Hide and replace BottomNavigationBar once pressed

Question

I have a BottomNavigationBar which if the user pressed on an icon, then it'll show the CarouselSlider and hide the BottomNavigationBar

This is my code, but I'm not sure if I'm getting the right index of the pressed icon and if this is the right way to execute it since I get this error

The argument type 'void Function()' can't be assigned to the parameter type 'void Function(int)?'

int _selectedIndex = 0;

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

    bool carosuel_vis = false;
    bool bottom_vis = true;

bottomNavigationBar: Stack(children: [
        Visibility(
          visible: bottom_vis,
          child: BottomNavigationBar(
            items: const <BottomNavigationBarItem>[
              BottomNavigationBarItem(
                icon: Icon(Icons.home),
                label: 'Carosuel',
              ),
              BottomNavigationBarItem(
                icon: Icon(Icons.business),
                label: 'Business',
              ),
              BottomNavigationBarItem(
                icon: Icon(Icons.school),
                label: 'School',
              ),
            ],
            onTap : () {
              _onItemTapped, 
                  if(_selectedIndex == 0) {carosuel_vis = !carosuel_vis}; // a lot of errors in here
            }
          ),
        ),
        BottomAppBar(
          color: Colors.white,
          child: Visibility(
              visible: carosuel_vis,
              child: CarouselSlider.builder(
                itemCount: imageList.length,
                options: CarouselOptions(
                  autoPlay: true,
                  aspectRatio: 2.0,
                  enlargeCenterPage: true,
                ),
                itemBuilder: (context, index, realIdx) {
                  return Container(
                      child: Center(
                    child: GestureDetector(
                        onTap: () {
                          ff(imageList[index], widget.image.path).then((value) {
                            setState(() {
                              finalsd = value; //update the image
                            });
                          });
                        },
                        child: Image.network(imageList[index],
                            fit: BoxFit.cover, width: 1000)),
                  ));
                },
              )),
        ),
      ])

Answer 1

BottomNavigationBar's onTap comes with index.

 onTap : (index) {
    _onItemTapped(index);
       if(_selectedIndex == 0) {carosuel_vis = !carosuel_vis}; 
    }

Answer 2

try this

onTap: _onItemTapped,


void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
      if(_selectedIndex == 0) {carosuel_vis = !carosuel_vis};
    });
  }