In Java, how can we ignore certain fields during JSON serialization?

If there are fields in the Java object that we do not want to be serialized, we can use the @JsonIgnore annotation in the Jackson library . @JsonIgnore can be used to ignore fields during serialization and deserialization.

Syntax

public @interface JsonIgnore

Example

import java.io.*;
import java.util.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.annotation.*;
public class JsonIgnoreAnnotationTest {
   public static void main(String args[]) throws JsonGenerationException, JsonMappingException, IOException {
      Employee emp = new Employee();
      emp.setFirstName("Raja");
      emp.setLastName("Ramesh");
      emp.setEmpId(120);
      emp.getTechnologies().add("Java");
      emp.getTechnologies().add("Scala");
      emp.getTechnologies().add("Python");
      ObjectMapper mapper = new ObjectMapper();
      mapper.writerWithDefaultPrettyPrinter().writeValue(System.out, emp);
   }
}
// Employee class
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
   "firstName",
   "lastName",
   "technologies",
   "empId"
})
class Employee {
<strong>   </strong>@JsonProperty("EMPLOYEE_ID")
   private int empId;
   @JsonProperty("EMPLOYEE_FIRST_NAME")
   private String firstName;
   @JsonProperty("EMPLOYEE_LAST_NAME")
   private String lastName;
   @JsonIgnore <strong>
</strong>   private List<String> technologies = new ArrayList<>();
   public int getEmpId() {
      return empId;
   }
   public void setEmpId(int empId) {
      this.empId = empId;
   }
   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;
   }
   public List<String> getTechnologies() {
      return technologies;
   }
   public void setTechnologies(List<String> technologies) {
      this.technologies = technologies;
   }
}

Output

{
   "EMPLOYEE_FIRST_NAME" : "Raja",
   "EMPLOYEE_LAST_NAME" : "Ramesh",
   "EMPLOYEE_ID" : 120
}

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