json_util.txt

private void writeToFile(final String data) {
    new AsyncTask<Void, Void, Void>() {
        @Override
        protected Void doInBackground(Void... params) {
            try {
                Context context = Application.getApplication().getBaseContext();

                File path = context.getExternalFilesDir(null);
                File file = new File(path, "my_json.json");
                FileOutputStream stream = new FileOutputStream(file);
                stream.write(data.getBytes());
                stream.close();

                MyLog.info("done with the json");
            } catch (IOException e) {
                Log.e("Exception", "File write failed: " + e.toString());
            }
            return null;
        }
    }.execute();
}

@Override
public void someMethod() {
    InputStream is = Application.getApplication().getResources().openRawResource(R.raw.my_json);
    final BufferedReader reader = new BufferedReader(new InputStreamReader(is));

    MockResponse mockResponse = new Gson().fromJson(reader, MockResponse.class);
}