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:
Maven dependencies
We should provide JSON.simple Dependency in pom.xml file like below
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<?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> |
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”.
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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:
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{"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
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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:
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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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