Read and write JSON

1. adding dependency to pom.xml file

 com.googlecode.json-simple
 json-simple
 1.1
  

2. write JSON to file

import java.io.FileWriter;
import java.io.IOException;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
 
public class JsonSimpleExample {
     public static void main(String[] args) {
 
 JSONObject obj = new JSONObject();
 obj.put("name", "mkyong.com");
 obj.put("age", new Integer(100));
 
 JSONArray list = new JSONArray();
 list.add("msg 1");
 list.add("msg 2");
 list.add("msg 3");
 
 obj.put("messages", list);
 
 try {
 
  FileWriter file = new FileWriter("c:\\test.json");
  file.write(obj.toJSONString());
  file.flush();
  file.close();
 
 } catch (IOException e) {
  e.printStackTrace();
 }
 
 System.out.print(obj);
 
     }
 
}

output

{
 "age":100,
 "name":"mkyong.com",
 "messages":["msg 1","msg 2","msg 3"]
}

3. read JSON from file

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 JsonSimpleExample {
     public static void main(String[] args) {
 
 JSONParser parser = new JSONParser();
 
 try {
 
  Object obj = parser.parse(new FileReader("c:\\test.json"));
 
  JSONObject jsonObject = (JSONObject) obj;
 
  String name = (String) jsonObject.get("name");
  System.out.println(name);
 
  long age = (Long) jsonObject.get("age");
  System.out.println(age);
 
  // loop array
  JSONArray msg = (JSONArray) jsonObject.get("messages");
  Iterator 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();
 }
 
     }
 
}

output

mkyong.com
100
msg 1
msg 2
msg 3

original source : http://www.mkyong.com/java/json-simple-example-read-and-write-json/