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How to convert java object to json string using Gson APIs?


This page shows how to convert java object to JSON string using Google gson API.

As a first step add google gson dependent jar file to your classpath. Here is the pom.xml file for your reference:

<project xmlns="http://maven.apache.org/POM/4.0.0" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
    					http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>gson_exmp</groupId>
  <artifactId>gson_exmp</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <dependencies>
  	<dependency>
  		<groupId>com.google.code.gson</groupId>
  		<artifactId>gson</artifactId>
  		<version>2.3.1</version>
  	</dependency>
  </dependencies>
</project>

Create a simple Employee pojo. We will convert this pojo to JSON value.

package com.java2novice.json.gson;

public class Employee {

	private int empId;
	private String name;
	private String designation;
	private String department;
	private int salary;
	
	public int getEmpId() {
		return empId;
	}
	public void setEmpId(int empId) {
		this.empId = empId;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getDesignation() {
		return designation;
	}
	public void setDesignation(String designation) {
		this.designation = designation;
	}
	public String getDepartment() {
		return department;
	}
	public void setDepartment(String department) {
		this.department = department;
	}
	public int getSalary() {
		return salary;
	}
	public void setSalary(int salary) {
		this.salary = salary;
	}
}

Finally here is the example to convert java object to JSON string:

package com.java2novice.json.gson;

import com.google.gson.Gson;

public class ObjectToJsonEx {

	public static void main(String a[]){
		
		Employee emp = new Employee();
		emp.setEmpId(1016);
		emp.setName("Nataraj G");
		emp.setSalary(20000);
		emp.setDesignation("Manager");
		emp.setDepartment("Accounts");
		
		Gson gsonObj = new Gson();
		// converts object to json string
		String jsonStr = gsonObj.toJson(emp);
		System.out.println(jsonStr);
	}
}

Output:
{"empId":1016,"name":"Nataraj G","designation":"Manager","department":"Accounts","salary":20000}
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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