Related
lib/main.dart:143:13: Error: Field 'searchBar' should be initialized because its type 'SearchBar' doesn't allow null.
'SearchBar' is from 'package:flutter_search_bar/src/flutter_search_bar_base.dart' ('../Documents/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_search_bar-2.1.0/lib/src/flutter_search_bar_base.dart').
SearchBar searchBar;
^^^^^^^^^
Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:
package:flutter_search_bar
So I ran dart pub upgrade --null-safety in terminal.
Error: Cannot open file, path = 'C:\Users\Miche\Documents\flutter\version' (OS Error: The system cannot find the file specified.
, errno = 2)
Code: /// Flutter code sample for BottomNavigationBar
// This example shows a [BottomNavigationBar] as it is used within a [Scaffold]
// widget. The [BottomNavigationBar] has three [BottomNavigationBarItem]
// widgets, which means it defaults to [BottomNavigationBarType.fixed], and
// the [currentIndex] is set to index 0. The selected item is
// amber. The `_onItemTapped` function changes the selected item's index
// and displays a corresponding message in the center of the [Scaffold].
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_search_bar/flutter_search_bar.dart';
void main() => runApp(const MyApp()); // This is the main application widget.
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
static const String _title = 'Flutter Code Sample';
#override
Widget build(BuildContext context) {
return const MaterialApp(
title: _title,
home: MyStatefulWidget(),
);
}
}
/// This is the stateful widget that the main application instantiates.
class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({Key? key}) : super(key: key);
#override
State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}
/// This is the private State class that goes with MyStatefulWidget.
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
int _selectedIndex = 0;
static const List<Widget> _widgetOptions = <Widget>[
Text(
'Reuse',
style: TextStyle(fontSize: 20),
),
Text(
"Reduce",
style: TextStyle(fontSize: 20),
),
Text(
'Recycle',
style: TextStyle(fontSize: 20),
)
];
void _onItemTapped(int index) {
setState(() {
_selectedIndex = index;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Food3Rs'),
backgroundColor: Colors.green,
),
drawer: Drawer(
child: ListView(padding: EdgeInsets.zero, children: const <Widget>[
DrawerHeader(
decoration: BoxDecoration(color: Colors.green),
child: Text(
'Food Reduction',
style: TextStyle(
color: Colors.white,
fontSize: 24,
),
),
),
ListTile(
leading: Icon(Icons.bookmark),
title: Text('Saved Recipes'),
),
ListTile(
leading: Icon(Icons.account_circle),
title: Text('Profile'),
),
ListTile(leading: Icon(Icons.settings), title: Text('Settings'))
]),
),
body: Center(
child: _widgetOptions.elementAt(_selectedIndex),
),
bottomNavigationBar: BottomNavigationBar(
items: const <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(Icons.food_bank_outlined),
label: ('Reduce'),
backgroundColor: (Colors.lightGreen),
),
BottomNavigationBarItem(
icon: Icon(Icons.food_bank),
label: ('Reuse'),
),
BottomNavigationBarItem(
icon: Icon(Icons.cloud),
label: ('Recycle'),
backgroundColor: (Colors.lightGreen),
)
],
currentIndex: _selectedIndex,
selectedItemColor: Colors.amber[800],
onTap: _onItemTapped,
),
);
}
}
class SearchBarDemoApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Search Bar Demo',
theme: new ThemeData(primarySwatch: Colors.blue),
home: new SearchBarDemoHome());
}
}
class SearchBarDemoHome extends StatefulWidget {
#override
_SearchBarDemoHomeState createState() => new _SearchBarDemoHomeState();
}
class _SearchBarDemoHomeState extends State<SearchBarDemoHome> {
final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
SearchBar searchBar;
AppBar buildAppBar(BuildContext context) {
return new AppBar(
title: new Text('Search Bar Demo'),
actions: [searchBar.getSearchAction(context)]);
}
void onSubmitted(String value) {
setState(() {
var context = _scaffoldKey.currentContext;
if (context == null) {
return;
}
ScaffoldMessenger.maybeOf(context)
?.showSnackBar(new SnackBar(content: new Text('You wrote "$value"!')));
});
}
_SearchBarDemoHomeState() {
searchBar = new SearchBar(
inBar: false,
buildDefaultAppBar: buildAppBar,
setState: setState,
onSubmitted: onSubmitted,
onCleared: () {
print("Search bar has been cleared");
},
onClosed: () {
print("Search bar has been closed");
});
}
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: searchBar.build(context),
key: _scaffoldKey,
body: new Center(
child: new Text("Don't look at me! Press the search button!")),
);
}
}
Since you are definately setting the search bar to a non-null value, just not where it's required for the compiler to recognize it, you can use the late keyword:
late SearchBar searchBar;
See the documentation for the late keyword for more information.
The stable version of flutter_search_bar don't support null safety.
Try changing to 3.0.0-dev.1`
I have the following code that is working properly:
import 'package:flutter/material.dart';
import 'screen_curiosities.dart';
import 'screen_movies.dart';
import 'screen_releases.dart';
import '../utils/side_menu.dart';
import '../utils/bottom_menu.dart';
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
int selectedIndex = 0;
List screens = [
ScreenMovies(),
ScreenReleases(),
ScreenCuriosities()
];
void onClicked(int index) {
setState(() {
selectedIndex = index;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Movies'),
backgroundColor: Colors.black,
),
body: Center(
child: screens.elementAt(selectedIndex),
),
drawer: SideMenu(),
bottomNavigationBar: BottomNavigationBar(
items:[
BottomNavigationBarItem(
icon: Icon(Icons.home),
label: 'Movies',
),
BottomNavigationBarItem(
icon: Icon(Icons.new_releases),
label: 'Releases',
),
BottomNavigationBarItem(
icon: Icon(Icons.question_answer),
label: 'Curiosities',
)
],
currentIndex: selectedIndex,
onTap: onClicked,
selectedItemColor: Colors.red[800],
backgroundColor: Colors.black,
unselectedItemColor: Colors.white,
)
);
}
}
Now I am trying to separate the Widget BottomNavigationBar to another file and call him on the property "bottomNavigationBar" from Scaffold. It would be like this:
bottomNavigationBar: BottomMenu()
I did it with the Widget Drawer and it worked, but when I tried the same thing with bottomNavigationBar it wasn't successful.
When I try to use the variable selectedIndex in the new Widget it is always undefined.
I tried many things, but I couldn't solve this. Is there any way to use the Widget bottomNavigationBar in a separated file?
EDIT
Below, follow the 2 files that I need to make this link from the menu to the page in order to make them work together:
file home.dart
import 'package:flutter/material.dart';
import 'screen_curiosities.dart';
import 'screen_movies.dart';
import 'screen_releases.dart';
import '../utils/side_menu.dart';
import '../utils/bottom_menu.dart';
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
int selectedIndex = 0;
List screens = [
ScreenMovies(),
ScreenReleases(),
ScreenCuriosities()
];
void onClicked(int index) {
setState(() {
selectedIndex = index;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Movies'),
backgroundColor: Colors.black,
),
body: Center(
child: screens.elementAt(selectedIndex),
),
drawer: SideMenu(),
bottomNavigationBar: BottomMenu() // Using the Widget here
}
}
file bottom_menu.dart
import 'package:flutter/material.dart';
class BottomMenu extends StatelessWidget {
#override
Widget build(BuildContext context) {
return BottomNavigationBar(
items:[
BottomNavigationBarItem(
icon: Icon(Icons.home),
label: 'Movies',
),
BottomNavigationBarItem(
icon: Icon(Icons.new_releases),
label: 'Releases',
),
BottomNavigationBarItem(
icon: Icon(Icons.question_answer),
label: 'Curiosities',
)
],
currentIndex: selectedIndex, // the variable is undefined
onTap: onClicked, // the function is undefined
selectedItemColor: Colors.red[800],
backgroundColor: Colors.black,
unselectedItemColor: Colors.white,
);
}
}
You can copy paste run two full code below
You can pass selectedIndex and onClicked to BottomMenu
code snippet
bottomNavigationBar: BottomMenu(
selectedIndex: selectedIndex,
onClicked: onClicked,
));
...
class BottomMenu extends StatelessWidget {
final selectedIndex;
ValueChanged<int> onClicked;
BottomMenu({this.selectedIndex, this.onClicked});
working demo
full code main.dart
import 'package:flutter/material.dart';
import 'bottom.dart';
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
int selectedIndex = 0;
List screens = [ScreenMovies(), ScreenReleases(), ScreenCuriosities()];
void onClicked(int index) {
setState(() {
selectedIndex = index;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Movies'),
backgroundColor: Colors.black,
),
body: Center(
child: screens.elementAt(selectedIndex),
),
//drawer: SideMenu(),
bottomNavigationBar: BottomMenu(
selectedIndex: selectedIndex,
onClicked: onClicked,
));
}
}
class ScreenMovies extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Center(
child: Text("ScreenMovies"),
);
}
}
class ScreenReleases extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Center(
child: Text("ScreenReleases"),
);
}
}
class ScreenCuriosities extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Center(
child: Text("ScreenCuriosities"),
);
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Home(),
);
}
}
full code bottom.dart
import 'package:flutter/material.dart';
class BottomMenu extends StatelessWidget {
final selectedIndex;
ValueChanged<int> onClicked;
BottomMenu({this.selectedIndex, this.onClicked});
#override
Widget build(BuildContext context) {
return BottomNavigationBar(
items: [
BottomNavigationBarItem(
icon: Icon(Icons.home),
label: 'Movies',
),
BottomNavigationBarItem(
icon: Icon(Icons.new_releases),
label: 'Releases',
),
BottomNavigationBarItem(
icon: Icon(Icons.question_answer),
label: 'Curiosities',
)
],
currentIndex: selectedIndex,
onTap: onClicked,
selectedItemColor: Colors.red[800],
backgroundColor: Colors.black,
unselectedItemColor: Colors.white,
);
}
}
I have a BottomNavigationBar that navigates to other pages when pressing an icon. This works fine, except the value of the currentIndex property in BottomNavigationBar doesn't update when the state updates, which means there is no change on the acual BottomNavigationBar. enter image description here
I'm using a vaiable (_selectedPage) to keep track of the selected index in the BottomNavigationBar, and the value changes when tapping an item, but it's not updating the currentIndex property when the state updates.. why is that?
import 'package:flutter/material.dart';
import 'package:independentproject/pages/home_page.dart';
import 'package:independentproject/pages/cook_recipe.dart';
class PageNavigationBar extends StatefulWidget {
#override
_PageNavigationBarState createState() => _PageNavigationBarState();
}
class _PageNavigationBarState extends State<PageNavigationBar> {
//default page showing in bottom navigation bar will be CookRecipe()
int _selectedPage = 1;
//all pages optional in bottom navigation bar
final List<Widget> _pageOptions = [
HomePage(),
CookRecipe(),
];
void onTapped(int pageTapped) {
setState(() {
//print(pageTapped);
_selectedPage = pageTapped;
Navigator.push(context, MaterialPageRoute(builder: (context) => _pageOptions[pageTapped]));
//print(_selectedPage);
});
}
#override
Widget build(BuildContext context) {
return BottomNavigationBar(
//TODO: currentIndex: doesn't update when the state updates, why?
currentIndex: _selectedPage,
//items showing in bottom navigation bar
items: [
BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text('Homepage'),
),
BottomNavigationBarItem(
icon: Icon(Icons.search),
title: Text('Search recipe'),
),
],
onTap: (int pageTapped) {
onTapped(pageTapped);
},
);
}
}
import 'package:flutter/material.dart';
import 'package:independentproject/page_navigation_bar.dart';
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text('Home page'),
),
body: Center(
child: Text('Home page'),
),
bottomNavigationBar: PageNavigationBar(),
),
);
}
}
import 'package:flutter/material.dart';
import 'package:independentproject/page_navigation_bar.dart';
class CookRecipe extends StatefulWidget {
#override
_CookRecipeState createState() => _CookRecipeState();
}
class _CookRecipeState extends State<CookRecipe> {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text('Search recipe'),
),
body: Center(
child: Text('Search recipes'),
),
bottomNavigationBar: PageNavigationBar(),
),
);
}
}
I would advise you to create a widget that will contain the BottomNavigationBar and also PageView that would allow you to switch pages with PageController.
For example:
class _MainScreenState extends State<MainScreen> {
PageController _pageController;
int _page = 1;
Duration pageChanging = Duration(milliseconds: 300);//this is for page animation-not necessary
Curve animationCurve = Curves.linear;//this is for page animation-not necessary
_MainScreenState();
#override
void initState() {
super.initState();
_pageController = PageController(initialPage: 1);
}
Widget build(BuildContext context) {
return Scaffold(
body: PageView(
physics: BouncingScrollPhysics(),
scrollDirection: Axis.horizontal,
controller: _pageController,
onPageChanged: onPageChanged,
children: <Widget>[
//here are all the pages you need:
//CookRecipe(),
],
),
bottomNavigationBar: BottomNavigationBar(
type: BottomNavigationBarType.fixed,
items: <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(
Icons.message,
),
title: Container(height: 0.0),
),
BottomNavigationBarItem(
icon: Icon(
Icons.home,
),
title: Container(height: 0.0),
),
BottomNavigationBarItem(
icon: Icon(
Icons.person,
),
title: Container(height: 0.0),
),
],
onTap: navigationTapped,
selectedItemColor: Theme.of(context).backgroundColor,
currentIndex: _page,
),
),
);
}
void navigationTapped(int page) {
_pageController.animateToPage(page,duration: pageChanging,
curve: animationCurve,);
}
#override
void dispose() {
super.dispose();
_pageController.dispose();
}
void onPageChanged(int page) {
if (this.mounted){
setState(() {
this._page = page;
});
}}
You can also do this without the PageView,and use only the controller to switch pages.
BTW-you create new instance of the navigation bar when you load a page which is bad practice
it is because PageNavigationBar is a own class, when you call there a setstate only this class updates
take a look at the Provider
a very usefull state management Package
or you can also handle your Page, when the NavBar is your Main Page and you have only one Page
return MaterialApp(
home: Scaffold(
appBar: ownAppBar(_selectedPage),
body: _bodyOptions[_selectedPage],
bottomNavigationBar: BottomNavigationBar(
currentIndex: _selectedPage,
items: [
BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text('Homepage'),
),
BottomNavigationBarItem(
icon: Icon(Icons.search),
title: Text('Search recipe'),
),
],
onTap: (int pageTapped) {
onTapped(pageTapped);
},
)
),
);
final List<Widget> _bodyOptions = [
HomePage(),
CookRecipe(),
];
You don't need to use Navigator to change pages, I modified your code just try.
import 'package:flutter/material.dart';
main() {
runApp(MaterialApp(home: PageNavigationBar()));
}
class PageNavigationBar extends StatefulWidget {
#override
_PageNavigationBarState createState() => _PageNavigationBarState();
}
class _PageNavigationBarState extends State<PageNavigationBar> {
//default page showing in bottom navigation bar will be CookRecipe()
int _selectedPage = 1;
//all pages optional in bottom navigation bar
final List<Widget> _pageOptions = [
HomePage(),
CookRecipe(),
];
void onTapped(int pageTapped) {
setState(() {
//print(pageTapped);
_selectedPage = pageTapped;
// Navigator.push(context, MaterialPageRoute(builder: (context) => _pageOptions[pageTapped]));
//print(_selectedPage);
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: _pageOptions[_selectedPage],
bottomNavigationBar: BottomNavigationBar(
//TODO: currentIndex: doesn't update when the state updates, why?
currentIndex: _selectedPage,
//items showing in bottom navigation bar
items: [
BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text('Homepage'),
),
BottomNavigationBarItem(
icon: Icon(Icons.search),
title: Text('Search recipe'),
),
],
onTap: (int pageTapped) {
onTapped(pageTapped);
},
),
);
}
}
class CookRecipe extends StatefulWidget {
#override
_CookRecipeState createState() => _CookRecipeState();
}
class _CookRecipeState extends State<CookRecipe> {
#override
Widget build(BuildContext context) {
return Center(
child: Text('Search recipes'),
);
}
}
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
#override
Widget build(BuildContext context) {
return Center(
child: Text('Home page'),
);
}
}
I wonna animate my appbar color the same way as the bottomnavigationbar does with the shifting type. So the appbar and bottomnavigationbar change color together.
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
int _tabIndex = 0;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Dash')),
body: Container(),
bottomNavigationBar: BottomNavigationBar(
currentIndex: _tabIndex,
onTap: (value) => setState(() => _tabIndex = value),
type: BottomNavigationBarType.shifting,
unselectedItemColor: Theme.of(context).unselectedWidgetColor,
items: [
BottomNavigationBarItem(
icon: Icon(Icons.dashboard), title: Text('Dash'), backgroundColor: Colors.blue),
BottomNavigationBarItem(
icon: Icon(Icons.insert_chart), title: Text('Data'), backgroundColor: Colors.red),
BottomNavigationBarItem(
icon: Icon(Icons.monetization_on), title: Text('Income'), backgroundColor: Colors.orange),
]),
);
}
}
How can I do this? (I'm fairly new to flutter) Thanks!
It's very simple. Simply change color based on the selected index.
Here you go
import 'package:flutter/material.dart';
final Color darkBlue = Color.fromARGB(255, 18, 32, 47);
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
debugShowCheckedModeBanner: false,
home: HomePage(),
);
}
}
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
int _tabIndex = 0;
var colors = [Colors.blue, Colors.red, Colors.orange];
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Dash'),
backgroundColor: colors[_tabIndex],
),
body: Container(),
bottomNavigationBar: BottomNavigationBar(
currentIndex: _tabIndex,
onTap: (value) => setState(() => _tabIndex = value),
type: BottomNavigationBarType.shifting,
unselectedItemColor: Theme.of(context).unselectedWidgetColor,
items: [
BottomNavigationBarItem(
icon: Icon(Icons.dashboard),
title: Text('Dash'),
backgroundColor: colors[0]),
BottomNavigationBarItem(
icon: Icon(Icons.insert_chart),
title: Text('Data'),
backgroundColor: colors[1]),
BottomNavigationBarItem(
icon: Icon(Icons.monetization_on),
title: Text('Income'),
backgroundColor: colors[2]),
]),
);
}
}
See the live demo here.
I have an app with three routes and uses the bottomNavigationBar to navigate between them. In one of the routes I have a button in the page that will also navigate to one of the pages.
Heres my main page
import 'package:flutter/material.dart';
import 'page_two.dart';
import 'page_three.dart';
void main() {
return runApp(MyApp());
}
/// This Widget is the main application widget.
class MyApp extends StatelessWidget {
static const String _title = 'Flutter Code Sample';
#override
Widget build(BuildContext context) {
return MaterialApp(
title: _title,
home: MyStatefulWidget(),
);
}
}
class MyStatefulWidget extends StatefulWidget {
MyStatefulWidget({Key key}) : super(key: key);
#override
_MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
int _selectedIndex = 0;
List<Widget> _widgetOptions = <Widget>[
Text('Main'),
PageTwo(),
PageThree(),
];
void _onItemTapped(int index) {
setState(() {
_selectedIndex = index;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('BottomNavigationBar Sample'),
),
body: Center(
child: _widgetOptions.elementAt(_selectedIndex),
),
bottomNavigationBar: BottomNavigationBar(
items: const <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(Icons.home, color: Colors.black),
title: Text('Home'),
),
BottomNavigationBarItem(
icon: Icon(Icons.business, color: Colors.black),
title: Text('Business'),
),
BottomNavigationBarItem(
icon: Icon(Icons.business, color: Colors.black),
title: Text('Business'),
),
],
currentIndex: _selectedIndex,
selectedItemColor: Colors.amber[800],
onTap: _onItemTapped,
),
);
}
}
Page Two
import 'package:flutter/material.dart';
import 'main.dart';
class PageTwo extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
child: RaisedButton(
child: Text('Go page 1'),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => MyApp()),
);
},
),
);
}
}
and Page Three with a button that navigates to page two
import 'package:flutter/material.dart';
import 'page_two.dart';
class PageThree extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
child: RaisedButton(
child: Text('Go page 1'),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => PageTwo()),
);
},
),
);
}
}
When I press the button on Page Three, it will go to Page Two without the AppBar and the BottomNavigationBar
Use GlobalKey and In PageTwo Widget call MyStatefulWidgetState's _onItemTapped function
You can see working demo and full code below
code snippet
final scakey = new GlobalKey<_MyStatefulWidgetState>();
...
child: Text('Go page 2'),
onPressed: () {
scakey.currentState._onItemTapped(1);
full code
import 'package:flutter/material.dart';
void main() {
return runApp(MyApp());
}
final scakey = new GlobalKey<_MyStatefulWidgetState>();
/// This Widget is the main application widget.
class MyApp extends StatelessWidget {
static const String _title = 'Flutter Code Sample';
#override
Widget build(BuildContext context) {
return MaterialApp(
title: _title,
home: MyStatefulWidget(key: scakey),
);
}
}
class MyStatefulWidget extends StatefulWidget {
MyStatefulWidget({Key key}) : super(key: key);
#override
_MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
int _selectedIndex = 0;
final myKey = new GlobalKey<_MyStatefulWidgetState>();
List<Widget> _widgetOptions = <Widget>[
Text('Main'),
PageTwo(),
PageThree(),
];
void _onItemTapped(int index) {
setState(() {
_selectedIndex = index;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
key: myKey,
appBar: AppBar(
title: const Text('BottomNavigationBar Sample'),
),
body: Center(
child: _widgetOptions.elementAt(_selectedIndex),
),
bottomNavigationBar: BottomNavigationBar(
items: const <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(Icons.home, color: Colors.black),
title: Text('Home'),
),
BottomNavigationBarItem(
icon: Icon(Icons.business, color: Colors.black),
title: Text('Business'),
),
BottomNavigationBarItem(
icon: Icon(Icons.business, color: Colors.black),
title: Text('Business'),
),
],
currentIndex: _selectedIndex,
selectedItemColor: Colors.amber[800],
onTap: _onItemTapped,
),
);
}
}
class PageTwo extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
child: RaisedButton(
child: Text('Go page 1'),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => MyApp()),
);
},
),
);
}
}
class PageThree extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
child: RaisedButton(
child: Text('Go page 2'),
onPressed: () {
scakey.currentState._onItemTapped(1);
/*Navigator.push(
context,
MaterialPageRoute(builder: (context) => PageTwo()),
);*/
},
),
);
}
}
When using navigation bar to navigate between pages, you are tapping on BottomNavigationBarItem to change the index by calling setState() and as the result, build method is triggered with a new _selectedIndex and that index is used to render your appropriate widget.
_widgetOptions.elementAt(_selectedIndex)
Navigator.push on the other hand is just pushing a new route on top of the navigation stack. You are not getting an AppBar or BottomNavigationBar since you don't have them on PageTwo. What I would recommend you is to create a callback function in PageTwo and call that function on button tap. You can now use that callback in MyStatefulWidget to change the index with setState. Here is an example
Declare a final like below in your pages.
final void Function(int index) pageChanged;
In the onTap event of your button, call this function.
widget.pageChanged(1); // PageTwo
In MyStatefulWidget, when you are creating pages, pass the function.
PageTwo(pageChanged:(index){
setState(){_selectedIndex = index;}
});