flutter variable is not passing in class widget - flutter

Question

How to pass variable declared to class widget.
It is showing error "undefined name abcd".
But I have already declared it.
How to pass this variable abcd in Text widget.
Code is attached.
Thanks in advance.
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final String abcd = "abcd";
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: Column(
children: [
TextField(),
OkButton(),
],
),
),
);
}
}
class OkButton extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
padding: EdgeInsets.all(4),
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.center,
children: [
FlatButton(
onPressed: () {},
child: Text("ok"),
),
Text(abcd),
],
),
);
}
}

Answer 1

Add a constructor in the OkButton which accepts a String.
class OkButton extends StatelessWidget {
OkButton({#required this.text});
final String text;
...
Text(text), // from Text(abcd),
...
}
Then, when you create OkButton, set the text property.
OkButton(text: abcd),

Answer 2

You can pass your value from one class to another by using Constructor
class _MyHomePageState extends State<MyHomePage> {
final String abcd = "abcd";
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: Column(
children: [
TextField(),
OkButton(abcd),
],
),
),
);
}
}
class OkButton extends StatelessWidget {
final String abcd;
OkButton(this.abcd);
#override
Widget build(BuildContext context) {
return Container(
padding: EdgeInsets.all(4),
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.center,
children: [
FlatButton(
onPressed: () {},
child: Text("ok"),
),
Text(abcd),
],
),
);
}
}