android studio remove navigation bar

1    protected void onResume() {
2        super.onResume();
3        View decorView = getWindow().getDecorView();
4        // Hides the status and navigation bar until the user clicks
5        // on the screeen.
6        int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
7                | View.SYSTEM_UI_FLAG_FULLSCREEN;
8        decorView.setSystemUiVisibility(uiOptions);