Parse JSON using Gson, convert JSON to Object and vice-versa

To parse JSON using Gson, you need to download gson-2.8.5.jar from gson-2.8.5.jar

For converting small- or medium-sized lists, Gson provides a better response compared to Jackson. For large lists, Jackson provides a better response than Gson.

Below is the JSON string to parse

{
    "id":12345, 
    "name":"Jason Bourne",
    "age":35,
    "emailaddress":["j.bourne@gmail.com", "j.bourne@yahoo.com"]
}
	

Java class used to convert JSON String to object and vice-versa.

import java.util.List;
    
public class Employee {
    
    private int id;
    private String name;
    private int age;
    private List<String> emailaddress;
        
    // removed getter and setter      
    
    @Override
	public String toString() {
		return "Employee [id=" + id + ", name=" + name + ","
            +" age=" + age + ", emailaddress=" + emailaddress + "]";
	}    
    
}
    

1) Convert JSON string to Java object using Gson.

import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
	
public class TestGsonParser {
    public static void main(String[] args) {
        String jsonString = "{\"id\":12345, \"name\":\"Jason Bourne\", \"age\":35,"
            + " \"emailaddress\":[\"j.bourne@gmail.com\", \"j.bourne@yahoo.com\"]}";
                
        Gson gson = new Gson();    
        // parse json string to object
        Employee employee = gson.fromJson(jsonString, Employee.class); 
        System.out.println(employee);
            
    }
}
	

Output :

Employee [id=12345, name=Jason Bourne, age=35, emailaddress=[j.bourne@gmail.com, j.bourne@yahoo.com]]
    

2) Convert Java object to JSON string using Gson.

import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
	
public class TestGsonParser {
    public static void main(String[] args) {
                
        Employee emp = new Employee();
        emp.setId(2345);
        emp.setName("James Bond");
        emp.setAge(40);
        
        List<String> emailaddress = new ArrayList<>();
        emailaddress.add("jbond@yahoo.com");
        emailaddress.add("jbond@gmail.com");
        emp.setEmailaddress(emailaddress);
		
        Gson gson = new Gson();    
        String jsonEmp = gson.toJson(emp); // create JSON String from Object
        System.out.print(jsonEmp);
    }
}
	

Output :

{"id":2345,"name":"James Bond","age":40,"emailaddress":["jbond@yahoo.com","jbond@gmail.com"]}
    

You can prettify above JSON

import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
	
public class TestGsonParser {
    public static void main(String[] args) {
                
        Employee emp = new Employee();
        emp.setId(2345);
        emp.setName("James Bond");
        emp.setAge(40);
        
        List<String> emailaddress = new ArrayList<>();
        emailaddress.add("jbond@yahoo.com");
        emailaddress.add("jbond@gmail.com");
        emp.setEmailaddress(emailaddress);
		
        Gson gson = new GsonBuilder().setPrettyPrinting().create();   
        String jsonEmp = gson.toJson(emp); // create JSON String from Object
        System.out.print(jsonEmp);
    }
}
	

Output :

{
  "id": 2345,
  "name": "James Bond",
  "age": 40,
  "emailaddress": [
    "jbond@yahoo.com",
    "jbond@gmail.com"
  ]
}