Nikos Maravitsas

About Nikos Maravitsas

Nikos has graduated from the Department of Informatics and Telecommunications of The National and Kapodistrian University of Athens. Currently, his main interests are system’s security, parallel systems, artificial intelligence, operating systems, system programming, telecommunications, web applications, human – machine interaction and mobile development.

Convert Java Object To / From JSON using Jackson example

In this example we are going to see how to conver a Java Object to JSON representation using Jackson. Jackson in a high performance JSON parser and processor java project.

1. Jackson Library

The complete Jackson library consists of 6 jar files that are used for many diffident operation. In this example we are going to need just one, mapper-asl.jar. If you want to install the full library to your project you can download and use jackson-all-*.jar that includes all the jars. You can download them from the Jackson Download Page.

If your using Maven in your project you just have to add the following repository and dependency in your pom.xml.

 <repositories>
	<repository>
		<id>codehaus</id>
		<url>http://repository.codehaus.org/org/codehaus</url>
	</repository>
  </repositories>

  <dependencies>
	<dependency>
		<groupId>org.codehaus.jackson</groupId>
		<artifactId>jackson-all-*</artifactId>
		<version>*</version>
	</dependency>
  </dependencies>

2. Java Object

This is the class we are going to use for the demonstration:

Student.java:

package com.javacodegeeks.java.core;

public class Student {

    private int id;
	private String firstName;
	private String lastName;
	private int age;

	public Student(){

	}

	public Student(String fname, String lname, int age, int id){
		this.firstName = fname;
		this.lastName  = lname;
		this.age        = age;
		this.id         = id;
	}

	public void setFirstName(String fname) {
		this.firstName = fname;
	}

	public String getFirstName() {
		return this.firstName;
	}

	public void setLastName(String lname) {
		this.lastName = lname;
	}

	public String getLastName() {
		return this.lastName;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public int getAge() {
		return this.age;
	}

	public void setId(int id){
		this.id = id;
	}

	public int getId(){
		return this.id;
	}

	@Override
	public String toString() {
		return new StringBuffer(" First Name : ").append(this.firstName)
				.append(" Last Name : ").append(this.lastName).append(" Age : ").append(this.age).append(" ID : ").append(this.id).toString();
	}

}

3. Convert Java Object to JSON represenation

JacksonJSONExample.java:

package com.javacodegeeks.java.core;

import java.io.File;
import java.io.IOException;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

public class JacksonJSONExample {

	private static final String jsonFilePath= "C:\\Users\\nikos7\\Desktop\\filesForExamples\\student.json";

	public static void main(String[] args) {

		Student student = new Student("Jacl", "Freeman", 32, 100);

		ObjectMapper mapper = new ObjectMapper();

		try {

			File jsonFile = new File(jsonFilePath);

			mapper.writeValue(jsonFile, student);

			//System.out.println(mapper.writeValueAsString(student));

		} catch (JsonGenerationException ex) {

			ex.printStackTrace();

		} catch (JsonMappingException ex) {

			ex.printStackTrace();

		} catch (IOException ex) {

			ex.printStackTrace();

		}
	}
}

student.json:

{"id":100,"firstName":"Jacl","lastName":"Freeman","age":32}

4. Convert a JSON representation to Java Object

JSONToJavaObjectJacksonExample.java:

package com.javacodegeeks.java.core;

import java.io.File;
import java.io.IOException;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

public class JSONToJavaObjectJacksonExample {

	private static final String jsonFilePath= "C:\\Users\\nikos7\\Desktop\\filesForExamples\\student.json";

	public static void main(String[] args) {

		ObjectMapper mapper = new ObjectMapper();

		try {
			File jsonFile = new File(jsonFilePath);

			Student student = mapper.readValue(jsonFile, Student.class);

			System.out.println(student);

		} catch (JsonGenerationException e) {

			e.printStackTrace();

		} catch (JsonMappingException e) {

			e.printStackTrace();

		} catch (IOException e) {

			e.printStackTrace();

		}
	}
}

Output:

 First Name : Jacl Last Name : Freeman Age : 32 ID : 100

 
This was an example on how to convert Java Object To / From JSON using Jackson.

Do you want to know how to develop your skillset to become a Java Rockstar?

Subscribe to our newsletter to start Rocking right now!

To get you started we give you two of our best selling eBooks for FREE!

JPA Mini Book

Learn how to leverage the power of JPA in order to create robust and flexible Java applications. With this Mini Book, you will get introduced to JPA and smoothly transition to more advanced concepts.

JVM Troubleshooting Guide

The Java virtual machine is really the foundation of any Java EE platform. Learn how to master it with this advanced guide!

Given email address is already subscribed, thank you!
Oops. Something went wrong. Please try again later.
Please provide a valid email address.
Thank you, your sign-up request was successful! Please check your e-mail inbox.
Please complete the CAPTCHA.
Please fill in the required fields.
Examples Java Code Geeks and all content copyright © 2010-2014, Exelixis Media Ltd | Terms of Use | Privacy Policy
All trademarks and registered trademarks appearing on Examples Java Code Geeks are the property of their respective owners.
Java is a trademark or registered trademark of Oracle Corporation in the United States and other countries.
Examples Java Code Geeks is not connected to Oracle Corporation and is not sponsored by Oracle Corporation.
Do you want to know how to develop your skillset and become a ...
Java Rockstar?

Subscribe to our newsletter to start Rocking right now!

To get you started we give you two of our best selling eBooks for FREE!

Get ready to Rock!
You can download the complementary eBooks using the links below:
Close