Convert Json String to Java Object Using GSON

Last Updated : 15 Apr, 2019

Pre-erquisite: Convert Java Object to Json String Using GSON

JSON Stand for JavaScript Object Notation. It’s a standard text-based format which 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 web application.

To convert a Java object into JSON, the following methods can be used:

GSON: It is an open-source Java library which is used to serialize and deserialize Java objects to JSON.
Jackson API

In this article, a predefined JSON String is converted into Java Object using GSON.

Examples:

Input:
{
“organisation_name” : “GeeksforGeeks”,
“description” : “A computer Science portal for Geeks”,
“Employee” : “2000”
}
Output:
Organisation [organisation_name=GeeksforGeeks, description=A computer Science portal for Geeks, Employees=0]

Input:
{
“Student_name” : “XYZ”,
“Organisation_name” : “GeeksForGeeks”
“Roll_No” : “1”
}
Output:
Student [Student_name=XYZ, Organisation_name=GeeksForGeeks, Roll_no=1]

The steps to do this are as follows:

Add jar files of Jackson (in case of Maven project add Gson dependencies in the pom.xml file)
<dependency>

       <groupId>com.google.code.gson</groupId>

       <artifactId>gson</artifactId>

       <version>2.6.2</version>

   </dependency>
Below is the screenshot showing this step:-

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

package GeeksforGeeks.Geeks; 
public class Organisation { 
    private String organisation_name; 
    private String description; 
    private int Employees; 
  
    // Calling getters and setters 
    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) 
    { 
        Employees = employees; 
    } 
  
    // Creating toString 
    @Override
    public String toString() 
    { 
        return "Organisation [organisation_name="
            + organisation_name 
            + ", description="
            + description 
            + ", Employees="
            + Employees + "]"; 
    } 
} 

Below is the screenshot showing this step:-

Create a String Variable for Storing Json String:
Note: This Json string should not be a simple Json String. Preprocess the JSON String and add slashes before passing it into GSON object.

Example of Preprocessing:

Intial JSON String:
{“organisation_name” : “GeeksforGeeks”, “description” : “A computer Science portal for Geeks”, “Employee” : “2000”}

Preprocessed JSON String:
{ \”organisation_name\” : \”GeeksforGeeks\”, \”description\” : \”A computer Science portal for Geeks\”, \”Employee\” : \”2000\” }

Create a Java class for converting the Json into Organisation object:

package GeeksforGeeks.Geeks; 
  
import com.google.gson.Gson; 
  
public class JsonToObject { 
  
    public static void main(String[] args) 
    { 
        // Creating object of Organisation 
        Organisation org = new Organisation(); 
  
        // Converting json to object 
        org = getOrganisationObject(); 
  
        // Displaying object 
        System.out.println(org); 
    } 
  
    private static Organisation getOrganisationObject() 
    { 
        // Storing preprocessed json(Added slashes) 
        String OrganisationJson 
            = "{\"organisation_name\"  
            : \"GeeksforGeeks\", 
            \"description\"  
            : \"A computer Science portal for Geeks\", 
            \"Employee\"  
            : \"2000\"}"; 
  
        // Creating a Gson Object 
        Gson gson = new Gson(); 
  
        // Converting json to object 
        // first parameter should be prpreocessed json 
        // and second should be mapping class 
        Organisation organisation 
            = gson.fromJson(OrganisationJson, 
                            Organisation.class); 
  
        // return object 
        return organisation; 
    } 
} 

Below is the screenshot showing this step:-

Execute the process
Output:

Organisation [organisation_name=GeeksforGeeks, description=A computer Science portal for Geeks, Employees=0]

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