Use textfield input to get a value output - variables

Question

I have made a simple textfield with a number keyboard.
The user is to put in a number (to make it simple I have set the number to sum=5).
If input is = sum, the text 'correct answer' will be printed on the screen. If the user input !=sum, the returned text will be 'wrong answer'.
To test if I actually got the numbers right I have a testprint, which functions correct.
My problem is how to transform this print output to text (so that it will show as text in the app).
I have been thinking about validating and form, but since I actually already get the correct answer printed, it shows I already get the values correct. Right?
I have tried a ton of things, but nothing has worked so far, so any help is appreciated. Thank you.
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Textfields2',
home: MyHomeScreen(),
);
}
}
class MyHomeScreen extends StatefulWidget {
#override
_MyHomeScreenState createState() => _MyHomeScreenState();
}
class _MyHomeScreenState extends State<MyHomeScreen> {
final int sum = 5;
String output;
String enterAnswer;
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
TextField(
textAlign: TextAlign.center,
keyboardType: TextInputType.number,
decoration: InputDecoration(hintText: '?'),
onChanged: (val) {
enterAnswer = val;
},
),
RaisedButton(
child: Text('Submit Answer'),
onPressed: () {
if (enterAnswer.isNotEmpty) {
if (enterAnswer == sum.toString()) {
print('Correct'); //INTO TEXT
} else {
print('Wrong Answer');//INTO TEXT
}
}
})
],
),
),
);
}
}

Answer 1

Below the RaisedButton add a Text Widget. It should look something like this:
Text(output)
, then replace the print() statement with a setState() function updating the output:
setState(() {output = 'Correct';});
To not get an error in the first place you have to initialize the output variable, so instead of only writing
String output;
write
String output = "";