TextFormField is not working properly, its blinking continuously - dart

Question

TextFormField is not working properly, its blinking continuously and it doesn't allow me to write anything, as I tap on the TextFormField my keyboard appears for a second and disappear instantly. I am confused what wrong I have done with my code, I've matched my code with previous working code, but still getting this behaviour .
Here is my code.
class ComingSoonState extends State<ComingSoon> {
String language;
TextEditingController _textEdititingController ;
#override
void initState() {
_textEdititingController = new TextEditingController(); //Initialised TextEditingController
super.initState();
}
#override
Widget build(BuildContext context) {
final theme = Theme.of(context);
final Size size = MediaQuery.of(context).size;
final formData = new Form(
key: widget._formKey,
child: new Container(
padding: const EdgeInsets.only(
left: 35.0,
right: 35.0),
child: new Column(
children: <Widget>[
new Theme(
data: theme.copyWith(primaryColor: Colors.black54),
child: new TextFormField(
controller: _textEdititingController, //ADDED CONTROLLER HERE
style: const TextStyle(color: Colors.black54),
decoration: new InputDecoration(
labelText: 'Amount',
labelStyle: const TextStyle(color: Colors.black54)
),
// validator: this._validateEmail,
validator: (val) {
return val.isEmpty
? "Please enter amount"
: null;
},
onSaved: (String value) {
// this._data.email = value;
this.language = value;
}
),
),
],
),
),
);
return Scaffold(
appBar: new AppBar(
leading: null,
title: const Text('Send Money', style: const TextStyle(
color: Colors.white
),
),
),
body: new Container(
color: Colors.grey[300],
child: new ListView(
children: <Widget>[
new Container(
child: new Column(
children: <Widget>[
new Container(
height: 60.0 ,
padding: const EdgeInsets.all(5.0),
child: new Card(
child: new Row(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(left: 8.0),
child: new Text("Available balance in wallet", style:
new TextStyle(color: Colors.black54,
fontSize: 16.0
),),
),
Padding(
padding: const EdgeInsets.only(left: 8.0),
child: new Text("123 KSH", style:
new TextStyle(color: Colors.blueAccent,
fontSize: 16.0
),),
),
],
),
),
) ,
new Container(
//height: 300.0,
padding: const EdgeInsets.all(5.0),
child: new Card(
child: new Container(
child: new Center(
child: new Column(
children: <Widget>[
formData
],
),
),
),
),
)
],
)
),
],
),
),
);
}
}

Answer 1

I added a floating action button that presents a dialog that will show what you entered into the TextField (using the controller). I'm not sure what form key you were passing in before but making the GlobalKey instance a member variable eliminates the keyboard present/dismiss issue.
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,
),
home: MyHomePage(title: 'Flutter Demo'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String language;
TextEditingController _textEditingController;
final _formKey = GlobalKey<FormState>();
#override
void initState() {
_textEditingController =
TextEditingController(); //Initialised TextEditingController
super.initState();
}
#override
Widget build(BuildContext context) {
final theme = Theme.of(context);
final Size size = MediaQuery.of(context).size;
final formData = Form(
key: _formKey,
child: Container(
padding: const EdgeInsets.only(left: 35.0, right: 35.0),
child: Column(
children: <Widget>[
Theme(
data: theme.copyWith(primaryColor: Colors.black54),
child: TextFormField(
controller: _textEditingController,
//ADDED CONTROLLER HERE
style: const TextStyle(color: Colors.black54),
decoration: InputDecoration(
labelText: 'Amount',
labelStyle: const TextStyle(color: Colors.black54)),
// validator: this._validateEmail,
validator: (val) {
return val.isEmpty ? "Please enter amount" : null;
},
onSaved: (String value) {
// this._data.email = value;
language = value;
}),
),
],
),
),
);
return Scaffold(
appBar: AppBar(
leading: null,
title: const Text(
'Send Money',
style: const TextStyle(color: Colors.white),
),
),
body: Container(
color: Colors.grey[300],
child: ListView(
children: <Widget>[
Container(
child: Column(
children: <Widget>[
Container(
height: 60.0,
padding: const EdgeInsets.all(5.0),
child: Card(
child: Row(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(left: 8.0),
child: Text(
"Available balance in wallet",
style: TextStyle(
color: Colors.black54, fontSize: 16.0),
),
),
Padding(
padding: const EdgeInsets.only(left: 8.0),
child: Text(
"123 KSH",
style: TextStyle(
color: Colors.blueAccent, fontSize: 16.0),
),
),
],
),
),
),
Container(
//height: 300.0,
padding: const EdgeInsets.all(5.0),
child: Card(
child: Container(
child: Center(
child: Column(
children: <Widget>[formData],
),
),
),
),
)
],
)),
],
),
),
floatingActionButton: FloatingActionButton(
// When the user presses the button, show an alert dialog with the
// text the user has typed into our text field.
onPressed: () {
return showDialog(
context: context,
builder: (context) {
return AlertDialog(
// Retrieve the text the user has typed in using our
// TextEditingController
content: Text(_textEditingController.text),
);
},
);
},
tooltip: 'Show me the value!',
child: Icon(Icons.text_fields),
),
);
}
}