Convert Json String to Java Object Using GSON - GeeksforGeeks

24 Jan, 2022
Pre-requisite: Convert Java Object to Json String Using GSONJSON 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)  
html
<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  
Java
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:  
Initial 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:
Java
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 preprocessed 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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