How to parse JSON response in android in the following format

I'm trying to parse the JSON response in Android for my Android application. I'm getting org.json.jsonexception. The response is as follows:

 {
    id: "12345"
    email:"abc@gmail.com"
firstName:"abcd"
lastName:"efgh"
userName:"abc123"
    }

I'm trying to parse the response as follows:

 if (response != null) {
                    try {
                        //JSONObject jsonObj = new JSONObject(text);

                        // Getting JSON Array node
                       JSONArray contacts = new JSONArray(response.toString());

                        // looping through All Contacts
                        for (int i = 0; i < contacts.length(); i++) {
                            JSONObject c = contacts.getJSONObject(i);

                             id = c.getString("_id");
                             email = c.getString("email");
                             firstName = c.getString("firstName");
                             lastName = c.getString("lastName");
                             userName = c.getString("userName");
 }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }

Who can let me know what mistakes I made in parsing the response. All suggestions are welcome

resolvent:

Just replace with "_id" instead of "Id"

id = c.getString("id");
email = c.getString("email");
firstName = c.getString("firstName");
lastName = c.getString("lastName");
userName = c.getString("userName");