private void doDelete() {

        File sdCard = Environment.getExternalStorageDirectory();


        File file = new File(sdCard + "/arana");
        String[] files;
        files = file.list();
        for (int i=0; i<files.length; i++) {
            File myFile = new File(file, files[i]);
            myFile.delete();
        }


        finish();


    }