Can't get data in JSON format

I want to get data in JSON format for my app, I tried different ways to solve this problem, but I couldn't find the answer at this error. I hope, you guys can help me, if you need more details, just tell me.

This is the Error I get:

E/MainActivity: Problem parsing the earthquake JSON results
    org.json.JSONException: End of input at character 0 of 
        at org.json.JSONTokener.syntaxError(JSONTokener.java:460)
        at org.json.JSONTokener.nextValue(JSONTokener.java:101)
        at org.json.JSONObject.<init>(JSONObject.java:164)
        at org.json.JSONObject.<init>(JSONObject.java:181)
        at com.example.android.soonami.MainActivity$TsunamiAsyncTask.extractFeatureFromJson(MainActivity.java:207)
        at com.example.android.soonami.MainActivity$TsunamiAsyncTask.doInBackground(MainActivity.java:121)
        at com.example.android.soonami.MainActivity$TsunamiAsyncTask.doInBackground(MainActivity.java:104)
        at android.os.AsyncTask$3.call(AsyncTask.java:378)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:289)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:919)

Method that extracts data in json format:

private Event extractFeatureFromJson(String earthquakeJSON) {
            try {
                JSONObject baseJsonResponse = new JSONObject(earthquakeJSON);
                JSONArray featureArray = baseJsonResponse.getJSONArray("features");

                // If there are results in the features array
                if (featureArray.length() > 0) {
                    // Extract out the first feature (which is an earthquake)
                    JSONObject firstFeature = featureArray.getJSONObject(0);
                    JSONObject properties = firstFeature.getJSONObject("properties");

                    // Extract out the title, time, and tsunami values
                    String title = properties.getString("title");
                    long time = properties.getLong("time");
                    int tsunamiAlert = properties.getInt("tsunami");

                    // Create a new {@link Event} object
                    return new Event(title, time, tsunamiAlert);
                }
            } catch (JSONException e) {
                Log.e(LOG_TAG, "Problem parsing the earthquake JSON results", e);
            }
            return null;
        }

Method that puts data in Event object:

@Override
        protected Event doInBackground(URL... urls) {
            // Create URL object
            URL url = createUrl(USGS_REQUEST_URL);

            // Perform HTTP request to the URL and receive a JSON response back
            String jsonResponse = "";
            try {
                jsonResponse = makeHttpRequest(url);
            } catch (IOException e) {
                // TODO Handle the IOException
                e.printStackTrace();
            }

            // Extract relevant fields from the JSON response and create an {@link Event} object
            Event earthquake = extractFeatureFromJson(jsonResponse);

            // Return the {@link Event} object as the result fo the {@link TsunamiAsyncTask}
            return earthquake;
        }

I guess that you receive empty string from jsonResponse = makeHttpRequest(url).
Have you checked that?