У овом одељку ћемо разумети како можемо да занемаримо нулл поља у време серијализације Јава класе коришћењем Џексона.

Можемо да занемаримо нула поља на нивоу класе, нивоу поља или глобално. Хајде да разумемо сваки од њих један по један.

Занемарите нула поља на нивоу класе

Да бисмо игнорисали нула поља на нивоу класе, користимо @ЈсонИнцлуде напомена са инцлуде.НОН_НУЛЛ . Узмимо пример да бисмо разумели како можемо да користимо @ЈсонИнцлуде анотацију да бисмо игнорисали нулл поља на нивоу класе.

ИгнореНуллФиелдЕкампле1.јава

 //import required classes and package if any import java.io.IOException; import java.util.Scanner; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.databind.ObjectMapper; //create class IgnoreNullFieldExample1 to understand how we can ignore the null field on marshalling public class IgnoreNullFieldExample1 { //main() methods start public static void main(String args[]) { // create an instance of ObjectMapper class ObjectMapper mapper = new ObjectMapper(); // create Scanner class object Scanner sc= new Scanner(System.in); // using try-catch try { College colg; String name, university, street, state, city, rank; System.out.println('Enter College Name:'); name = sc.nextLine(); System.out.println('Enter University Name:'); university = sc.nextLine(); System.out.println('Enter Street:'); street = sc.nextLine(); System.out.println('Enter City:'); city = sc.nextLine(); System.out.println('Enter State:'); state = sc.nextLine(); System.out.println('Enter College Rank:'); rank = sc.nextLine(); // set values to College object by using constructor colg = new College(name, university, new Address(street, state, null), null); // serialize College using mapper String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(colg); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } //close Scanner class object sc.close(); } } //create class College by using @JsonInclude(JsonInclude.Include.NON_NULL) @JsonInclude(JsonInclude.Include.NON_NULL) class College { //Creating properties of College class public String name; public String university; public Address address; public String rank; // constructor College(String name, String university, Address address, String rank){ this.name = name; this.university = university; this.address = address; this.rank = rank; } } //create class Address @JsonInclude(JsonInclude.Include.NON_NULL) class Address { public String street; public String state; public String city; Address(String street, String state, String city){ this.street = street; this.state = state; this.city = city; } } 

Излаз:

јфраме

Занемарите одређено нулл поље

Ево, користимо @ЈсонИнцлуде напомена са инцлуде.НОН_НУЛЛ на нивоу поља да игноришете одређено нулто поље. Узмимо пример да бисмо разумели како можемо да користимо напомену @ЈсонИнцлуде да бисмо игнорисали одређено нулто поље.

ИгнореНуллФиелдЕкампле2.јава

 //import required classes and package if any import java.io.IOException; import java.util.Scanner; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.databind.ObjectMapper; //create class IgnoreNullFieldExample2 to understand how we can ignore specific null fields on marshalling public class IgnoreNullFieldExample2 { //main() methods start public static void main(String args[]) { // create an instance of ObjectMapper class ObjectMapper mapper = new ObjectMapper(); // create Scanner class object Scanner sc= new Scanner(System.in); // using try-catch try { College colg; String name, university, street, state, city, rank; System.out.println('Enter College Name:'); name = sc.nextLine(); System.out.println('Enter University Name:'); university = sc.nextLine(); System.out.println('Enter Street:'); street = sc.nextLine(); System.out.println('Enter City:'); city = sc.nextLine(); System.out.println('Enter State:'); state = sc.nextLine(); System.out.println('Enter College Rank:'); rank = sc.nextLine(); // set values to College object by using constructor colg = new College(name, university, new Address(street, state, city), null); // serialize College using mapper String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(colg); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } //close Scanner class object sc.close(); } } //create class College by using @JsonInclude(JsonInclude.Include.NON_NULL) class College { //Creating properties of College class public String name; public String university; public Address address; @JsonInclude(JsonInclude.Include.NON_NULL) public String rank; // constructor College(String name, String university, Address address, String rank){ this.name = name; this.university = university; this.address = address; this.rank = rank; } } //create class Address class Address { public String street; public String state; public String city; Address(String street, String state, String city){ this.street = street; this.state = state; this.city = city; } } 

Излаз:

како избити из вхиле петље јава

Игноришите нулл поља глобално

Овде користимо ЈсонИнцлуде.Инцлуде.НОН_НУЛЛ у класи ОбјецтМаппер да бисмо конфигурисали понашање глобалног игнорисања нултих поља. Користимо сетСериализатионИнцлусион() метод са Инцлуде.НОН_НУЛЛ на следећи начин:

 mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL) 

Узмимо пример да бисмо разумели како можемо глобално да игноришемо нула поља коришћењем сетСериализатионИнцлусион() методом.

ИгнореНуллФиелдЕкампле3.јава

 //import required classes and package if any import java.io.IOException; import java.util.Scanner; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.databind.ObjectMapper; //create class IgnoreNullFieldExample3 to understand how we can ignore null fields globally public class IgnoreNullFieldExample3 { //main() methods start public static void main(String args[]) { // create an instance of ObjectMapper class ObjectMapper mapper = new ObjectMapper(); // create Scanner class object Scanner sc= new Scanner(System.in); // using try-catch try { College colg; String name, university, street, state, city, rank; System.out.println('Enter College Name:'); name = sc.nextLine(); System.out.println('Enter University Name:'); university = sc.nextLine(); System.out.println('Enter Street:'); street = sc.nextLine(); System.out.println('Enter City:'); city = sc.nextLine(); System.out.println('Enter State:'); state = sc.nextLine(); System.out.println('Enter College Rank:'); rank = sc.nextLine(); // set values to College object by using constructor colg = new College(name, university, new Address(street, state, null), null); // serialize College using mapper String jsonString = mapper .setSerializationInclusion(JsonInclude.Include.NON_NULL) .writerWithDefaultPrettyPrinter() .writeValueAsString(colg); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); } //close Scanner class object sc.close(); } } //create class College class College { //Creating properties of College class public String name; public String university; public Address address; public String rank; // constructor College(String name, String university, Address address, String rank){ this.name = name; this.university = university; this.address = address; this.rank = rank; } } //create class Address class Address { public String street; public String state; public String city; Address(String street, String state, String city){ this.street = street; this.state = state; this.city = city; } } 

Излаз:

Све горе наведене методе се користе за игнорисање нултих поља, при чему се сваки метод користи у различитим случајевима.