Convert Java Object to Json String using Jackson API

JSON stands for JavaScript Object Notation. It's a standard text-based format that shows structured data based on JavaScript object syntax. It is commonly used for transmitting data in web applications. JSON is highly recommended to transmit data between a server and a web application. To convert a Java object into JSON, the following two methods can be used, that are as listed below as follows:

GSON
JACKSON API

Java object is converted into JSON using Jackson API.

Steps to Convert Java Object to JSON String

Step 1: Add jar files of Jackson (in the case of the Maven project, add Jackson dependencies in the pom.xml file)

html

<dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.5.3</version>
</dependency>

Now pom.xml file is depicted below as follows:

File: Geeks/pom.xml

Step 2: Create a POJO (Plain Old Java Object) to be converted into JSON

Java

package com.Geeks;

public class Organisation {

    private String organisation_name;
    private String description;
    private int employees;

    public String getOrganisation_name() {
        return organisation_name;
    }

    public void setOrganisation_name(String organisation_name) {
        this.organisation_name = organisation_name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public int getEmployees() {
        return employees;
    }

    public void setEmployees(int employees) {
        this.employees = employees;
    }

    @Override
    public String toString() {
        return "Organisation [organisation_name=" + organisation_name
                + ", description=" + description
                + ", employees=" + employees + "]";
    }
}

Step 3: Create a Java class for converting the Organisation object into JSON.

Use the ObjectMapper class provided by Jackson to convert the Java object into a JSON string.

Java

package com.Geeks;

import com.fasterxml.jackson.databind.ObjectMapper;

public class ObjectToJson {

    public static void main(String[] args) {

        // Creating Organisation object
        Organisation org = getObjectData();

        // Creating ObjectMapper instance
        ObjectMapper mapper = new ObjectMapper();

        try {
            // Converting Java object to JSON string
            String jsonString = mapper.writeValueAsString(org);
            System.out.println(jsonString);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    // Method to populate object data
    public static Organisation getObjectData() {

        Organisation org = new Organisation();
        org.setOrganisation_name("GeeksforGeeks");
        org.setDescription("A Computer Science portal for Geeks");
        org.setEmployees(2000);

        return org;
    }
}

Step 3: Execute the process.

The output in the JSON will be as below:

Output:

Key Points:

ObjectMapper is the core class of Jackson for JSON processing
writeValueAsString() converts a Java object into a JSON string
Jackson automatically maps Java fields to JSON keys using getters
Exception handling is required as serialization may throw checked exceptions

Convert Java Object to Json String using Jackson API

Steps to Convert Java Object to JSON String

File: Geeks/pom.xml

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