That json.txt file contains response, which you had attached (res.txt) for the very first time you asked your question. You might be getting the response in ReadyAPI through APIs. You just need to remove the code where I have used to read the .txt file using StringBuilder and then run it.
Here it is :-
//Remove this code, since you are getting the response from ReadyAPI response tab.
BufferedReader reader = new BufferedReader(new FileReader("C:\\Users\\Desktop\\json.txt"));
String json = "";
try {
StringBuilder sb = new StringBuilder();
String line = reader.readLine();
while (line != null) {
sb.append(line);
sb.append("\n");
line = reader.readLine();
}
json = sb.toString();
} finally {
reader.close();
}
And into JSONObject, just pass the String JSON wwhich you are getting from ReadyAPI response tab.
If it helps you out, Don't forget to give kudos or accept as solution.