how do i use getter and setter in flutter? - flutter

Question

Im trying to create tic tac toe game, but im getting some logical error when Im trying to use
provider method.
in the home page i have column containing three widget. first for player scores , second for gird layout, third for winner result.
i did some research and i found out using provider calss is the best option to send data from a widget to another.
import 'package:flutter/cupertino.dart';
import 'package:tictactoe/widgets/scores.dart';
import '../widgets/layout.dart';
// import '../widgets/scores.dart';
class GameProvider with ChangeNotifier {
bool oTrue = true;
List displayXO = ['', '', '', '', '', '', '', '', ''];
String resultDetection = 'hey';
int oScores = 0;
int xScores = 0;
int failedScores = 0;
checkWinner() {
// checking 1 row
if ((displayXO[0] == displayXO[1]) &&
(displayXO[0] == displayXO[2]) &&
displayXO[0] != '') {
resultDetection = 'player ' + displayXO[0] + 'wins';
print('$resultDetection');
}
// checking 2 row
if ((displayXO[3] == displayXO[4]) &&
(displayXO[3] == displayXO[5]) &&
(displayXO[3] != '')) {
resultDetection = 'player ' + displayXO[3] + 'wins';
}
// checking 3 row
if ((displayXO[6] == displayXO[7]) &&
(displayXO[6] == displayXO[8]) &&
(displayXO[6] != '')) {
resultDetection = 'player ' + displayXO[6] + 'wins';
}
// checking 1 column
if ((displayXO[0] == displayXO[3]) &&
(displayXO[0] == displayXO[6]) &&
(displayXO[0] != '')) {
resultDetection = 'player ' + displayXO[0] + 'wins';
}
// checking 2 column
if ((displayXO[1] == displayXO[4]) &&
(displayXO[1] == displayXO[7]) &&
(displayXO[1] != '')) {
resultDetection = 'player ' + displayXO[1] + 'wins';
}
// checking 3 column
if ((displayXO[2] == displayXO[5]) &&
(displayXO[2] == displayXO[8]) &&
(displayXO[2] != '')) {
resultDetection = 'player ' + displayXO[2] + 'wins';
}
// checking 1 axis
if ((displayXO[6] == displayXO[4]) &&
(displayXO[6] == displayXO[2]) &&
(displayXO[6] != '')) {
resultDetection = 'player ' + displayXO[6] + 'wins';
}
// checking 2 axis
if ((displayXO[0] == displayXO[4]) &&
(displayXO[0] == displayXO[8]) &&
(displayXO[0] != '')) {
resultDetection = 'player ' + displayXO[0] + 'wins';
}
notifyListeners();
}
set upgrateScores(String winner) {
if (winner == 'O') {
oScores++;
} else if (winner == 'X') {
xScores++;
}
print('$oScores, $xScores');
notifyListeners();
}
get winnerfunction => checkWinner();
// get upgrarate => upgrateScores();
get result => resultDetection;
}
and this is my great layout
Widget build(BuildContext context) {
void _tap() {}
return GridView.builder(
itemCount: 9,
gridDelegate:
SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 3),
itemBuilder: ((context, index) {
return GestureDetector(
onTap: () {
tapped(index);
},
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(15),
border: Border.all(width: 5, color: Colors.red),
color: Colors.yellow,
),
child: Center(
child: Text(
displayXO[index],
style: GoogleFonts.coiny(fontSize: 64, color: Colors.red),
),
),
),
);
}));
}
void tapped(int tap) {
setState(() {
if (oTrue && displayXO[tap] == '') {
displayXO[tap] = 'O';
oTrue = false;
} else if (!oTrue && displayXO[tap] == '') {
displayXO[tap] = 'X';
oTrue = true;
}
print('object');
GameProvider provider = Provider.of<GameProvider>(context, listen: false);
provider.checkWinner();
});
}