Jackson - Ignore Fields or Properties on Serialization

🎓 Top 15 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare — All my Udemy courses are real-time and project oriented courses.

▶️ Subscribe to My YouTube Channel (178K+ subscribers): Java Guides on YouTube

▶️ For AI, ChatGPT, Web, Tech, and Generative AI, subscribe to another channel: Ramesh Fadatare on YouTube

<< Back to Jackson JSON Tutorial

This tutorial will show how to ignore certain fields when serializing an object to JSON using Jackson.

This is very useful when the Jackson defaults aren’t enough and we need to control exactly what gets serialized to JSON. There are several ways to ignore properties.

1. Ignore Fields at the Class Level
2. Ignore Field at the Field Level
3. Ignore all Fields by Type

Dependencies

Let’s first add the following dependencies to the pom.xml:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.8</version>
</dependency>

This dependency will also transitively add the following libraries to the classpath:

• jackson-annotations-2.9.8.jar
• jackson-core-2.9.8.jar
• jackson-databind-2.9.8.jar

Always use the latest versions on the Maven central repository for Jackson databind.

Let's demonstrate how to ignore certain fields when serializing an object to JSON using Jackson with examples.

1. Ignore Fields at the Class Level

We can ignore specific fields at the class level, using the @JsonIgnoreProperties annotation and specifying the fields:

package net.javaguides.jackson.ignore;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(value = {
    "id",
    "firstName"
})
public class CustomerDTO {
    private final String id;
    private final String firstName;
    private final String lastName;

    public CustomerDTO(String id, String firstName, String lastName) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public String getId() {
        return id;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }
}

Let's test above code with a main() method, note that after the object is written to JSON, the field is indeed not part of the output:

package net.javaguides.jackson.ignore;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class IgnoreFieldTest {
    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();

        CustomerDTO dtoObject = new CustomerDTO("CUST100", "Tony", "Stark");

        String dtoAsString = mapper.writeValueAsString(dtoObject);

        System.out.println(dtoAsString);
    }
}

Output:

{"lastName":"Stark"}

Note that we have ignored two fields "id" and "firstName" of CustomerDTO and printed only "lastName".

2. Ignore Field at the Field Level

We can also ignore a field directly via the @JsonIgnore annotation directly on the field:

package net.javaguides.jackson.ignore;

import com.fasterxml.jackson.annotation.JsonIgnore;

public class CustomerDTO {

    @JsonIgnore
    private final String id;

    @JsonIgnore
    private final String firstName;
    private final String lastName;

    public CustomerDTO(String id, String firstName, String lastName) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public String getId() {
        return id;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }
}

Let's test above code with a main() method, note that after the object is written to JSON, the field is indeed not part of the output:

package net.javaguides.jackson.ignore;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class IgnoreFieldTest {
    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();

        CustomerDTO dtoObject = new CustomerDTO("CUST100", "Tony", "Stark");

        String dtoAsString = mapper.writeValueAsString(dtoObject);

        System.out.println(dtoAsString);
    }
}

Output:

{"lastName":"Stark"}

Note that we have ignored two fields "id" and "firstName" of CustomerDTO using @JsonIgnore annotation and printed only "lastName".

3. Ignore all Fields by Type

We can also ignore all fields of a specified type, using the @JsonIgnoreType annotation. If we control the type, then we can annotate the class directly:

@JsonIgnoreType
public static class Name {
    public String firstName;
    public String lastName;
    public Name(String firstName, String lastName) {
        super();
        this.firstName = firstName;
        this.lastName = lastName;
    }
}

Here is the complete code:

package net.javaguides.jackson.ignore;

import com.fasterxml.jackson.annotation.JsonIgnoreType;

public class UserDTO {

    public int id;
    public Name name;


    public UserDTO(int id, Name name) {
        super();
        this.id = id;
        this.name = name;
    }

    @JsonIgnoreType
    public static class Name {
        public String firstName;
        public String lastName;
        public Name(String firstName, String lastName) {
            super();
            this.firstName = firstName;
            this.lastName = lastName;
        }
    }
}

Let's test above code with a main() method, note that after the object is written to JSON, the field is indeed not part of the output:

package net.javaguides.jackson.ignore;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonIgnoreTypeTest {

    public static void main(String[] args) throws JsonProcessingException {
        UserDTO.Name name = new UserDTO.Name("John", "Doe");
        UserDTO user = new UserDTO(1, name);

        String result = new ObjectMapper()
            .writeValueAsString(user);

        System.out.println(result);
    }
}

Output:

{"id":1}

Note that the Name class field is ignored by using @JsonIgnoreType annotation.

Related Articles

• Jackson - Convert Java Object to/from JSON Example  (popular)

• Jackson - List, Set, and Map Serialization and Deserialization in Java Examples

• Change Field Name in JSON using Jackson  (popular)

• How to Read / Write JSON Using Jackson JsonParser and JsonGenerator

• Jackson - Enable Pretty Print JSON Output  (popular)

• Jackson @JsonPropertyOrder Example

• Jackson - Ignore Fields or Properties on Serialization

• Jackson @JsonIgnore, @JsonIgnoreProperties and @JsonIgnoreType  (popular)

• Jackson Ignore Null and Empty Fields on Serialization  (popular)

• Jackson @JsonInclude Example

GitHub Repository

The source code of this article available on my GitHub repository at https://github.com/RameshMF/jackson-json-tutorial

My Top and Bestseller Udemy Courses. The sale is going on with a 70 - 80% discount. The discount coupon has been added to each course below:

Build REST APIs with Spring Boot 4, Spring Security 7, and JWT

🆕 High-Demand 80–90% OFF

[NEW] Learn Apache Maven with IntelliJ IDEA and Java 25

🆕 High-Demand 80–90% OFF

ChatGPT + Generative AI + Prompt Engineering for Beginners

🚀 Trending Now 80–90% OFF

Spring 7 and Spring Boot 4 for Beginners (Includes 8 Projects)

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Real-Time REST APIs with Spring Boot - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Microservices with Spring Boot and Spring Cloud

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Java Full-Stack Developer Course with Spring Boot and React JS

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Build 5 Spring Boot Projects with Java: Line-by-Line Coding

🌟 Top Rated 80–90% OFF

Testing Spring Boot Application with JUnit and Mockito

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot Thymeleaf Real-Time Web Application - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Master Spring Data JPA with Hibernate

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot + Apache Kafka Course - The Practical Guide

🎓 Student Favorite 80–90% OFF
Available in Udemy for Business

Java Testing: Mastering JUnit 5 Framework

🆕 New 80–90% OFF

Reactive Programming in Java: Spring WebFlux and Testing

🌟 Top Rated 80–90% OFF

Spring Boot + RabbitMQ Course - The Practical Guide

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Functional Programming in Java (Includes Java Collections)

🎓 Student Favorite 80–90% OFF

ChatGPT for Java Developers: Boost Your Productivity with AI

🚀 Trending Now 80–90% OFF