Convert Java object to JSON

This tutorial shows 2 ways for converting Java objects to JSON.

This kind of conversion is normally done via third-party libraries as it’s not supported by the JDK itself and requires a hard work to do it manually.

1- Gson

The most popular library used for converting Java objects to JSON is the Google Gson library.

Using Gson, you can get a JSON String out of an object through one line as the following:

public static String convertUsingGson(Student student)
{
	Gson gson = new Gson();
	String studentJson = gson.toJson(student);
	return studentJson;
}

All you have to do is to include gson jar in the classpath.

P.S: It’s worth to mention that toJson() method accepts also Hashmap, ArrayList and Arrays. 

2- Jackson

Another popular library is Jackson.

In order to convert Java objects to JSON using Jackson, you have to include 3 libraries: jackson-annotations, jackson-core and jackson-databind.

Here is the way:

public static String convertUsingJackson(Student student)
{
	String studentJson = "";
	try
	{
		ObjectMapper mapper = new ObjectMapper();
		studentJson = mapper.writeValueAsString(student);
	}
	catch(Exception ex)
	{
		System.out.println("Error while converting Student object to Json");
		ex.printStackTrace();
	}
	return studentJson;
}

P.S: writeValueAsString() method accepts also Hashmap, ArrayList and Arrays. 

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Hussein Terek

Owner of programmergate.com, I have a passion for software engineering and everything related to Java environment.

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