JSON Simple example – Read and write JSON

JSON Simple example show you how to use JSON.simple Java library for reading and writing JSON data into a file.
JSON.simple, is a simple Java library for JSON processing and full compliance with JSON specification (RFC4627).

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In this tutorial, we show you how to use JSON.simple to read and write JSON data from / to a file.

Project structure directory
In this JSON Simple example, we will create java project with directory structure like below:

JSON Simple example

Maven dependencies

We should provide JSON.simple Dependency in pom.xml file like below

<?xml version="1.0" encoding="UTF-8"?>
<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>com.javabycode.json</groupId>
	<artifactId>json-simple</artifactId>
	<version>1.0.0-SNAPSHOT</version>
	<name>JSON-EXAMPLE - ${project.artifactId}</name>
	<packaging>jar</packaging>

	<dependencies>
		<dependency>
			<groupId>com.googlecode.json-simple</groupId>
			<artifactId>json-simple</artifactId>
			<version>1.1.1</version>
		</dependency>
	</dependencies>

</project>

<?xml version="1.0" encoding="UTF-8"?>

<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">

<groupId>com.javabycode.json</groupId>

<artifactId>json-simple</artifactId>

<version>1.0.0-SNAPSHOT</version>

<name>JSON-EXAMPLE - ${project.artifactId}</name>

<groupId>com.googlecode.json-simple</groupId>

<artifactId>json-simple</artifactId>

</dependency>

</dependencies>

</project>

Create a program that write JSON to file
In this example, it initializes data via JSONObject and JSONArray. Then save it into a file named “test.json” that is placed in the directory “E:\tmp”.

package com.javabycode.json;

import java.io.FileWriter;
import java.io.IOException;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;


public class WriteJsonToFileExample {

	@SuppressWarnings("unchecked")
	public static void main(String[] args) {

		JSONObject obj = new JSONObject();
		obj.put("name", "javabycode.com");
		obj.put("visitor", new Integer(100));

		JSONArray array = new JSONArray();
		array.add("Learn Spring by Examples");
		array.add("Learn Hibernate by Examples");
		array.add("Learn Java by Examples");

		obj.put("titles", array);

		try {
			FileWriter file = new FileWriter("E:\\tmp\\test.json");
			file.write(obj.toJSONString());
			file.flush();
			file.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		System.out.print(obj);
	}
}

package com.javabycode.json;

import java.io.FileWriter;

import java.io.IOException;

import org.json.simple.JSONArray;

import org.json.simple.JSONObject;

public class WriteJsonToFileExample {

@SuppressWarnings("unchecked")

public static void main(String[] args) {

JSONObject obj = new JSONObject();

obj.put("name", "javabycode.com");

obj.put("visitor", new Integer(100));

JSONArray array = new JSONArray();

array.add("Learn Spring by Examples");

array.add("Learn Hibernate by Examples");

array.add("Learn Java by Examples");

obj.put("titles", array);

try {

FileWriter file = new FileWriter("E:\\tmp\\test.json");

file.write(obj.toJSONString());

file.flush();

file.close();

} catch (IOException e) {

e.printStackTrace();

}

System.out.print(obj);

}

Run the above program as java application and get the output in the file “test.json” like below:

{"name":"javabycode.com","titles":["Learn Spring by Examples","Learn Hibernate by Examples","Learn Java by Examples"],"visitor":100}

1	{"name":"javabycode.com","titles":["Learn Spring by Examples","Learn Hibernate by Examples","Learn Java by Examples"],"visitor":100}

Create a program that read JSON from file
In this program, we use JSONParser to read above the generated JSON file “test.json” and display it’s content

package com.javabycode.json;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

public class ReadJsonFromFileExample {

	@SuppressWarnings("unchecked")
	public static void main(String[] args) {

		JSONParser parser = new JSONParser();

		try {

			Object obj = parser.parse(new FileReader("E:\\tmp\\test.json"));

			JSONObject jsonObject = (JSONObject) obj;

			String name = (String) jsonObject.get("name");
			System.out.println(name);

			long age = (Long) jsonObject.get("visitor");
			System.out.println(age);

			// loop array
			JSONArray msg = (JSONArray) jsonObject.get("titles");
			Iterator<String> iterator = msg.iterator();
			while (iterator.hasNext()) {
				System.out.println(iterator.next());
			}

		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ParseException e) {
			e.printStackTrace();
		}

	}
}

package com.javabycode.json;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.IOException;

import java.util.Iterator;

import org.json.simple.JSONArray;

import org.json.simple.JSONObject;

import org.json.simple.parser.JSONParser;

import org.json.simple.parser.ParseException;

public class ReadJsonFromFileExample {

@SuppressWarnings("unchecked")

public static void main(String[] args) {

JSONParser parser = new JSONParser();

try {

Object obj = parser.parse(new FileReader("E:\\tmp\\test.json"));

JSONObject jsonObject = (JSONObject) obj;

String name = (String) jsonObject.get("name");

System.out.println(name);

long age = (Long) jsonObject.get("visitor");

System.out.println(age);

// loop array

JSONArray msg = (JSONArray) jsonObject.get("titles");

Iterator<String> iterator = msg.iterator();

while (iterator.hasNext()) {

System.out.println(iterator.next());

}

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

} catch (ParseException e) {

e.printStackTrace();

}

Run above program as java application and output will be generated like below:

javabycode.com
100
Learn Spring by Examples
Learn Hibernate by Examples
Learn Java by Examples

javabycode.com

100

Learn Spring by Examples

Learn Hibernate by Examples

Learn Java by Examples

Noticed that if you want to convert object to / from JSON, you should consider Jackson or Gson.
That’t it on the JSON Simple example tutorial.

Download source code, click link below

jsonsimple-example.zip

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