@JsonInclude(JsonInclude.Include.NON_DEFAULT) can be used to exclude the properties with POJO defaults. This is applied differently as follows:

• If @JsonInclude(JsonInclude.Include.NON_DEFAULT) is used on the class level then default values of the fields are excluded. This is done by creating an instance of POJO using zero-argument constructor, and comparing the property values, excluding the ones having default values e.g. default int value is 0, default String value is null and so on.
• if either @JsonInclude(JsonInclude.Include.NON_DEFAULT) is used on the property level or using:
  ObjectMapper.setDefaultPropertyInclusion(JsonInclude.Include.NON_DEFAULT);
  In both cases :
  • All values which are considered "empty" (as per NON_EMPTY last tutorial) are excluded
  • Primitive/wrapper default values are excluded
  • Date/time values that have milliseconds of `0L` are excluded

Example

Using NON_DEFAULT at class level

@JsonInclude(JsonInclude.Include.NON_DEFAULT)
public class Employee {
  private String name;
  private String dept;
  private Integer salary;
  private boolean fullTime;
  private List<String> phones;
  private Date dateOfBirth;
    .............
}

public class ExampleMain {
  public static void main(String[] args) throws IOException {
      Employee employee = new Employee();
      employee.setName("Trish");
      employee.setFullTime(false);
      employee.setPhones(new ArrayList<>());
      employee.setSalary(Integer.valueOf(0));
      employee.setDateOfBirth(new Date(0));

      ObjectMapper om = new ObjectMapper();
      String jsonString = om.writeValueAsString(employee);
      System.out.println(jsonString);
  }
}

{"name":"Trish","salary":0,"phones":[],"dateOfBirth":0}

As seen in above output only properties with default member values were excluded. Integer with 0 (primitive wrapper - salary) is not excluded, Date with 0 milliseconds is not excluded and also 'empty' collection (phones) is not excluded.

Using NON_DEFAULT at property level

public class Employee2 {
  @JsonInclude(JsonInclude.Include.NON_DEFAULT)
  private String name;
  @JsonInclude(JsonInclude.Include.NON_DEFAULT)
  private String dept;
  @JsonInclude(JsonInclude.Include.NON_DEFAULT)
  private Integer salary;
  @JsonInclude(JsonInclude.Include.NON_DEFAULT)
  private boolean fullTime;
  @JsonInclude(JsonInclude.Include.NON_DEFAULT)
  private List<String> phones;
  @JsonInclude(JsonInclude.Include.NON_DEFAULT)
  private Date dateOfBirth;
    .............
}

public class ExampleMain2 {
  public static void main(String[] args) throws IOException {
      Employee2 employee = new Employee2();
      employee.setName("Trish");
      employee.setFullTime(false);
      employee.setPhones(new ArrayList<>());
      employee.setSalary(Integer.valueOf(0));
      employee.setDateOfBirth(new Date(0));

      ObjectMapper om = new ObjectMapper();
      String jsonString = om.writeValueAsString(employee);
      System.out.println(jsonString);
  }
}

{"name":"Trish"}

Using NON_DEFAULT globally

public class Employee3 {
  private String name;
  private String dept;
  private Integer salary;
  private boolean fullTime;
  private List<String> phones;
  private Date dateOfBirth;
    .............
}

public class ExampleMain3 {
  public static void main(String[] args) throws IOException {
      Employee2 employee = new Employee2();
      employee.setName("Trish");
      employee.setFullTime(false);
      employee.setPhones(new ArrayList<>());
      employee.setSalary(Integer.valueOf(0));
      employee.setDateOfBirth(new Date(0));

      ObjectMapper om = new ObjectMapper();
      om.setDefaultPropertyInclusion(JsonInclude.Include.NON_DEFAULT);
      String jsonString = om.writeValueAsString(employee);
      System.out.println(jsonString);
  }
}

{"name":"Trish"}

As seen above last two options produced the same results, i.e. 'empty' values, primitive/wrapper default values, and date with 0L milliseconds were also excluded.

Example Project

Dependencies and Technologies Used:

• jackson-databind 2.9.6: General data-binding functionality for Jackson: works on core streaming API.
• JDK 10
• Maven 3.5.4