@Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            final View visibleDrawer = findVisibleDrawer();
            if (visibleDrawer != null && getDrawerLockMode(visibleDrawer) == LOCK_MODE_UNLOCKED) {
                closeDrawers();
            }
            return visibleDrawer != null;
        }
        return super.onKeyUp(keyCode, event);
    }
Check if a given drawer view is currently visible on-screen. The drawer
may be only peeking onto the screen, fully extended, or anywhere in between.
If there is no drawer with the given gravity this method will return false.

@param drawerGravity Gravity of the drawer to check
@return true if the given drawer is visible on-screen
app/src/main/java/com/sunnyweather/android/ui/customerUIs/HomeDrawerLayout.java