[android] Hide Home button

https://developer.android.com/training/system-ui/immersive.html

android 4.4(kitkat)  이상

@Override
protected void onResume()
{
  super.onResume();
  
  toggleHideyBar();
}


private void toggleHideyBar()
{
  int uiOptions = getWindow().getDecorView().getSystemUiVisibility();
  int newUiOptions = uiOptions;
  newUiOptions ^= View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
  newUiOptions ^= View.SYSTEM_UI_FLAG_FULLSCREEN;
  newUiOptions ^= View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
  getWindow().getDecorView().setSystemUiVisibility(newUiOptions);
}