Null Values 

JSON (JavaScript Object Notation) is a lightweight text-based open standard designed for human-readable data interchange. Douglas Crockford has provided a reference implementation of JSON in Java at http://json.org/ useful for JSON serialization and deserialization. Click here to download the compiled library. The following example shows serializing and de-serializing null values .

File Name  :   com/bethecoder/tutorials/json_java/tests/NullValues.java  Author  :   Sudhakar KV Email  :   [email protected]

package com.bethecoder.tutorials.json_java.tests; import org.json.JSONException; import org.json.JSONObject; public class NullValues {   /**    * @param args    * @throws JSONException     */   public static void main(String[] args) throws JSONException {     JSONObject obj = new JSONObject(         "{ \"message1\" : \"null\",  \"message2\" : null }");          System.out.println(obj);     System.out.println(obj.isNull("message1"));  //false - string 'null'     System.out.println(obj.isNull("message2"));  //true  - actual null value          JSONObject obj2 = new JSONObject();     obj2.put("message1", "null");     obj2.put("message2", JSONObject.NULL); //java script null value     System.out.println(obj2);        } }

{"message1":"null","message2":null}
false
true
{"message1":"null","message2":null}