CODE:
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return GetMaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
_counter++;
}
#override
Widget build(BuildContext context) {
TestInt testInt2 = TestInt(100);
TestInt testInt1 = TestInt(0);
Get.put<TestInt>(testInt2, tag: "testInt2");
Get.put<TestInt>(testInt1, tag: "testInt1");
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times: $_counter',
),
GetBuilder<TestInt>(
init: Get.find<TestInt>(tag: "testInt2"),
builder: (_) {
return Text(
'${Get.find<TestInt>(tag: "testInt2").number}',
style: Theme.of(context).textTheme.headline4,
);
},
),
GetBuilder<TestInt>(
init: Get.find<TestInt>(tag: "testInt1"),
builder: (_) {
return Text(
'${Get.find<TestInt>(tag: "testInt1").number}',
style: Theme.of(context).textTheme.headline4,
);
},
),
],
),
),
persistentFooterButtons: [
FloatingActionButton(
onPressed: () {
_incrementCounter();
Get.find<TestInt>(tag: "testInt2").increment();
},
tooltip: 'Increment',
child: Icon(Icons.add),
),
FloatingActionButton(
onPressed: () {
_incrementCounter();
Get.find<TestInt>(tag: "testInt1").increment();
},
tooltip: 'Increment',
child: Icon(Icons.add),
),
], // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class TestInt extends GetxController {
late int number;
TestInt(number) {
this.number = number;
}
void increment() {
this.number = number + 1;
update();
}
}
Summary:
On the code above, I made 2 floating buttons and 2 GetBuilder to show testInt1's number and testInt2's number separately.
But Only one button works well and the other button doesn't work.
I think it might works only first initiation with init: Get.find<TestInt>(tag: "testInt2"), and second init: Get.find<TestInt>(tag: "testInt1"), does not works..
Question:
How to make both works?
Set global:false to your GetBuilder.
GetBuilder<TestInt>(
init: Get.find<TestInt>(tag: "testInt2"),
global: false,
builder: (_) {
return Text(
'${Get.find<TestInt>(tag: "testInt2").number}',
style: Theme.of(context).textTheme.headline4,
);
},
),
Related
How do I close a screen (call Navigator.pop) when a certain value changes?
I am using riverpod to watch for the values.
Use the WidgetRef.listen to listen to state changes. From the docs:
Listen to a provider and call listener whenever its value changes.
This is useful for showing modals or other imperative logic.
The code is going to be something like this:
class MyHomePage extends ConsumerWidget {
const MyHomePage({super.key});
#override
Widget build(context, ref) {
ref.listen(theProvider, (previous, next) {
if (isTheEnd(next)) {
Navigator.of(context).pop();
}
});
...
Here's a complete example:
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
void main() {
runApp(
const ProviderScope(
child: MyApp(),
),
);
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends ConsumerWidget {
const MyHomePage({super.key});
#override
Widget build(context, ref) {
ref.listen(counterProvider, (previous, next) {
if (next % 2 == 0) {
showDialog(
context: context,
builder: (_) => AlertDialog(
title: Text('Value is even: $next'),
),
);
}
});
final counter = ref.watch(counterProvider);
return Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
const Text(
'You have pushed the button this many times:',
),
Text(
'$counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () => ref.read(counterProvider.notifier).increment(),
tooltip: 'Increment',
child: const Icon(Icons.add),
),
);
}
}
final counterProvider = StateNotifierProvider<Counter, int>((ref) {
return Counter();
});
class Counter extends StateNotifier<int> {
Counter() : super(0);
void increment() => state++;
}
You need to create some kind of Function that handle that. The function required a build context to get the Navigator and you could call the Navigator.of(context).pop or Navigator.pop(context) when you want.
onChangeValue(BuildContext context, dynamic value){
if(value!=null){
Navigator.of(context).pop();
}
}
I am having a problem with the NotificationListener in flutter. I've build a simple testing app because I am struggling with it.
After clicking on the FlatButton the Notification should be dispatched and then caught by the NotificationListener in onNotification.
So the expected console output would be:
"TestNot"
"Bubble"
But all I am getting is "TestNot".
So the notification is not caught by the listener.
Any idea what I could be doing wrong?
Thank you :-)
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyNotification extends Notification {
final String title;
const MyNotification({this.title});
}
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,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
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> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: NotificationListener<MyNotification>(
onNotification: (notification) {
print("Bubble");
return true;
},
child: Center(
child: Column(
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
FlatButton(onPressed: () {print("TestNot"); MyNotification(title: "TestNot").dispatch(context);}, child: Text("TestNot")),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
)),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
When you need a child to notify its parent, you can use NotificationListener.
But, when you need communications to be implemented inversely, in other words, a parent to notify its children, you can use ValueListenableBuilder
A nice doc about it available here:
https://medium.com/flutter-community/flutter-notifications-bubble-up-and-values-go-down-c1a499d22d5f
"Flutter, notifications ‘bubble up’ and values ‘go down’"
You cannot receive the notification at the same level of where it was dispatched. Please refer to docs : https://api.flutter.dev/flutter/widgets/NotificationListener-class.html
NotificationListener class :
A widget that listens for Notifications bubbling up the tree.
I've updated your code to make it work.
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyNotification extends Notification {
final String title;
const MyNotification({this.title});
}
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,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
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> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: NotificationListener<MyNotification>(
onNotification: (MyNotification notification) {
print("Bubble");
return true;
},
child: Center(
child: Column(
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
MyChild(),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
)),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class MyChild extends StatelessWidget {
#override
Widget build(BuildContext context) {
return FlatButton(
onPressed: () {
print("TestNot");
MyNotification(title: "TestNot").dispatch(context);
},
child: Text("TestNot"));
}
}
i want to dial this number as it is, in flutter url launcher but it removes the hashtag sign in the last bit of the String,
onTap: () {
String no = '*477*4*1#';
launch('tel:$no');
},
You can copy paste run full code below
You can use Uri.encodeComponent('*477*4*1#');
code snippet
onPressed: () {
String no = Uri.encodeComponent('*477*4*1#');
launch('tel:$no');
},
working demo
full code
import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
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> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
RaisedButton(
child: Text('click'),
onPressed: () {
String no = Uri.encodeComponent('*477*4*1#');
launch('tel:$no');
},
),
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
You need to use URL Encoding for special character so # is equals to \%23.
Please, someone, help on this, I am not sure if this is a framework glitch then how are there not more post on this and if it is me then how come there is not much on this error!
===========================
main.dart
import 'package:flutter/material.dart';
import 'dialog_reusable.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
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> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
showDialog( context: context, builder: (context) { return MyDialog(); });
},
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
===========================
dialog_reusable.dart
import 'package:flutter/material.dart';
import 'dialog_reusable.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
showDialog( context: context, builder: (context) { return MyDialog(); });
},
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
===========================
===========================
Steps to Reproduce
The Textfield is part of a Dialog() along with 2 buttons 'ok' and 'cancel'
Create a new Flutter project with standard options
Remove the files in LIB folder
Make new files with the code and name provided above
When the Dialog() pops up and the 'cancel' button is clicked the following error happens.
════════ Exception caught by widgets library ════════
The following assertion was thrown building MouseRegion(listeners: [enter, exit], state: _MouseRegionState#1877d):
A TextEditingController was used after being disposed.
Once you have called dispose() on a TextEditingController, it can no longer be used.
The relevant error-causing widget was:
TextField file:///C:/MobileApps/Apps/Clima-Flutter/lib/utilities/mydialog.dart:90:15
When the exception was thrown, this was the stack:
#0 ChangeNotifier._debugAssertNotDisposed. (package:flutter/src/foundation/change_notifier.dart:106:9)
#1 ChangeNotifier._debugAssertNotDisposed (package:flutter/src/foundation/change_notifier.dart:112:6)
#2 ChangeNotifier.removeListener (package:flutter/src/foundation/change_notifier.dart:167:12)
#3 _AnimatedState.didUpdateWidget (package:flutter/src/widgets/transitions.dart:159:28)
#4 StatefulElement.update (package:flutter/src/widgets/framework.dart:4690:58)
Steps Tried:
Disable the Textfield before Dispose() by using a variable in 'enable' property of Textfield
Assign NULL to 'Controller' property of TextField if the variable that holds enable property for TextField is false before Dispose(), via the ternary operator and if clause
Assign NULL to 'onChanged:' property of TextField if the variable that holds enable property for TextField is false before Dispose(), via the ternary operator and if clause
To prevent getting the error Flutter/Dart: A TextEditingController was used after being disposed, the previously disposed TextEditingController shouldn't be used again. One way that you can do here is pass a new instance of TextEditingController to be used in the AlertDialog, or depending on how you use a TextEditingController.
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
#override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
var textEditingController = TextEditingController();
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Text(
'You have entered ${textEditingController.text}',
),
),
floatingActionButton: FloatingActionButton(
onPressed: () => alertDialog(textEditingController),
tooltip: 'Increment',
child: const Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
alertDialog(TextEditingController textEditingController) {
return showDialog<String>(
context: context,
builder: (BuildContext context) {
return AlertDialog(
content: TextField(
controller: textEditingController,
decoration: const InputDecoration(hintText: 'Enter Something'),
),
actions: <Widget>[
TextButton(
child: const Text(
"Cancel",
style: TextStyle(color: Colors.black),
),
onPressed: () => Navigator.of(context).pop(),
),
TextButton(
child: const Text(
"OK",
style: TextStyle(color: Colors.red),
),
onPressed: () {
setState(() {
// Triggers a Widget rebuild to update textEditingController state
});
Navigator.of(context).pop();
},
),
],
);
},
);
}
}
I have a dummy list of data. I want each item on the list to show a different widget when it is tapped, similar to a contacts app. Defining the widget in the onPressed method always returns the same widget. How can I generate each widget without manually creating each one?
void az() {
int c = "A".codeUnitAt(0);
int end = "Z".codeUnitAt(0);
while (c <= end) {
items.add(FlatButton.icon(
icon: Icon(Icons.image_aspect_ratio),
label: Text(
String.fromCharCode(c),
style: TextStyle(fontSize: 20),
),
onPressed: (){
print(String.fromCharCode(c)); //This should return a different widget
},
));
c++;
}
}
You can copy paste run full code below
You can declare a local variable start in for loop
code snippet
void az() {
int c = "A".codeUnitAt(0);
int end = "Z".codeUnitAt(0);
for (int start = c; start <= end; start++) {
items.add(FlatButton.icon(
icon: Icon(Icons.image_aspect_ratio),
label: Text(
String.fromCharCode(start),
style: TextStyle(fontSize: 20),
),
onPressed: () {
print(String.fromCharCode(
start)); //This should return a different widget
},
));
}
}
output
I/flutter (12880): A
I/flutter (12880): B
I/flutter (12880): C
working demo
full code
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
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> {
int _counter = 0;
List<Widget> items = [];
void az() {
int c = "A".codeUnitAt(0);
int end = "Z".codeUnitAt(0);
for (int start = c; start <= end; start++) {
items.add(FlatButton.icon(
icon: Icon(Icons.image_aspect_ratio),
label: Text(
String.fromCharCode(start),
style: TextStyle(fontSize: 20),
),
onPressed: () {
print(String.fromCharCode(
start)); //This should return a different widget
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
SecondRoute(yourParameter: String.fromCharCode(start))));
},
));
}
}
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
void initState() {
// TODO: implement initState
super.initState();
WidgetsBinding.instance.addPostFrameCallback((_) {
az();
setState(() {});
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: SingleChildScrollView(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: items,
),
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
class SecondRoute extends StatelessWidget {
final String yourParameter;
const SecondRoute({Key key, this.yourParameter}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('$yourParameter'),
),
body: Center(
child: RaisedButton(
onPressed: () {
Navigator.pop(context);
},
child: Text('Go back!'),
),
),
);
}
}