protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);

        setContentView(R.layout.activity_main);

        if (savedInstanceState == null) {

            getFragmentManager().beginTransaction()

                    .add(R.id.container, new PlaceholderFragment()).commit();

        }

    }