In this tutorial, we will learn how to convert POJO into a JSON & JSON back into POJO using java based Jackson-databind API. The ObjectMapper class provided by Jackson API provides functionality for converting between Java Objects and JSON.
Maven dependencies
If you are using Maven as a build tool in your project, then add the following dependency in your pom.xml file.
<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.4</version> </dependency>
else, download & add the following Jars into your project classpath:
- jackson-core
- jackson-databind
- jackson-annotation
Convert POJO to JSON and vice versa using Jackson API...!!! Share on X
Example 1. POJO to JSON conversion
import java.io.File;
import com.fasterxml.jackson.databind.ObjectMapper;
public class PojoToJson_Jackson {
public static void main(String[] args) throws Exception {
//**Create ObjectMapper
ObjectMapper mapperObj = new ObjectMapper();
Student student = new Student();
student.setId(5);
student.setName("Isha");
student.setSkill("Google Analytics");
//**Save Java Objects to a JSON File
mapperObj.writeValue(new File("c:\\temp\\student.json"), student);
//**Convert Java Objects to JSON String
//Normal print
String json1 = mapperObj.writeValueAsString(student);
System.out.println("Normal print: \n" + json1);
//Pretty print
String json2 = mapperObj.writerWithDefaultPrettyPrinter().writeValueAsString(student);
System.out.println("\nPretty print: \n" + json2);
}
}
class Student {
int id;
String name;
String skill;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSkill() {
return skill;
}
public void setSkill(String skill) {
this.skill = skill;
}
}
Output:
Normal print:
{"id":5,"name":"Isha","skill":"Google Analytics"}
Pretty print:
{
"id" : 5,
"name" : "Isha",
"skill" : "Google Analytics"
}
Example 2. JSON to POJO conversion
import java.io.FileInputStream;
import com.fasterxml.jackson.databind.ObjectMapper;
public class JsonToPojo_Jackson {
public static void main(String[] args) throws Exception {
//**Create ObjectMapper
ObjectMapper mapperObj = new ObjectMapper();
//**Extract JSON format data from a file and convert it to plain Java object using ObjectMapper
FileInputStream fileInputStreamObj = new FileInputStream("c:\\temp\\student.json");
Student student = mapperObj.readValue(fileInputStreamObj, Student.class);
//**Print POJOs
System.out.println("Student ID : " + student.getId());
System.out.println("Student Name : " + student.getName());
System.out.println("Student Skill : " + student.getSkill());
fileInputStreamObj.close();
}
}
class Student {
int id;
String name;
String skill;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSkill() {
return skill;
}
public void setSkill(String skill) {
this.skill = skill;
}
}
Output:
Student ID : 5 Student Name : Isha Student Skill : Google Analytics
Convert POJO to JSON and vice versa using Jackson API...!!! Share on X
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