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Widget build(BuildContext context) {
return const MaterialApp(
title: 'Text Field Focus',
home: MyCustomForm(),
);
}
}
// Define a custom Form widget.
class MyCustomForm extends StatefulWidget {
const MyCustomForm({super.key});
@override
State<MyCustomForm> createState() => _MyCustomFormState();
}
// Define a corresponding State class.
// This class holds data related to the form.
class _MyCustomFormState extends State<MyCustomForm> {
// Define the focus node. To manage the lifecycle, create the FocusNode in
// the initState method, and clean it up in the dispose method.
late FocusNode myFocusNode;
@override
void initState() {
super.initState();
myFocusNode = FocusNode();
}
@override
void dispose() {
// Clean up the focus node when the Form is disposed.
myFocusNode.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Text Field Focus'),
),
body: Padding(
padding: const EdgeInsets.all(16),
child: Column(
children: [
// The first text field is focused on as soon as the app starts.
const TextField(
autofocus: true,
),
// The second text field is focused on when a user taps the
// FloatingActionButton.
TextField(
focusNode: myFocusNode,
),
],
),
),
floatingActionButton: FloatingActionButton(
// When the button is pressed,
// give focus to the text field using myFocusNode.
onPressed: () => myFocusNode.requestFocus(),
tooltip: 'Focus Second Text Field',
child: const Icon(Icons.edit),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}<code_end>
<topic_end>
<topic_start>Build a form with validation
Apps often require users to enter information into a text field.
For example, you might require users to log in with an email address
and password combination.To make apps secure and easy to use, check whether the
information the user has provided is valid. If the user has correctly filled
out the form, process the information. If the user submits incorrect
information, display a friendly error message letting them know what went
wrong.In this example, learn how to add validation to a form that has
a single text field using the following steps:<topic_end>
<topic_start>
1. Create a Form with a GlobalKey
Create a Form.
The Form widget acts as a container for grouping and
validating multiple form fields.When creating the form, provide a GlobalKey.
This assigns a unique identifier to your Form.
It also allows you to validate the form later.Create the form as a StatefulWidget.
This allows you to create a unique GlobalKey<FormState>() once.
You can then store it as a variable and access it at different points.If you made this a StatelessWidget, you’d need to store this key somewhere.
As it is resource expensive, you wouldn’t want to generate a new
GlobalKey each time you run the build method.
<code_start>import 'package:flutter/material.dart';
// Define a custom Form widget.
class MyCustomForm extends StatefulWidget {
const MyCustomForm({super.key});
@override
MyCustomFormState createState() {
return MyCustomFormState();
}
}
// Define a corresponding State class.
// This class holds data related to the form.
class MyCustomFormState extends State<MyCustomForm> {
// Create a global key that uniquely identifies the Form widget
// and allows validation of the form.
//
// Note: This is a `GlobalKey<FormState>`,
// not a GlobalKey<MyCustomFormState>.