How to use a BottomAppBar for navigation in flutter

Question

Im fairly new to flutter, I have created a nice BottomAppBar with a docked FAB however i also want to use this AppBar for page navigation. I've tried it with a BottomNavigationBar but then i lose the docked floating action button. How can i implement navigation into the bottom app bar??

floatingActionButton: Container(
        height: 65.0,
        width: 65.0,
        child: FittedBox(
          child: FloatingActionButton(

        onPressed: (){},
        child: Icon(Icons.add, color: Colors.white,),
        // elevation: 5.0,
      ),
        ),
      ),


      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      bottomNavigationBar: BottomAppBar(
        // elevation: 20.0,

        shape: CircularNotchedRectangle(),
        child: Container( 
          height: 75,
          child: Row( 

        mainAxisSize: MainAxisSize.max,
        mainAxisAlignment: MainAxisAlignment.spaceBetween,

        children: <Widget>[
          IconButton(
            iconSize: 30.0,
            padding: EdgeInsets.only(left: 28.0),
            icon: Icon(Icons.home),
            onPressed: () {
              setState(() {
                currentIndex = 0;
              });
            },
          ),

          IconButton(            
            iconSize: 30.0,
            padding: EdgeInsets.only(right: 28.0),
            icon: Icon(Icons.search),
            onPressed: () {
               setState(() {
                currentIndex = 1;
                print("${currentIndex}");

              });
            },
          ),
          IconButton(
            iconSize: 30.0,
            padding: EdgeInsets.only(left: 28.0),
            icon: Icon(Icons.notifications),
            onPressed: () {
               setState(() {
                currentIndex = 2;
                print("${currentIndex}");

              });
            },
          ),
          IconButton(
            iconSize: 30.0,
            padding: EdgeInsets.only(right: 28.0),
            icon: Icon(Icons.list),
            onPressed: () {
               setState(() {
                currentIndex = 3;
                print("${currentIndex}");
              });
            },
          )
        ],
      ),
        )
      )

Answer 1

One Way of Doing it is with - PageView widget.

Example Code with your Coded BottomAppBar.

class _DemoPageState extends State<FormPage> {
  PageController _myPage = PageController(initialPage: 0);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      bottomNavigationBar: BottomAppBar(
        shape: CircularNotchedRectangle(),
        child: Container(
          height: 75,
          child: Row(
            mainAxisSize: MainAxisSize.max,
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              IconButton(
                iconSize: 30.0,
                padding: EdgeInsets.only(left: 28.0),
                icon: Icon(Icons.home),
                onPressed: () {
                  setState(() {
                    _myPage.jumpToPage(0);
                  });
                },
              ),
              IconButton(
                iconSize: 30.0,
                padding: EdgeInsets.only(right: 28.0),
                icon: Icon(Icons.search),
                onPressed: () {
                  setState(() {
                    _myPage.jumpToPage(1);
                  });
                },
              ),
              IconButton(
                iconSize: 30.0,
                padding: EdgeInsets.only(left: 28.0),
                icon: Icon(Icons.notifications),
                onPressed: () {
                  setState(() {
                    _myPage.jumpToPage(2);
                  });
                },
              ),
              IconButton(
                iconSize: 30.0,
                padding: EdgeInsets.only(right: 28.0),
                icon: Icon(Icons.list),
                onPressed: () {
                  setState(() {
                    _myPage.jumpToPage(3);
                  });
                },
              )
            ],
          ),
        ),
      ),
      body: PageView(
        controller: _myPage,
        onPageChanged: (int) {
          print('Page Changes to index $int');
        },
        children: <Widget>[
          Center(
            child: Container(
              child: Text('Empty Body 0'),
            ),
          ),
          Center(
            child: Container(
              child: Text('Empty Body 1'),
            ),
          ),
          Center(
            child: Container(
              child: Text('Empty Body 2'),
            ),
          ),
          Center(
            child: Container(
              child: Text('Empty Body 3'),
            ),
          )
        ],
        physics: NeverScrollableScrollPhysics(), // Comment this if you need to use Swipe.
      ),
      floatingActionButton: Container(
        height: 65.0,
        width: 65.0,
        child: FittedBox(
          child: FloatingActionButton(
            onPressed: () {},
            child: Icon(
              Icons.add,
              color: Colors.white,
            ),
            // elevation: 5.0,
          ),
        ),
      ),
    );
  }
}