializing all values including null as well. Using @JsonInclude we can define the values which are to be ignored during serialization.