Android provides four different classes to manipulate JSON data. These classes are JSONArray,JSONObject,JSONStringer
and JSONTokenizer.

{

   "sys":

   {

      "country":"GB",

      "sunrise":1381107633,

      "sunset":1381149604

   },

   "weather":[

   {

      "id":711,

      "main":"Smoke",

      "description":"smoke",

      "icon":"50n"

   }

],

"main":

   {

      "temp":304.15,

      "pressure":1009,

   }

}

JSON - Elements

An JSON file consist of many components. Here is the table defining the components of an JSON file and their description −

Sr.No	Component & description
1	Array([) In a JSON file , square bracket ([) represents a JSON array
2	Objects({) In a JSON file, curly bracket ({) represents a JSON object
3	Key A JSON object contains a key that is just a string. Pairs of key/value make up a JSON object
4	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. Its syntax is:

String in;

JSONObject reader = new JSONObject(in);

The last step is to parse the JSON. An 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. Its syntax is given below:

JSONObject sys  = reader.getJSONObject("sys");

country = sys.getString("country");

JSONObject main  = reader.getJSONObject("main");

temperature = main.getString("temp");

The method getJSONObject returns the JSON object. The method getStringreturns the string value of the specified key.

Apart from the these methods , there are other methods provided by this class for better parsing JSON files. These methods are listed below −

Sr.No	Method & description
1	get(String name) This method just Returns the value but in the form of Object type
2	getBoolean(String name) This method returns the boolean value specified by the key
3	getDouble(String name) This method returns the double value specified by the key
4	getInt(String name) This method returns the integer value specified by the key
5	getLong(String name) This method returns the long value specified by the key
6	length() This method returns the number of name/value mappings in this object..
7	names() This method returns an array containing the string names in this object.