import org.json.*;

String jsonString = ... ; //assign your JSON String here
JSONObject obj = new JSONObject(jsonString);
String pageName = obj.getJSONObject("pageInfo").getString("pageName");

JSONArray arr = obj.getJSONArray("posts");
for (int i = 0; i < arr.length(); i++)
{
    String post_id = arr.getJSONObject(i).getString("post_id");
    ......
}

import org.json.simple.JSONObject;

class JsonEncodeDemo {

   public static void main(String[] args) {
      JSONObject obj = new JSONObject();

	    inputJSON.put("subscriberName", "subscriber");
	    inputJSON.put("msisdn","7055389495");

      System.out.print(obj);
   }
}

//from object to JSON 
Gson gson = new Gson();
gson.toJson(yourObject);

// from JSON to object 
yourObject o = gson.fromJson(JSONString,yourObject.class);

import org.json.*;
//JSON de test
string maTasse = {\couleur\: \Rouge\};
JSONObject tasse = new JSONObject(maTasse);
System.out.println(tasse.getString(couleur)); //Rouge