How can we ignore the fields during JSON serialization in Java?

JavaJSONObject Oriented ProgrammingProgramming

If there are fields in Java objects that do not wish to be serialized, we can use the @JsonIgnore annotation in the Jackson library. The @JsonIgnore can be used at the field level, for ignoring fields during the 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 {
   @JsonProperty("EMPLOYEE_ID")
   private int empId;
   @JsonProperty("EMPLOYEE_FIRST_NAME")
   private String firstName;
   @JsonProperty("EMPLOYEE_LAST_NAME")
   private String lastName;
   @JsonIgnore 
   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
}
raja
Published on 10-Oct-2019 15:49:39
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