Nikos Maravitsas

About Nikos Maravitsas

Nikos has graduated from the Department of Informatics and Telecommunications of The National and Kapodistrian University of Athens. Currently, his main interests are system’s security, parallel systems, artificial intelligence, operating systems, system programming, telecommunications, web applications, human – machine interaction and mobile development.

JSON.Simple Example to read and write JSON in Java

In this example we are going to see a very nice JSON framwork, JSON.simple. In this tutorial we are going to see how to read and write JSON to file using this framework, and you will notice yourself how simple :) it really is.

1. JSON.simple library and dependencies

If your are using Maven to build your project, you just have to add the following dependency to your pom.xml:
 
 
 

<dependency>
	<groupId>com.googlecode.json-simple</groupId>
	<artifactId>json-simple</artifactId>
	<version>1.1</version>
  </dependency>

2. Write JSON to file

package com.javacodegeeks.java.core;

import java.io.FileWriter;
import java.io.IOException;

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

public class JsonSimpleLibraryExample {

	private static final String jsonFilePath = "F:\\nikos7\\Desktop\\filesForExamples\\jsonFile.json";

	public static void main(String[] args) {

		JSONObject jsonObject = new JSONObject();

		jsonObject.put("URL", "www.javacodegeeks.com");

		jsonObject.put("Site Name", "Java Code Geeks");

		jsonObject.put("Members", 120);

		JSONArray jsonArray = new JSONArray();

		jsonArray.add("Jack");
		jsonArray.add("James");

		jsonObject.put("Names", jsonArray);

		try {

			FileWriter jsonFileWriter = new FileWriter(jsonFilePath);
			jsonFileWriter.write(jsonObject.toJSONString());
			jsonFileWriter.flush();
			jsonFileWriter.close();

			System.out.print(jsonObject);

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

	}

}

jsonFile.json:

{"Site Name":"Java Code Geeks","Members":120,"URL":"www.javacodegeeks.com","Names":["Jack","James"]}

3. Parse JSON from File

package com.javacodegeeks.java.core;

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 JsonSimpleLibraryExample {

	private static final String jsonFilePath = "F:\\nikos7\\Desktop\\filesForExamples\\jsonFile.json";

	public static void main(String[] args) {

		JSONParser jsonParser = new JSONParser();

		try {

			FileReader fileReader = new FileReader(jsonFilePath);

			JSONObject jsonObject = (JSONObject) jsonParser.parse(fileReader);

			String siteName = (String) jsonObject.get("Site Name");

			System.out.println("Site Name: " + siteName);

			long members = (long) jsonObject.get("Members");

			System.out.println("Members: " + members);

			String url = (String) jsonObject.get("URL");

			System.out.println("URL: " + url);

			JSONArray names = (JSONArray) jsonObject.get("Names");

			Iterator i = names.iterator();

			while (i.hasNext()) {

				System.out.println(" "+i.next());

			}

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

	}

}

output:

Site Name: Java Code Geeks
Members: 120
URL: www.javacodegeeks.com
 Jack
 James

 
This was a JSON.Simple Example on how to read and write JSON in Java.

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