@Override
protected void onCreate(Bundle icicle) {
  hideNavigationBar();
}

// 隱藏虛擬按鍵
public void hideNavigationBar()
{
  int uiFlags = 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 // hide nav bar
    | View.SYSTEM_UI_FLAG_FULLSCREEN; // hide status bar

  if( android.os.Build.VERSION.SDK_INT >= 19 ){
    uiFlags |= 0x00001000;  //SYSTEM_UI_FLAG_IMMERSIVE_STICKY: hide navigation bars - compatibility: building API level is lower thatn 19, use magic number directly for higher API target level
  } else {
    uiFlags |= View.SYSTEM_UI_FLAG_LOW_PROFILE;
  }
  getWindow().getDecorView().setSystemUiVisibility(uiFlags);
}

@Override
public void onWindowFocusChanged(boolean hasFocus) {
  super.onWindowFocusChanged(hasFocus);
  if( hasFocus ) {
    hideNavigationBar();
  }
}

private Point getDisplay(MainActivity context)
{
  DisplayMetrics metrics = new DisplayMetrics();
  Display display = context.getWindowManager().getDefaultDisplay();
  display.getMetrics(metrics);
  DisplayMetrics dm = new DisplayMetrics();
  @SuppressWarnings("rawtypes")
  Class c;
  try {
    c = Class.forName("android.view.Display");
    @SuppressWarnings("unchecked")
    Method method = c.getMethod("getRealMetrics", DisplayMetrics.class);
    method.invoke(display, dm);
    return new Point(dm.widthPixels, dm.heightPixels);
  } catch (Exception e) {
    return new Point(dm.widthPixels, dm.heightPixels);
  }
}