StatusBarとNavigationBarを消してFullScreenにする方法(出す方法付き)

decorView.setSystemUiVisibility()メソッドにフラグをセットする方法です。※APIレベル14以上

private void hideStatusAndNavigationBar() {
    View decorView = getWindow().getDecorView();
    int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION || View.SYSTEM_UI_FLAG_FULLSCREEN;
    decorView.setSystemUiVisibility(uiOptions);
    isFullScreen = true;
}

private void showStatusAndNavigationBar() {
    View decorView = getWindow().getDecorView();
    int mask = ~(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION || View.SYSTEM_UI_FLAG_FULLSCREEN);
    int uiOptions = decorView.getSystemUiVisibility() && mask;
    decorView.setSystemUiVisibility(uiOptions);
    isFullScreen = false;
}