I just want to pass my int and bool values into another class in another dart file.
I am trying to pass values the method.
Try this.
import 'package:flutter/material.dart';
void main() => runApp(new MaterialApp(
home: new MainPage(),
));
class MainPage extends StatefulWidget {
#override
_MainPageState createState() => new _MainPageState();
}
class _MainPageState extends State<MainPage> {
int count = 0;
bool isMultiSelectStarted = false;
void onMultiSelectStarted(int count, bool isMultiSelect) {
print('Count: $count isMultiSelectStarted: $isMultiSelect');
}
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
backgroundColor: Colors.blue,
title: new Text('Home'),
),
body: new Center(
child: new RaisedButton(
child: new Text('Go to SecondPage'),
onPressed: () {
Navigator.of(context).push(
new MaterialPageRoute(
builder: (context) {
return new SecondPage(onMultiSelectStarted);
},
),
);
},
),
),
);
}
}
class SecondPage extends StatefulWidget {
int count = 1;
bool isMultiSelectStarted = true;
final Function multiSelect;
SecondPage(this.multiSelect);
#override
_SecondPageState createState() => new _SecondPageState();
}
class _SecondPageState extends State<SecondPage> {
#override
Widget build(BuildContext context) {
return new Center(
child: new RaisedButton(
child: new Text('Pass data to MainPage'),
onPressed: () {
widget.multiSelect(widget.count, widget.isMultiSelectStarted);
},
),
);
}
}
Related
So I'm learning basics of bloc and I wanted to know how to change a text using a button without setstate(), this whole time ive been using setstate but I would like to know how to change a text after a button click using bloc, state, event.
This is what I have so far
Main.dart
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MultiProvider(
providers: [
BlocProvider(
create: (_) => SecscreenBloc(),
),
],
child: MaterialApp(
onGenerateRoute: Routes().onGenerateRoute,
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: SecScreen()),
);
}
}
SecScreen.dart
class SecScreen extends StatefulWidget {
const SecScreen({Key? key}) : super(key: key);
#override
State<SecScreen> createState() => _SecScreenState();
}
class _SecScreenState extends State<SecScreen> {
var numm = 1;
#override
Widget build(BuildContext context) {
return BlocProvider(
create: (context) => SecscreenBloc()..add(LoadSecscreenEvent(numm)),
child: Scaffold(
appBar: AppBar(
title: Text("Bloc Increment"),
),
body: BlocBuilder<SecscreenBloc,SecscreenState>(
builder: (context,state){
if(state is SecScreenLoadedState){
return Column(
children: [
Text("Activity: ${state.number}"),
SizedBox(height: 30),
ElevatedButton(
onPressed: () => BlocProvider.of<SecscreenBloc>(context).add(LoadSecscreenEvent(
numm
)),
child: Icon(Icons.add),
),
],
);
}
return Container(
color: Colors.red,
);
}
),
),
);
}
}
SecScreen_event.dart
abstract class SecscreenEvent extends Equatable {
const SecscreenEvent();
}
class LoadSecscreenEvent extends SecscreenEvent{
final int number;
LoadSecscreenEvent(this.number);
#override
List<Object?> get props => [number];
}
SecScreen_state.dart
part of 'secscreen_bloc.dart';
abstract class SecscreenState extends Equatable {
const SecscreenState();
}
class SecscreenInitial extends SecscreenState {
#override
List<Object> get props => [];
}
class SecScreenLoadedState extends SecscreenState{
final int number;
SecScreenLoadedState(this.number);
#override
List<Object?> get props => [number];
}
secscreen_bloc.dart
class SecscreenBloc extends Bloc<SecscreenEvent, SecscreenState> {
SecscreenBloc() : super(SecscreenInitial()) {
on<LoadSecscreenEvent>((event, emit) {
if (event is LoadSecscreenEvent){
emit(SecScreenLoadedState(event.number + 1));
}
});
}
}
I've been stuck at this for an embarssingly long time, would appreciate some help!
actually it is changed every time you press but every time the value gone to the bloc 1 and back 2 so you did not see the effection
just change the following line
onPressed: () => BlocProvider.of<SecscreenBloc>(context).add(LoadSecscreenEvent(
numm
)),
to this one :
onPressed: () => BlocProvider.of<SecscreenBloc>(context)
.add(LoadSecscreenEvent(state.number)),
This is code：
main
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider<Something>(
create: (_) => Something(),
child: Consumer<Something>(
builder: (BuildContext context, Something value, Widget child) {
return MaterialApp(
title: 'Flutter Demo',
home: MyHomePage(),
);
},
),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key}) : super(key: key);
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String mockData = '';
#override
void initState() {
super.initState();
initData();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('demo'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'moceData:$mockData',
),
Text(
'${Provider.of<Something>(context).count}',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
Navigator.push(context, MaterialPageRoute(builder: (_) {
return SecondPage();
}));
},
child: Icon(Icons.add),
),
);
}
initData() {
Future.delayed(Duration(seconds: 1), () {
mockData = 'mock 123';
setState(() {});
});
}
}
SecondPage
class SecondPage extends StatefulWidget {
#override
_SecondPageState createState() => _SecondPageState();
}
class _SecondPageState extends State<SecondPage> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: Center(
child: GestureDetector(
onTap: () {
Provider.of<Something>(context, listen: false).doSomething();
},
child: Text('click'),
),
),
),
);
}
}
Something
class Something extends ChangeNotifier {
var count =0;
void doSomething() {
print('doSomething');
count++;
notifyListeners();
}
}
when we open this app, MyHomePage request data in initState，
when we push secondPage，we click ‘click’ btn，We want the first page to retrieve the data（iniData()）.
when we click ,notifiyListeners() and _MyHomePageState build()is called, but initState（）is not，so
how to do？we can invoke initData again.
Similar situation：
1.We have changed the language on other pages. The data on the home page needs to re-request the language interface of the response.
2.After the user logs in successfully, refresh the user inventory, the inventory page already exists
Try this :
setState(() {
mockData = 'mock 123';
});
But here you are not initializing data to use it with Provider, if you are looking to get data ( i mean mockData var ) with Provider , you can do that :
in Something class you add this:
String mockData="123";
String get mockdata => mockData;
and then in the HomePage you access this data using the Provider :
Provider.of<Something>(context, listen:false).mockdata;
i hope i could help you.. good luck !
sorry，Maybe I didn't describe the problem clearly enough, but I have found a solution now.
use
ChangeNotifierProxyProvider<Foo, MyChangeNotifier>(
create: (_) => MyChangeNotifier(),
update: (_, foo, myNotifier) => myNotifier
..foo = foo,
child: ...
);
/// A [ChangeNotifierProvider] that builds and synchronizes a [ChangeNotifier]
/// from values obtained from other providers.
Thanks
I am trying to make a history page in flutter. When I press 'a','b' or 'c' in my homepage, I want it to show what I pressed and the date I pressed the text on my history page similar to 'my activity' on google. This is what I came up with so far, and I don't even know if it is the best way to make it. It also has an error
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int count = 0;
#override
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: <Widget>[
Tile(text: Text("a")),
Tile(text: Text("b")),
Tile(text: Text("c")),
],
));
}
}
int count = 0;
class Tile extends StatefulWidget {
final Text text;
Tile({this.text});
#override
TileState createState() => TileState();
}
class TileState extends State<Tile> {
#override
Widget build(BuildContext context) {
return ListTile(
title: widget.text,
onTap: () {
count++;
print(count);
Navigator.push(
context,
MaterialPageRoute(builder: (context) => HistoryPage()),
);
},
);
}
}
class HistoryPage extends StatefulWidget {
#override
HistoryPageState createState() => HistoryPageState();
}
class HistoryPageState extends State<HistoryPage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: IconButton(
icon: Icon(Icons.arrow_back),
onPressed: () {
Navigator.pop(context);
})),
body: ListView.builder(
itemCount: count,
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(text),
);
},
),
);
}
}
How should I make my user history page?
You can copy paste run full code below
You can put your click event in a History List and use ListView to show this History List
working demo
full code
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int count = 0;
#override
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: <Widget>[
Tile(text: Text("a")),
Tile(text: Text("b")),
Tile(text: Text("c")),
],
));
}
}
int count = 0;
List<History> historyList = [];
class History {
String data;
DateTime dateTime;
History({this.data, this.dateTime});
}
class Tile extends StatefulWidget {
final Text text;
Tile({this.text});
#override
TileState createState() => TileState();
}
class TileState extends State<Tile> {
#override
Widget build(BuildContext context) {
return ListTile(
title: widget.text,
onTap: () {
count++;
print(count);
historyList
.add(History(data: widget.text.data, dateTime: DateTime.now()));
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => HistoryPage(),
));
},
);
}
}
class HistoryPage extends StatefulWidget {
#override
HistoryPageState createState() => HistoryPageState();
}
class HistoryPageState extends State<HistoryPage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: IconButton(
icon: Icon(Icons.arrow_back),
onPressed: () {
Navigator.pop(context);
})),
body: ListView.builder(
itemCount: historyList.length,
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(
' ${historyList[index].data} ${historyList[index].dateTime.toString()}'),
);
},
),
);
}
}
There is count variable in the first stateful widget, I have passed it to Setting class. And, Setting class passes it toSettingStateBuilder. Then, its value is changed in incrementing() in SettingStateBuilder. I want the updated value to return back to HomePageBody for further work. How can I do that?
The first stateful widget is created as follow:
class HomePage extends StatefulWidget {
#override
HomePageBody createState() => HomePageBody();
}
class HomePageBody extends State<HomePage> {
int count=0;
#override
Widget build(BuildContext context) {
...
new Setting(count);
}
}
The second stateful widget is created as follow:
class Setting extends StatefulWidget {
int count;
Setting(this.count);
#override
SettingStateBuilder createState() => SettingStateBuilder(count);
}
class SettingStateBuilder extends State<Setting> {
int count;
SettingStateBuilder(this.count);
#override
Widget build(BuildContext context) {
return new Container(
new Text(count.toString());
....
onPressed: () => setState(() => incrementing(context))),
);
}
incrementing(context) { count += 1; }
}
You could add a Function property to the Settings widget that will be called when the counter is incremented, and pass that function when you create the widget so in HomePage you can update the counter:
class HomePage extends StatefulWidget {
#override
HomePageBody createState() => HomePageBody();
}
class HomePageBody extends State<HomePage> {
int count = 0;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
actions: <Widget>[
MaterialButton(
child: Text('Settings'),
onPressed: () {
Navigator.of(context).push(
MaterialPageRoute(
builder: (BuildContext context) => Settings(
count,
(newCount) {
setState(
() {
count = newCount;
},
);
},
),
),
);
},
)
],
),
body: Center(
child: Text('$count'),
),
);
}
}
class Settings extends StatefulWidget {
final int count;
final Function(int) onCounterChanged;
Settings(this.count, onCounterChanged);
#override
SettingsStateBuilder createState() => SettingsStateBuilder(count);
}
class SettingsStateBuilder extends State<Settings> {
int count;
SettingsStateBuilder(this.count);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text('$count'),
MaterialButton(
child: Text('Increment'),
onPressed: () => setState(
() {
increment();
},
),
),
],
),
),
);
}
increment() {
count += 1;
widget.onCounterChanged(count);
}
}
If you are dealing with a more complex use case I suggest you to read for how to approach state management in Flutter, some resources:
https://flutter.dev/docs/development/data-and-backend/state-mgmt/intro
https://flutter.dev/docs/development/data-and-backend/state-mgmt/options
While passing an object from one class to another class by using Navigator.push(), the object does not get modifying even its declared as not final.
Main Screen : Created an object(userBean) and passing to First screen
First Screen : displaying the same object(userBean) values, and passing again the same object(userBean) to second screen.
Second screen : trying to get modify the same object (userBean) in second screen, and printing the same object(userBean) in first screen by using refreshData.then method.
Main.dart
import 'package:flutter/material.dart';
import 'package:flutter_app_poc1/firstSceeen.dart';
import 'package:flutter_app_poc1/secondScreen.dart';
import 'package:flutter_app_poc1/userbean.dart';
void main() => runApp(MyApp());
typedef void refreshCallBack(int index);
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
UserBean user = new UserBean();
final List<String> hhList = ["General", "edu"];
int _counter = 0;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new FlatButton(
child: Text("Next Screen"),
onPressed: () {
user.id = 1;
user.name = "Ramesh";
Future<dynamic> refreshData =
Navigator.of(context).push(new MaterialPageRoute<dynamic>(
builder: (BuildContext context) {
return new FirstScreen(userbean: user);
},
));
refreshData.then((_) {
});
}),
],
),
),
);
}
}
Firstscreen.dart
import 'package:flutter/material.dart';
import 'package:flutter_app_poc1/secondScreen.dart';
import 'package:flutter_app_poc1/userbean.dart';
typedef void refreshCallBack(int index);
class FirstScreen extends StatefulWidget {
UserBean userbean;
FirstScreen({Key key, this.userbean}) : super(key: key);
#override
_FirstScreenState createState() => _FirstScreenState();
}
class _FirstScreenState extends State<FirstScreen> {
String userName;
final List<String> hhList = ["General", "edu"];
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("first"),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Text(widget.userbean.name),
new RaisedButton(onPressed: (){
Future<dynamic> refreshData =
Navigator.of(context).push(new MaterialPageRoute<dynamic>(
builder: (BuildContext context) {
return new SecondScreen(userbean: widget.userbean);
},
));
refreshData.then((_) {
print(widget.userbean.name);
});
}),
],
),
),
);
}
}
secondscreen.dart
import 'package:flutter/material.dart';
import 'package:flutter_app_poc1/userbean.dart';
class SecondScreen extends StatefulWidget {
UserBean userbean;
SecondScreen({Key key, this.userbean}) : super(key: key);
#override
_SecondScreenState createState() => _SecondScreenState();
}
class _SecondScreenState extends State<SecondScreen> {
UserBean bean = UserBean();
#override
Widget build(BuildContext context) {
bean.name = "suresh";
return Scaffold(
appBar: AppBar(
title: Text("Previous Screen"),
),
body: Center(
child: new FlatButton(
child: Text(bean.name),
onPressed: () {
print(bean.name);
widget.userbean = bean;
Navigator.pop(context, true);
}),
));
}
}
#Murali
If you want to follow the same procedure pass object, then follow the below procedure.
From Navigator.pop push again new Object
onPressed: () {
print("TEST second screen :"+bean.name);
/// here modifying with new object.
widget.userbean = bean;
Navigator.pop(context, widget.userbean);
}),
In second screen Get new Object from Feature Method as below
Future<UserBean> refreshData =
Navigator.of(context).push(new MaterialPageRoute<UserBean>(
builder: (BuildContext context) {
return new SecondScreen(userbean: widget.userbean);
},
));
refreshData.then((res) {
print("TEST First screen : ${res.name}");
});
Then Object will change with new values.