타이틀, 하단 홈 백버튼 등 안보이게 처리하기

private void noTitleNoSystemUi() {
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().takeSurface(null);
setTheme(android.R.style.Theme_NoTitleBar_Fullscreen);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

View decorView = getWindow().getDecorView();
int uiOption = getWindow().getDecorView().getSystemUiVisibility();
uiOption |= (View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION |
View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION |
View.SYSTEM_UI_FLAG_FULLSCREEN | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);

decorView.setSystemUiVisibility(uiOption);
}