Not able to import variable from a different class in Flutter - flutter

Question

I am going off of a login screen tempalte,a nd am trying to get a widget class for a button to just show the username input as an alert on the screen. The usernameinput widget is defined but when I import it, it does not work.
class _InputEmailState extends State<InputEmail> {
final myController = new TextEditingController();
This is the part where I define the input, and this is where I import the class in the button widget:
import 'package:login_minimalist/widget/inputEmail.dart';
When I try and reference the myController.text value, I get the error
The getter 'myController' isn't defined for the class '_ButtonLoginState'.
import 'package:flutter/material.dart';
import 'package:login_minimalist/widget/inputEmail.dart';
class ButtonLogin extends StatefulWidget {
#override
ButtonLoginState createState() => ButtonLoginState();
}
class ButtonLoginState extends State<ButtonLogin> {
#override
Here is the button widget code:
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.only(top: 40, right: 50, left: 200),
child: Container(
alignment: Alignment.bottomRight,
height: 50,
width: MediaQuery.of(context).size.width,
decoration: BoxDecoration(
boxShadow: [
BoxShadow(
color: Colors.blue[300],
blurRadius: 10.0, // has the effect of softening the shadow
spreadRadius: 1.0, // has the effect of extending the shadow
offset: Offset(
5.0, // horizontal, move right 10
5.0, // vertical, move down 10
),
),
],
color: Colors.white,
borderRadius: BorderRadius.circular(30),
),
child: FlatButton(
onPressed: () {
return showDialog(
context: context,
builder: (context) {
return AlertDialog(
// Retrieve the text the user has entered by using the
// TextEditingController.
content: Text(InputEmailState.getUsername),
);
},
);
},
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'Sign in',
style: TextStyle(
color: Colors.lightBlueAccent,
fontSize: 14,
fontWeight: FontWeight.w700,
),
),
Icon(
Icons.arrow_forward,
color: Colors.lightBlueAccent,
),
],
),
),
),
);
And here is the Input code:
class InputEmailState extends State<InputEmail> {
final myController = new TextEditingController();
getUsername() {
return(myController.text);
}
#override
void dispose() {
// Clean up the controller when the widget is disposed.
myController.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.only(top: 50, left: 50, right: 50),
child: Container(
height: 60,
width: MediaQuery.of(context).size.width,
child: TextField(
controller: myController,
style: TextStyle(
color: Colors.white,
),
decoration: InputDecoration(
border: InputBorder.none,
fillColor: Colors.lightBlueAccent,
labelText: 'Student ID',
labelStyle: TextStyle(
color: Colors.white70,
fontSize: 20,
),
),
),
),
);
}

Answer 1

If I understand your question correctly, you're trying to access _ButtonLoginState from another class/file. However, in Dart, classes, members, variables, etc. that begin with an underline ("_") are considered private. You can't access them from a different file (except in some special situations with libraries).
To solve this, you can change the name of the class to ButtonLoginState and it should work.
EDIT: In response to more info:
You don't seem to have fully understood the concepts of State in a StatefulWidget. I would strongly recommend taking a good look through the Flutter guide on the subject.
There are many different ways of managing state and what I am going to explain is almost definitely not the best option most of the time (this was the introductory approach some time ago, but I can't even find the example anymore), however, it does work. For a more general option, I recommend Provider.
In your case, the problem starts with this: Text(InputEmailState.getUsername). You're not calling InputEmailState.getUsername, you're simply passing a reference to it. You need to include parentheses to actually call it - InputEmailState.getUsername().
However, this isn't the whole issue. You're trying to access this function using the name of the class, which means you're trying to use it as a static method. However, its an instance method (ie: you need a specific instance of the class to access it. This is the state I was talking about.
To simply get access to the state object of a specific widget, you can use a Key (generally a GlobalKey). You can define this in a parent widget, for example, and pass it as the key parameter of your InputEmail widget and keep a reference in the parent class. Then, to get the username, you can call <key>.currentState.getUsername() which will return the instance value. The exact implementation varies, and I don't have your code to know how it should be implemented.
As I say, this isn't really the recommended approach anymore. I strongly recommend getting to grips with the state concept, then it should be obvious what the best approach is.