Parser

JSON stands for JavaScript Object Notation. It is an independent data exchange format and is the best alternative for XML.

Android provides four different classes to manipulate JSON data.
These classes are JSONArray,JSONObject,JSONStringer and JSONTokenizer.
The first step is to identify the fields in the JSON data in which you are interested in.
For example in the JSON given below we interested in getting temperature only.

{
   "sys":
   {
      "country":"GB",
      "sunrise":1381107633,
      "sunset":1381149604
   },
   "weather":[
      {
         "id":711,
         "main":"Smoke",
         "description":"smoke",
         "icon":"50n"
      }
   ],
	
  "main":
   {
      "temp":304.15,
      "pressure":1009,
   }
}

Method	Description
Array []	In a JSON file , square bracket [ represents a JSON array
Objects {}	In a JSON file, curly bracket { represents a JSON object
Key	A JSON object contains a key that is just a string. Pairs of key/value make up a JSON object
Value	Each key has a value that could be string , integer or double e.t.c

JSON Parsing

For parsing a JSON object, we will create an object of class JSONObject and specify a string containing JSON data to it.

String in;
JSONObject reader = new JSONObject(in);

The last step is to parse the JSON. A JSON file consist of different object with different key/value pair e.t.c.
So JSONObject has a separate function for parsing each of the component of JSON file.

JSONObject sys  = reader.getJSONObject("sys");
country = sys.getString("country");
JSONObject main  = reader.getJSONObject("main");
temperature = main.getString("temp");