public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            Intent intent = new Intent(Intent.ACTION_MAIN);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            intent.addCategory(Intent.CATEGORY_HOME);
            startActivity(intent);
            return true;
        }
        return super.onKeyDown(keyCode, event);
}