The Jackson is a library for Java and it has very powerful data binding capabilities and provides a framework to serialize custom java objects to JSON and deserialize JSON back to Java object. The Jackson library provides @JsonInclude annotation that controls the serialization of a class as a whole or its individual fields based on their values during serialization.
The @JsonInclude annotation contains below two values
- Include.NON_NULL: Indicates that only properties with not null values will be included in JSON.
- Include.NON_EMPTY: Indicates that only properties that are not empty will be included in JSON
Example
import com.fasterxml.jackson.annotation.*; import com.fasterxml.jackson.annotation.JsonInclude.Include; import com.fasterxml.jackson.core.*; import com.fasterxml.jackson.databind.*; public class IgnoreNullAndEmptyFieldTest { public static void main(String[] args) throws JsonProcessingException { ObjectMapper mapper = new ObjectMapper(); mapper.enable(SerializationFeature.INDENT_OUTPUT); Employee employee = new Employee(115, null, ""); // passing null and empty fields String result = mapper.writeValueAsString(employee); System.out.println(result); } } // Employee class class Employee { private int id; @JsonInclude(Include.NON_NULL) private String firstName; @JsonInclude(Include.NON_EMPTY) private String lastName; public Employee(int id, String firstName, String lastName) { super(); this.id = id; this.firstName = firstName; this.lastName = lastName; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } }
Output
{ "id" : 115 }