Json with Google Gson in Java

Json is a widely used lightweight text format for data exchange on the Web, it is supposed to be a replacement for XML as it is more compact and easier to read. In this example we will convert a Java object with information to a text string in Json format with the help of the Google Gson library.

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We import the dependency into Maven:

<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.5</version>
</dependency>

The code is the following:

package com.geekole; // Name of your java package

import com.google.gson.Gson;
import java.io.FileWriter;

/**
 *
 * @author geekole.com
 */
public class JsonWithGson {
    public static void main(String args[]){
        try {
            CompanyData companyData = new CompanyData();
            companyData.setId(1);
            companyData.setName("Auto parts distributor");
            companyData.setAddress("Central Street No. 111");
            
            Gson gson = new Gson();
            
            String stringJson = gson.toJson(companyData);
            System.out.println("companyData Json: " + stringJson);

            FileWriter fileWriter = new FileWriter("/path/jsonFile.json");
            fileWriter.write(stringJson);
            fileWriter.close();
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}    

Additionally we use a CompanyData class that serves as an example to convert to Json format.

package com.geekole; // Name of your java package

/**
 *
 * @author geekole.com
 */
public class CompanyData {
    private long id;
    private String name;
    private String address;
    private boolean status;

    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public boolean isStatus() {
        return status;
    }
    public void setStatus(boolean status) {
        this.status = status;
    }
}

We convert our CompanyData instance to a Json string that can be used to respond to a request in the case of a servlet or to be stored in a text file depending on your need.

There really isn’t much to do, we just use the gson.toJson(companyData) method and convert our companyData object to a string.

Gson gson = new Gson();
String stringJson = gson.toJson(companyData);

Running the example we get the following output:

Additionally, we save our Json object in a fileJson.json file:

And that’s it. We hope that this example of Json with Google Gson in Java will be useful to you.