Change ListTile Widget at Runtime Problem - flutter

Question

https://pub.dev/packages/table_calendar
I created a calendar using the package i linked. Trying to update ListTile's leading image at runtime.
im trying to send data as string so every event has to have a spectacular string. i have to Data class to send variables to next page and it's working but image variable always stays null. Hope that someone can explain why setState function below is not working .Thanks.
class Calender extends StatefulWidget {
#override
_CalenderState createState() => _CalenderState();
}
class Data {
String title, image, subText, subTitle;
Data({this.image, this.title, this.subTitle, this.subText});
}
class _CalenderState extends State<Calender> with TickerProviderStateMixin {
Map<DateTime, List> _events;
List _selectedEvents, names;
String image = " ";
AnimationController _animationController;
CalendarController _calendarController;
#override
void initState() {
print("work");
super.initState();
final _selectedDay = DateTime.now();
_calendarController = CalendarController();
_events = {
_selectedDay: [
'TRY 1',
],
_selectedDay.add(Duration(days: 15)): ['TRY 2'],
_selectedDay.add(Duration(days: 20)): ['TTRY 3'],
};
_selectedEvents = _events[_selectedDay] ?? [];
_animationController = AnimationController(
vsync: this, duration: const Duration(milliseconds: 400));
}
#override
void dispose() {
_animationController.dispose();
_calendarController.dispose();
super.dispose();
}
void _onDaySelected(DateTime day, List events) {
print('CALLBACK: _onDaySelected');
setState(() {
_selectedEvents = events;
//working
});
}
void _onVisibleDaysChanged(
DateTime first, DateTime last, CalendarFormat format) {
print('CALLBACK: _onVisibleDaysChanged');
}
void _onCalendarCreated(
DateTime first, DateTime last, CalendarFormat format) {
print('CALLBACK: _onCalendarCreated');
}
Data _data;
Data get data {
if (_data == null) {
_data = Data();
}
return _data;
}
#override
Widget build(BuildContext context) {
names = _events.values.toList();
//trying to match strings with elements of list here but not working
setState(() {
if (names[0] == 'TRY 1') {
//image =
image = 'https://www.w3schools.com/w3images/lights.jpg';
// 'https://b.zmtcdn.com/data/pictures/5/18869335/85b9f0bc435132ec116846fafc335030.jpg';
_data.subTitle = "8.01 PM door opening";
}
if (names[1] == 'TRY 2') {
image =
'https://cdn.pixabay.com/photo/2015/04/23/22/00/tree-736885__340.jpg';
_data.subTitle = "8.02 PM door opening";
}
if (names[2] == 'TRY 3') {
image =
'https://previews.123rf.com/images/alexis84/alexis841404/alexis84140400557/27773925-planet-earth-and-blue-human-eye-elements-of-this-image-furnished-by-nasa-.jpg';
_data.subTitle = "8.01 PM door opening";
}
});
return SafeArea(
child: Container(
decoration: BoxDecoration(),
child: Scaffold(
body: Column(
children: [
_buildTableCalendar(),
SizedBox(
height: 10,
),
Expanded(
child: _buildEventList(image, data),
)
],
),
),
),
}
Widget _buildTableCalendar() {
return TableCalendar(
calendarController: _calendarController,
events: _events,
startingDayOfWeek: StartingDayOfWeek.monday,
calendarStyle: CalendarStyle(
selectedColor: Colors.deepOrange[400],
todayColor: Colors.deepOrange[200],
markersColor: Colors.brown[700],
outsideDaysVisible: false,
),
headerStyle: HeaderStyle(
formatButtonTextStyle:
TextStyle().copyWith(color: Colors.white, fontSize: 15.0),
formatButtonDecoration: BoxDecoration(
color: Colors.deepOrange[400],
borderRadius: BorderRadius.circular(16.0),
),
),
onDaySelected: _onDaySelected,
onVisibleDaysChanged: _onVisibleDaysChanged,
onCalendarCreated: _onCalendarCreated,
);
}
Widget _buildEventList(String image, Data data) {
print(data.image);
return ListView(
children: _selectedEvents
.map((event) => Container(
decoration: BoxDecoration(
border: Border.all(width: 0.8),
borderRadius: BorderRadius.circular(12.0),
),
margin:
const EdgeInsets.symmetric(horizontal: 8.0, vertical: 4.0),
child: ListTile(
subtitle: Text("8 pm"),
leading: CircleAvatar(
//image comes here null
backgroundImage: NetworkImage(image),
),
title: Text(event.toString()),
onTap: () {
setState(() {
if (event.toString() == "Beyond Akaretler") {
print("check1");
setState(() {
data.image =
"https://b.zmtcdn.com/data/pictures/5/18869335/85b9f0bc435132ec116846fafc335030.jpg";
data.title = "TRY1";
});
}
if (event.toString() == "Dorock XL") {
setState(() {
data.image =
"https://www.habervesaire.com/wp-content/uploads/2019/03/dorock-xl.jpg-1547825520-810x456.jpeg";
data.title = "TRY2 ";
});
}
if (event.toString() == "The Wall Kadıköy") {
setState(() {
data.image =
"https://b.zmtcdn.com/data/pictures/2/19165732/302d1418f06c81dca13e7c06bcc44ba9.jpg?fit=around|750:500&crop=750:500;*,*";
data.title = event.toString();
});
}
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => EventPage(
data: data,
)));
});
},
),
))
.toList(),
);
}
}
class EventPage extends StatelessWidget {
final Data data;
const EventPage({Key key, this.data}) : super(key: key);
#override
Widget build(BuildContext context) {
return Container(
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage("${data.image}"), fit: BoxFit.cover)),
child: Scaffold(
backgroundColor: Colors.transparent,
appBar: AppBar(
backgroundColor: Colors.black,
title: Text("${data.title}"),
),
),
);
}
}