Using bottom navy bar flutter to navigate pages

Question

I'm using this package to navigate via the bottom navigation bar, I did not understand how to manage to navigate between my screens. How can I navigate between my screens via bottom navigation bar icons?

import 'dart:async';
import 'dart:io';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'package:bottom_navy_bar/bottom_navy_bar.dart';

class HaberScreen extends StatefulWidget {
  @override
  _HaberScreenState createState() => _HaberScreenState();
}

class _HaberScreenState extends State<HaberScreen> {
  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  @override
  void initState() {
    super.initState();
    if (Platform.isAndroid) WebView.platform = SurfaceAndroidWebView();
  }

  int _currentIndex = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: PreferredSize(
        preferredSize: Size.fromHeight(60.0),
        child: AppBar(
          backgroundColor: Colors.white,
          automaticallyImplyLeading: true,
          leading: IconButton(
            icon: Icon(
              Icons.arrow_back_ios,
              color: Colors.red,
            ),
            //onPressed:() => Navigator.pop(context, false),
            onPressed: () => Navigator.pop(context),
          ),
          title: Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Text(
                'Haberler',
                style: TextStyle(color: Colors.red, fontSize: 25.0),
              )
            ],
          ),

          // This drop down menu demonstrates that Flutter widgets can be shown over the web view.
          actions: <Widget>[
            NavigationControls(
              _controller.future,
            ),
          ],
        ),
      ),
      body: Builder(builder: (BuildContext context) {
        return WebView(
          initialUrl: 'https://www.google.com',
          javascriptMode: JavascriptMode.unrestricted,
          onWebViewCreated: (WebViewController webViewController) {
            _controller.complete(webViewController);
          },
          onProgress: (int progress) {
            print("WebView is loading (progress : $progress%)");
          },
          javascriptChannels: <JavascriptChannel>{
            _toasterJavascriptChannel(context),
          },
          navigationDelegate: (NavigationRequest request) {
            if (request.url.startsWith('https://www.youtube.com/')) {
              print('blocking navigation to $request}');
              return NavigationDecision.prevent;
            }
            print('allowing navigation to $request');
            return NavigationDecision.navigate;
          },
          onPageStarted: (String url) {
            print('Page started loading: $url');
          },
          onPageFinished: (String url) {
            print('Page finished loading: $url');
          },
          gestureNavigationEnabled: true,
        );
      }),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
      floatingActionButton: favoriteButton(),
      
      
      bottomNavigationBar: BottomNavyBar(
        selectedIndex: _currentIndex,
        showElevation: true,
        itemCornerRadius: 24,
        curve: Curves.easeIn,
        onItemSelected: (index) => setState(() => _currentIndex = index),
        items: <BottomNavyBarItem>[
          BottomNavyBarItem(
            icon: Icon(Icons.apps),
            title: Text('Haberler'),
            activeColor: Colors.red,
            textAlign: TextAlign.center,
          ),
          BottomNavyBarItem(
            icon: Icon(Icons.pie_chart),
            title: Text('Sektörler'),
            activeColor: Colors.red,
            textAlign: TextAlign.center,
          ),
          BottomNavyBarItem(
            icon: Icon(Icons.monetization_on),
            title: Text(
              'Kurlar',
            ),
            activeColor: Colors.red,
            textAlign: TextAlign.center,
          ),
          BottomNavyBarItem(
            icon: Icon(Icons.plagiarism_sharp),
            title: Text('Raporlar'),
            activeColor: Colors.red,
            textAlign: TextAlign.center,
          ),
          BottomNavyBarItem(
            icon: Icon(Icons.settings),
            title: Text('Ayarlar'),
            activeColor: Colors.red,
            textAlign: TextAlign.center,
          ),
        ],
      ),
    );
  }

  JavascriptChannel _toasterJavascriptChannel(BuildContext context) {
    return JavascriptChannel(
        name: 'Toaster',
        onMessageReceived: (JavascriptMessage message) {
          // ignore: deprecated_member_use
          Scaffold.of(context).showSnackBar(
            SnackBar(content: Text(message.message)),
          );
        });
  }

  Widget favoriteButton() {
    return FutureBuilder<WebViewController>(
        future: _controller.future,
        builder: (BuildContext context,
            AsyncSnapshot<WebViewController> controller) {
          if (controller.hasData) {
            return FloatingActionButton(
              onPressed: () async {
                final String url = (await controller.data!.currentUrl())!;
                // ignore: deprecated_member_use
                Scaffold.of(context).showSnackBar(
                  SnackBar(content: Text('Favorited $url')),
                );
              },
              child: const Icon(
                Icons.favorite,
                color: Colors.white,
              ),
            );
          }
          return Container();
        });
  }
}

class NavigationControls extends StatelessWidget {
  const NavigationControls(this._webViewControllerFuture)
      : assert(_webViewControllerFuture != null);

  final Future<WebViewController> _webViewControllerFuture;

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<WebViewController>(
      future: _webViewControllerFuture,
      builder:
          (BuildContext context, AsyncSnapshot<WebViewController> snapshot) {
        final bool webViewReady =
            snapshot.connectionState == ConnectionState.done;
        final WebViewController controller = snapshot.data!;
        return Row(
          children: <Widget>[
            IconButton(
              icon: const Icon(
                Icons.arrow_back_ios,
                color: Colors.red,
              ),
              onPressed: !webViewReady
                  ? null
                  : () async {
                      if (await controller.canGoBack()) {
                        await controller.goBack();
                      } else {
                        // ignore: deprecated_member_use
                        Scaffold.of(context).showSnackBar(
                          const SnackBar(content: Text("Geçmiş Bulunamadı")),
                        );
                        return;
                      }
                    },
            ),
            IconButton(
              icon: const Icon(
                Icons.arrow_forward_ios,
                color: Colors.red,
              ),
              onPressed: !webViewReady
                  ? null
                  : () async {
                      if (await controller.canGoForward()) {
                        await controller.goForward();
                      } else {
                        // ignore: deprecated_member_use
                        Scaffold.of(context).showSnackBar(
                          const SnackBar(content: Text("Geçmiş Bulunamadı")),
                        );
                        return;
                      }
                    },
            ),
          ],
        );
      },
    );
  }
}

Answer 1

you have provided only one widget as a body, so changing _currentIndex does not affect the displayed body. According to the example of this package ( in the Use with PageView and PageController section), you can use PageView for changing the display image! Or you can use a list of widgets and show the item that is related to the _currentIndex. so you have two solutions:

1. using PageView in your body section use PageView as follow:

  child: PageView(
          controller: _pageController,
          onPageChanged: (index) {
            setState(() => _currentIndex = index);
          },
          children: <Widget>[
            Container(color: Colors.blueGrey,),
            Container(color: Colors.red,),
            Container(color: Colors.green,),
            Container(color: Colors.blue,),
          ],
        ),
      ),

don't forget to create and dispose page controller:

PageController _pageController;

  @override
  void initState() {
    super.initState();
    _pageController = PageController();
  }

  @override
  void dispose() {
    _pageController.dispose();
    super.dispose();
  }

2. using a list of widgets create a list of widgets:

List<Widget> bodyList = [widget1, widget2, ...]

then provide it as body:

body: bodyList[_currentIndex]