how to parse json in java

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

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