How to convert Java objects to JSON

In this code snippet, we do the following:

• Create a Student object and set its properties using the setter method.

• Create JSONObject Call object and use the Student object as a parameter to its constructor.

• #JSONObjectUse the getter method to generate a JSON string.

• Call the object.toString() method to obtain the JSON string.

 import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.gson.Gson;
import org.json.JSONObject;
 
import java.util.Arrays;
 
public class PojoToJSON {
 
    public static void main(String[] args) throws JsonProcessingException {
        Student student = new Student();
        student.setId(1L);
        student.setName("Alice");
        student.setAge(20);
        student.setCourses(Arrays.asList("Engineering", "Finance", "Chemistry"));
 
        JSONObject object = new JSONObject(student);
        String json = object.toString();
        System.out.println(json);
        System.out.println(new Gson().toJson(student));
        // Creating Object of ObjectMapper define in Jackson API
        ObjectMapper Obj = new ObjectMapper();
 
        // Converting the Java object into a JSON string
        String jsonStr = Obj.writeValueAsString(student);
        // Displaying Java object into a JSON string
        System.out.println(jsonStr);
 
    }
}

Running this code produces the following results:

##{"courses":["Engineering","Finance", "Chemistry"],"name":"Alice","id":1,"age":20}

{"id":1,"name":"Alice","age":20," courses":["Engineering","Finance","Chemistry"]}
{"id":1,"name":"Alice","age":20,"courses":["Engineering", "Finance","Chemistry"]}

Student class used in the above code:

 import java.util.List;
 
public class Student {
 
    private Long id;
    private String name;
    private int age;
    private List courses;
 
    public Student(Long id, String name, int age, List courses) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.courses = courses;
    }
 
    Student() {
 
    }
 
    public Long getId() {
        return id;
    }
 
    public void setId(Long id) {
        this.id = id;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public int getAge() {
        return age;
    }
 
    public void setAge(int age) {
        this.age = age;
    }
 
    public List getCourses() {
        return courses;
    }
 
    public void setCourses(List courses) {
        this.courses = courses;
    }
 
}

Maven dependencies

    4.0.0
    com.example.javaobjectjson
    JavaObjectJSON
    1.0-SNAPSHOT
    
 
        
        
            org.json
            json
            20211205
        
        
        
            com.google.code.gson
            gson
            2.9.0
        
        
            com.fasterxml.jackson.core
            jackson-databind
            2.12.1
          
    
    

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