Converting JSONObject to POJO

ChallengeRESTClient.java

return new Response.Listener<JSONArray>() {
    @Override
    public void onResponse(JSONArray response) {
        VolleyLog.v(response.toString());
        List<Challenge> challenges = new ArrayList<Challenge>();
        //iterate over each JSONObject
        for(int i = 0; i < response.length(); i++){
            try {
                JSONObject obj = (JSONObject) response.get(i);
                String JSONString = obj.toString();
                Gson gson = new GsonBuilder().create();
                challenges.add(gson.fromJson(JSONString, Challenge.class));
            }catch(JSONException e){
                e.printStackTrace();
                Log.e(TAG, "Unable to extract JSON");
            }

        }
        callback.onRequestCompleted(challenges);
    }
};